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6904817607
most architectures are relying on mmap_sem for write in their arch_setup_additional_pages. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Andy Lutomirski <luto@amacapital.net> [x86 vdso] Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
313 lines
7.8 KiB
C
313 lines
7.8 KiB
C
/*
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* vdso setup for s390
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*
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* Copyright IBM Corp. 2008
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License (version 2 only)
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* as published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/stddef.h>
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#include <linux/unistd.h>
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#include <linux/slab.h>
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#include <linux/user.h>
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#include <linux/elf.h>
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#include <linux/security.h>
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#include <linux/bootmem.h>
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#include <linux/compat.h>
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#include <asm/asm-offsets.h>
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#include <asm/pgtable.h>
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#include <asm/processor.h>
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#include <asm/mmu.h>
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#include <asm/mmu_context.h>
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#include <asm/sections.h>
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#include <asm/vdso.h>
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#include <asm/facility.h>
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#ifdef CONFIG_COMPAT
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extern char vdso32_start, vdso32_end;
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static void *vdso32_kbase = &vdso32_start;
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static unsigned int vdso32_pages;
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static struct page **vdso32_pagelist;
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#endif
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extern char vdso64_start, vdso64_end;
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static void *vdso64_kbase = &vdso64_start;
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static unsigned int vdso64_pages;
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static struct page **vdso64_pagelist;
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/*
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* Should the kernel map a VDSO page into processes and pass its
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* address down to glibc upon exec()?
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*/
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unsigned int __read_mostly vdso_enabled = 1;
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static int __init vdso_setup(char *s)
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{
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unsigned long val;
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int rc;
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rc = 0;
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if (strncmp(s, "on", 3) == 0)
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vdso_enabled = 1;
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else if (strncmp(s, "off", 4) == 0)
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vdso_enabled = 0;
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else {
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rc = kstrtoul(s, 0, &val);
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vdso_enabled = rc ? 0 : !!val;
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}
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return !rc;
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}
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__setup("vdso=", vdso_setup);
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/*
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* The vdso data page
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*/
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static union {
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struct vdso_data data;
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u8 page[PAGE_SIZE];
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} vdso_data_store __page_aligned_data;
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struct vdso_data *vdso_data = &vdso_data_store.data;
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/*
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* Setup vdso data page.
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*/
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static void __init vdso_init_data(struct vdso_data *vd)
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{
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vd->ectg_available = test_facility(31);
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}
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/*
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* Allocate/free per cpu vdso data.
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*/
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#define SEGMENT_ORDER 2
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int vdso_alloc_per_cpu(struct lowcore *lowcore)
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{
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unsigned long segment_table, page_table, page_frame;
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struct vdso_per_cpu_data *vd;
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u32 *psal, *aste;
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int i;
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lowcore->vdso_per_cpu_data = __LC_PASTE;
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if (!vdso_enabled)
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return 0;
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segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER);
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page_table = get_zeroed_page(GFP_KERNEL | GFP_DMA);
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page_frame = get_zeroed_page(GFP_KERNEL);
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if (!segment_table || !page_table || !page_frame)
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goto out;
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/* Initialize per-cpu vdso data page */
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vd = (struct vdso_per_cpu_data *) page_frame;
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vd->cpu_nr = lowcore->cpu_nr;
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vd->node_id = cpu_to_node(vd->cpu_nr);
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/* Set up access register mode page table */
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clear_table((unsigned long *) segment_table, _SEGMENT_ENTRY_EMPTY,
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PAGE_SIZE << SEGMENT_ORDER);
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clear_table((unsigned long *) page_table, _PAGE_INVALID,
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256*sizeof(unsigned long));
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*(unsigned long *) segment_table = _SEGMENT_ENTRY + page_table;
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*(unsigned long *) page_table = _PAGE_PROTECT + page_frame;
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psal = (u32 *) (page_table + 256*sizeof(unsigned long));
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aste = psal + 32;
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for (i = 4; i < 32; i += 4)
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psal[i] = 0x80000000;
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lowcore->paste[4] = (u32)(addr_t) psal;
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psal[0] = 0x02000000;
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psal[2] = (u32)(addr_t) aste;
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*(unsigned long *) (aste + 2) = segment_table +
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_ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT;
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aste[4] = (u32)(addr_t) psal;
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lowcore->vdso_per_cpu_data = page_frame;
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return 0;
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out:
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free_page(page_frame);
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free_page(page_table);
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free_pages(segment_table, SEGMENT_ORDER);
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return -ENOMEM;
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}
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void vdso_free_per_cpu(struct lowcore *lowcore)
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{
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unsigned long segment_table, page_table, page_frame;
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u32 *psal, *aste;
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if (!vdso_enabled)
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return;
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psal = (u32 *)(addr_t) lowcore->paste[4];
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aste = (u32 *)(addr_t) psal[2];
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segment_table = *(unsigned long *)(aste + 2) & PAGE_MASK;
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page_table = *(unsigned long *) segment_table;
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page_frame = *(unsigned long *) page_table;
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free_page(page_frame);
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free_page(page_table);
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free_pages(segment_table, SEGMENT_ORDER);
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}
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static void vdso_init_cr5(void)
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{
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unsigned long cr5;
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if (!vdso_enabled)
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return;
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cr5 = offsetof(struct lowcore, paste);
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__ctl_load(cr5, 5, 5);
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}
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/*
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* This is called from binfmt_elf, we create the special vma for the
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* vDSO and insert it into the mm struct tree
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*/
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int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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{
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struct mm_struct *mm = current->mm;
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struct page **vdso_pagelist;
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unsigned long vdso_pages;
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unsigned long vdso_base;
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int rc;
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if (!vdso_enabled)
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return 0;
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/*
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* Only map the vdso for dynamically linked elf binaries.
