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https://github.com/torvalds/linux.git
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c150b809f7
* Support for various vector-accelerated crypto routines. * Hibernation is now enabled for portable kernel builds. * mmap_rnd_bits_max is larger on systems with larger VAs. * Support for fast GUP. * Support for membarrier-based instruction cache synchronization. * Support for the Andes hart-level interrupt controller and PMU. * Some cleanups around unaligned access speed probing and Kconfig settings. * Support for ACPI LPI and CPPC. * Various cleanus related to barriers. * A handful of fixes. -----BEGIN PGP SIGNATURE----- iQJHBAABCAAxFiEEKzw3R0RoQ7JKlDp6LhMZ81+7GIkFAmX9icgTHHBhbG1lckBk YWJiZWx0LmNvbQAKCRAuExnzX7sYib+UD/4xyL6UMixx6A06BVBL9UT4vOrxRvNr JIihG5y5QNMjes9DHWL35mZTMqFtQ0tq94ViWFLmJWloV/8KRVM2C9R9KX7vplf3 M/OwvP106spxgvNHoeQbycgs42RU1t2mpqT7N1iK2hCjqieP3vLn6hsSLXWTAG0L 3gQbQw6XCLC3hPyLq+nbFY2i4faeCmpXWmixoy/IvQ5calZQrRU0LNlP6lcMBhVo uocjG0uGAhrahw2s81jxcMZcxa3AvUCiplapdD5H5v9rBM85SkYJj2Q9SqdSorkb xzuimRnKPI5s47yM3pTfZY0qnQUYHV7PXXuw4WujpCQVQdhaG+Ggq63UUZA61J9t IzZK2zdcfHqICrGTtXImUzRT3dcc3oq+IFq4tTY+rEJm29hrXkAtx+qBm5xtMvax fJz5feJ/iT0u7MDj4Oq24n+Kpl+Olm+MJaZX3m5Ovi/9V6a9iK9HXqxg9/Fs0fMO +J/0kTgd8Vu9CYH7KNWz3uztcO9eMAH3VyzuXuab4BGj1i1Y/9EjpALQi7rDN73S OsYQX6NnzMkBV4dvElJVLXiPlvNlMHZZwdak5CqPb48jaJu6iiIZAuvOrG6/naGP wnQSLVA2WWWoOkl3AJhxfpa11CLhbMl9E2gYm1VtNvASXoSFIxlAq1Yv3sG8yjty 4ZT0rYFJOstYiQ== =3dL5 -----END PGP SIGNATURE----- Merge tag 'riscv-for-linus-6.9-mw2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux Pull RISC-V updates from Palmer Dabbelt: - Support for various vector-accelerated crypto routines - Hibernation is now enabled for portable kernel builds - mmap_rnd_bits_max is larger on systems with larger VAs - Support for fast GUP - Support for membarrier-based instruction cache synchronization - Support for the Andes hart-level interrupt controller and PMU - Some cleanups around unaligned access speed probing and Kconfig settings - Support for ACPI LPI and CPPC - Various cleanus related to barriers - A handful of fixes * tag 'riscv-for-linus-6.9-mw2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (66 commits) riscv: Fix syscall wrapper for >word-size arguments crypto: riscv - add vector crypto accelerated AES-CBC-CTS crypto: riscv - parallelize AES-CBC decryption riscv: Only flush the mm icache when setting an exec pte riscv: Use kcalloc() instead of kzalloc() riscv/barrier: Add missing space after ',' riscv/barrier: Consolidate fence definitions riscv/barrier: Define RISCV_FULL_BARRIER riscv/barrier: Define __{mb,rmb,wmb} RISC-V: defconfig: Enable CONFIG_ACPI_CPPC_CPUFREQ cpufreq: Move CPPC configs to common Kconfig and add RISC-V ACPI: RISC-V: Add CPPC driver ACPI: Enable ACPI_PROCESSOR for RISC-V ACPI: RISC-V: Add LPI driver cpuidle: RISC-V: Move few functions to arch/riscv riscv: Introduce set_compat_task() in asm/compat.h riscv: Introduce is_compat_thread() into compat.h riscv: add compile-time test into is_compat_task() riscv: Replace direct thread flag check with is_compat_task() riscv: Improve arch_get_mmap_end() macro ...
3946 lines
105 KiB
C
3946 lines
105 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* mm/mmap.c
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*
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* Written by obz.
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*
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* Address space accounting code <alan@lxorguk.ukuu.org.uk>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/backing-dev.h>
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#include <linux/mm.h>
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#include <linux/mm_inline.h>
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#include <linux/shm.h>
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#include <linux/mman.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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#include <linux/syscalls.h>
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#include <linux/capability.h>
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#include <linux/init.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/personality.h>
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#include <linux/security.h>
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#include <linux/hugetlb.h>
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#include <linux/shmem_fs.h>
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#include <linux/profile.h>
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#include <linux/export.h>
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#include <linux/mount.h>
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#include <linux/mempolicy.h>
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#include <linux/rmap.h>
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#include <linux/mmu_notifier.h>
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#include <linux/mmdebug.h>
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#include <linux/perf_event.h>
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#include <linux/audit.h>
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#include <linux/khugepaged.h>
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#include <linux/uprobes.h>
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#include <linux/notifier.h>
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#include <linux/memory.h>
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#include <linux/printk.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/moduleparam.h>
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#include <linux/pkeys.h>
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#include <linux/oom.h>
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#include <linux/sched/mm.h>
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#include <linux/ksm.h>
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#include <linux/uaccess.h>
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#include <asm/cacheflush.h>
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#include <asm/tlb.h>
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#include <asm/mmu_context.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/mmap.h>
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#include "internal.h"
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#ifndef arch_mmap_check
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#define arch_mmap_check(addr, len, flags) (0)
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#endif
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#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
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const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
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int mmap_rnd_bits_max __ro_after_init = CONFIG_ARCH_MMAP_RND_BITS_MAX;
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int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
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#endif
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#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
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const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
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const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
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int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
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#endif
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static bool ignore_rlimit_data;
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core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
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static void unmap_region(struct mm_struct *mm, struct ma_state *mas,
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struct vm_area_struct *vma, struct vm_area_struct *prev,
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struct vm_area_struct *next, unsigned long start,
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unsigned long end, unsigned long tree_end, bool mm_wr_locked);
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static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
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{
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return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
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}
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/* Update vma->vm_page_prot to reflect vma->vm_flags. */
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void vma_set_page_prot(struct vm_area_struct *vma)
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{
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unsigned long vm_flags = vma->vm_flags;
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pgprot_t vm_page_prot;
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vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
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if (vma_wants_writenotify(vma, vm_page_prot)) {
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vm_flags &= ~VM_SHARED;
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vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags);
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}
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/* remove_protection_ptes reads vma->vm_page_prot without mmap_lock */
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WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
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}
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/*
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* Requires inode->i_mapping->i_mmap_rwsem
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*/
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static void __remove_shared_vm_struct(struct vm_area_struct *vma,
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struct address_space *mapping)
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{
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if (vma_is_shared_maywrite(vma))
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mapping_unmap_writable(mapping);
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flush_dcache_mmap_lock(mapping);
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vma_interval_tree_remove(vma, &mapping->i_mmap);
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flush_dcache_mmap_unlock(mapping);
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}
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/*
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* Unlink a file-based vm structure from its interval tree, to hide
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* vma from rmap and vmtruncate before freeing its page tables.
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*/
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void unlink_file_vma(struct vm_area_struct *vma)
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{
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struct file *file = vma->vm_file;
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if (file) {
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struct address_space *mapping = file->f_mapping;
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i_mmap_lock_write(mapping);
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__remove_shared_vm_struct(vma, mapping);
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i_mmap_unlock_write(mapping);
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}
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}
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/*
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* Close a vm structure and free it.
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*/
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static void remove_vma(struct vm_area_struct *vma, bool unreachable)
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{
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might_sleep();
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if (vma->vm_ops && vma->vm_ops->close)
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vma->vm_ops->close(vma);
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if (vma->vm_file)
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fput(vma->vm_file);
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mpol_put(vma_policy(vma));
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if (unreachable)
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__vm_area_free(vma);
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else
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vm_area_free(vma);
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}
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static inline struct vm_area_struct *vma_prev_limit(struct vma_iterator *vmi,
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unsigned long min)
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{
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return mas_prev(&vmi->mas, min);
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}
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/*
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* check_brk_limits() - Use platform specific check of range & verify mlock
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* limits.
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* @addr: The address to check
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* @len: The size of increase.
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*
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* Return: 0 on success.
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*/
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static int check_brk_limits(unsigned long addr, unsigned long len)
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{
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unsigned long mapped_addr;
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mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
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if (IS_ERR_VALUE(mapped_addr))
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return mapped_addr;
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return mlock_future_ok(current->mm, current->mm->def_flags, len)
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? 0 : -EAGAIN;
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}
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static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *brkvma,
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unsigned long addr, unsigned long request, unsigned long flags);
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SYSCALL_DEFINE1(brk, unsigned long, brk)
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{
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unsigned long newbrk, oldbrk, origbrk;
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *brkvma, *next = NULL;
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unsigned long min_brk;
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bool populate = false;
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LIST_HEAD(uf);
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struct vma_iterator vmi;
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if (mmap_write_lock_killable(mm))
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return -EINTR;
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origbrk = mm->brk;
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#ifdef CONFIG_COMPAT_BRK
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/*
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* CONFIG_COMPAT_BRK can still be overridden by setting
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* randomize_va_space to 2, which will still cause mm->start_brk
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* to be arbitrarily shifted
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*/
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if (current->brk_randomized)
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min_brk = mm->start_brk;
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else
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min_brk = mm->end_data;
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#else
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min_brk = mm->start_brk;
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#endif
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if (brk < min_brk)
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goto out;
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/*
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* Check against rlimit here. If this check is done later after the test
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* of oldbrk with newbrk then it can escape the test and let the data
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* segment grow beyond its set limit the in case where the limit is
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* not page aligned -Ram Gupta
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*/
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if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
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mm->end_data, mm->start_data))
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goto out;
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newbrk = PAGE_ALIGN(brk);
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oldbrk = PAGE_ALIGN(mm->brk);
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if (oldbrk == newbrk) {
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mm->brk = brk;
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goto success;
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}
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/* Always allow shrinking brk. */
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if (brk <= mm->brk) {
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/* Search one past newbrk */
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vma_iter_init(&vmi, mm, newbrk);
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brkvma = vma_find(&vmi, oldbrk);
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if (!brkvma || brkvma->vm_start >= oldbrk)
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goto out; /* mapping intersects with an existing non-brk vma. */
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/*
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* mm->brk must be protected by write mmap_lock.
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* do_vma_munmap() will drop the lock on success, so update it
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* before calling do_vma_munmap().
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*/
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mm->brk = brk;
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if (do_vma_munmap(&vmi, brkvma, newbrk, oldbrk, &uf, true))
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goto out;
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goto success_unlocked;
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}
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if (check_brk_limits(oldbrk, newbrk - oldbrk))
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goto out;
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/*
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* Only check if the next VMA is within the stack_guard_gap of the
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* expansion area
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*/
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vma_iter_init(&vmi, mm, oldbrk);
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next = vma_find(&vmi, newbrk + PAGE_SIZE + stack_guard_gap);
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if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
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goto out;
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brkvma = vma_prev_limit(&vmi, mm->start_brk);
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/* Ok, looks good - let it rip. */
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if (do_brk_flags(&vmi, brkvma, oldbrk, newbrk - oldbrk, 0) < 0)
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goto out;
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mm->brk = brk;
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if (mm->def_flags & VM_LOCKED)
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populate = true;
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success:
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mmap_write_unlock(mm);
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success_unlocked:
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userfaultfd_unmap_complete(mm, &uf);
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if (populate)
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mm_populate(oldbrk, newbrk - oldbrk);
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return brk;
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out:
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mm->brk = origbrk;
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mmap_write_unlock(mm);
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return origbrk;
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}
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#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
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static void validate_mm(struct mm_struct *mm)
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{
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int bug = 0;
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int i = 0;
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struct vm_area_struct *vma;
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VMA_ITERATOR(vmi, mm, 0);
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mt_validate(&mm->mm_mt);
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for_each_vma(vmi, vma) {
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#ifdef CONFIG_DEBUG_VM_RB
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struct anon_vma *anon_vma = vma->anon_vma;
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struct anon_vma_chain *avc;
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#endif
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unsigned long vmi_start, vmi_end;
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bool warn = 0;
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vmi_start = vma_iter_addr(&vmi);
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vmi_end = vma_iter_end(&vmi);
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if (VM_WARN_ON_ONCE_MM(vma->vm_end != vmi_end, mm))
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warn = 1;
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if (VM_WARN_ON_ONCE_MM(vma->vm_start != vmi_start, mm))
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warn = 1;
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if (warn) {
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pr_emerg("issue in %s\n", current->comm);
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dump_stack();
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dump_vma(vma);
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pr_emerg("tree range: %px start %lx end %lx\n", vma,
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vmi_start, vmi_end - 1);
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vma_iter_dump_tree(&vmi);
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}
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#ifdef CONFIG_DEBUG_VM_RB
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if (anon_vma) {
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anon_vma_lock_read(anon_vma);
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list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
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anon_vma_interval_tree_verify(avc);
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anon_vma_unlock_read(anon_vma);
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}
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#endif
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i++;
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}
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if (i != mm->map_count) {
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pr_emerg("map_count %d vma iterator %d\n", mm->map_count, i);
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bug = 1;
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}
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VM_BUG_ON_MM(bug, mm);
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}
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#else /* !CONFIG_DEBUG_VM_MAPLE_TREE */
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#define validate_mm(mm) do { } while (0)
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#endif /* CONFIG_DEBUG_VM_MAPLE_TREE */
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/*
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* vma has some anon_vma assigned, and is already inserted on that
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* anon_vma's interval trees.
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*
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* Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
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* vma must be removed from the anon_vma's interval trees using
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* anon_vma_interval_tree_pre_update_vma().
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*
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* After the update, the vma will be reinserted using
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* anon_vma_interval_tree_post_update_vma().
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*
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* The entire update must be protected by exclusive mmap_lock and by
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* the root anon_vma's mutex.
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*/
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static inline void
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anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
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{
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struct anon_vma_chain *avc;
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list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
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anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
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}
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static inline void
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anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
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{
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struct anon_vma_chain *avc;
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list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
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anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
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}
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static unsigned long count_vma_pages_range(struct mm_struct *mm,
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unsigned long addr, unsigned long end)
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{
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VMA_ITERATOR(vmi, mm, addr);
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struct vm_area_struct *vma;
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unsigned long nr_pages = 0;
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for_each_vma_range(vmi, vma, end) {
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unsigned long vm_start = max(addr, vma->vm_start);
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unsigned long vm_end = min(end, vma->vm_end);
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nr_pages += PHYS_PFN(vm_end - vm_start);
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}
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return nr_pages;
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}
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static void __vma_link_file(struct vm_area_struct *vma,
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struct address_space *mapping)
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{
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if (vma_is_shared_maywrite(vma))
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mapping_allow_writable(mapping);
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flush_dcache_mmap_lock(mapping);
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vma_interval_tree_insert(vma, &mapping->i_mmap);
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flush_dcache_mmap_unlock(mapping);
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}
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static void vma_link_file(struct vm_area_struct *vma)
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{
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struct file *file = vma->vm_file;
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struct address_space *mapping;
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if (file) {
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mapping = file->f_mapping;
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i_mmap_lock_write(mapping);
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__vma_link_file(vma, mapping);
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i_mmap_unlock_write(mapping);
|
|
}
|
|
}
|
|
|
|
static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma)
|
|
{
|
|
VMA_ITERATOR(vmi, mm, 0);
|
|
|
|
vma_iter_config(&vmi, vma->vm_start, vma->vm_end);
|
|
if (vma_iter_prealloc(&vmi, vma))
|
|
return -ENOMEM;
|
|
|
|
vma_start_write(vma);
|
|
vma_iter_store(&vmi, vma);
|
|
vma_link_file(vma);
|
|
mm->map_count++;
|
|
validate_mm(mm);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* init_multi_vma_prep() - Initializer for struct vma_prepare
|
|
* @vp: The vma_prepare struct
|
|
* @vma: The vma that will be altered once locked
|
|
* @next: The next vma if it is to be adjusted
|
|
* @remove: The first vma to be removed
|
|
* @remove2: The second vma to be removed
|
|
*/
|
|
static inline void init_multi_vma_prep(struct vma_prepare *vp,
|
|
struct vm_area_struct *vma, struct vm_area_struct *next,
|
|
struct vm_area_struct *remove, struct vm_area_struct *remove2)
|
|
{
|
|
memset(vp, 0, sizeof(struct vma_prepare));
|
|
vp->vma = vma;
|
|
vp->anon_vma = vma->anon_vma;
|
|
vp->remove = remove;
|
|
vp->remove2 = remove2;
|
|
vp->adj_next = next;
|
|
if (!vp->anon_vma && next)
|
|
vp->anon_vma = next->anon_vma;
|
|
|
|
vp->file = vma->vm_file;
|
|
if (vp->file)
|
|
vp->mapping = vma->vm_file->f_mapping;
|
|
|
|
}
|
|
|
|
/*
|
|
* init_vma_prep() - Initializer wrapper for vma_prepare struct
|
|
* @vp: The vma_prepare struct
|
|
* @vma: The vma that will be altered once locked
|
|
*/
|
|
static inline void init_vma_prep(struct vma_prepare *vp,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
init_multi_vma_prep(vp, vma, NULL, NULL, NULL);
|
|
}
|
|
|
|
|
|
/*
|
|
* vma_prepare() - Helper function for handling locking VMAs prior to altering
|
|
* @vp: The initialized vma_prepare struct
|
|
*/
|
|
static inline void vma_prepare(struct vma_prepare *vp)
|
|
{
|
|
if (vp->file) {
|
|
uprobe_munmap(vp->vma, vp->vma->vm_start, vp->vma->vm_end);
|
|
|
|
if (vp->adj_next)
|
|
uprobe_munmap(vp->adj_next, vp->adj_next->vm_start,
|
|
vp->adj_next->vm_end);
|
|
|
|
i_mmap_lock_write(vp->mapping);
|
|
if (vp->insert && vp->insert->vm_file) {
|
|
/*
|
|
* Put into interval tree now, so instantiated pages
|
|
* are visible to arm/parisc __flush_dcache_page
|
|
* throughout; but we cannot insert into address
|
|
* space until vma start or end is updated.
