013bb59dbb
Currently, on an anonymous page fault, the kernel allocates a zeroed
page and maps it in user space. If the mapping is tagged (PROT_MTE),
set_pte_at() additionally clears the tags. It is, however, more
efficient to clear the tags at the same time as zeroing the data on
allocation. To avoid clearing the tags on any page (which may not be
mapped as tagged), only do this if the vma flags contain VM_MTE. This
requires introducing a new GFP flag that is used to determine whether
to clear the tags.
The DC GZVA instruction with a 0 top byte (and 0 tag) requires
top-byte-ignore. Set the TCR_EL1.{TBI1,TBID1} bits irrespective of
whether KASAN_HW is enabled.
Signed-off-by: Peter Collingbourne <pcc@google.com>
Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://linux-review.googlesource.com/id/Id46dc94e30fe11474f7e54f5d65e7658dbdddb26
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20210602235230.3928842-4-pcc@google.com
Signed-off-by: Will Deacon <will@kernel.org>
141 lines
3.3 KiB
C
141 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2020 ARM Ltd.
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*/
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#ifndef __ASM_MTE_H
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#define __ASM_MTE_H
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#include <asm/compiler.h>
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#include <asm/mte-def.h>
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#ifndef __ASSEMBLY__
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#include <linux/bitfield.h>
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#include <linux/page-flags.h>
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#include <linux/types.h>
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#include <asm/pgtable-types.h>
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extern u64 gcr_kernel_excl;
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void mte_clear_page_tags(void *addr);
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unsigned long mte_copy_tags_from_user(void *to, const void __user *from,
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unsigned long n);
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unsigned long mte_copy_tags_to_user(void __user *to, void *from,
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unsigned long n);
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int mte_save_tags(struct page *page);
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void mte_save_page_tags(const void *page_addr, void *tag_storage);
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bool mte_restore_tags(swp_entry_t entry, struct page *page);
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void mte_restore_page_tags(void *page_addr, const void *tag_storage);
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void mte_invalidate_tags(int type, pgoff_t offset);
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void mte_invalidate_tags_area(int type);
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void *mte_allocate_tag_storage(void);
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void mte_free_tag_storage(char *storage);
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#ifdef CONFIG_ARM64_MTE
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/* track which pages have valid allocation tags */
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#define PG_mte_tagged PG_arch_2
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void mte_zero_clear_page_tags(void *addr);
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void mte_sync_tags(pte_t *ptep, pte_t pte);
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void mte_copy_page_tags(void *kto, const void *kfrom);
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void mte_thread_init_user(void);
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void mte_thread_switch(struct task_struct *next);
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void mte_suspend_enter(void);
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void mte_suspend_exit(void);
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long set_mte_ctrl(struct task_struct *task, unsigned long arg);
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long get_mte_ctrl(struct task_struct *task);
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int mte_ptrace_copy_tags(struct task_struct *child, long request,
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unsigned long addr, unsigned long data);
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#else /* CONFIG_ARM64_MTE */
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/* unused if !CONFIG_ARM64_MTE, silence the compiler */
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#define PG_mte_tagged 0
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static inline void mte_zero_clear_page_tags(void *addr)
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{
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}
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static inline void mte_sync_tags(pte_t *ptep, pte_t pte)
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{
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}
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static inline void mte_copy_page_tags(void *kto, const void *kfrom)
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{
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}
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static inline void mte_thread_init_user(void)
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{
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}
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static inline void mte_thread_switch(struct task_struct *next)
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{
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}
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static inline void mte_suspend_enter(void)
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{
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}
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static inline void mte_suspend_exit(void)
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{
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}
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static inline long set_mte_ctrl(struct task_struct *task, unsigned long arg)
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{
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return 0;
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}
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static inline long get_mte_ctrl(struct task_struct *task)
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{
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return 0;
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}
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static inline int mte_ptrace_copy_tags(struct task_struct *child,
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long request, unsigned long addr,
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unsigned long data)
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{
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return -EIO;
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}
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#endif /* CONFIG_ARM64_MTE */
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#ifdef CONFIG_KASAN_HW_TAGS
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/* Whether the MTE asynchronous mode is enabled. */
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DECLARE_STATIC_KEY_FALSE(mte_async_mode);
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static inline bool system_uses_mte_async_mode(void)
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{
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return static_branch_unlikely(&mte_async_mode);
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}
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void mte_check_tfsr_el1(void);
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static inline void mte_check_tfsr_entry(void)
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{
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mte_check_tfsr_el1();
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}
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static inline void mte_check_tfsr_exit(void)
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{
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/*
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* The asynchronous faults are sync'ed automatically with
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* TFSR_EL1 on kernel entry but for exit an explicit dsb()
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* is required.
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*/
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dsb(nsh);
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isb();
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mte_check_tfsr_el1();
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}
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#else
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static inline bool system_uses_mte_async_mode(void)
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{
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return false;
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}
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static inline void mte_check_tfsr_el1(void)
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{
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}
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static inline void mte_check_tfsr_entry(void)
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{
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}
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static inline void mte_check_tfsr_exit(void)
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{
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}
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#endif /* CONFIG_KASAN_HW_TAGS */
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#endif /* __ASSEMBLY__ */
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#endif /* __ASM_MTE_H */
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