From: Dave McCracken <dmccr@us.ibm.com>
To: Andrew Morton <akpm@digeo.com>
Cc: Linux Memory Management <linux-mm@kvack.org>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: [PATCH 2.5.41-mm2+] Shared page table bugfix for mprotect
Date: Thu, 10 Oct 2002 14:32:18 -0500 [thread overview]
Message-ID: <167610000.1034278338@baldur.austin.ibm.com> (raw)
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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
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[-- Type: text/plain, Size: 4278 bytes --]
--- 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;
next reply other threads:[~2002-10-10 19:26 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-10 19:32 Dave McCracken [this message]
[not found] ` <3DA5D893.CDD2407C@digeo.com>
2002-10-10 19:59 ` Fork timing numbers for shared page tables Dave McCracken
2002-10-10 20:02 ` William Lee Irwin III
2002-10-10 21:21 ` Benjamin LaHaise
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