diff options
author | Fathi Boudra <fathi.boudra@linaro.org> | 2013-04-28 09:33:08 +0300 |
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committer | Fathi Boudra <fathi.boudra@linaro.org> | 2013-04-28 09:33:08 +0300 |
commit | 3b4bd47f8f4ed3aaf7c81c9b5d2d37ad79fadf4a (patch) | |
tree | b9996006addfd7ae70a39672b76843b49aebc189 /mm/mprotect.c |
Imported Upstream version 3.9.0HEADupstream/3.9.0upstreammaster
Diffstat (limited to 'mm/mprotect.c')
-rw-r--r-- | mm/mprotect.c | 419 |
1 files changed, 419 insertions, 0 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c new file mode 100644 index 00000000..94722a4d --- /dev/null +++ b/mm/mprotect.c @@ -0,0 +1,419 @@ +/* + * mm/mprotect.c + * + * (C) Copyright 1994 Linus Torvalds + * (C) Copyright 2002 Christoph Hellwig + * + * Address space accounting code <alan@lxorguk.ukuu.org.uk> + * (C) Copyright 2002 Red Hat Inc, All Rights Reserved + */ + +#include <linux/mm.h> +#include <linux/hugetlb.h> +#include <linux/shm.h> +#include <linux/mman.h> +#include <linux/fs.h> +#include <linux/highmem.h> +#include <linux/security.h> +#include <linux/mempolicy.h> +#include <linux/personality.h> +#include <linux/syscalls.h> +#include <linux/swap.h> +#include <linux/swapops.h> +#include <linux/mmu_notifier.h> +#include <linux/migrate.h> +#include <linux/perf_event.h> +#include <asm/uaccess.h> +#include <asm/pgtable.h> +#include <asm/cacheflush.h> +#include <asm/tlbflush.h> + +#ifndef pgprot_modify +static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot) +{ + return newprot; +} +#endif + +static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, + unsigned long addr, unsigned long end, pgprot_t newprot, + int dirty_accountable, int prot_numa, bool *ret_all_same_node) +{ + struct mm_struct *mm = vma->vm_mm; + pte_t *pte, oldpte; + spinlock_t *ptl; + unsigned long pages = 0; + bool all_same_node = true; + int last_nid = -1; + + pte = pte_offset_map_lock(mm, pmd, addr, &ptl); + arch_enter_lazy_mmu_mode(); + do { + oldpte = *pte; + if (pte_present(oldpte)) { + pte_t ptent; + bool updated = false; + + ptent = ptep_modify_prot_start(mm, addr, pte); + if (!prot_numa) { + ptent = pte_modify(ptent, newprot); + updated = true; + } else { + struct page *page; + + page = vm_normal_page(vma, addr, oldpte); + if (page) { + int this_nid = page_to_nid(page); + if (last_nid == -1) + last_nid = this_nid; + if (last_nid != this_nid) + all_same_node = false; + + /* only check non-shared pages */ + if (!pte_numa(oldpte) && + page_mapcount(page) == 1) { + ptent = pte_mknuma(ptent); + updated = true; + } + } + } + + /* + * Avoid taking write faults for pages we know to be + * dirty. + */ + if (dirty_accountable && pte_dirty(ptent)) { + ptent = pte_mkwrite(ptent); + updated = true; + } + + if (updated) + pages++; + ptep_modify_prot_commit(mm, addr, pte, ptent); + } else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) { + swp_entry_t entry = pte_to_swp_entry(oldpte); + + if (is_write_migration_entry(entry)) { + /* + * A protection check is difficult so + * just be safe and disable write + */ + make_migration_entry_read(&entry); + set_pte_at(mm, addr, pte, + swp_entry_to_pte(entry)); + } + pages++; + } + } while (pte++, addr += PAGE_SIZE, addr != end); + arch_leave_lazy_mmu_mode(); + pte_unmap_unlock(pte - 1, ptl); + + *ret_all_same_node = all_same_node; + return pages; +} + +#ifdef CONFIG_NUMA_BALANCING +static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr, + pmd_t *pmd) +{ + spin_lock(&mm->page_table_lock); + set_pmd_at(mm, addr & PMD_MASK, pmd, pmd_mknuma(*pmd)); + spin_unlock(&mm->page_table_lock); +} +#else +static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr, + pmd_t *pmd) +{ + BUG(); +} +#endif /* CONFIG_NUMA_BALANCING */ + +static inline unsigned long change_pmd_range(struct vm_area_struct *vma, + pud_t *pud, unsigned long addr, unsigned long end, + pgprot_t newprot, int dirty_accountable, int prot_numa) +{ + pmd_t *pmd; + unsigned long next; + unsigned long pages = 0; + bool all_same_node; + + pmd = pmd_offset(pud, addr); + do { + next = pmd_addr_end(addr, end); + if (pmd_trans_huge(*pmd)) { + if (next - addr != HPAGE_PMD_SIZE) + split_huge_page_pmd(vma, addr, pmd); + else if (change_huge_pmd(vma, pmd, addr, newprot, + prot_numa)) { + pages += HPAGE_PMD_NR; + continue; + } + /* fall through */ + } + if (pmd_none_or_clear_bad(pmd)) + continue; + pages += change_pte_range(vma, pmd, addr, next, newprot, + dirty_accountable, prot_numa, &all_same_node); + + /* + * If we are changing protections for NUMA hinting faults then + * set pmd_numa if the examined pages were all on the same + * node. This allows a regular PMD to be handled as one fault + * and effectively batches the taking of the PTL + */ + if (prot_numa && all_same_node) + change_pmd_protnuma(vma->vm_mm, addr, pmd); + } while (pmd++, addr = next, addr != end); + + return pages; +} + +static inline unsigned long change_pud_range(struct vm_area_struct *vma, + pgd_t *pgd, unsigned long addr, unsigned long end, + pgprot_t newprot, int dirty_accountable, int prot_numa) +{ + pud_t *pud; + unsigned long next; + unsigned long pages = 0; + + pud = pud_offset(pgd, addr); + do { + next = pud_addr_end(addr, end); + if (pud_none_or_clear_bad(pud)) + continue; + pages += change_pmd_range(vma, pud, addr, next, newprot, + dirty_accountable, prot_numa); + } while (pud++, addr = next, addr != end); + + return pages; +} + +static unsigned long change_protection_range(struct vm_area_struct *vma, + unsigned long addr, unsigned long end, pgprot_t newprot, + int dirty_accountable, int prot_numa) +{ + struct mm_struct *mm = vma->vm_mm; + pgd_t *pgd; + unsigned long next; + unsigned long start = addr; + unsigned long pages = 0; + + BUG_ON(addr >= end); + pgd = pgd_offset(mm, addr); + flush_cache_range(vma, addr, end); + do { + next = pgd_addr_end(addr, end); + if (pgd_none_or_clear_bad(pgd)) + continue; + pages += change_pud_range(vma, pgd, addr, next, newprot, + dirty_accountable, prot_numa); + } while (pgd++, addr = next, addr != end); + + /* Only flush the TLB if we actually modified any entries: */ + if (pages) + flush_tlb_range(vma, start, end); + + return pages; +} + +unsigned long change_protection(struct vm_area_struct *vma, unsigned long start, + unsigned long end, pgprot_t newprot, + int dirty_accountable, int prot_numa) +{ + struct mm_struct *mm = vma->vm_mm; + unsigned long pages; + + mmu_notifier_invalidate_range_start(mm, start, end); + if (is_vm_hugetlb_page(vma)) + pages = hugetlb_change_protection(vma, start, end, newprot); + else + pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa); + mmu_notifier_invalidate_range_end(mm, start, end); + + return pages; +} + +int +mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, + unsigned long start, unsigned long end, unsigned long newflags) +{ + struct mm_struct *mm = vma->vm_mm; + unsigned long oldflags = vma->vm_flags; + long nrpages = (end - start) >> PAGE_SHIFT; + unsigned long charged = 0; + pgoff_t pgoff; + int error; + int dirty_accountable = 0; + + if (newflags == oldflags) { + *pprev = vma; + return 0; + } + + /* + * If we make a private mapping writable we increase our commit; + * but (without finer accounting) cannot reduce our commit if we + * make it unwritable again. hugetlb mapping were accounted for + * even if