|
|
*/
|
|
__vma_link_file(vp->insert,
|
|
vp->insert->vm_file->f_mapping);
|
|
}
|
|
}
|
|
|
|
if (vp->anon_vma) {
|
|
anon_vma_lock_write(vp->anon_vma);
|
|
anon_vma_interval_tree_pre_update_vma(vp->vma);
|
|
if (vp->adj_next)
|
|
anon_vma_interval_tree_pre_update_vma(vp->adj_next);
|
|
}
|
|
|
|
if (vp->file) {
|
|
flush_dcache_mmap_lock(vp->mapping);
|
|
vma_interval_tree_remove(vp->vma, &vp->mapping->i_mmap);
|
|
if (vp->adj_next)
|
|
vma_interval_tree_remove(vp->adj_next,
|
|
&vp->mapping->i_mmap);
|
|
}
|
|
|
|
}
|
|
|
|
/*
|
|
* vma_complete- Helper function for handling the unlocking after altering VMAs,
|
|
* or for inserting a VMA.
|
|
*
|
|
* @vp: The vma_prepare struct
|
|
* @vmi: The vma iterator
|
|
* @mm: The mm_struct
|
|
*/
|
|
static inline void vma_complete(struct vma_prepare *vp,
|
|
struct vma_iterator *vmi, struct mm_struct *mm)
|
|
{
|
|
if (vp->file) {
|
|
if (vp->adj_next)
|
|
vma_interval_tree_insert(vp->adj_next,
|
|
&vp->mapping->i_mmap);
|
|
vma_interval_tree_insert(vp->vma, &vp->mapping->i_mmap);
|
|
flush_dcache_mmap_unlock(vp->mapping);
|
|
}
|
|
|
|
if (vp->remove && vp->file) {
|
|
__remove_shared_vm_struct(vp->remove, vp->mapping);
|
|
if (vp->remove2)
|
|
__remove_shared_vm_struct(vp->remove2, vp->mapping);
|
|
} else if (vp->insert) {
|
|
/*
|
|
* split_vma has split insert from vma, and needs
|
|
* us to insert it before dropping the locks
|
|
* (it may either follow vma or precede it).
|
|
*/
|
|
vma_iter_store(vmi, vp->insert);
|
|
mm->map_count++;
|
|
}
|
|
|
|
if (vp->anon_vma) {
|
|
anon_vma_interval_tree_post_update_vma(vp->vma);
|
|
if (vp->adj_next)
|
|
anon_vma_interval_tree_post_update_vma(vp->adj_next);
|
|
anon_vma_unlock_write(vp->anon_vma);
|
|
}
|
|
|
|
if (vp->file) {
|
|
i_mmap_unlock_write(vp->mapping);
|
|
uprobe_mmap(vp->vma);
|
|
|
|
if (vp->adj_next)
|
|
uprobe_mmap(vp->adj_next);
|
|
}
|
|
|
|
if (vp->remove) {
|
|
again:
|
|
vma_mark_detached(vp->remove, true);
|
|
if (vp->file) {
|
|
uprobe_munmap(vp->remove, vp->remove->vm_start,
|
|
vp->remove->vm_end);
|
|
fput(vp->file);
|
|
}
|
|
if (vp->remove->anon_vma)
|
|
anon_vma_merge(vp->vma, vp->remove);
|
|
mm->map_count--;
|
|
mpol_put(vma_policy(vp->remove));
|
|
if (!vp->remove2)
|
|
WARN_ON_ONCE(vp->vma->vm_end < vp->remove->vm_end);
|
|
vm_area_free(vp->remove);
|
|
|
|
/*
|
|
* In mprotect's case 6 (see comments on vma_merge),
|
|
* we are removing both mid and next vmas
|
|
*/
|
|
if (vp->remove2) {
|
|
vp->remove = vp->remove2;
|
|
vp->remove2 = NULL;
|
|
goto again;
|
|
}
|
|
}
|
|
if (vp->insert && vp->file)
|
|
uprobe_mmap(vp->insert);
|
|
validate_mm(mm);
|
|
}
|
|
|
|
/*
|
|
* dup_anon_vma() - Helper function to duplicate anon_vma
|
|
* @dst: The destination VMA
|
|
* @src: The source VMA
|
|
* @dup: Pointer to the destination VMA when successful.
|
|
*
|
|
* Returns: 0 on success.
|
|
*/
|
|
static inline int dup_anon_vma(struct vm_area_struct *dst,
|
|
struct vm_area_struct *src, struct vm_area_struct **dup)
|
|
{
|
|
/*
|
|
* Easily overlooked: when mprotect shifts the boundary, make sure the
|
|
* expanding vma has anon_vma set if the shrinking vma had, to cover any
|
|
* anon pages imported.
|
|
*/
|
|
if (src->anon_vma && !dst->anon_vma) {
|
|
int ret;
|
|
|
|
vma_assert_write_locked(dst);
|
|
dst->anon_vma = src->anon_vma;
|
|
ret = anon_vma_clone(dst, src);
|
|
if (ret)
|
|
return ret;
|
|
|
|
*dup = dst;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* vma_expand - Expand an existing VMA
|
|
*
|
|
* @vmi: The vma iterator
|
|
* @vma: The vma to expand
|
|
* @start: The start of the vma
|
|
* @end: The exclusive end of the vma
|
|
* @pgoff: The page offset of vma
|
|
* @next: The current of next vma.
|
|
*
|
|
* Expand @vma to @start and @end. Can expand off the start and end. Will
|
|
* expand over @next if it's different from @vma and @end == @next->vm_end.
|
|
* Checking if the @vma can expand and merge with @next needs to be handled by
|
|
* the caller.
|
|
*
|
|
* Returns: 0 on success
|
|
*/
|
|
int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
|
|
unsigned long start, unsigned long end, pgoff_t pgoff,
|
|
struct vm_area_struct *next)
|
|
{
|
|
struct vm_area_struct *anon_dup = NULL;
|
|
bool remove_next = false;
|
|
struct vma_prepare vp;
|
|
|
|
vma_start_write(vma);
|
|
if (next && (vma != next) && (end == next->vm_end)) {
|
|
int ret;
|
|
|
|
remove_next = true;
|
|
vma_start_write(next);
|
|
ret = dup_anon_vma(vma, next, &anon_dup);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL);
|
|
/* Not merging but overwriting any part of next is not handled. */
|
|
VM_WARN_ON(next && !vp.remove &&
|
|
next != vma && end > next->vm_start);
|
|
/* Only handles expanding */
|
|
VM_WARN_ON(vma->vm_start < start || vma->vm_end > end);
|
|
|
|
/* Note: vma iterator must be pointing to 'start' */
|
|
vma_iter_config(vmi, start, end);
|
|
if (vma_iter_prealloc(vmi, vma))
|
|
goto nomem;
|
|
|
|
vma_prepare(&vp);
|
|
vma_adjust_trans_huge(vma, start, end, 0);
|
|
vma_set_range(vma, start, end, pgoff);
|
|
vma_iter_store(vmi, vma);
|
|
|
|
vma_complete(&vp, vmi, vma->vm_mm);
|
|
return 0;
|
|
|
|
nomem:
|
|
if (anon_dup)
|
|
unlink_anon_vmas(anon_dup);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/*
|
|
* vma_shrink() - Reduce an existing VMAs memory area
|
|
* @vmi: The vma iterator
|
|
* @vma: The VMA to modify
|
|
* @start: The new start
|
|
* @end: The new end
|
|
*
|
|
* Returns: 0 on success, -ENOMEM otherwise
|
|
*/
|
|
int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
|
|
unsigned long start, unsigned long end, pgoff_t pgoff)
|
|
{
|
|
struct vma_prepare vp;
|
|
|
|
WARN_ON((vma->vm_start != start) && (vma->vm_end != end));
|
|
|
|
if (vma->vm_start < start)
|
|
vma_iter_config(vmi, vma->vm_start, start);
|
|
else
|
|
vma_iter_config(vmi, end, vma->vm_end);
|
|
|
|
if (vma_iter_prealloc(vmi, NULL))
|
|
return -ENOMEM;
|
|
|
|
vma_start_write(vma);
|
|
|
|
init_vma_prep(&vp, vma);
|
|
vma_prepare(&vp);
|
|
vma_adjust_trans_huge(vma, start, end, 0);
|
|
|
|
vma_iter_clear(vmi);
|
|
vma_set_range(vma, start, end, pgoff);
|
|
vma_complete(&vp, vmi, vma->vm_mm);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* If the vma has a ->close operation then the driver probably needs to release
|
|
* per-vma resources, so we don't attempt to merge those if the caller indicates
|
|
* the current vma may be removed as part of the merge.
|
|
*/
|
|
static inline bool is_mergeable_vma(struct vm_area_struct *vma,
|
|
struct file *file, unsigned long vm_flags,
|
|
struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
|
|
struct anon_vma_name *anon_name, bool may_remove_vma)
|
|
{
|
|
/*
|
|
* VM_SOFTDIRTY should not prevent from VMA merging, if we
|
|
* match the flags but dirty bit -- the caller should mark
|
|
* merged VMA as dirty. If dirty bit won't be excluded from
|
|
* comparison, we increase pressure on the memory system forcing
|
|
* the kernel to generate new VMAs when old one could be
|
|
* extended instead.
|
|
*/
|
|
if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
|
|
return false;
|
|
if (vma->vm_file != file)
|
|
return false;
|
|
if (may_remove_vma && vma->vm_ops && vma->vm_ops->close)
|
|
return false;
|
|
if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
|
|
return false;
|
|
if (!anon_vma_name_eq(anon_vma_name(vma), anon_name))
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
static inline bool is_mergeable_anon_vma(struct anon_vma *anon_vma1,
|
|
struct anon_vma *anon_vma2, struct vm_area_struct *vma)
|
|
{
|
|
/*
|
|
* The list_is_singular() test is to avoid merging VMA cloned from
|
|
* parents. This can improve scalability caused by anon_vma lock.
|
|
*/
|
|
if ((!anon_vma1 || !anon_vma2) && (!vma ||
|
|
list_is_singular(&vma->anon_vma_chain)))
|
|
return true;
|
|
return anon_vma1 == anon_vma2;
|
|
}
|
|
|
|
/*
|
|
* Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
|
|
* in front of (at a lower virtual address and file offset than) the vma.
|
|
*
|
|
* We cannot merge two vmas if they have differently assigned (non-NULL)
|
|
* anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
|
|
*
|
|
* We don't check here for the merged mmap wrapping around the end of pagecache
|
|
* indices (16TB on ia32) because do_mmap() does not permit mmap's which
|
|
* wrap, nor mmaps which cover the final page at index -1UL.
|
|
*
|
|
* We assume the vma may be removed as part of the merge.
|
|
*/
|
|
static bool
|
|
can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
|
|
struct anon_vma *anon_vma, struct file *file,
|
|
pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
|
|
struct anon_vma_name *anon_name)
|
|
{
|
|
if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, true) &&
|
|
is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
|
|
if (vma->vm_pgoff == vm_pgoff)
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
|
|
* beyond (at a higher virtual address and file offset than) the vma.
|
|
*
|
|
* We cannot merge two vmas if they have differently assigned (non-NULL)
|
|
* anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
|
|
*
|
|
* We assume that vma is not removed as part of the merge.
|
|
*/
|
|
static bool
|
|
can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
|
|
struct anon_vma *anon_vma, struct file *file,
|
|
pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
|
|
struct anon_vma_name *anon_name)
|
|
{
|
|
if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, false) &&
|
|
is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
|
|
pgoff_t vm_pglen;
|
|
vm_pglen = vma_pages(vma);
|
|
if (vma->vm_pgoff + vm_pglen == vm_pgoff)
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Given a mapping request (addr,end,vm_flags,file,pgoff,anon_name),
|
|
* figure out whether that can be merged with its predecessor or its
|
|
* successor. Or both (it neatly fills a hole).
|
|
*
|
|
* In most cases - when called for mmap, brk or mremap - [addr,end) is
|
|
* certain not to be mapped by the time vma_merge is called; but when
|
|
* called for mprotect, it is certain to be already mapped (either at
|
|
* an offset within prev, or at the start of next), and the flags of
|
|
* this area are about to be changed to vm_flags - and the no-change
|
|
* case has already been eliminated.
|
|
*
|
|
* The following mprotect cases have to be considered, where **** is
|
|
* the area passed down from mprotect_fixup, never extending beyond one
|
|
* vma, PPPP is the previous vma, CCCC is a concurrent vma that starts
|
|
* at the same address as **** and is of the same or larger span, and
|
|
* NNNN the next vma after ****:
|
|
*
|
|
* **** **** ****
|
|
* PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPCCCCCC
|
|
* cannot merge might become might become
|
|
* PPNNNNNNNNNN PPPPPPPPPPCC
|
|
* mmap, brk or case 4 below case 5 below
|
|
* mremap move:
|
|
* **** ****
|
|
* PPPP NNNN PPPPCCCCNNNN
|
|
* might become might become
|
|
* PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or
|
|
* PPPPPPPPNNNN 2 or PPPPPPPPNNNN 7 or
|
|
* PPPPNNNNNNNN 3 PPPPNNNNNNNN 8
|
|
*
|
|
* It is important for case 8 that the vma CCCC overlapping the
|
|
* region **** is never going to extended over NNNN. Instead NNNN must
|
|
* be extended in region **** and CCCC must be removed. This way in
|
|
* all cases where vma_merge succeeds, the moment vma_merge drops the
|
|
* rmap_locks, the properties of the merged vma will be already
|
|
* correct for the whole merged range. Some of those properties like
|
|
* vm_page_prot/vm_flags may be accessed by rmap_walks and they must
|
|
* be correct for the whole merged range immediately after the
|
|
* rmap_locks are released. Otherwise if NNNN would be removed and
|
|
* CCCC would be extended over the NNNN range, remove_migration_ptes
|
|
* or other rmap walkers (if working on addresses beyond the "end"
|
|
* parameter) may establish ptes with the wrong permissions of CCCC
|
|
* instead of the right permissions of NNNN.
|
|
*
|
|
* In the code below:
|
|
* PPPP is represented by *prev
|
|
* CCCC is represented by *curr or not represented at all (NULL)
|
|
* NNNN is represented by *next or not represented at all (NULL)
|
|
* **** is not represented - it will be merged and the vma containing the
|
|
* area is returned, or the function will return NULL
|
|
*/
|
|
static struct vm_area_struct
|
|
*vma_merge(struct vma_iterator *vmi, struct vm_area_struct *prev,
|
|
struct vm_area_struct *src, unsigned long addr, unsigned long end,
|
|
unsigned long vm_flags, pgoff_t pgoff, struct mempolicy *policy,
|
|
struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
|
|
struct anon_vma_name *anon_name)
|
|
{
|
|
struct mm_struct *mm = src->vm_mm;
|
|
struct anon_vma *anon_vma = src->anon_vma;
|
|
struct file *file = src->vm_file;
|
|
struct vm_area_struct *curr, *next, *res;
|
|
struct vm_area_struct *vma, *adjust, *remove, *remove2;
|
|
struct vm_area_struct *anon_dup = NULL;
|
|
struct vma_prepare vp;
|
|
pgoff_t vma_pgoff;
|
|
int err = 0;
|
|
bool merge_prev = false;
|
|
bool merge_next = false;
|
|
bool vma_expanded = false;
|
|
unsigned long vma_start = addr;
|
|
unsigned long vma_end = end;
|
|
pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
|
|
long adj_start = 0;
|
|
|
|
/*
|
|
* We later require that vma->vm_flags == vm_flags,
|
|
* so this tests vma->vm_flags & VM_SPECIAL, too.
|
|
*/
|
|
if (vm_flags & VM_SPECIAL)
|
|
return NULL;
|
|
|
|
/* Does the input range span an existing VMA? (cases 5 - 8) */
|
|
curr = find_vma_intersection(mm, prev ? prev->vm_end : 0, end);
|
|
|
|
if (!curr || /* cases 1 - 4 */
|
|
end == curr->vm_end) /* cases 6 - 8, adjacent VMA */
|
|
next = vma_lookup(mm, end);
|
|
else
|
|
next = NULL; /* case 5 */
|
|
|
|
if (prev) {
|
|
vma_start = prev->vm_start;
|
|
vma_pgoff = prev->vm_pgoff;
|
|
|
|
/* Can we merge the predecessor? */
|
|
if (addr == prev->vm_end && mpol_equal(vma_policy(prev), policy)
|
|
&& can_vma_merge_after(prev, vm_flags, anon_vma, file,
|
|
pgoff, vm_userfaultfd_ctx, anon_name)) {
|
|
merge_prev = true;
|
|
vma_prev(vmi);
|
|
}
|
|
}
|
|
|
|
/* Can we merge the successor? */
|
|
if (next && mpol_equal(policy, vma_policy(next)) &&
|
|
can_vma_merge_before(next, vm_flags, anon_vma, file, pgoff+pglen,
|
|
vm_userfaultfd_ctx, anon_name)) {
|
|
merge_next = true;
|
|
}
|
|
|
|
/* Verify some invariant that must be enforced by the caller. */
|
|
VM_WARN_ON(prev && addr <= prev->vm_start);
|
|
VM_WARN_ON(curr && (addr != curr->vm_start || end > curr->vm_end));
|
|
VM_WARN_ON(addr >= end);
|
|
|
|
if (!merge_prev && !merge_next)
|
|
return NULL; /* Not mergeable. */
|
|
|
|
if (merge_prev)
|
|
vma_start_write(prev);
|
|
|
|
res = vma = prev;
|
|
remove = remove2 = adjust = NULL;
|
|
|
|
/* Can we merge both the predecessor and the successor? */
|
|
if (merge_prev && merge_next &&
|
|
is_mergeable_anon_vma(prev->anon_vma, next->anon_vma, NULL)) {
|
|
vma_start_write(next);
|
|
remove = next; /* case 1 */
|
|
vma_end = next->vm_end;
|
|
err = dup_anon_vma(prev, next, &anon_dup);
|
|
if (curr) { /* case 6 */
|
|
vma_start_write(curr);
|
|
remove = curr;
|
|
remove2 = next;
|
|
/*
|
|
* Note that the dup_anon_vma below cannot overwrite err
|
|
* since the first caller would do nothing unless next
|
|
* has an anon_vma.
