X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=mm%2Fmprotect.c;h=258197b76fb4142d01b81d7871fddbca80510114;hb=c654b8a9cba6002aad1c01919e4928a79a4a6dcf;hp=e9fbd013ad9afa26804bc89f9b42cf335f2ac167;hpb=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2;p=safe%2Fjmp%2Flinux-2.6 diff --git a/mm/mprotect.c b/mm/mprotect.c index e9fbd01..258197b 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -4,7 +4,7 @@ * (C) Copyright 1994 Linus Torvalds * (C) Copyright 2002 Christoph Hellwig * - * Address space accounting code + * Address space accounting code * (C) Copyright 2002 Red Hat Inc, All Rights Reserved */ @@ -19,36 +19,68 @@ #include #include #include - +#include +#include +#include +#include #include #include #include #include +#ifndef pgprot_modify +static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot) +{ + return newprot; +} +#endif + static void change_pte_range(struct mm_struct *mm, pmd_t *pmd, - unsigned long addr, unsigned long end, pgprot_t newprot) + unsigned long addr, unsigned long end, pgprot_t newprot, + int dirty_accountable) { - pte_t *pte; + pte_t *pte, oldpte; + spinlock_t *ptl; - pte = pte_offset_map(pmd, addr); + pte = pte_offset_map_lock(mm, pmd, addr, &ptl); + arch_enter_lazy_mmu_mode(); do { - if (pte_present(*pte)) { + oldpte = *pte; + if (pte_present(oldpte)) { pte_t ptent; - /* Avoid an SMP race with hardware updated dirty/clean - * bits by wiping the pte and then setting the new pte - * into place. + ptent = ptep_modify_prot_start(mm, addr, pte); + ptent = pte_modify(ptent, newprot); + + /* + * Avoid taking write faults for pages we know to be + * dirty. */ - ptent = pte_modify(ptep_get_and_clear(mm, addr, pte), newprot); - set_pte_at(mm, addr, pte, ptent); - lazy_mmu_prot_update(ptent); + if (dirty_accountable && pte_dirty(ptent)) + ptent = pte_mkwrite(ptent); + + ptep_modify_prot_commit(mm, addr, pte, ptent); + } else if (PAGE_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)); + } } } while (pte++, addr += PAGE_SIZE, addr != end); - pte_unmap(pte - 1); + arch_leave_lazy_mmu_mode(); + pte_unmap_unlock(pte - 1, ptl); } static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud, - unsigned long addr, unsigned long end, pgprot_t newprot) + unsigned long addr, unsigned long end, pgprot_t newprot, + int dirty_accountable) { pmd_t *pmd; unsigned long next; @@ -58,12 +90,13 @@ static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud, next = pmd_addr_end(addr, end); if (pmd_none_or_clear_bad(pmd)) continue; - change_pte_range(mm, pmd, addr, next, newprot); + change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable); } while (pmd++, addr = next, addr != end); } static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd, - unsigned long addr, unsigned long end, pgprot_t newprot) + unsigned long addr, unsigned long end, pgprot_t newprot, + int dirty_accountable) { pud_t *pud; unsigned long next; @@ -73,12 +106,13 @@ static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd, next = pud_addr_end(addr, end); if (pud_none_or_clear_bad(pud)) continue; - change_pmd_range(mm, pud, addr, next, newprot); + change_pmd_range(mm, pud, addr, next, newprot, dirty_accountable); } while (pud++, addr = next, addr != end); } static void change_protection(struct vm_area_struct *vma, - unsigned long addr, unsigned long end, pgprot_t newprot) + unsigned long addr, unsigned long end, pgprot_t newprot, + int dirty_accountable) { struct mm_struct *mm = vma->vm_mm; pgd_t *pgd; @@ -88,18 +122,16 @@ static void change_protection(struct vm_area_struct *vma, BUG_ON(addr >= end); pgd = pgd_offset(mm, addr); flush_cache_range(vma, addr, end); - spin_lock(&mm->page_table_lock); do { next = pgd_addr_end(addr, end); if (pgd_none_or_clear_bad(pgd)) continue; - change_pud_range(mm, pgd, addr, next, newprot); + change_pud_range(mm, pgd, addr, next, newprot, dirty_accountable); } while (pgd++, addr = next, addr != end); flush_tlb_range(vma, start, end); - spin_unlock(&mm->page_table_lock); } -static int +int mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, unsigned long start, unsigned long end, unsigned long newflags) { @@ -107,9 +139,9 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, unsigned long oldflags = vma->vm_flags; long nrpages = (end - start) >> PAGE_SHIFT; unsigned long charged = 0; - pgprot_t newprot; pgoff_t pgoff; int error; + int dirty_accountable = 0; if (newflags == oldflags) { *pprev = vma; @@ -119,13 +151,12 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, /* * 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. - * - * FIXME? We haven't defined a VM_NORESERVE flag, so mprotecting - * a MAP_NORESERVE private mapping to writable will now reserve. + * 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_SHARED|VM_HUGETLB))) { + if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB| + VM_SHARED|VM_NORESERVE))) { charged = nrpages; if (security_vm_enough_memory(charged)) return -ENOMEM; @@ -133,8 +164,6 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, } } - newprot = protection_map[newflags & 0xf]; - /* * First try to merge with previous and/or next vma. */ @@ -166,10 +195,22 @@ success: * held in write mode. */ vma->vm_flags = newflags; - vma->vm_page_prot = newprot; - change_protection(vma, start, end, newprot); - __vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); - __vm_stat_account(mm, newflags, vma->vm_file, nrpages); + 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; + } + + mmu_notifier_invalidate_range_start(mm, start, end); + if (is_vm_hugetlb_page(vma)) + hugetlb_change_protection(vma, start, end, vma->vm_page_prot); + else + change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable); + mmu_notifier_invalidate_range_end(mm, start, end); + vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); + vm_stat_account(mm, newflags, vma->vm_file, nrpages); return 0; fail: @@ -177,8 +218,8 @@ fail: return error; } -asmlinkage long -sys_mprotect(unsigned long start, size_t len, unsigned long prot) +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; @@ -196,15 +237,14 @@ sys_mprotect(unsigned long start, size_t len, unsigned long prot) end = start + len; if (end <= start) return -ENOMEM; - if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM)) + if (!arch_validate_prot(prot)) return -EINVAL; reqprot = prot; /* * Does the application expect PROT_READ to imply PROT_EXEC: */ - if (unlikely((prot & PROT_READ) && - (current->personality & READ_IMPLIES_EXEC))) + if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) prot |= PROT_EXEC; vm_flags = calc_vm_prot_bits(prot); @@ -241,14 +281,10 @@ sys_mprotect(unsigned long start, size_t len, unsigned long prot) /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ - if (is_vm_hugetlb_page(vma)) { - error = -EACCES; - goto out; - } - newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); - if ((newflags & ~(newflags >> 4)) & 0xf) { + /* newflags >> 4 shift VM_MAY% in place of VM_% */ + if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) { error = -EACCES; goto out; }