Messages in this thread Patch in this message | | | Date | Thu, 10 Oct 2002 14:32:18 -0500 | From | Dave McCracken <> | Subject | [PATCH 2.5.41-mm2+] Shared page table bugfix for mprotect |
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I discovered I hadn't done the right things for mprotect, so here's a patch that fixes it. It goes on top of the #ifdef cleanup I sent earlier today.
Dave McCracken
====================================================================== Dave McCracken IBM Linux Base Kernel Team 1-512-838-3059 dmccr@us.ibm.com T/L 678-3059 --- 2.5.41-mm2-shsent/./include/linux/mm.h 2002-10-10 10:34:58.000000000 -0500 +++ 2.5.41-mm2-shpte/./include/linux/mm.h 2002-10-10 13:23:30.000000000 -0500 @@ -360,6 +360,7 @@ extern void zap_page_range(struct vm_area_struct *vma, unsigned long address, unsigned long size); #ifdef CONFIG_SHAREPTE +extern pte_t *pte_unshare(struct mm_struct *mm, pmd_t *pmd, unsigned long address); extern int share_page_range(struct mm_struct *dst, struct mm_struct *src, struct vm_area_struct *vma, pmd_t **prev_pmd); #else extern int copy_page_range(struct mm_struct *dst, struct mm_struct *src, struct vm_area_struct *vma); --- 2.5.41-mm2-shsent/./include/asm-i386/pgtable.h 2002-10-10 10:17:55.000000000 -0500 +++ 2.5.41-mm2-shpte/./include/asm-i386/pgtable.h 2002-10-10 13:14:48.000000000 -0500 @@ -212,6 +212,7 @@ static inline pte_t pte_mkwrite(pte_t pte) { (pte).pte_low |= _PAGE_RW; return pte; } static inline int pmd_write(pmd_t pmd) { return (pmd).pmd & _PAGE_RW; } static inline pmd_t pmd_wrprotect(pmd_t pmd) { (pmd).pmd &= ~_PAGE_RW; return pmd; } +static inline pmd_t pmd_mkwrite(pmd_t pmd) { (pmd).pmd |= _PAGE_RW; return pmd; } static inline int ptep_test_and_clear_dirty(pte_t *ptep) { return test_and_clear_bit(_PAGE_BIT_DIRTY, &ptep->pte_low); } static inline int ptep_test_and_clear_young(pte_t *ptep) { return test_and_clear_bit(_PAGE_BIT_ACCESSED, &ptep->pte_low); } --- 2.5.41-mm2-shsent/./mm/mprotect.c 2002-10-10 10:17:57.000000000 -0500 +++ 2.5.41-mm2-shpte/./mm/mprotect.c 2002-10-10 13:31:14.000000000 -0500 @@ -16,6 +16,7 @@ #include <linux/fs.h> #include <linux/highmem.h> #include <linux/security.h> +#include <linux/rmap-locking.h> #include <asm/uaccess.h> #include <asm/pgalloc.h> @@ -24,10 +25,11 @@ #include <asm/tlbflush.h> static inline void -change_pte_range(pmd_t *pmd, unsigned long address, +change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, unsigned long address, unsigned long size, pgprot_t newprot) { pte_t * pte; + struct page *ptepage; unsigned long end; if (pmd_none(*pmd)) @@ -37,11 +39,32 @@ pmd_clear(pmd); return; } - pte = pte_offset_map(pmd, address); + ptepage = pmd_page(*pmd); + pte_page_lock(ptepage); address &= ~PMD_MASK; end = address + size; if (end > PMD_SIZE) end = PMD_SIZE; + +#ifdef CONFIG_SHAREPTE + if (page_count(ptepage) > 1) { + if ((address == 0) && (end == PMD_SIZE)) { + pmd_t pmdval = *pmd; + + if (vma->vm_flags & VM_MAYWRITE) + pmdval = pmd_mkwrite(pmdval); + else + pmdval = pmd_wrprotect(pmdval); + set_pmd(pmd, pmdval); + pte_page_unlock(ptepage); + return; + } + pte = pte_unshare(vma->vm_mm, pmd, address); + ptepage = pmd_page(*pmd); + } else +#endif + pte = pte_offset_map(pmd, address); + do { if (pte_present(*pte)) { pte_t entry; @@ -56,11 +79,12 @@ address += PAGE_SIZE; pte++; } while (address && (address < end)); + pte_page_unlock(ptepage); pte_unmap(pte - 1); } static inline void -change_pmd_range(pgd_t *pgd, unsigned long address, +change_pmd_range(struct vm_area_struct *vma, pgd_t *pgd, unsigned long address, unsigned long size, pgprot_t newprot) { pmd_t * pmd; @@ -79,7 +103,7 @@ if (end > PGDIR_SIZE) end = PGDIR_SIZE; do { - change_pte_range(pmd, address, end - address, newprot); + change_pte_range(vma, pmd, address, end - address, newprot); address = (address + PMD_SIZE) & PMD_MASK; pmd++; } while (address && (address < end)); @@ -98,7 +122,7 @@ BUG(); spin_lock(¤t->mm->page_table_lock); do { - change_pmd_range(dir, start, end - start, newprot); + change_pmd_range(vma, dir, start, end - start, newprot); start = (start + PGDIR_SIZE) & PGDIR_MASK; dir++; } while (start && (start < end)); --- 2.5.41-mm2-shsent/./mm/memory.c 2002-10-10 10:35:34.000000000 -0500 +++ 2.5.41-mm2-shpte/./mm/memory.c 2002-10-10 13:22:29.000000000 -0500 @@ -218,7 +218,7 @@ * held. */ -static pte_t *pte_unshare(struct mm_struct *mm, pmd_t *pmd, unsigned long address) +pte_t *pte_unshare(struct mm_struct *mm, pmd_t *pmd, unsigned long address) { pte_t *src_ptb, *dst_ptb; struct page *oldpage, *newpage, *tmppage;
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