|
|
*/
|
|
if (!next->anon_vma)
|
|
err = dup_anon_vma(prev, curr, &anon_dup);
|
|
}
|
|
} else if (merge_prev) { /* case 2 */
|
|
if (curr) {
|
|
vma_start_write(curr);
|
|
if (end == curr->vm_end) { /* case 7 */
|
|
/*
|
|
* can_vma_merge_after() assumed we would not be
|
|
* removing prev vma, so it skipped the check
|
|
* for vm_ops->close, but we are removing curr
|
|
*/
|
|
if (curr->vm_ops && curr->vm_ops->close)
|
|
err = -EINVAL;
|
|
remove = curr;
|
|
} else { /* case 5 */
|
|
adjust = curr;
|
|
adj_start = (end - curr->vm_start);
|
|
}
|
|
if (!err)
|
|
err = dup_anon_vma(prev, curr, &anon_dup);
|
|
}
|
|
} else { /* merge_next */
|
|
vma_start_write(next);
|
|
res = next;
|
|
if (prev && addr < prev->vm_end) { /* case 4 */
|
|
vma_start_write(prev);
|
|
vma_end = addr;
|
|
adjust = next;
|
|
adj_start = -(prev->vm_end - addr);
|
|
err = dup_anon_vma(next, prev, &anon_dup);
|
|
} else {
|
|
/*
|
|
* Note that cases 3 and 8 are the ONLY ones where prev
|
|
* is permitted to be (but is not necessarily) NULL.
|
|
*/
|
|
vma = next; /* case 3 */
|
|
vma_start = addr;
|
|
vma_end = next->vm_end;
|
|
vma_pgoff = next->vm_pgoff - pglen;
|
|
if (curr) { /* case 8 */
|
|
vma_pgoff = curr->vm_pgoff;
|
|
vma_start_write(curr);
|
|
remove = curr;
|
|
err = dup_anon_vma(next, curr, &anon_dup);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Error in anon_vma clone. */
|
|
if (err)
|
|
goto anon_vma_fail;
|
|
|
|
if (vma_start < vma->vm_start || vma_end > vma->vm_end)
|
|
vma_expanded = true;
|
|
|
|
if (vma_expanded) {
|
|
vma_iter_config(vmi, vma_start, vma_end);
|
|
} else {
|
|
vma_iter_config(vmi, adjust->vm_start + adj_start,
|
|
adjust->vm_end);
|
|
}
|
|
|
|
if (vma_iter_prealloc(vmi, vma))
|
|
goto prealloc_fail;
|
|
|
|
init_multi_vma_prep(&vp, vma, adjust, remove, remove2);
|
|
VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma &&
|
|
vp.anon_vma != adjust->anon_vma);
|
|
|
|
vma_prepare(&vp);
|
|
vma_adjust_trans_huge(vma, vma_start, vma_end, adj_start);
|
|
vma_set_range(vma, vma_start, vma_end, vma_pgoff);
|
|
|
|
if (vma_expanded)
|
|
vma_iter_store(vmi, vma);
|
|
|
|
if (adj_start) {
|
|
adjust->vm_start += adj_start;
|
|
adjust->vm_pgoff += adj_start >> PAGE_SHIFT;
|
|
if (adj_start < 0) {
|
|
WARN_ON(vma_expanded);
|
|
vma_iter_store(vmi, next);
|
|
}
|
|
}
|
|
|
|
vma_complete(&vp, vmi, mm);
|
|
khugepaged_enter_vma(res, vm_flags);
|
|
return res;
|
|
|
|
prealloc_fail:
|
|
if (anon_dup)
|
|
unlink_anon_vmas(anon_dup);
|
|
|
|
anon_vma_fail:
|
|
vma_iter_set(vmi, addr);
|
|
vma_iter_load(vmi);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Rough compatibility check to quickly see if it's even worth looking
|
|
* at sharing an anon_vma.
|
|
*
|
|
* They need to have the same vm_file, and the flags can only differ
|
|
* in things that mprotect may change.
|
|
*
|
|
* NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
|
|
* we can merge the two vma's. For example, we refuse to merge a vma if
|
|
* there is a vm_ops->close() function, because that indicates that the
|
|
* driver is doing some kind of reference counting. But that doesn't
|
|
* really matter for the anon_vma sharing case.
|
|
*/
|
|
static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
|
|
{
|
|
return a->vm_end == b->vm_start &&
|
|
mpol_equal(vma_policy(a), vma_policy(b)) &&
|
|
a->vm_file == b->vm_file &&
|
|
!((a->vm_flags ^ b->vm_flags) & ~(VM_ACCESS_FLAGS | VM_SOFTDIRTY)) &&
|
|
b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
|
|
}
|
|
|
|
/*
|
|
* Do some basic sanity checking to see if we can re-use the anon_vma
|
|
* from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
|
|
* the same as 'old', the other will be the new one that is trying
|
|
* to share the anon_vma.
|
|
*
|
|
* NOTE! This runs with mmap_lock held for reading, so it is possible that
|
|
* the anon_vma of 'old' is concurrently in the process of being set up
|
|
* by another page fault trying to merge _that_. But that's ok: if it
|
|
* is being set up, that automatically means that it will be a singleton
|
|
* acceptable for merging, so we can do all of this optimistically. But
|
|
* we do that READ_ONCE() to make sure that we never re-load the pointer.
|
|
*
|
|
* IOW: that the "list_is_singular()" test on the anon_vma_chain only
|
|
* matters for the 'stable anon_vma' case (ie the thing we want to avoid
|
|
* is to return an anon_vma that is "complex" due to having gone through
|
|
* a fork).
|
|
*
|
|
* We also make sure that the two vma's are compatible (adjacent,
|
|
* and with the same memory policies). That's all stable, even with just
|
|
* a read lock on the mmap_lock.
|
|
*/
|
|
static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
|
|
{
|
|
if (anon_vma_compatible(a, b)) {
|
|
struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
|
|
|
|
if (anon_vma && list_is_singular(&old->anon_vma_chain))
|
|
return anon_vma;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* find_mergeable_anon_vma is used by anon_vma_prepare, to check
|
|
* neighbouring vmas for a suitable anon_vma, before it goes off
|
|
* to allocate a new anon_vma. It checks because a repetitive
|
|
* sequence of mprotects and faults may otherwise lead to distinct
|
|
* anon_vmas being allocated, preventing vma merge in subsequent
|
|
* mprotect.
|
|
*/
|
|
struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
|
|
{
|
|
MA_STATE(mas, &vma->vm_mm->mm_mt, vma->vm_end, vma->vm_end);
|
|
struct anon_vma *anon_vma = NULL;
|
|
struct vm_area_struct *prev, *next;
|
|
|
|
/* Try next first. */
|
|
next = mas_walk(&mas);
|
|
if (next) {
|
|
anon_vma = reusable_anon_vma(next, vma, next);
|
|
if (anon_vma)
|
|
return anon_vma;
|
|
}
|
|
|
|
prev = mas_prev(&mas, 0);
|
|
VM_BUG_ON_VMA(prev != vma, vma);
|
|
prev = mas_prev(&mas, 0);
|
|
/* Try prev next. */
|
|
if (prev)
|
|
anon_vma = reusable_anon_vma(prev, prev, vma);
|
|
|
|
/*
|
|
* We might reach here with anon_vma == NULL if we can't find
|
|
* any reusable anon_vma.
|
|
* There's no absolute need to look only at touching neighbours:
|
|
* we could search further afield for "compatible" anon_vmas.
|
|
* But it would probably just be a waste of time searching,
|
|
* or lead to too many vmas hanging off the same anon_vma.
|
|
* We're trying to allow mprotect remerging later on,
|
|
* not trying to minimize memory used for anon_vmas.
|
|
*/
|
|
return anon_vma;
|
|
}
|
|
|
|
/*
|
|
* If a hint addr is less than mmap_min_addr change hint to be as
|
|
* low as possible but still greater than mmap_min_addr
|
|
*/
|
|
static inline unsigned long round_hint_to_min(unsigned long hint)
|
|
{
|
|
hint &= PAGE_MASK;
|
|
if (((void *)hint != NULL) &&
|
|
(hint < mmap_min_addr))
|
|
return PAGE_ALIGN(mmap_min_addr);
|
|
return hint;
|
|
}
|
|
|
|
bool mlock_future_ok(struct mm_struct *mm, unsigned long flags,
|
|
unsigned long bytes)
|
|
{
|
|
unsigned long locked_pages, limit_pages;
|
|
|
|
if (!(flags & VM_LOCKED) || capable(CAP_IPC_LOCK))
|
|
return true;
|
|
|
|
locked_pages = bytes >> PAGE_SHIFT;
|
|
locked_pages += mm->locked_vm;
|
|
|
|
limit_pages = rlimit(RLIMIT_MEMLOCK);
|
|
limit_pages >>= PAGE_SHIFT;
|
|
|
|
return locked_pages <= limit_pages;
|
|
}
|
|
|
|
static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
|
|
{
|
|
if (S_ISREG(inode->i_mode))
|
|
return MAX_LFS_FILESIZE;
|
|
|
|
if (S_ISBLK(inode->i_mode))
|
|
return MAX_LFS_FILESIZE;
|
|
|
|
if (S_ISSOCK(inode->i_mode))
|
|
return MAX_LFS_FILESIZE;
|
|
|
|
/* Special "we do even unsigned file positions" case */
|
|
if (file->f_mode & FMODE_UNSIGNED_OFFSET)
|
|
return 0;
|
|
|
|
/* Yes, random drivers might want more. But I'm tired of buggy drivers */
|
|
return ULONG_MAX;
|
|
}
|
|
|
|
static inline bool file_mmap_ok(struct file *file, struct inode *inode,
|
|
unsigned long pgoff, unsigned long len)
|
|
{
|
|
u64 maxsize = file_mmap_size_max(file, inode);
|
|
|
|
if (maxsize && len > maxsize)
|
|
return false;
|
|
maxsize -= len;
|
|
if (pgoff > maxsize >> PAGE_SHIFT)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* The caller must write-lock current->mm->mmap_lock.
|
|
*/
|
|
unsigned long do_mmap(struct file *file, unsigned long addr,
|
|
unsigned long len, unsigned long prot,
|
|
unsigned long flags, vm_flags_t vm_flags,
|
|
unsigned long pgoff, unsigned long *populate,
|
|
struct list_head *uf)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
int pkey = 0;
|
|
|
|
*populate = 0;
|
|
|
|
if (!len)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Does the application expect PROT_READ to imply PROT_EXEC?
|
|
*
|
|
* (the exception is when the underlying filesystem is noexec
|
|
* mounted, in which case we don't add PROT_EXEC.)
|
|
*/
|
|
if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
|
|
if (!(file && path_noexec(&file->f_path)))
|
|
prot |= PROT_EXEC;
|
|
|
|
/* force arch specific MAP_FIXED handling in get_unmapped_area */
|
|
if (flags & MAP_FIXED_NOREPLACE)
|
|
flags |= MAP_FIXED;
|
|
|
|
if (!(flags & MAP_FIXED))
|
|
addr = round_hint_to_min(addr);
|
|
|
|
/* Careful about overflows.. */
|
|
len = PAGE_ALIGN(len);
|
|
if (!len)
|
|
return -ENOMEM;
|
|
|
|
/* offset overflow? */
|
|
if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
|
|
return -EOVERFLOW;
|
|
|
|
/* Too many mappings? */
|
|
if (mm->map_count > sysctl_max_map_count)
|
|
return -ENOMEM;
|
|
|
|
/* Obtain the address to map to. we verify (or select) it and ensure
|
|
* that it represents a valid section of the address space.
|
|
*/
|
|
addr = get_unmapped_area(file, addr, len, pgoff, flags);
|
|
if (IS_ERR_VALUE(addr))
|
|
return addr;
|
|
|
|
if (flags & MAP_FIXED_NOREPLACE) {
|
|
if (find_vma_intersection(mm, addr, addr + len))
|
|
return -EEXIST;
|
|
}
|
|
|
|
if (prot == PROT_EXEC) {
|
|
pkey = execute_only_pkey(mm);
|
|
if (pkey < 0)
|
|
pkey = 0;
|
|
}
|
|
|
|
/* Do simple checking here so the lower-level routines won't have
|
|
* to. we assume access permissions have been handled by the open
|
|
* of the memory object, so we don't do any here.
|
|
*/
|
|
vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
|
|
mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
|
|
|
|
if (flags & MAP_LOCKED)
|
|
if (!can_do_mlock())
|
|
return -EPERM;
|
|
|
|
if (!mlock_future_ok(mm, vm_flags, len))
|
|
return -EAGAIN;
|
|
|
|
if (file) {
|
|
struct inode *inode = file_inode(file);
|
|
unsigned long flags_mask;
|
|
|
|
if (!file_mmap_ok(file, inode, pgoff, len))
|
|
return -EOVERFLOW;
|
|
|
|
flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
|
|
|
|
switch (flags & MAP_TYPE) {
|
|
case MAP_SHARED:
|
|
/*
|
|
* Force use of MAP_SHARED_VALIDATE with non-legacy
|
|
* flags. E.g. MAP_SYNC is dangerous to use with
|
|
* MAP_SHARED as you don't know which consistency model
|
|
* you will get. We silently ignore unsupported flags
|
|
* with MAP_SHARED to preserve backward compatibility.
|
|
*/
|
|
flags &= LEGACY_MAP_MASK;
|
|
fallthrough;
|
|
case MAP_SHARED_VALIDATE:
|
|
if (flags & ~flags_mask)
|
|
return -EOPNOTSUPP;
|
|
if (prot & PROT_WRITE) {
|
|
if (!(file->f_mode & FMODE_WRITE))
|
|
return -EACCES;
|
|
if (IS_SWAPFILE(file->f_mapping->host))
|
|
return -ETXTBSY;
|
|
}
|
|
|
|
/*
|
|
* Make sure we don't allow writing to an append-only
|
|
* file..
|
|
*/
|
|
if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
|
|
return -EACCES;
|
|
|
|
vm_flags |= VM_SHARED | VM_MAYSHARE;
|
|
if (!(file->f_mode & FMODE_WRITE))
|
|
vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
|
|
fallthrough;
|
|
case MAP_PRIVATE:
|
|
if (!(file->f_mode & FMODE_READ))
|
|
return -EACCES;
|
|
if (path_noexec(&file->f_path)) {
|
|
if (vm_flags & VM_EXEC)
|
|
return -EPERM;
|
|
vm_flags &= ~VM_MAYEXEC;
|
|
}
|
|
|
|
if (!file->f_op->mmap)
|
|
return -ENODEV;
|
|
if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
|
|
return -EINVAL;
|
|
break;
|
|
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
} else {
|
|
switch (flags & MAP_TYPE) {
|
|
case MAP_SHARED:
|
|
if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
|
|
return -EINVAL;
|
|
/*
|
|
* Ignore pgoff.
|
|
*/
|
|
pgoff = 0;
|
|
vm_flags |= VM_SHARED | VM_MAYSHARE;
|
|
break;
|
|
case MAP_PRIVATE:
|
|
/*
|
|
* Set pgoff according to addr for anon_vma.
|
|
*/
|
|
pgoff = addr >> PAGE_SHIFT;
|
|
break;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Set 'VM_NORESERVE' if we should not account for the
|
|
* memory use of this mapping.