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*/
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if (!uses_interp)
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return 0;
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vdso_pagelist = vdso64_pagelist;
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vdso_pages = vdso64_pages;
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#ifdef CONFIG_COMPAT
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if (is_compat_task()) {
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vdso_pagelist = vdso32_pagelist;
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vdso_pages = vdso32_pages;
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}
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#endif
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/*
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* vDSO has a problem and was disabled, just don't "enable" it for
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* the process
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*/
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if (vdso_pages == 0)
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return 0;
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current->mm->context.vdso_base = 0;
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/*
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* pick a base address for the vDSO in process space. We try to put
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* it at vdso_base which is the "natural" base for it, but we might
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* fail and end up putting it elsewhere.
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*/
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if (down_write_killable(&mm->mmap_sem))
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return -EINTR;
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vdso_base = get_unmapped_area(NULL, 0, vdso_pages << PAGE_SHIFT, 0, 0);
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if (IS_ERR_VALUE(vdso_base)) {
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rc = vdso_base;
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goto out_up;
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}
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/*
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* Put vDSO base into mm struct. We need to do this before calling
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* install_special_mapping or the perf counter mmap tracking code
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* will fail to recognise it as a vDSO (since arch_vma_name fails).
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*/
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current->mm->context.vdso_base = vdso_base;
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/*
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* our vma flags don't have VM_WRITE so by default, the process
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* isn't allowed to write those pages.
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* gdb can break that with ptrace interface, and thus trigger COW
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* on those pages but it's then your responsibility to never do that
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* on the "data" page of the vDSO or you'll stop getting kernel
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* updates and your nice userland gettimeofday will be totally dead.
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* It's fine to use that for setting breakpoints in the vDSO code
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* pages though.
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*/
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rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
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VM_READ|VM_EXEC|
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
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vdso_pagelist);
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if (rc)
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current->mm->context.vdso_base = 0;
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out_up:
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up_write(&mm->mmap_sem);
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return rc;
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}
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const char *arch_vma_name(struct vm_area_struct *vma)
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{
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if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso_base)
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return "[vdso]";
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return NULL;
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}
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static int __init vdso_init(void)
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{
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int i;
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if (!vdso_enabled)
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return 0;
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vdso_init_data(vdso_data);
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#ifdef CONFIG_COMPAT
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/* Calculate the size of the 32 bit vDSO */
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vdso32_pages = ((&vdso32_end - &vdso32_start
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+ PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
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/* Make sure pages are in the correct state */
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vdso32_pagelist = kzalloc(sizeof(struct page *) * (vdso32_pages + 1),
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GFP_KERNEL);
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BUG_ON(vdso32_pagelist == NULL);
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for (i = 0; i < vdso32_pages - 1; i++) {
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struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
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ClearPageReserved(pg);
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get_page(pg);
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vdso32_pagelist[i] = pg;
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}
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vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data);
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vdso32_pagelist[vdso32_pages] = NULL;
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#endif
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/* Calculate the size of the 64 bit vDSO */
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vdso64_pages = ((&vdso64_end - &vdso64_start
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+ PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
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/* Make sure pages are in the correct state */
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vdso64_pagelist = kzalloc(sizeof(struct page *) * (vdso64_pages + 1),
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GFP_KERNEL);
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BUG_ON(vdso64_pagelist == NULL);
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for (i = 0; i < vdso64_pages - 1; i++) {
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struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
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ClearPageReserved(pg);
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get_page(pg);
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vdso64_pagelist[i] = pg;
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}
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vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
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vdso64_pagelist[vdso64_pages] = NULL;
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if (vdso_alloc_per_cpu(&S390_lowcore))
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BUG();
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vdso_init_cr5();
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get_page(virt_to_page(vdso_data));
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return 0;
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}
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early_initcall(vdso_init);
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