read-only so there is no need to account for them here + */ + if (newflags & VM_WRITE) { + if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB| + VM_SHARED|VM_NORESERVE))) { + charged = nrpages; + if (security_vm_enough_memory_mm(mm, charged)) + return -ENOMEM; + newflags |= VM_ACCOUNT; + } + } + + /* + * First try to merge with previous and/or next vma. + */ + pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); + *pprev = vma_merge(mm, *pprev, start, end, newflags, + vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); + if (*pprev) { + vma = *pprev; + goto success; + } + + *pprev = vma; + + if (start != vma->vm_start) { + error = split_vma(mm, vma, start, 1); + if (error) + goto fail; + } + + if (end != vma->vm_end) { + error = split_vma(mm, vma, end, 0); + if (error) + goto fail; + } + +success: + /* + * vm_flags and vm_page_prot are protected by the mmap_sem + * held in write mode. + */ + vma->vm_flags = newflags; + vma->vm_page_prot = pgprot_modify(vma->vm_page_prot, + vm_get_page_prot(newflags)); + + if (vma_wants_writenotify(vma)) { + vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED); + dirty_accountable = 1; + } + + change_protection(vma, start, end, vma->vm_page_prot, + dirty_accountable, 0); + + vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); + vm_stat_account(mm, newflags, vma->vm_file, nrpages); + perf_event_mmap(vma); + return 0; + +fail: + vm_unacct_memory(charged); + return error; +} + +SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, + unsigned long, prot) +{ + unsigned long vm_flags, nstart, end, tmp, reqprot; + struct vm_area_struct *vma, *prev; + int error = -EINVAL; + const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); + prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); + if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ + return -EINVAL; + + if (start & ~PAGE_MASK) + return -EINVAL; + if (!len) + return 0; + len = PAGE_ALIGN(len); + end = start + len; + if (end <= start) + return -ENOMEM; + if (!arch_validate_prot(prot)) + return -EINVAL; + + reqprot = prot; + /* + * Does the application expect PROT_READ to imply PROT_EXEC: + */ + if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) + prot |= PROT_EXEC; + + vm_flags = calc_vm_prot_bits(prot); + + down_write(¤t->mm->mmap_sem); + + vma = find_vma(current->mm, start); + error = -ENOMEM; + if (!vma) + goto out; + prev = vma->vm_prev; + if (unlikely(grows & PROT_GROWSDOWN)) { + if (vma->vm_start >= end) + goto out; + start = vma->vm_start; + error = -EINVAL; + if (!(vma->vm_flags & VM_GROWSDOWN)) + goto out; + } else { + if (vma->vm_start > start) + goto out; + if (unlikely(grows & PROT_GROWSUP)) { + end = vma->vm_end; + error = -EINVAL; + if (!(vma->vm_flags & VM_GROWSUP)) + goto out; + } + } + if (start > vma->vm_start) + prev = vma; + + for (nstart = start ; ; ) { + unsigned long newflags; + + /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ + + newflags = vm_flags; + newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); + + /* newflags >> 4 shift VM_MAY% in place of VM_% */ + if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) { + error = -EACCES; + goto out; + } + + error = security_file_mprotect(vma, reqprot, prot); + if (error) + goto out; + + tmp = vma->vm_end; + if (tmp > end) + tmp = end; + error = mprotect_fixup(vma, &prev, nstart, tmp, newflags); + if (error) + goto out; + nstart = tmp; + + if (nstart < prev->vm_end) + nstart = prev->vm_end; + if (nstart >= end) + goto out; + + vma = prev->vm_next; + if (!vma || vma->vm_start != nstart) { + error = -ENOMEM; + goto out; + } + } +out: + up_write(¤t->mm->mmap_sem); + return error; +} |