|
|
*/
|
|
if (flags & MAP_NORESERVE) {
|
|
/* We honor MAP_NORESERVE if allowed to overcommit */
|
|
if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
|
|
vm_flags |= VM_NORESERVE;
|
|
|
|
/* hugetlb applies strict overcommit unless MAP_NORESERVE */
|
|
if (file && is_file_hugepages(file))
|
|
vm_flags |= VM_NORESERVE;
|
|
}
|
|
|
|
addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
|
|
if (!IS_ERR_VALUE(addr) &&
|
|
((vm_flags & VM_LOCKED) ||
|
|
(flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
|
|
*populate = len;
|
|
return addr;
|
|
}
|
|
|
|
unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
|
|
unsigned long prot, unsigned long flags,
|
|
unsigned long fd, unsigned long pgoff)
|
|
{
|
|
struct file *file = NULL;
|
|
unsigned long retval;
|
|
|
|
if (!(flags & MAP_ANONYMOUS)) {
|
|
audit_mmap_fd(fd, flags);
|
|
file = fget(fd);
|
|
if (!file)
|
|
return -EBADF;
|
|
if (is_file_hugepages(file)) {
|
|
len = ALIGN(len, huge_page_size(hstate_file(file)));
|
|
} else if (unlikely(flags & MAP_HUGETLB)) {
|
|
retval = -EINVAL;
|
|
goto out_fput;
|
|
}
|
|
} else if (flags & MAP_HUGETLB) {
|
|
struct hstate *hs;
|
|
|
|
hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
|
|
if (!hs)
|
|
return -EINVAL;
|
|
|
|
len = ALIGN(len, huge_page_size(hs));
|
|
/*
|
|
* VM_NORESERVE is used because the reservations will be
|
|
* taken when vm_ops->mmap() is called
|
|
*/
|
|
file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
|
|
VM_NORESERVE,
|
|
HUGETLB_ANONHUGE_INODE,
|
|
(flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
|
|
if (IS_ERR(file))
|
|
return PTR_ERR(file);
|
|
}
|
|
|
|
retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
|
|
out_fput:
|
|
if (file)
|
|
fput(file);
|
|
return retval;
|
|
}
|
|
|
|
SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
|
|
unsigned long, prot, unsigned long, flags,
|
|
unsigned long, fd, unsigned long, pgoff)
|
|
{
|
|
return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
|
|
}
|
|
|
|
#ifdef __ARCH_WANT_SYS_OLD_MMAP
|
|
struct mmap_arg_struct {
|
|
unsigned long addr;
|
|
unsigned long len;
|
|
unsigned long prot;
|
|
unsigned long flags;
|
|
unsigned long fd;
|
|
unsigned long offset;
|
|
};
|
|
|
|
SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
|
|
{
|
|
struct mmap_arg_struct a;
|
|
|
|
if (copy_from_user(&a, arg, sizeof(a)))
|
|
return -EFAULT;
|
|
if (offset_in_page(a.offset))
|
|
return -EINVAL;
|
|
|
|
return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
|
|
a.offset >> PAGE_SHIFT);
|
|
}
|
|
#endif /* __ARCH_WANT_SYS_OLD_MMAP */
|
|
|
|
static bool vm_ops_needs_writenotify(const struct vm_operations_struct *vm_ops)
|
|
{
|
|
return vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite);
|
|
}
|
|
|
|
static bool vma_is_shared_writable(struct vm_area_struct *vma)
|
|
{
|
|
return (vma->vm_flags & (VM_WRITE | VM_SHARED)) ==
|
|
(VM_WRITE | VM_SHARED);
|
|
}
|
|
|
|
static bool vma_fs_can_writeback(struct vm_area_struct *vma)
|
|
{
|
|
/* No managed pages to writeback. */
|
|
if (vma->vm_flags & VM_PFNMAP)
|
|
return false;
|
|
|
|
return vma->vm_file && vma->vm_file->f_mapping &&
|
|
mapping_can_writeback(vma->vm_file->f_mapping);
|
|
}
|
|
|
|
/*
|
|
* Does this VMA require the underlying folios to have their dirty state
|
|
* tracked?
|
|
*/
|
|
bool vma_needs_dirty_tracking(struct vm_area_struct *vma)
|
|
{
|
|
/* Only shared, writable VMAs require dirty tracking. */
|
|
if (!vma_is_shared_writable(vma))
|
|
return false;
|
|
|
|
/* Does the filesystem need to be notified? */
|
|
if (vm_ops_needs_writenotify(vma->vm_ops))
|
|
return true;
|
|
|
|
/*
|
|
* Even if the filesystem doesn't indicate a need for writenotify, if it
|
|
* can writeback, dirty tracking is still required.
|
|
*/
|
|
return vma_fs_can_writeback(vma);
|
|
}
|
|
|
|
/*
|
|
* Some shared mappings will want the pages marked read-only
|
|
* to track write events. If so, we'll downgrade vm_page_prot
|
|
* to the private version (using protection_map[] without the
|
|
* VM_SHARED bit).
|
|
*/
|
|
int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
|
|
{
|
|
/* If it was private or non-writable, the write bit is already clear */
|
|
if (!vma_is_shared_writable(vma))
|
|
return 0;
|
|
|
|
/* The backer wishes to know when pages are first written to? */
|
|
if (vm_ops_needs_writenotify(vma->vm_ops))
|
|
return 1;
|
|
|
|
/* The open routine did something to the protections that pgprot_modify
|
|
* won't preserve? */
|
|
if (pgprot_val(vm_page_prot) !=
|
|
pgprot_val(vm_pgprot_modify(vm_page_prot, vma->vm_flags)))
|
|
return 0;
|
|
|
|
/*
|
|
* Do we need to track softdirty? hugetlb does not support softdirty
|
|
* tracking yet.
|
|
*/
|
|
if (vma_soft_dirty_enabled(vma) && !is_vm_hugetlb_page(vma))
|
|
return 1;
|
|
|
|
/* Do we need write faults for uffd-wp tracking? */
|
|
if (userfaultfd_wp(vma))
|
|
return 1;
|
|
|
|
/* Can the mapping track the dirty pages? */
|
|
return vma_fs_can_writeback(vma);
|
|
}
|
|
|
|
/*
|
|
* We account for memory if it's a private writeable mapping,
|
|
* not hugepages and VM_NORESERVE wasn't set.
|
|
*/
|
|
static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
|
|
{
|
|
/*
|
|
* hugetlb has its own accounting separate from the core VM
|
|
* VM_HUGETLB may not be set yet so we cannot check for that flag.
|
|
*/
|
|
if (file && is_file_hugepages(file))
|
|
return 0;
|
|
|
|
return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
|
|
}
|
|
|
|
/**
|
|
* unmapped_area() - Find an area between the low_limit and the high_limit with
|
|
* the correct alignment and offset, all from @info. Note: current->mm is used
|
|
* for the search.
|
|
*
|
|
* @info: The unmapped area information including the range [low_limit -
|
|
* high_limit), the alignment offset and mask.
|
|
*
|
|
* Return: A memory address or -ENOMEM.
|
|
*/
|
|
static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
|
|
{
|
|
unsigned long length, gap;
|
|
unsigned long low_limit, high_limit;
|
|
struct vm_area_struct *tmp;
|
|
|
|
MA_STATE(mas, ¤t->mm->mm_mt, 0, 0);
|
|
|
|
/* Adjust search length to account for worst case alignment overhead */
|
|
length = info->length + info->align_mask;
|
|
if (length < info->length)
|
|
return -ENOMEM;
|
|
|
|
low_limit = info->low_limit;
|
|
if (low_limit < mmap_min_addr)
|
|
low_limit = mmap_min_addr;
|
|
high_limit = info->high_limit;
|
|
retry:
|
|
if (mas_empty_area(&mas, low_limit, high_limit - 1, length))
|
|
return -ENOMEM;
|
|
|
|
gap = mas.index;
|
|
gap += (info->align_offset - gap) & info->align_mask;
|
|
tmp = mas_next(&mas, ULONG_MAX);
|
|
if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */
|
|
if (vm_start_gap(tmp) < gap + length - 1) {
|
|
low_limit = tmp->vm_end;
|
|
mas_reset(&mas);
|
|
goto retry;
|
|
}
|
|
} else {
|
|
tmp = mas_prev(&mas, 0);
|
|
if (tmp && vm_end_gap(tmp) > gap) {
|
|
low_limit = vm_end_gap(tmp);
|
|
mas_reset(&mas);
|
|
goto retry;
|
|
}
|
|
}
|
|
|
|
return gap;
|
|
}
|
|
|
|
/**
|
|
* unmapped_area_topdown() - Find an area between the low_limit and the
|
|
* high_limit with the correct alignment and offset at the highest available
|
|
* address, all from @info. Note: current->mm is used for the search.
|
|
*
|
|
* @info: The unmapped area information including the range [low_limit -
|
|
* high_limit), the alignment offset and mask.
|
|
*
|
|
* Return: A memory address or -ENOMEM.
|
|
*/
|
|
static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
|
|
{
|
|
unsigned long length, gap, gap_end;
|
|
unsigned long low_limit, high_limit;
|
|
struct vm_area_struct *tmp;
|
|
|
|
MA_STATE(mas, ¤t->mm->mm_mt, 0, 0);
|
|
/* Adjust search length to account for worst case alignment overhead */
|
|
length = info->length + info->align_mask;
|
|
if (length < info->length)
|
|
return -ENOMEM;
|
|
|
|
low_limit = info->low_limit;
|
|
if (low_limit < mmap_min_addr)
|
|
low_limit = mmap_min_addr;
|
|
high_limit = info->high_limit;
|
|
retry:
|
|
if (mas_empty_area_rev(&mas, low_limit, high_limit - 1, length))
|
|
return -ENOMEM;
|
|
|
|
gap = mas.last + 1 - info->length;
|
|
gap -= (gap - info->align_offset) & info->align_mask;
|
|
gap_end = mas.last;
|
|
tmp = mas_next(&mas, ULONG_MAX);
|
|
if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */
|
|
if (vm_start_gap(tmp) <= gap_end) {
|
|
high_limit = vm_start_gap(tmp);
|
|
mas_reset(&mas);
|
|
goto retry;
|
|
}
|
|
} else {
|
|
tmp = mas_prev(&mas, 0);
|
|
if (tmp && vm_end_gap(tmp) > gap) {
|
|
high_limit = tmp->vm_start;
|
|
mas_reset(&mas);
|
|
goto retry;
|
|
}
|
|
}
|
|
|
|
return gap;
|
|
}
|
|
|
|
/*
|
|
* Search for an unmapped address range.
|
|
*
|
|
* We are looking for a range that:
|
|
* - does not intersect with any VMA;
|
|
* - is contained within the [low_limit, high_limit) interval;
|
|
* - is at least the desired size.
|
|
* - satisfies (begin_addr & align_mask) == (align_offset & align_mask)
|
|
*/
|
|
unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
|
|
{
|
|
unsigned long addr;
|
|
|
|
if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
|
|
addr = unmapped_area_topdown(info);
|
|
else
|
|
addr = unmapped_area(info);
|
|
|
|
trace_vm_unmapped_area(addr, info);
|
|
return addr;
|
|
}
|
|
|
|
/* Get an address range which is currently unmapped.
|
|
* For shmat() with addr=0.
|
|
*
|
|
* Ugly calling convention alert:
|
|
* Return value with the low bits set means error value,
|
|
* ie
|
|
* if (ret & ~PAGE_MASK)
|
|
* error = ret;
|
|
*
|
|
* This function "knows" that -ENOMEM has the bits set.
|
|
*/
|
|
unsigned long
|
|
generic_get_unmapped_area(struct file *filp, unsigned long addr,
|
|
unsigned long len, unsigned long pgoff,
|
|
unsigned long flags)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma, *prev;
|
|
struct vm_unmapped_area_info info;
|
|
const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
|
|
|
|
if (len > mmap_end - mmap_min_addr)
|
|
return -ENOMEM;
|
|
|
|
if (flags & MAP_FIXED)
|
|
return addr;
|
|
|
|
if (addr) {
|
|
addr = PAGE_ALIGN(addr);
|
|
vma = find_vma_prev(mm, addr, &prev);
|
|
if (mmap_end - len >= addr && addr >= mmap_min_addr &&
|
|
(!vma || addr + len <= vm_start_gap(vma)) &&
|
|
(!prev || addr >= vm_end_gap(prev)))
|
|
return addr;
|
|
}
|
|
|
|
info.flags = 0;
|
|
info.length = len;
|
|
info.low_limit = mm->mmap_base;
|
|
info.high_limit = mmap_end;
|
|
info.align_mask = 0;
|
|
info.align_offset = 0;
|
|
return vm_unmapped_area(&info);
|
|
}
|
|
|
|
#ifndef HAVE_ARCH_UNMAPPED_AREA
|
|
unsigned long
|
|
arch_get_unmapped_area(struct file *filp, unsigned long addr,
|
|
unsigned long len, unsigned long pgoff,
|
|
unsigned long flags)
|
|
{
|
|
return generic_get_unmapped_area(filp, addr, len, pgoff, flags);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* This mmap-allocator allocates new areas top-down from below the
|
|
* stack's low limit (the base):
|
|
*/
|
|
unsigned long
|
|
generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
|
|
unsigned long len, unsigned long pgoff,
|
|
unsigned long flags)
|
|
{
|
|
struct vm_area_struct *vma, *prev;
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_unmapped_area_info info;
|
|
const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
|
|
|
|
/* requested length too big for entire address space */
|
|
if (len > mmap_end - mmap_min_addr)
|
|
return -ENOMEM;
|
|
|
|
if (flags & MAP_FIXED)
|
|
return addr;
|
|
|
|
/* requesting a specific address */
|
|
if (addr) {
|
|
addr = PAGE_ALIGN(addr);
|
|
vma = find_vma_prev(mm, addr, &prev);
|
|
if (mmap_end - len >= addr && addr >= mmap_min_addr &&
|
|
(!vma || addr + len <= vm_start_gap(vma)) &&
|
|
(!prev || addr >= vm_end_gap(prev)))
|
|
return addr;
|
|
}
|
|
|
|
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
|
|
info.length = len;
|
|
info.low_limit = PAGE_SIZE;
|
|
info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
|
|
info.align_mask = 0;
|
|
info.align_offset = 0;
|
|
addr = vm_unmapped_area(&info);
|
|
|
|
/*
|
|
* A failed mmap() very likely causes application failure,
|
|
* so fall back to the bottom-up function here. This scenario
|
|
* can happen with large stack limits and large mmap()
|
|
* allocations.
|
|
*/
|
|
if (offset_in_page(addr)) {
|
|
VM_BUG_ON(addr != -ENOMEM);
|
|
info.flags = 0;
|
|
info.low_limit = TASK_UNMAPPED_BASE;
|
|
info.high_limit = mmap_end;
|
|
addr = vm_unmapped_area(&info);
|
|
}
|
|
|
|
return addr;
|
|
}
|
|
|
|
#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
|
|
unsigned long
|
|
arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
|
|
unsigned long len, unsigned long pgoff,
|
|
unsigned long flags)
|
|
{
|
|
return generic_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
|
|
}
|
|
#endif
|
|
|
|
unsigned long
|
|
get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
|
|
unsigned long pgoff, unsigned long flags)
|
|
{
|
|
unsigned long (*get_area)(struct file *, unsigned long,
|
|
unsigned long, unsigned long, unsigned long);
|
|
|
|
unsigned long error = arch_mmap_check(addr, len, flags);
|
|
if (error)
|
|
return error;
|
|
|
|
/* Careful about overflows.. */
|
|
if (len > TASK_SIZE)
|
|
return -ENOMEM;
|
|
|
|
get_area = current->mm->get_unmapped_area;
|
|
if (file) {
|
|
if (file->f_op->get_unmapped_area)
|
|
get_area = file->f_op->get_unmapped_area;
|
|
} else if (flags & MAP_SHARED) {
|
|
/*
|
|
* mmap_region() will call shmem_zero_setup() to create a file,
|
|
* so use shmem's get_unmapped_area in case it can be huge.
|
|
*/
|
|
get_area = shmem_get_unmapped_area;
|
|
} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
|
|
/* Ensures that larger anonymous mappings are THP aligned. */
|
|
get_area = thp_get_unmapped_area;
|
|
}
|
|
|
|
/* Always treat pgoff as zero for anonymous memory. */
|
|
if (!file)
|
|
pgoff = 0;
|
|
|
|
addr = get_area(file, addr, len, pgoff, flags);
|
|
if (IS_ERR_VALUE(addr))
|
|
return addr;
|
|
|
|
if (addr > TASK_SIZE - len)
|
|
return -ENOMEM;
|
|
if (offset_in_page(addr))
|
|
return -EINVAL;
|
|
|
|
error = security_mmap_addr(addr);
|
|
return error ? error : addr;
|
|
}
|
|
|
|
EXPORT_SYMBOL(get_unmapped_area);
|
|
|
|
/**
|
|
* find_vma_intersection() - Look up the first VMA which intersects the interval
|
|
* @mm: The process address space.
|
|
* @start_addr: The inclusive start user address.
|
|
* @end_addr: The exclusive end user address.
|
|
*
|
|
* Returns: The first VMA within the provided range, %NULL otherwise. Assumes
|
|
* start_addr < end_addr.
|
|
*/
|
|
struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
|
|
unsigned long start_addr,
|
|
unsigned long end_addr)
|
|
{
|
|
unsigned long index = start_addr;
|
|
|
|
mmap_assert_locked(mm);
|
|
return mt_find(&mm->mm_mt, &index, end_addr - 1);
|
|
}
|
|
EXPORT_SYMBOL(find_vma_intersection);
|
|
|
|
/**
|
|
* find_vma() - Find the VMA for a given address, or the next VMA.
|
|
* @mm: The mm_struct to check
|
|
* @addr: The address
|
|
*
|
|
* Returns: The VMA associated with addr, or the next VMA.
|
|
* May return %NULL in the case of no VMA at addr or above.
|
|
*/
|
|
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
unsigned long index = addr;
|
|
|
|
mmap_assert_locked(mm);
|
|
return mt_find(&mm->mm_mt, &index, ULONG_MAX);
|
|
}
|
|
EXPORT_SYMBOL(find_vma);
|
|
|
|
/**
|
|
* find_vma_prev() - Find the VMA for a given address, or the next vma and
|
|
* set %pprev to the previous VMA, if any.
|
|
* @mm: The mm_struct to check
|
|
* @addr: The address
|
|
* @pprev: The pointer to set to the previous VMA
|
|
*
|
|
* Note that RCU lock is missing here since the external mmap_lock() is used
|
|
* instead.
|
|
*
|
|
* Returns: The VMA associated with @addr, or the next vma.
|
|
* May return %NULL in the case of no vma at addr or above.
|
|
*/
|
|
struct vm_area_struct *
|
|
find_vma_prev(struct mm_struct *mm, unsigned long addr,
|
|
struct vm_area_struct **pprev)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
MA_STATE(mas, &mm->mm_mt, addr, addr);
|
|
|
|
vma = mas_walk(&mas);
|
|
*pprev = mas_prev(&mas, 0);
|
|
if (!vma)
|
|
vma = mas_next(&mas, ULONG_MAX);
|
|
return vma;
|
|
}
|
|
|
|
/*
|
|
* Verify that the stack growth is acceptable and
|
|
* update accounting. This is shared with both the
|
|
* grow-up and grow-down cases.
|
|
*/
|
|
static int acct_stack_growth(struct vm_area_struct *vma,
|
|
unsigned long size, unsigned long grow)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
unsigned long new_start;
|
|
|
|
/* address space limit tests */
|
|
if (!may_expand_vm(mm, vma->vm_flags, grow))
|
|
return -ENOMEM;
|
|
|
|
/* Stack limit test */
|
|
if (size > rlimit(RLIMIT_STACK))
|
|
return -ENOMEM;
|
|
|
|
/* mlock limit tests */
|
|
if (!mlock_future_ok(mm, vma->vm_flags, grow << PAGE_SHIFT))
|
|
return -ENOMEM;
|
|
|
|
/* Check to ensure the stack will not grow into a hugetlb-only region */
|
|
new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
|
|
vma->vm_end - size;
|
|
if (is_hugepage_only_range(vma->vm_mm, new_start, size))
|
|
return -EFAULT;
|
|
|
|
/*
|
|
* Overcommit.. This must be the final test, as it will
|
|
* update security statistics.
|
|
*/
|
|
if (security_vm_enough_memory_mm(mm, grow))
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
#if defined(CONFIG_STACK_GROWSUP)
|
|
/*
|
|
* PA-RISC uses this for its stack.
|
|
* vma is the last one with address > vma->vm_end. Have to extend vma.
|
|
*/
|
|
static int expand_upwards(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct vm_area_struct *next;
|
|
unsigned long gap_addr;
|
|
int error = 0;
|
|
MA_STATE(mas, &mm->mm_mt, vma->vm_start, address);
|
|
|
|
if (!(vma->vm_flags & VM_GROWSUP))
|
|
return -EFAULT;
|
|
|
|
/* Guard against exceeding limits of the address space. */
|
|
address &= PAGE_MASK;
|
|
if (address >= (TASK_SIZE & PAGE_MASK))
|
|
return -ENOMEM;
|
|
address += PAGE_SIZE;
|
|
|
|
/* Enforce stack_guard_gap */
|
|
gap_addr = address + stack_guard_gap;
|
|
|
|
/* Guard against overflow */
|
|
if (gap_addr < address || gap_addr > TASK_SIZE)
|
|
gap_addr = TASK_SIZE;
|
|
|
|
next = find_vma_intersection(mm, vma->vm_end, gap_addr);
|
|
if (next && vma_is_accessible(next)) {
|
|
if (!(next->vm_flags & VM_GROWSUP))
|
|
return -ENOMEM;
|
|
/* Check that both stack segments have the same anon_vma? */
|
|
}
|
|
|
|
if (next)
|
|
mas_prev_range(&mas, address);
|
|
|
|
__mas_set_range(&mas, vma->vm_start, address - 1);
|
|
if (mas_preallocate(&mas, vma, GFP_KERNEL))
|
|
return -ENOMEM;
|
|
|
|
/* We must make sure the anon_vma is allocated. */
|
|
if (unlikely(anon_vma_prepare(vma))) {
|
|
mas_destroy(&mas);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* Lock the VMA before expanding to prevent concurrent page faults */
|
|
vma_start_write(vma);
|
|
/*
|
|
* vma->vm_start/vm_end cannot change under us because the caller
|
|
* is required to hold the mmap_lock in read mode. We need the
|
|
* anon_vma lock to serialize against concurrent expand_stacks.
|
|
*/
|
|
anon_vma_lock_write(vma->anon_vma);
|
|
|
|
/* Somebody else might have raced and expanded it already */
|
|
if (address > vma->vm_end) {
|
|
unsigned long size, grow;
|
|
|
|
size = address - vma->vm_start;
|
|
grow = (address - vma->vm_end) >> PAGE_SHIFT;
|
|
|
|
error = -ENOMEM;
|
|
if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
|
|
error = acct_stack_growth(vma, size, grow);
|
|
if (!error) {
|
|
/*
|
|
* We only hold a shared mmap_lock lock here, so
|
|
* we need to protect against concurrent vma
|
|
* expansions. anon_vma_lock_write() doesn't
|
|
* help here, as we don't guarantee that all
|
|
* growable vmas in a mm share the same root
|
|
* anon vma. So, we reuse mm->page_table_lock
|
|
* to guard against concurrent vma expansions.
|
|
*/
|
|
spin_lock(&mm->page_table_lock);
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
mm->locked_vm += grow;
|
|
vm_stat_account(mm, vma->vm_flags, grow);
|
|
anon_vma_interval_tree_pre_update_vma(vma);
|
|
vma->vm_end = address;
|
|
/* Overwrite old entry in mtree. */
|
|
mas_store_prealloc(&mas, vma);
|
|
anon_vma_interval_tree_post_update_vma(vma);
|
|
spin_unlock(&mm->page_table_lock);
|
|
|
|
perf_event_mmap(vma);
|
|
}
|
|
}
|
|
}
|
|
anon_vma_unlock_write(vma->anon_vma);
|
|
mas_destroy(&mas);
|
|
validate_mm(mm);
|
|
return error;
|
|
}
|
|
#endif /* CONFIG_STACK_GROWSUP */
|
|
|
|
/*
|
|
* vma is the first one with address < vma->vm_start. Have to extend vma.
|
|
* mmap_lock held for writing.
|
|
*/
|
|
int expand_downwards(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
MA_STATE(mas, &mm->mm_mt, vma->vm_start, vma->vm_start);
|
|
struct vm_area_struct *prev;
|
|
int error = 0;
|
|
|
|
if (!(vma->vm_flags & VM_GROWSDOWN))
|
|
return -EFAULT;
|
|
|
|
address &= PAGE_MASK;
|
|
if (address < mmap_min_addr || address < FIRST_USER_ADDRESS)
|
|
return -EPERM;
|
|
|
|
/* Enforce stack_guard_gap */
|
|
prev = mas_prev(&mas, 0);
|
|
/* Check that both stack segments have the same anon_vma? */
|
|
if (prev) {
|
|
if (!(prev->vm_flags & VM_GROWSDOWN) &&
|
|
vma_is_accessible(prev) &&
|
|
(address - prev->vm_end < stack_guard_gap))
|
|
return -ENOMEM;
|
|
}
|
|
|
|
if (prev)
|
|
mas_next_range(&mas, vma->vm_start);
|
|
|
|
__mas_set_range(&mas, address, vma->vm_end - 1);
|
|
if (mas_preallocate(&mas, vma, GFP_KERNEL))
|
|
return -ENOMEM;
|
|
|
|
/* We must make sure the anon_vma is allocated. */
|
|
if (unlikely(anon_vma_prepare(vma))) {
|
|
mas_destroy(&mas);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* Lock the VMA before expanding to prevent concurrent page faults */
|
|
vma_start_write(vma);
|
|
/*
|
|
* vma->vm_start/vm_end cannot change under us because the caller
|
|
* is required to hold the mmap_lock in read mode. We need the
|
|
* anon_vma lock to serialize against concurrent expand_stacks.
|
|
*/
|
|
anon_vma_lock_write(vma->anon_vma);
|
|
|
|
/* Somebody else might have raced and expanded it already */
|
|
if (address < vma->vm_start) {
|
|
unsigned long size, grow;
|
|
|
|
size = vma->vm_end - address;
|
|
grow = (vma->vm_start - address) >> PAGE_SHIFT;
|
|
|
|
error = -ENOMEM;
|
|
if (grow <= vma->vm_pgoff) {
|
|
error = acct_stack_growth(vma, size, grow);
|
|
if (!error) {
|
|
/*
|
|
* We only hold a shared mmap_lock lock here, so
|
|
* we need to protect against concurrent vma
|
|
* expansions. anon_vma_lock_write() doesn't
|
|
* help here, as we don't guarantee that all
|
|
* growable vmas in a mm share the same root
|
|
* anon vma. So, we reuse mm->page_table_lock
|
|
* to guard against concurrent vma expansions.
|
|
*/
|
|
spin_lock(&mm->page_table_lock);
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
mm->locked_vm += grow;
|
|
vm_stat_account(mm, vma->vm_flags, grow);
|
|
anon_vma_interval_tree_pre_update_vma(vma);
|
|
vma->vm_start = address;
|
|
vma->vm_pgoff -= grow;
|
|
/* Overwrite old entry in mtree. */
|
|
mas_store_prealloc(&mas, vma);
|
|
anon_vma_interval_tree_post_update_vma(vma);
|
|
spin_unlock(&mm->page_table_lock);
|
|
|
|
perf_event_mmap(vma);
|
|
}
|
|
}
|
|
}
|
|
anon_vma_unlock_write(vma->anon_vma);
|
|
mas_destroy(&mas);
|
|
validate_mm(mm);
|
|
return error;
|
|
}
|
|
|
|
/* enforced gap between the expanding stack and other mappings. */
|
|
unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
|
|
|
|
static int __init cmdline_parse_stack_guard_gap(char *p)
|
|
{
|
|
unsigned long val;
|
|
char *endptr;
|
|
|
|
val = simple_strtoul(p, &endptr, 10);
|
|
if (!*endptr)
|
|
stack_guard_gap = val << PAGE_SHIFT;
|
|
|
|
return 1;
|
|
}
|
|
__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
|
|
|
|
#ifdef CONFIG_STACK_GROWSUP
|
|
int expand_stack_locked(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
return expand_upwards(vma, address);
|
|
}
|
|
|
|
struct vm_area_struct *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
struct vm_area_struct *vma, *prev;
|
|
|
|
addr &= PAGE_MASK;
|
|
vma = find_vma_prev(mm, addr, &prev);
|
|
if (vma && (vma->vm_start <= addr))
|
|
return vma;
|
|
if (!prev)
|
|
return NULL;
|
|
if (expand_stack_locked(prev, addr))
|
|
return NULL;
|
|
if (prev->vm_flags & VM_LOCKED)
|
|
populate_vma_page_range(prev, addr, prev->vm_end, NULL);
|
|
return prev;
|
|
}
|
|
#else
|
|
int expand_stack_locked(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
return expand_downwards(vma, address);
|
|
}
|
|
|
|
struct vm_area_struct *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
unsigned long start;
|
|
|
|
addr &= PAGE_MASK;
|
|
vma = find_vma(mm, addr);
|
|
if (!vma)
|
|
return NULL;
|
|
if (vma->vm_start <= addr)
|
|
return vma;
|
|
start = vma->vm_start;
|
|
if (expand_stack_locked(vma, addr))
|
|
return NULL;
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
populate_vma_page_range(vma, addr, start, NULL);
|
|
return vma;
|
|
}
|
|
#endif
|
|
|
|
#if defined(CONFIG_STACK_GROWSUP)
|
|
|
|
#define vma_expand_up(vma,addr) expand_upwards(vma, addr)
|
|
#define vma_expand_down(vma, addr) (-EFAULT)
|
|
|
|
#else
|
|
|
|
#define vma_expand_up(vma,addr) (-EFAULT)
|
|
#define vma_expand_down(vma, addr) expand_downwards(vma, addr)
|
|
|
|
#endif
|
|
|
|
/*
|
|
* expand_stack(): legacy interface for page faulting. Don't use unless
|
|
* you have to.
|
|
*
|
|
* This is called with the mm locked for reading, drops the lock, takes
|
|
* the lock for writing, tries to look up a vma again, expands it if
|
|
* necessary, and downgrades the lock to reading again.
|
|
*
|
|
* If no vma is found or it can't be expanded, it returns NULL and has
|
|
* dropped the lock.
|
|
*/
|
|
struct vm_area_struct *expand_stack(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
struct vm_area_struct *vma, *prev;
|
|
|
|
mmap_read_unlock(mm);
|
|
if (mmap_write_lock_killable(mm))
|
|
return NULL;
|
|
|
|
vma = find_vma_prev(mm, addr, &prev);
|
|
if (vma && vma->vm_start <= addr)
|
|
goto success;
|
|
|
|
if (prev && !vma_expand_up(prev, addr)) {
|
|
vma = prev;
|
|
goto success;
|
|
}
|
|
|
|
if (vma && !vma_expand_down(vma, addr))
|
|
goto success;
|
|
|
|
mmap_write_unlock(mm);
|
|
return NULL;
|
|
|
|
success:
|
|
mmap_write_downgrade(mm);
|
|
return vma;
|
|
}
|
|
|
|
/*
|
|
* Ok - we have the memory areas we should free on a maple tree so release them,
|
|
* and do the vma updates.
|
|
*
|
|
* Called with the mm semaphore held.
|
|
*/
|
|
static inline void remove_mt(struct mm_struct *mm, struct ma_state *mas)
|
|
{
|
|
unsigned long nr_accounted = 0;
|
|
struct vm_area_struct *vma;
|
|
|
|
/* Update high watermark before we lower total_vm */
|
|
update_hiwater_vm(mm);
|
|
mas_for_each(mas, vma, ULONG_MAX) {
|
|
long nrpages = vma_pages(vma);
|
|
|
|
if (vma->vm_flags & VM_ACCOUNT)
|
|
nr_accounted += nrpages;
|
|
vm_stat_account(mm, vma->vm_flags, -nrpages);
|
|
remove_vma(vma, false);
|
|
}
|
|
vm_unacct_memory(nr_accounted);
|
|
}
|
|
|
|
/*
|
|
* Get rid of page table information in the indicated region.
|
|
*
|
|
* Called with the mm semaphore held.
|
|
*/
|
|
static void unmap_region(struct mm_struct *mm, struct ma_state *mas,
|
|
struct vm_area_struct *vma, struct vm_area_struct *prev,
|
|
struct vm_area_struct *next, unsigned long start,
|
|
unsigned long end, unsigned long tree_end, bool mm_wr_locked)
|
|
{
|
|
struct mmu_gather tlb;
|
|
unsigned long mt_start = mas->index;
|
|
|
|
lru_add_drain();
|
|
tlb_gather_mmu(&tlb, mm);
|
|
update_hiwater_rss(mm);
|
|
unmap_vmas(&tlb, mas, vma, start, end, tree_end, mm_wr_locked);
|
|
mas_set(mas, mt_start);
|
|
free_pgtables(&tlb, mas, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
|
|
next ? next->vm_start : USER_PGTABLES_CEILING,
|
|
mm_wr_locked);
|
|
tlb_finish_mmu(&tlb);
|
|
}
|
|
|
|
/*
|
|
* __split_vma() bypasses sysctl_max_map_count checking. We use this where it
|
|
* has already been checked or doesn't make sense to fail.
|
|
* VMA Iterator will point to the end VMA.
|
|
*/
|
|
static int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
|
|
unsigned long addr, int new_below)
|
|
{
|
|
struct vma_prepare vp;
|
|
struct vm_area_struct *new;
|
|
int err;
|
|
|
|
WARN_ON(vma->vm_start >= addr);
|
|
WARN_ON(vma->vm_end <= addr);
|
|
|
|
if (vma->vm_ops && vma->vm_ops->may_split) {
|
|
err = vma->vm_ops->may_split(vma, addr);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
new = vm_area_dup(vma);
|
|
if (!new)
|
|
return -ENOMEM;
|
|
|
|
if (new_below) {
|
|
new->vm_end = addr;
|
|
} else {
|
|
new->vm_start = addr;
|
|
new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
|
|
}
|
|
|
|
err = -ENOMEM;
|
|
vma_iter_config(vmi, new->vm_start, new->vm_end);
|
|
if (vma_iter_prealloc(vmi, new))
|
|
goto out_free_vma;
|
|
|
|
err = vma_dup_policy(vma, new);
|
|
if (err)
|
|
goto out_free_vmi;
|
|
|
|
err = anon_vma_clone(new, vma);
|
|
if (err)
|
|
goto out_free_mpol;
|
|
|
|
if (new->vm_file)
|
|
get_file(new->vm_file);
|
|
|
|
if (new->vm_ops && new->vm_ops->open)
|
|
new->vm_ops->open(new);
|
|
|
|
vma_start_write(vma);
|
|
vma_start_write(new);
|
|
|
|
init_vma_prep(&vp, vma);
|
|
vp.insert = new;
|
|
vma_prepare(&vp);
|
|
vma_adjust_trans_huge(vma, vma->vm_start, addr, 0);
|
|
|
|
if (new_below) {
|
|
vma->vm_start = addr;
|
|
vma->vm_pgoff += (addr - new->vm_start) >> PAGE_SHIFT;
|
|
} else {
|
|
vma->vm_end = addr;
|
|
}
|
|
|
|
/* vma_complete stores the new vma */
|
|
vma_complete(&vp, vmi, vma->vm_mm);
|
|
|
|
/* Success. */
|
|
if (new_below)
|
|
vma_next(vmi);
|
|
return 0;
|
|
|
|
out_free_mpol:
|
|
mpol_put(vma_policy(new));
|
|
out_free_vmi:
|
|
vma_iter_free(vmi);
|
|
out_free_vma:
|
|
vm_area_free(new);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Split a vma into two pieces at address 'addr', a new vma is allocated
|
|
* either for the first part or the tail.
|
|
*/
|
|
static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
|
|
unsigned long addr, int new_below)
|
|
{
|
|
if (vma->vm_mm->map_count >= sysctl_max_map_count)
|
|
return -ENOMEM;
|
|
|
|
return __split_vma(vmi, vma, addr, new_below);
|
|
}
|
|
|
|
/*
|
|
* We are about to modify one or multiple of a VMA's flags, policy, userfaultfd
|
|
* context and anonymous VMA name within the range [start, end).
|
|
*
|
|
* As a result, we might be able to merge the newly modified VMA range with an
|
|
* adjacent VMA with identical properties.
|
|
*
|
|
* If no merge is possible and the range does not span the entirety of the VMA,
|
|
* we then need to split the VMA to accommodate the change.
|
|
*
|
|
* The function returns either the merged VMA, the original VMA if a split was
|
|
* required instead, or an error if the split failed.
|
|
*/
|
|
struct vm_area_struct *vma_modify(struct vma_iterator *vmi,
|
|
struct vm_area_struct *prev,
|
|
struct vm_area_struct *vma,
|
|
unsigned long start, unsigned long end,
|
|
unsigned long vm_flags,
|
|
struct mempolicy *policy,
|
|
struct vm_userfaultfd_ctx uffd_ctx,
|
|
struct anon_vma_name *anon_name)
|
|
{
|
|
pgoff_t pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
|
|
struct vm_area_struct *merged;
|
|
|
|
merged = vma_merge(vmi, prev, vma, start, end, vm_flags,
|
|
pgoff, policy, uffd_ctx, anon_name);
|
|
if (merged)
|
|
return merged;
|
|
|
|
if (vma->vm_start < start) {
|
|
int err = split_vma(vmi, vma, start, 1);
|
|
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
if (vma->vm_end > end) {
|
|
int err = split_vma(vmi, vma, end, 0);
|
|
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
return vma;
|
|
}
|
|
|
|
/*
|
|
* Attempt to merge a newly mapped VMA with those adjacent to it. The caller
|
|
* must ensure that [start, end) does not overlap any existing VMA.
|
|
*/
|
|
static struct vm_area_struct
|
|
*vma_merge_new_vma(struct vma_iterator *vmi, struct vm_area_struct *prev,
|
|
struct vm_area_struct *vma, unsigned long start,
|
|
unsigned long end, pgoff_t pgoff)
|
|
{
|
|
return vma_merge(vmi, prev, vma, start, end, vma->vm_flags, pgoff,
|
|
vma_policy(vma), vma->vm_userfaultfd_ctx, anon_vma_name(vma));
|
|
}
|
|
|
|
/*
|
|
* Expand vma by delta bytes, potentially merging with an immediately adjacent
|
|
* VMA with identical properties.
|
|
*/
|
|
struct vm_area_struct *vma_merge_extend(struct vma_iterator *vmi,
|
|
struct vm_area_struct *vma,
|
|
unsigned long delta)
|
|
{
|
|
pgoff_t pgoff = vma->vm_pgoff + vma_pages(vma);
|
|
|
|
/* vma is specified as prev, so case 1 or 2 will apply. */
|
|
return vma_merge(vmi, vma, vma, vma->vm_end, vma->vm_end + delta,
|
|
vma->vm_flags, pgoff, vma_policy(vma),
|
|
vma->vm_userfaultfd_ctx, anon_vma_name(vma));
|
|
}
|
|
|
|
/*
|
|
* do_vmi_align_munmap() - munmap the aligned region from @start to @end.
|
|
* @vmi: The vma iterator
|
|
* @vma: The starting vm_area_struct
|
|
* @mm: The mm_struct
|
|
* @start: The aligned start address to munmap.
|
|
* @end: The aligned end address to munmap.
|
|
* @uf: The userfaultfd list_head
|
|
* @unlock: Set to true to drop the mmap_lock. unlocking only happens on
|
|
* success.
|
|
*
|
|
* Return: 0 on success and drops the lock if so directed, error and leaves the
|
|
* lock held otherwise.
|
|
*/
|
|
static int
|
|
do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
|
|
struct mm_struct *mm, unsigned long start,
|
|
unsigned long end, struct list_head *uf, bool unlock)
|
|
{
|
|
struct vm_area_struct *prev, *next = NULL;
|
|
struct maple_tree mt_detach;
|
|
int count = 0;
|
|
int error = -ENOMEM;
|
|
unsigned long locked_vm = 0;
|
|
MA_STATE(mas_detach, &mt_detach, 0, 0);
|
|
mt_init_flags(&mt_detach, vmi->mas.tree->ma_flags & MT_FLAGS_LOCK_MASK);
|
|
mt_on_stack(mt_detach);
|
|
|
|
/*
|
|
* If we need to split any vma, do it now to save pain later.
|
|
*
|
|
* Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
|
|
* unmapped vm_area_struct will remain in use: so lower split_vma
|
|
* places tmp vma above, and higher split_vma places tmp vma below.
|
|
*/
|
|
|
|
/* Does it split the first one? */
|
|
if (start > vma->vm_start) {
|
|
|
|
/*
|
|
* Make sure that map_count on return from munmap() will
|
|
* not exceed its limit; but let map_count go just above
|
|
* its limit temporarily, to help free resources as expected.
|
|
*/
|
|
if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
|
|
goto map_count_exceeded;
|
|
|
|
error = __split_vma(vmi, vma, start, 1);
|
|
if (error)
|
|
goto start_split_failed;
|
|
}
|
|
|
|
/*
|
|
* Detach a range of VMAs from the mm. Using next as a temp variable as
|
|
* it is always overwritten.
|
|
*/
|
|
next = vma;
|
|
do {
|
|
/* Does it split the end? */
|
|
if (next->vm_end > end) {
|
|
error = __split_vma(vmi, next, end, 0);
|
|
if (error)
|
|
goto end_split_failed;
|
|
}
|
|
vma_start_write(next);
|
|
mas_set(&mas_detach, count);
|
|
error = mas_store_gfp(&mas_detach, next, GFP_KERNEL);
|
|
if (error)
|
|
goto munmap_gather_failed;
|
|
vma_mark_detached(next, true);
|
|
if (next->vm_flags & VM_LOCKED)
|
|
locked_vm += vma_pages(next);
|
|
|
|
count++;
|
|
if (unlikely(uf)) {
|
|
/*
|
|
* If userfaultfd_unmap_prep returns an error the vmas
|
|
* will remain split, but userland will get a
|
|
* highly unexpected error anyway. This is no
|
|
* different than the case where the first of the two
|
|
* __split_vma fails, but we don't undo the first
|
|
* split, despite we could. This is unlikely enough
|
|
* failure that it's not worth optimizing it for.
|
|
*/
|
|
error = userfaultfd_unmap_prep(next, start, end, uf);
|
|
|
|
if (error)
|
|
goto userfaultfd_error;
|
|
}
|
|
#ifdef CONFIG_DEBUG_VM_MAPLE_TREE
|
|
BUG_ON(next->vm_start < start);
|
|
BUG_ON(next->vm_start > end);
|
|
#endif
|
|
} for_each_vma_range(*vmi, next, end);
|
|
|
|
#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
|
|
/* Make sure no VMAs are about to be lost. */
|
|
{
|
|
MA_STATE(test, &mt_detach, 0, 0);
|
|
struct vm_area_struct *vma_mas, *vma_test;
|
|
int test_count = 0;
|
|
|
|
vma_iter_set(vmi, start);
|
|
rcu_read_lock();
|
|
vma_test = mas_find(&test, count - 1);
|
|
for_each_vma_range(*vmi, vma_mas, end) {
|
|
BUG_ON(vma_mas != vma_test);
|
|
test_count++;
|
|
vma_test = mas_next(&test, count - 1);
|
|
}
|
|
rcu_read_unlock();
|
|
BUG_ON(count != test_count);
|
|
}
|
|
#endif
|
|
|
|
while (vma_iter_addr(vmi) > start)
|
|
vma_iter_prev_range(vmi);
|
|
|
|
error = vma_iter_clear_gfp(vmi, start, end, GFP_KERNEL);
|
|
if (error)
|
|
goto clear_tree_failed;
|
|
|
|
/* Point of no return */
|
|
mm->locked_vm -= locked_vm;
|
|
mm->map_count -= count;
|
|
if (unlock)
|
|
mmap_write_downgrade(mm);
|
|
|
|
prev = vma_iter_prev_range(vmi);
|
|
next = vma_next(vmi);
|
|
if (next)
|
|
vma_iter_prev_range(vmi);
|
|
|
|
/*
|
|
* We can free page tables without write-locking mmap_lock because VMAs
|
|
* were isolated before we downgraded mmap_lock.
|
|
*/
|
|
mas_set(&mas_detach, 1);
|
|
unmap_region(mm, &mas_detach, vma, prev, next, start, end, count,
|
|
!unlock);
|
|
/* Statistics and freeing VMAs */
|
|
mas_set(&mas_detach, 0);
|
|
remove_mt(mm, &mas_detach);
|
|
validate_mm(mm);
|
|
if (unlock)
|
|
mmap_read_unlock(mm);
|
|
|
|
__mt_destroy(&mt_detach);
|
|
return 0;
|
|
|
|
clear_tree_failed:
|
|
userfaultfd_error:
|
|
munmap_gather_failed:
|
|
end_split_failed:
|
|
mas_set(&mas_detach, 0);
|
|
mas_for_each(&mas_detach, next, end)
|
|
vma_mark_detached(next, false);
|
|
|
|
__mt_destroy(&mt_detach);
|
|
start_split_failed:
|
|
map_count_exceeded:
|
|
validate_mm(mm);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* do_vmi_munmap() - munmap a given range.
|
|
* @vmi: The vma iterator
|
|
* @mm: The mm_struct
|
|
* @start: The start address to munmap
|
|
* @len: The length of the range to munmap
|
|
* @uf: The userfaultfd list_head
|
|
* @unlock: set to true if the user wants to drop the mmap_lock on success
|
|
*
|
|
* This function takes a @mas that is either pointing to the previous VMA or set
|
|
* to MA_START and sets it up to remove the mapping(s). The @len will be
|
|
* aligned and any arch_unmap work will be preformed.
|
|
*
|
|
* Return: 0 on success and drops the lock if so directed, error and leaves the
|
|
* lock held otherwise.
|
|
*/
|
|
int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
|
|
unsigned long start, size_t len, struct list_head *uf,
|
|
bool unlock)
|
|
{
|
|
unsigned long end;
|
|
struct vm_area_struct *vma;
|
|
|
|
if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
|
|
return -EINVAL;
|
|
|
|
end = start + PAGE_ALIGN(len);
|
|
if (end == start)
|
|
return -EINVAL;
|
|
|
|
/* arch_unmap() might do unmaps itself. */
|
|
arch_unmap(mm, start, end);
|
|
|
|
/* Find the first overlapping VMA */
|
|
vma = vma_find(vmi, end);
|
|
if (!vma) {
|
|
if (unlock)
|
|
mmap_write_unlock(mm);
|
|
return 0;
|
|
}
|
|
|
|
return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock);
|
|
}
|
|
|
|
/* do_munmap() - Wrapper function for non-maple tree aware do_munmap() calls.
|
|
* @mm: The mm_struct
|
|
* @start: The start address to munmap
|
|
* @len: The length to be munmapped.
|
|
* @uf: The userfaultfd list_head
|
|
*
|
|
* Return: 0 on success, error otherwise.
|
|
*/
|
|
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
|
|
struct list_head *uf)
|
|
{
|
|
VMA_ITERATOR(vmi, mm, start);
|
|
|
|
return do_vmi_munmap(&vmi, mm, start, len, uf, false);
|
|
}
|
|
|
|
unsigned long mmap_region(struct file *file, unsigned long addr,
|
|
unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
|
|
struct list_head *uf)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma = NULL;
|
|
struct vm_area_struct *next, *prev, *merge;
|
|
pgoff_t pglen = len >> PAGE_SHIFT;
|
|
unsigned long charged = 0;
|
|
unsigned long end = addr + len;
|
|
unsigned long merge_start = addr, merge_end = end;
|
|
bool writable_file_mapping = false;
|
|
pgoff_t vm_pgoff;
|
|
int error;
|
|
VMA_ITERATOR(vmi, mm, addr);
|
|
|
|
/* Check against address space limit. */
|
|
if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
|
|
unsigned long nr_pages;
|
|
|
|
/*
|
|
* MAP_FIXED may remove pages of mappings that intersects with
|
|
* requested mapping. Account for the pages it would unmap.
|
|
*/
|
|
nr_pages = count_vma_pages_range(mm, addr, end);
|
|
|
|
if (!may_expand_vm(mm, vm_flags,
|
|
(len >> PAGE_SHIFT) - nr_pages))
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* Unmap any existing mapping in the area */
|
|
if (do_vmi_munmap(&vmi, mm, addr, len, uf, false))
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* Private writable mapping: check memory availability
|
|
*/
|
|
if (accountable_mapping(file, vm_flags)) {
|
|
charged = len >> PAGE_SHIFT;
|
|
if (security_vm_enough_memory_mm(mm, charged))
|
|
return -ENOMEM;
|
|
vm_flags |= VM_ACCOUNT;
|
|
}
|
|
|
|
next = vma_next(&vmi);
|
|
prev = vma_prev(&vmi);
|
|
if (vm_flags & VM_SPECIAL) {
|
|
if (prev)
|
|
vma_iter_next_range(&vmi);
|
|
goto cannot_expand;
|
|
}
|
|
|
|
/* Attempt to expand an old mapping */
|
|
/* Check next */
|
|
if (next && next->vm_start == end && !vma_policy(next) &&
|
|
can_vma_merge_before(next, vm_flags, NULL, file, pgoff+pglen,
|
|
NULL_VM_UFFD_CTX, NULL)) {
|
|
merge_end = next->vm_end;
|
|
vma = next;
|
|
vm_pgoff = next->vm_pgoff - pglen;
|
|
}
|
|
|
|
/* Check prev */
|
|
if (prev && prev->vm_end == addr && !vma_policy(prev) &&
|
|
(vma ? can_vma_merge_after(prev, vm_flags, vma->anon_vma, file,
|
|
pgoff, vma->vm_userfaultfd_ctx, NULL) :
|
|
can_vma_merge_after(prev, vm_flags, NULL, file, pgoff,
|
|
NULL_VM_UFFD_CTX, NULL))) {
|
|
merge_start = prev->vm_start;
|
|
vma = prev;
|
|
vm_pgoff = prev->vm_pgoff;
|
|
} else if (prev) {
|
|
vma_iter_next_range(&vmi);
|
|
}
|
|
|
|
/* Actually expand, if possible */
|
|
if (vma &&
|
|
!vma_expand(&vmi, vma, merge_start, merge_end, vm_pgoff, next)) {
|
|
khugepaged_enter_vma(vma, vm_flags);
|
|
goto expanded;
|
|
}
|
|
|
|
if (vma == prev)
|
|
vma_iter_set(&vmi, addr);
|
|
cannot_expand:
|
|
|
|
/*
|
|
* Determine the object being mapped and call the appropriate
|
|
* specific mapper. the address has already been validated, but
|
|
* not unmapped, but the maps are removed from the list.
|
|
*/
|
|
vma = vm_area_alloc(mm);
|
|
if (!vma) {
|
|
error = -ENOMEM;
|
|
goto unacct_error;
|
|
}
|
|
|
|
vma_iter_config(&vmi, addr, end);
|
|
vma_set_range(vma, addr, end, pgoff);
|
|
vm_flags_init(vma, vm_flags);
|
|
vma->vm_page_prot = vm_get_page_prot(vm_flags);
|
|
|
|
if (file) {
|
|
vma->vm_file = get_file(file);
|
|
error = call_mmap(file, vma);
|
|
if (error)
|
|
goto unmap_and_free_vma;
|
|
|
|
if (vma_is_shared_maywrite(vma)) {
|
|
error = mapping_map_writable(file->f_mapping);
|
|
if (error)
|
|
goto close_and_free_vma;
|
|
|
|
writable_file_mapping = true;
|
|
}
|
|
|
|
/*
|
|
* Expansion is handled above, merging is handled below.
|
|
* Drivers should not alter the address of the VMA.
|
|
*/
|
|
error = -EINVAL;
|
|
if (WARN_ON((addr != vma->vm_start)))
|
|
goto close_and_free_vma;
|
|
|
|
vma_iter_config(&vmi, addr, end);
|
|
/*
|
|
* If vm_flags changed after call_mmap(), we should try merge
|
|
* vma again as we may succeed this time.
|
|
*/
|
|
if (unlikely(vm_flags != vma->vm_flags && prev)) {
|
|
merge = vma_merge_new_vma(&vmi, prev, vma,
|
|
vma->vm_start, vma->vm_end,
|
|
vma->vm_pgoff);
|
|
if (merge) {
|
|
/*
|
|
* ->mmap() can change vma->vm_file and fput
|
|
* the original file. So fput the vma->vm_file
|
|
* here or we would add an extra fput for file
|
|
* and cause general protection fault
|
|
* ultimately.
|
|
*/
|
|
fput(vma->vm_file);
|
|
vm_area_free(vma);
|
|
vma = merge;
|
|
/* Update vm_flags to pick up the change. */
|
|
vm_flags = vma->vm_flags;
|
|
goto unmap_writable;
|
|
}
|
|
}
|
|
|
|
vm_flags = vma->vm_flags;
|
|
} else if (vm_flags & VM_SHARED) {
|
|
error = shmem_zero_setup(vma);
|
|
if (error)
|
|
goto free_vma;
|
|
} else {
|
|
vma_set_anonymous(vma);
|
|
}
|
|
|
|
if (map_deny_write_exec(vma, vma->vm_flags)) {
|
|
error = -EACCES;
|
|
goto close_and_free_vma;
|
|
}
|
|
|
|
/* Allow architectures to sanity-check the vm_flags */
|
|
error = -EINVAL;
|
|
if (!arch_validate_flags(vma->vm_flags))
|
|
goto close_and_free_vma;
|
|
|
|
error = -ENOMEM;
|
|
if (vma_iter_prealloc(&vmi, vma))
|
|
goto close_and_free_vma;
|
|
|
|
/* Lock the VMA since it is modified after insertion into VMA tree */
|
|
vma_start_write(vma);
|
|
vma_iter_store(&vmi, vma);
|
|
mm->map_count++;
|
|
vma_link_file(vma);
|
|
|
|
/*
|
|
* vma_merge() calls khugepaged_enter_vma() either, the below
|
|
* call covers the non-merge case.
|
|
*/
|
|
khugepaged_enter_vma(vma, vma->vm_flags);
|
|
|
|
/* Once vma denies write, undo our temporary denial count */
|
|
unmap_writable:
|
|
if (writable_file_mapping)
|
|
mapping_unmap_writable(file->f_mapping);
|
|
file = vma->vm_file;
|
|
ksm_add_vma(vma);
|
|
expanded:
|
|
perf_event_mmap(vma);
|
|
|
|
vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
|
|
if (vm_flags & VM_LOCKED) {
|
|
if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
|
|
is_vm_hugetlb_page(vma) ||
|
|
vma == get_gate_vma(current->mm))
|
|
vm_flags_clear(vma, VM_LOCKED_MASK);
|
|
else
|
|
mm->locked_vm += (len >> PAGE_SHIFT);
|
|
}
|
|
|
|
if (file)
|
|
uprobe_mmap(vma);
|
|
|
|
/*
|
|
* New (or expanded) vma always get soft dirty status.
|
|
* Otherwise user-space soft-dirty page tracker won't
|
|
* be able to distinguish situation when vma area unmapped,
|
|
* then new mapped in-place (which must be aimed as
|
|
* a completely new data area).
|
|
*/
|
|
vm_flags_set(vma, VM_SOFTDIRTY);
|
|
|
|
vma_set_page_prot(vma);
|
|
|
|
validate_mm(mm);
|
|
return addr;
|
|
|
|
close_and_free_vma:
|
|
if (file && vma->vm_ops && vma->vm_ops->close)
|
|
vma->vm_ops->close(vma);
|
|
|
|
if (file || vma->vm_file) {
|
|
unmap_and_free_vma:
|
|
fput(vma->vm_file);
|
|
vma->vm_file = NULL;
|
|
|
|
vma_iter_set(&vmi, vma->vm_end);
|
|
/* Undo any partial mapping done by a device driver. */
|
|
unmap_region(mm, &vmi.mas, vma, prev, next, vma->vm_start,
|
|
vma->vm_end, vma->vm_end, true);
|
|
}
|
|
if (writable_file_mapping)
|
|
mapping_unmap_writable(file->f_mapping);
|
|
free_vma:
|
|
vm_area_free(vma);
|
|
unacct_error:
|
|
if (charged)
|
|
vm_unacct_memory(charged);
|
|
validate_mm(mm);
|
|
return error;
|
|
}
|
|
|
|
static int __vm_munmap(unsigned long start, size_t len, bool unlock)
|
|
{
|
|
int ret;
|
|
struct mm_struct *mm = current->mm;
|
|
LIST_HEAD(uf);
|
|
VMA_ITERATOR(vmi, mm, start);
|
|
|
|
if (mmap_write_lock_killable(mm))
|
|
return -EINTR;
|
|
|
|
ret = do_vmi_munmap(&vmi, mm, start, len, &uf, unlock);
|
|
if (ret || !unlock)
|
|
mmap_write_unlock(mm);
|
|
|
|
userfaultfd_unmap_complete(mm, &uf);
|
|
return ret;
|
|
}
|
|
|
|
int vm_munmap(unsigned long start, size_t len)
|
|
{
|
|
return __vm_munmap(start, len, false);
|
|
}
|
|
EXPORT_SYMBOL(vm_munmap);
|
|
|
|
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
|
|
{
|
|
addr = untagged_addr(addr);
|
|
return __vm_munmap(addr, len, true);
|
|
}
|
|
|
|
|
|
/*
|
|
* Emulation of deprecated remap_file_pages() syscall.
|
|
*/
|
|
SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
|
|
unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
|
|
{
|
|
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma;
|
|
unsigned long populate = 0;
|
|
unsigned long ret = -EINVAL;
|
|
struct file *file;
|
|
|
|
pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/mm/remap_file_pages.rst.\n",
|
|
current->comm, current->pid);
|
|
|
|
if (prot)
|
|
return ret;
|
|
start = start & PAGE_MASK;
|
|
size = size & PAGE_MASK;
|
|
|
|
if (start + size <= start)
|
|
return ret;
|
|
|
|
/* Does pgoff wrap? */
|
|
if (pgoff + (size >> PAGE_SHIFT) < pgoff)
|
|
return ret;
|
|
|
|
if (mmap_write_lock_killable(mm))
|
|
return -EINTR;
|
|
|
|
vma = vma_lookup(mm, start);
|
|
|
|
if (!vma || !(vma->vm_flags & VM_SHARED))
|
|
goto out;
|
|
|
|
if (start + size > vma->vm_end) {
|
|
VMA_ITERATOR(vmi, mm, vma->vm_end);
|
|
struct vm_area_struct *next, *prev = vma;
|
|
|
|
for_each_vma_range(vmi, next, start + size) {
|
|
/* hole between vmas ? */
|
|
if (next->vm_start != prev->vm_end)
|
|
goto out;
|
|
|
|
if (next->vm_file != vma->vm_file)
|
|
goto out;
|
|
|
|
if (next->vm_flags != vma->vm_flags)
|
|
goto out;
|
|
|
|
if (start + size <= next->vm_end)
|
|
break;
|
|
|
|
prev = next;
|
|
}
|
|
|
|
if (!next)
|
|
goto out;
|
|
}
|
|
|
|
prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
|
|
prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
|
|
prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
|
|
|
|
flags &= MAP_NONBLOCK;
|
|
flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
flags |= MAP_LOCKED;
|
|
|
|
file = get_file(vma->vm_file);
|
|
ret = do_mmap(vma->vm_file, start, size,
|
|
prot, flags, 0, pgoff, &populate, NULL);
|
|
fput(file);
|
|
out:
|
|
mmap_write_unlock(mm);
|
|
if (populate)
|
|
mm_populate(ret, populate);
|
|
if (!IS_ERR_VALUE(ret))
|
|
ret = 0;
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* do_vma_munmap() - Unmap a full or partial vma.
|
|
* @vmi: The vma iterator pointing at the vma
|
|
* @vma: The first vma to be munmapped
|
|
* @start: the start of the address to unmap
|
|
* @end: The end of the address to unmap
|
|
* @uf: The userfaultfd list_head
|
|
* @unlock: Drop the lock on success
|
|
*
|
|
* unmaps a VMA mapping when the vma iterator is already in position.
|
|
* Does not handle alignment.
|
|
*
|
|
* Return: 0 on success drops the lock of so directed, error on failure and will
|
|
* still hold the lock.
|
|
*/
|
|
int do_vma_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
|
|
unsigned long start, unsigned long end, struct list_head *uf,
|
|
bool unlock)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
|
|
arch_unmap(mm, start, end);
|
|
return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock);
|
|
}
|
|
|
|
/*
|
|
* do_brk_flags() - Increase the brk vma if the flags match.
|
|
* @vmi: The vma iterator
|
|
* @addr: The start address
|
|
* @len: The length of the increase
|
|
* @vma: The vma,
|
|
* @flags: The VMA Flags
|
|
*
|
|
* Extend the brk VMA from addr to addr + len. If the VMA is NULL or the flags
|
|
* do not match then create a new anonymous VMA. Eventually we may be able to
|
|
* do some brk-specific accounting here.
|
|
*/
|
|
static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
|
|
unsigned long addr, unsigned long len, unsigned long flags)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vma_prepare vp;
|
|
|
|
/*
|
|
* Check against address space limits by the changed size
|
|
* Note: This happens *after* clearing old mappings in some code paths.
|
|
*/
|
|
flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
|
|
if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
|
|
return -ENOMEM;
|
|
|
|
if (mm->map_count > sysctl_max_map_count)
|
|
return -ENOMEM;
|
|
|
|
if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* Expand the existing vma if possible; Note that singular lists do not
|
|
* occur after forking, so the expand will only happen on new VMAs.
|
|
*/
|
|
if (vma && vma->vm_end == addr && !vma_policy(vma) &&
|
|
can_vma_merge_after(vma, flags, NULL, NULL,
|
|
addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) {
|
|
vma_iter_config(vmi, vma->vm_start, addr + len);
|
|
if (vma_iter_prealloc(vmi, vma))
|
|
goto unacct_fail;
|
|
|
|
vma_start_write(vma);
|
|
|
|
init_vma_prep(&vp, vma);
|
|
vma_prepare(&vp);
|
|
vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
|
|
vma->vm_end = addr + len;
|
|
vm_flags_set(vma, VM_SOFTDIRTY);
|
|
vma_iter_store(vmi, vma);
|
|
|
|
vma_complete(&vp, vmi, mm);
|
|
khugepaged_enter_vma(vma, flags);
|
|
goto out;
|
|
}
|
|
|
|
if (vma)
|
|
vma_iter_next_range(vmi);
|
|
/* create a vma struct for an anonymous mapping */
|
|
vma = vm_area_alloc(mm);
|
|
if (!vma)
|
|
goto unacct_fail;
|
|
|
|
vma_set_anonymous(vma);
|
|
vma_set_range(vma, addr, addr + len, addr >> PAGE_SHIFT);
|
|
vm_flags_init(vma, flags);
|
|
vma->vm_page_prot = vm_get_page_prot(flags);
|
|
vma_start_write(vma);
|
|
if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL))
|
|
goto mas_store_fail;
|
|
|
|
mm->map_count++;
|
|
validate_mm(mm);
|
|
ksm_add_vma(vma);
|
|
out:
|
|
perf_event_mmap(vma);
|
|
mm->total_vm += len >> PAGE_SHIFT;
|
|
mm->data_vm += len >> PAGE_SHIFT;
|
|
if (flags & VM_LOCKED)
|
|
mm->locked_vm += (len >> PAGE_SHIFT);
|
|
vm_flags_set(vma, VM_SOFTDIRTY);
|
|
return 0;
|
|
|
|
mas_store_fail:
|
|
vm_area_free(vma);
|
|
unacct_fail:
|
|
vm_unacct_memory(len >> PAGE_SHIFT);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma = NULL;
|
|
unsigned long len;
|
|
int ret;
|
|
bool populate;
|
|
LIST_HEAD(uf);
|
|
VMA_ITERATOR(vmi, mm, addr);
|
|
|
|
len = PAGE_ALIGN(request);
|
|
if (len < request)
|
|
return -ENOMEM;
|
|
if (!len)
|
|
return 0;
|
|
|
|
/* Until we need other flags, refuse anything except VM_EXEC. */
|
|
if ((flags & (~VM_EXEC)) != 0)
|
|
return -EINVAL;
|
|
|
|
if (mmap_write_lock_killable(mm))
|
|
return -EINTR;
|
|
|
|
ret = check_brk_limits(addr, len);
|
|
if (ret)
|
|
goto limits_failed;
|
|
|
|
ret = do_vmi_munmap(&vmi, mm, addr, len, &uf, 0);
|
|
if (ret)
|
|
goto munmap_failed;
|
|
|
|
vma = vma_prev(&vmi);
|
|
ret = do_brk_flags(&vmi, vma, addr, len, flags);
|
|
populate = ((mm->def_flags & VM_LOCKED) != 0);
|
|
mmap_write_unlock(mm);
|
|
userfaultfd_unmap_complete(mm, &uf);
|
|
if (populate && !ret)
|
|
mm_populate(addr, len);
|
|
return ret;
|
|
|
|
munmap_failed:
|
|
limits_failed:
|
|
mmap_write_unlock(mm);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(vm_brk_flags);
|
|
|
|
/* Release all mmaps. */
|
|
void exit_mmap(struct mm_struct *mm)
|
|
{
|
|
struct mmu_gather tlb;
|
|
struct vm_area_struct *vma;
|
|
unsigned long nr_accounted = 0;
|
|
MA_STATE(mas, &mm->mm_mt, 0, 0);
|
|
int count = 0;
|
|
|
|
/* mm's last user has gone, and its about to be pulled down */
|
|
mmu_notifier_release(mm);
|
|
|
|
mmap_read_lock(mm);
|
|
arch_exit_mmap(mm);
|
|
|
|
vma = mas_find(&mas, ULONG_MAX);
|
|
if (!vma || unlikely(xa_is_zero(vma))) {
|
|
/* Can happen if dup_mmap() received an OOM */
|
|
mmap_read_unlock(mm);
|
|
mmap_write_lock(mm);
|
|
goto destroy;
|
|
}
|
|
|
|
lru_add_drain();
|
|
flush_cache_mm(mm);
|
|
tlb_gather_mmu_fullmm(&tlb, mm);
|
|
/* update_hiwater_rss(mm) here? but nobody should be looking */
|
|
/* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */
|
|
unmap_vmas(&tlb, &mas, vma, 0, ULONG_MAX, ULONG_MAX, false);
|
|
mmap_read_unlock(mm);
|
|
|
|
/*
|
|
* Set MMF_OOM_SKIP to hide this task from the oom killer/reaper
|
|
* because the memory has been already freed.
|
|
*/
|
|
set_bit(MMF_OOM_SKIP, &mm->flags);
|
|
mmap_write_lock(mm);
|
|
mt_clear_in_rcu(&mm->mm_mt);
|
|
mas_set(&mas, vma->vm_end);
|
|
free_pgtables(&tlb, &mas, vma, FIRST_USER_ADDRESS,
|
|
USER_PGTABLES_CEILING, true);
|
|
tlb_finish_mmu(&tlb);
|
|
|
|
/*
|
|
* Walk the list again, actually closing and freeing it, with preemption
|
|
* enabled, without holding any MM locks besides the unreachable
|
|
* mmap_write_lock.
|
|
*/
|
|
mas_set(&mas, vma->vm_end);
|
|
do {
|
|
if (vma->vm_flags & VM_ACCOUNT)
|
|
nr_accounted += vma_pages(vma);
|
|
remove_vma(vma, true);
|
|
count++;
|
|
cond_resched();
|
|
vma = mas_find(&mas, ULONG_MAX);
|
|
} while (vma && likely(!xa_is_zero(vma)));
|
|
|
|
BUG_ON(count != mm->map_count);
|
|
|
|
trace_exit_mmap(mm);
|
|
destroy:
|
|
__mt_destroy(&mm->mm_mt);
|
|
mmap_write_unlock(mm);
|
|
vm_unacct_memory(nr_accounted);
|
|
}
|
|
|
|
/* Insert vm structure into process list sorted by address
|
|
* and into the inode's i_mmap tree. If vm_file is non-NULL
|
|
* then i_mmap_rwsem is taken here.
|
|
*/
|
|
int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
|
|
{
|
|
unsigned long charged = vma_pages(vma);
|
|
|
|
|
|
if (find_vma_intersection(mm, vma->vm_start, vma->vm_end))
|
|
return -ENOMEM;
|
|
|
|
if ((vma->vm_flags & VM_ACCOUNT) &&
|
|
security_vm_enough_memory_mm(mm, charged))
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* The vm_pgoff of a purely anonymous vma should be irrelevant
|
|
* until its first write fault, when page's anon_vma and index
|
|
* are set. But now set the vm_pgoff it will almost certainly
|
|
* end up with (unless mremap moves it elsewhere before that
|
|
* first wfault), so /proc/pid/maps tells a consistent story.
|
|
*
|
|
* By setting it to reflect the virtual start address of the
|
|
* vma, merges and splits can happen in a seamless way, just
|
|
* using the existing file pgoff checks and manipulations.
|
|
* Similarly in do_mmap and in do_brk_flags.
|
|
*/
|
|
if (vma_is_anonymous(vma)) {
|
|
BUG_ON(vma->anon_vma);
|
|
vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
|
|
}
|
|
|
|
if (vma_link(mm, vma)) {
|
|
if (vma->vm_flags & VM_ACCOUNT)
|
|
vm_unacct_memory(charged);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Copy the vma structure to a new location in the same mm,
|
|
* prior to moving page table entries, to effect an mremap move.
|
|
*/
|
|
struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
|
|
unsigned long addr, unsigned long len, pgoff_t pgoff,
|
|
bool *need_rmap_locks)
|
|
{
|
|
struct vm_area_struct *vma = *vmap;
|
|
unsigned long vma_start = vma->vm_start;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct vm_area_struct *new_vma, *prev;
|
|
bool faulted_in_anon_vma = true;
|
|
VMA_ITERATOR(vmi, mm, addr);
|
|
|
|
/*
|
|
* If anonymous vma has not yet been faulted, update new pgoff
|
|
* to match new location, to increase its chance of merging.
|
|
*/
|
|
if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
|
|
pgoff = addr >> PAGE_SHIFT;
|
|
faulted_in_anon_vma = false;
|
|
}
|
|
|
|
new_vma = find_vma_prev(mm, addr, &prev);
|
|
if (new_vma && new_vma->vm_start < addr + len)
|
|
return NULL; /* should never get here */
|
|
|
|
new_vma = vma_merge_new_vma(&vmi, prev, vma, addr, addr + len, pgoff);
|
|
if (new_vma) {
|
|
/*
|
|
* Source vma may have been merged into new_vma
|
|
*/
|
|
if (unlikely(vma_start >= new_vma->vm_start &&
|
|
vma_start < new_vma->vm_end)) {
|
|
/*
|
|
* The only way we can get a vma_merge with
|
|
* self during an mremap is if the vma hasn't
|
|
* been faulted in yet and we were allowed to
|
|
* reset the dst vma->vm_pgoff to the
|
|
* destination address of the mremap to allow
|
|
* the merge to happen. mremap must change the
|
|
* vm_pgoff linearity between src and dst vmas
|
|
* (in turn preventing a vma_merge) to be
|
|
* safe. It is only safe to keep the vm_pgoff
|
|
* linear if there are no pages mapped yet.
|
|
*/
|
|
VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
|
|
*vmap = vma = new_vma;
|
|
}
|
|
*need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
|
|
} else {
|
|
new_vma = vm_area_dup(vma);
|
|
if (!new_vma)
|
|
goto out;
|
|
vma_set_range(new_vma, addr, addr + len, pgoff);
|
|
if (vma_dup_policy(vma, new_vma))
|
|
goto out_free_vma;
|
|
if (anon_vma_clone(new_vma, vma))
|
|
goto out_free_mempol;
|
|
if (new_vma->vm_file)
|
|
get_file(new_vma->vm_file);
|
|
if (new_vma->vm_ops && new_vma->vm_ops->open)
|
|
new_vma->vm_ops->open(new_vma);
|
|
if (vma_link(mm, new_vma))
|
|
goto out_vma_link;
|
|
*need_rmap_locks = false;
|
|
}
|
|
return new_vma;
|
|
|
|
out_vma_link:
|
|
if (new_vma->vm_ops && new_vma->vm_ops->close)
|
|
new_vma->vm_ops->close(new_vma);
|
|
|
|
if (new_vma->vm_file)
|
|
fput(new_vma->vm_file);
|
|
|
|
unlink_anon_vmas(new_vma);
|
|
out_free_mempol:
|
|
mpol_put(vma_policy(new_vma));
|
|
out_free_vma:
|
|
vm_area_free(new_vma);
|
|
out:
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Return true if the calling process may expand its vm space by the passed
|
|
* number of pages
|
|
*/
|
|
bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
|
|
{
|
|
if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
|
|
return false;
|
|
|
|
if (is_data_mapping(flags) &&
|
|
mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
|
|
/* Workaround for Valgrind */
|
|
if (rlimit(RLIMIT_DATA) == 0 &&
|
|
mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
|
|
return true;
|
|
|
|
pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
|
|
current->comm, current->pid,
|
|
(mm->data_vm + npages) << PAGE_SHIFT,
|
|
rlimit(RLIMIT_DATA),
|
|
ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
|
|
|
|
if (!ignore_rlimit_data)
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
|
|
{
|
|
WRITE_ONCE(mm->total_vm, READ_ONCE(mm->total_vm)+npages);
|
|
|
|
if (is_exec_mapping(flags))
|
|
mm->exec_vm += npages;
|
|
else if (is_stack_mapping(flags))
|
|
mm->stack_vm += npages;
|
|
else if (is_data_mapping(flags))
|
|
mm->data_vm += npages;
|
|
}
|
|
|
|
static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
|
|
|
|
/*
|
|
* Having a close hook prevents vma merging regardless of flags.
|
|
*/
|
|
static void special_mapping_close(struct vm_area_struct *vma)
|
|
{
|
|
}
|
|
|
|
static const char *special_mapping_name(struct vm_area_struct *vma)
|
|
{
|
|
return ((struct vm_special_mapping *)vma->vm_private_data)->name;
|
|
}
|
|
|
|
static int special_mapping_mremap(struct vm_area_struct *new_vma)
|
|
{
|
|
struct vm_special_mapping *sm = new_vma->vm_private_data;
|
|
|
|
if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
|
|
return -EFAULT;
|
|
|
|
if (sm->mremap)
|
|
return sm->mremap(sm, new_vma);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int special_mapping_split(struct vm_area_struct *vma, unsigned long addr)
|
|
{
|
|
/*
|
|
* Forbid splitting special mappings - kernel has expectations over
|
|
* the number of pages in mapping. Together with VM_DONTEXPAND
|
|
* the size of vma should stay the same over the special mapping's
|
|
* lifetime.
|
|
*/
|
|
return -EINVAL;
|
|
}
|
|
|
|
static const struct vm_operations_struct special_mapping_vmops = {
|
|
.close = special_mapping_close,
|
|
.fault = special_mapping_fault,
|
|
.mremap = special_mapping_mremap,
|
|
.name = special_mapping_name,
|
|
/* vDSO code relies that VVAR can't be accessed remotely */
|
|
.access = NULL,
|
|
.may_split = special_mapping_split,
|
|
};
|
|
|
|
static const struct vm_operations_struct legacy_special_mapping_vmops = {
|
|
.close = special_mapping_close,
|
|
.fault = special_mapping_fault,
|
|
};
|
|
|
|
static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
|
|
{
|
|
struct vm_area_struct *vma = vmf->vma;
|
|
pgoff_t pgoff;
|
|
struct page **pages;
|
|
|
|
if (vma->vm_ops == &legacy_special_mapping_vmops) {
|
|
pages = vma->vm_private_data;
|
|
} else {
|
|
struct vm_special_mapping *sm = vma->vm_private_data;
|
|
|
|
if (sm->fault)
|
|
return sm->fault(sm, vmf->vma, vmf);
|
|
|
|
pages = sm->pages;
|
|
}
|
|
|
|
for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
|
|
pgoff--;
|
|
|
|
if (*pages) {
|
|
struct page *page = *pages;
|
|
get_page(page);
|
|
vmf->page = page;
|
|
return 0;
|
|
}
|
|
|
|
return VM_FAULT_SIGBUS;
|
|
}
|
|
|
|
static struct vm_area_struct *__install_special_mapping(
|
|
struct mm_struct *mm,
|
|
unsigned long addr, unsigned long len,
|
|
unsigned long vm_flags, void *priv,
|
|
const struct vm_operations_struct *ops)
|
|
{
|
|
int ret;
|
|
struct vm_area_struct *vma;
|
|
|
|
vma = vm_area_alloc(mm);
|
|
if (unlikely(vma == NULL))
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
vma_set_range(vma, addr, addr + len, 0);
|
|
vm_flags_init(vma, (vm_flags | mm->def_flags |
|
|
VM_DONTEXPAND | VM_SOFTDIRTY) & ~VM_LOCKED_MASK);
|
|
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
|
|
|
|
vma->vm_ops = ops;
|
|
vma->vm_private_data = priv;
|
|
|
|
ret = insert_vm_struct(mm, vma);
|
|
if (ret)
|
|
goto out;
|
|
|
|
vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
|
|
|
|
perf_event_mmap(vma);
|
|
|
|
return vma;
|
|
|
|
out:
|
|
vm_area_free(vma);
|
|
return ERR_PTR(ret);
|
|
}
|
|
|
|
bool vma_is_special_mapping(const struct vm_area_struct *vma,
|
|
const struct vm_special_mapping *sm)
|
|
{
|
|
return vma->vm_private_data == sm &&
|
|
(vma->vm_ops == &special_mapping_vmops ||
|
|
vma->vm_ops == &legacy_special_mapping_vmops);
|
|
}
|
|
|
|
/*
|
|
* Called with mm->mmap_lock held for writing.
|
|
* Insert a new vma covering the given region, with the given flags.
|
|
* Its pages are supplied by the given array of struct page *.
|
|
* The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
|
|
* The region past the last page supplied will always produce SIGBUS.
|
|
* The array pointer and the pages it points to are assumed to stay alive
|
|
* for as long as this mapping might exist.
|
|
*/
|
|
struct vm_area_struct *_install_special_mapping(
|
|
struct mm_struct *mm,
|
|
unsigned long addr, unsigned long len,
|
|
unsigned long vm_flags, const struct vm_special_mapping *spec)
|
|
{
|
|
return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
|
|
&special_mapping_vmops);
|
|
}
|
|
|
|
int install_special_mapping(struct mm_struct *mm,
|
|
unsigned long addr, unsigned long len,
|
|
unsigned long vm_flags, struct page **pages)
|
|
{
|
|
struct vm_area_struct *vma = __install_special_mapping(
|
|
mm, addr, len, vm_flags, (void *)pages,
|
|
&legacy_special_mapping_vmops);
|
|
|
|
return PTR_ERR_OR_ZERO(vma);
|
|
}
|
|
|
|
static DEFINE_MUTEX(mm_all_locks_mutex);
|
|
|
|
static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
|
|
{
|
|
if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
|
|
/*
|
|
* The LSB of head.next can't change from under us
|
|
* because we hold the mm_all_locks_mutex.
|
|
*/
|
|
down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_lock);
|
|
/*
|
|
* We can safely modify head.next after taking the
|
|
* anon_vma->root->rwsem. If some other vma in this mm shares
|
|
* the same anon_vma we won't take it again.
|
|
*
|
|
* No need of atomic instructions here, head.next
|
|
* can't change from under us thanks to the
|
|
* anon_vma->root->rwsem.
|
|
*/
|
|
if (__test_and_set_bit(0, (unsigned long *)
|
|
&anon_vma->root->rb_root.rb_root.rb_node))
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
|
|
{
|
|
if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
|
|
/*
|
|
* AS_MM_ALL_LOCKS can't change from under us because
|
|
* we hold the mm_all_locks_mutex.
|
|
*
|
|
* Operations on ->flags have to be atomic because
|
|
* even if AS_MM_ALL_LOCKS is stable thanks to the
|
|
* mm_all_locks_mutex, there may be other cpus
|
|
* changing other bitflags in parallel to us.
|
|
*/
|
|
if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
|
|
BUG();
|
|
down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_lock);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This operation locks against the VM for all pte/vma/mm related
|
|
* operations that could ever happen on a certain mm. This includes
|
|
* vmtruncate, try_to_unmap, and all page faults.
|
|
*
|
|
* The caller must take the mmap_lock in write mode before calling
|
|
* mm_take_all_locks(). The caller isn't allowed to release the
|
|
* mmap_lock until mm_drop_all_locks() returns.
|
|
*
|
|
* mmap_lock in write mode is required in order to block all operations
|
|
* that could modify pagetables and free pages without need of
|
|
* altering the vma layout. It's also needed in write mode to avoid new
|
|
* anon_vmas to be associated with existing vmas.
|
|
*
|
|
* A single task can't take more than one mm_take_all_locks() in a row
|
|
* or it would deadlock.
|
|
*
|
|
* The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
|
|
* mapping->flags avoid to take the same lock twice, if more than one
|
|
* vma in this mm is backed by the same anon_vma or address_space.
|
|
*
|
|
* We take locks in following order, accordingly to comment at beginning
|
|
* of mm/rmap.c:
|
|
* - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
|
|
* hugetlb mapping);
|
|
* - all vmas marked locked
|
|
* - all i_mmap_rwsem locks;
|
|
* - all anon_vma->rwseml
|
|
*
|
|
* We can take all locks within these types randomly because the VM code
|
|
* doesn't nest them and we protected from parallel mm_take_all_locks() by
|
|
* mm_all_locks_mutex.
|
|
*
|
|
* mm_take_all_locks() and mm_drop_all_locks are expensive operations
|
|
* that may have to take thousand of locks.
|
|
*
|
|
* mm_take_all_locks() can fail if it's interrupted by signals.
|
|
*/
|
|
int mm_take_all_locks(struct mm_struct *mm)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct anon_vma_chain *avc;
|
|
MA_STATE(mas, &mm->mm_mt, 0, 0);
|
|
|
|
mmap_assert_write_locked(mm);
|
|
|
|
mutex_lock(&mm_all_locks_mutex);
|
|
|
|
/*
|
|
* vma_start_write() does not have a complement in mm_drop_all_locks()
|
|
* because vma_start_write() is always asymmetrical; it marks a VMA as
|
|
* being written to until mmap_write_unlock() or mmap_write_downgrade()
|
|
* is reached.
|
|
*/
|
|
mas_for_each(&mas, vma, ULONG_MAX) {
|
|
if (signal_pending(current))
|
|
goto out_unlock;
|
|
vma_start_write(vma);
|
|
}
|
|
|
|
mas_set(&mas, 0);
|
|
mas_for_each(&mas, vma, ULONG_MAX) {
|
|
if (signal_pending(current))
|
|
goto out_unlock;
|
|
if (vma->vm_file && vma->vm_file->f_mapping &&
|
|
is_vm_hugetlb_page(vma))
|
|
vm_lock_mapping(mm, vma->vm_file->f_mapping);
|
|
}
|
|
|
|
mas_set(&mas, 0);
|
|
mas_for_each(&mas, vma, ULONG_MAX) {
|
|
if (signal_pending(current))
|
|
goto out_unlock;
|
|
if (vma->vm_file && vma->vm_file->f_mapping &&
|
|
!is_vm_hugetlb_page(vma))
|
|
vm_lock_mapping(mm, vma->vm_file->f_mapping);
|
|
}
|
|
|
|
mas_set(&mas, 0);
|
|
mas_for_each(&mas, vma, ULONG_MAX) {
|
|
if (signal_pending(current))
|
|
goto out_unlock;
|
|
if (vma->anon_vma)
|
|
list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
|
|
vm_lock_anon_vma(mm, avc->anon_vma);
|
|
}
|
|
|
|
return 0;
|
|
|
|
out_unlock:
|
|
mm_drop_all_locks(mm);
|
|
return -EINTR;
|
|
}
|
|
|
|
static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
|
|
{
|
|
if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
|
|
/*
|
|
* The LSB of head.next can't change to 0 from under
|
|
* us because we hold the mm_all_locks_mutex.
|
|
*
|
|
* We must however clear the bitflag before unlocking
|
|
* the vma so the users using the anon_vma->rb_root will
|
|
* never see our bitflag.
|
|
*
|
|
* No need of atomic instructions here, head.next
|
|
* can't change from under us until we release the
|
|
* anon_vma->root->rwsem.
|
|
*/
|
|
if (!__test_and_clear_bit(0, (unsigned long *)
|
|
&anon_vma->root->rb_root.rb_root.rb_node))
|
|
BUG();
|
|
anon_vma_unlock_write(anon_vma);
|
|
}
|
|
}
|
|
|
|
static void vm_unlock_mapping(struct address_space *mapping)
|
|
{
|
|
if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
|
|
/*
|
|
* AS_MM_ALL_LOCKS can't change to 0 from under us
|
|
* because we hold the mm_all_locks_mutex.
|
|
*/
|
|
i_mmap_unlock_write(mapping);
|
|
if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
|
|
&mapping->flags))
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The mmap_lock cannot be released by the caller until
|
|
* mm_drop_all_locks() returns.
|
|
*/
|
|
void mm_drop_all_locks(struct mm_struct *mm)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct anon_vma_chain *avc;
|
|
MA_STATE(mas, &mm->mm_mt, 0, 0);
|
|
|
|
mmap_assert_write_locked(mm);
|
|
BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
|
|
|
|
mas_for_each(&mas, vma, ULONG_MAX) {
|
|
if (vma->anon_vma)
|
|
list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
|
|
vm_unlock_anon_vma(avc->anon_vma);
|
|
if (vma->vm_file && vma->vm_file->f_mapping)
|
|
vm_unlock_mapping(vma->vm_file->f_mapping);
|
|
}
|
|
|
|
mutex_unlock(&mm_all_locks_mutex);
|
|
}
|
|
|
|
/*
|
|
* initialise the percpu counter for VM
|
|
*/
|
|
void __init mmap_init(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
|
|
VM_BUG_ON(ret);
|
|
}
|
|
|
|
/*
|
|
* Initialise sysctl_user_reserve_kbytes.
|
|
*
|
|
* This is intended to prevent a user from starting a single memory hogging
|
|
* process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
|
|
* mode.
|
|
*
|
|
* The default value is min(3% of free memory, 128MB)
|
|
* 128MB is enough to recover with sshd/login, bash, and top/kill.
|
|
*/
|
|
static int init_user_reserve(void)
|
|
{
|
|
unsigned long free_kbytes;
|
|
|
|
free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
|
|
|
|
sysctl_user_reserve_kbytes = min(free_kbytes / 32, SZ_128K);
|
|
return 0;
|
|
}
|
|
subsys_initcall(init_user_reserve);
|
|
|
|
/*
|
|
* Initialise sysctl_admin_reserve_kbytes.
|
|
*
|
|
* The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
|
|
* to log in and kill a memory hogging process.
|
|
*
|
|
* Systems with more than 256MB will reserve 8MB, enough to recover
|
|
* with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
|
|
* only reserve 3% of free pages by default.
|
|
*/
|
|
static int init_admin_reserve(void)
|
|
{
|
|
unsigned long free_kbytes;
|
|
|
|
free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
|
|
|
|
sysctl_admin_reserve_kbytes = min(free_kbytes / 32, SZ_8K);
|
|
return 0;
|
|
}
|
|
subsys_initcall(init_admin_reserve);
|
|
|
|
/*
|
|
* Reinititalise user and admin reserves if memory is added or removed.
|
|
*
|
|
* The default user reserve max is 128MB, and the default max for the
|
|
* admin reserve is 8MB. These are usually, but not always, enough to
|
|
* enable recovery from a memory hogging process using login/sshd, a shell,
|
|
* and tools like top. It may make sense to increase or even disable the
|
|
* reserve depending on the existence of swap or variations in the recovery
|
|
* tools. So, the admin may have changed them.
|
|
*
|
|
* If memory is added and the reserves have been eliminated or increased above
|
|
* the default max, then we'll trust the admin.
|
|
*
|
|
* If memory is removed and there isn't enough free memory, then we
|
|
* need to reset the reserves.
|
|
*
|
|
* Otherwise keep the reserve set by the admin.
|
|
*/
|
|
static int reserve_mem_notifier(struct notifier_block *nb,
|
|
unsigned long action, void *data)
|
|
{
|
|
unsigned long tmp, free_kbytes;
|
|
|
|
switch (action) {
|
|
case MEM_ONLINE:
|
|
/* Default max is 128MB. Leave alone if modified by operator. */
|
|
tmp = sysctl_user_reserve_kbytes;
|
|
if (tmp > 0 && tmp < SZ_128K)
|
|
init_user_reserve();
|
|
|
|
/* Default max is 8MB. Leave alone if modified by operator. */
|
|
tmp = sysctl_admin_reserve_kbytes;
|
|
if (tmp > 0 && tmp < SZ_8K)
|
|
init_admin_reserve();
|
|
|
|
break;
|
|
case MEM_OFFLINE:
|
|
free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
|
|
|
|
if (sysctl_user_reserve_kbytes > free_kbytes) {
|
|
init_user_reserve();
|
|
pr_info("vm.user_reserve_kbytes reset to %lu\n",
|
|
sysctl_user_reserve_kbytes);
|
|
}
|
|
|
|
if (sysctl_admin_reserve_kbytes > free_kbytes) {
|
|
init_admin_reserve();
|
|
pr_info("vm.admin_reserve_kbytes reset to %lu\n",
|
|
sysctl_admin_reserve_kbytes);
|
|
}
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
static int __meminit init_reserve_notifier(void)
|
|
{
|
|
if (hotplug_memory_notifier(reserve_mem_notifier, DEFAULT_CALLBACK_PRI))
|
|
pr_err("Failed registering memory add/remove notifier for admin reserve\n");
|
|
|
|
return 0;
|
|
}
|
|
subsys_initcall(init_reserve_notifier);
|