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authorEugene Surovegin <ebs@ebshome.net>2006-03-28 13:13:12 -0500
committerPaul Mackerras <paulus@samba.org>2006-03-28 21:44:15 -0500
commitbab70a4af737f623de5b034976a311055308ab86 (patch)
treef8c0e9463de01323db2cb1a62f4eb83adb5ce7ca /arch/ppc
parentbac30d1a78d0f11c613968fc8b351a91ed465386 (diff)
[PATCH] lock PTE before updating it in 440/BookE page fault handler
Fix 44x and BookE page fault handler to correctly lock PTE before trying to pte_update() it, otherwise this PTE might be swapped out after pte_present() check but before pte_uptdate() call, resulting in corrupted PTE. This can happen with enabled preemption and low memory condition. Signed-off-by: Eugene Surovegin <ebs@ebshome.net> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/ppc')
-rw-r--r--arch/ppc/mm/fault.c30
-rw-r--r--arch/ppc/mm/pgtable.c6
2 files changed, 21 insertions, 15 deletions
diff --git a/arch/ppc/mm/fault.c b/arch/ppc/mm/fault.c
index 0217188ef465..8e08ca32531a 100644
--- a/arch/ppc/mm/fault.c
+++ b/arch/ppc/mm/fault.c
@@ -202,6 +202,7 @@ good_area:
202 /* an exec - 4xx/Book-E allows for per-page execute permission */ 202 /* an exec - 4xx/Book-E allows for per-page execute permission */
203 } else if (TRAP(regs) == 0x400) { 203 } else if (TRAP(regs) == 0x400) {
204 pte_t *ptep; 204 pte_t *ptep;
205 pmd_t *pmdp;
205 206
206#if 0 207#if 0
207 /* It would be nice to actually enforce the VM execute 208 /* It would be nice to actually enforce the VM execute
@@ -215,21 +216,24 @@ good_area:
215 /* Since 4xx/Book-E supports per-page execute permission, 216 /* Since 4xx/Book-E supports per-page execute permission,
216 * we lazily flush dcache to icache. */ 217 * we lazily flush dcache to icache. */
217 ptep = NULL; 218 ptep = NULL;
218 if (get_pteptr(mm, address, &ptep) && pte_present(*ptep)) { 219 if (get_pteptr(mm, address, &ptep, &pmdp)) {
219 struct page *page = pte_page(*ptep); 220 spinlock_t *ptl = pte_lockptr(mm, pmdp);
220 221 spin_lock(ptl);
221 if (! test_bit(PG_arch_1, &page->flags)) { 222 if (pte_present(*ptep)) {
222 flush_dcache_icache_page(page); 223 struct page *page = pte_page(*ptep);
223 set_bit(PG_arch_1, &page->flags); 224
225 if (!test_bit(PG_arch_1, &page->flags)) {
226 flush_dcache_icache_page(page);
227 set_bit(PG_arch_1, &page->flags);
228 }
229 pte_update(ptep, 0, _PAGE_HWEXEC);
230 _tlbie(address);
231 pte_unmap_unlock(ptep, ptl);
232 up_read(&mm->mmap_sem);
233 return 0;
224 } 234 }
225 pte_update(ptep, 0, _PAGE_HWEXEC); 235 pte_unmap_unlock(ptep, ptl);
226 _tlbie(address);
227 pte_unmap(ptep);
228 up_read(&mm->mmap_sem);
229 return 0;
230 } 236 }
231 if (ptep != NULL)
232 pte_unmap(ptep);
233#endif 237#endif
234 /* a read */ 238 /* a read */
235 } else { 239 } else {
diff --git a/arch/ppc/mm/pgtable.c b/arch/ppc/mm/pgtable.c
index a1924876cad6..706bca8eb144 100644
--- a/arch/ppc/mm/pgtable.c
+++ b/arch/ppc/mm/pgtable.c
@@ -368,7 +368,7 @@ void __init io_block_mapping(unsigned long virt, phys_addr_t phys,
368 * the PTE pointer is unmodified if PTE is not found. 368 * the PTE pointer is unmodified if PTE is not found.
369 */ 369 */
370int 370int
371get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep) 371get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)
372{ 372{
373 pgd_t *pgd; 373 pgd_t *pgd;
374 pmd_t *pmd; 374 pmd_t *pmd;
@@ -383,6 +383,8 @@ get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep)
383 if (pte) { 383 if (pte) {
384 retval = 1; 384 retval = 1;
385 *ptep = pte; 385 *ptep = pte;
386 if (pmdp)
387 *pmdp = pmd;
386 /* XXX caller needs to do pte_unmap, yuck */ 388 /* XXX caller needs to do pte_unmap, yuck */
387 } 389 }
388 } 390 }
@@ -420,7 +422,7 @@ unsigned long iopa(unsigned long addr)
420 mm = &init_mm; 422 mm = &init_mm;
421 423
422 pa = 0; 424 pa = 0;
423 if (get_pteptr(mm, addr, &pte)) { 425 if (get_pteptr(mm, addr, &pte, NULL)) {
424 pa = (pte_val(*pte) & PAGE_MASK) | (addr & ~PAGE_MASK); 426 pa = (pte_val(*pte) & PAGE_MASK) | (addr & ~PAGE_MASK);
425 pte_unmap(pte); 427 pte_unmap(pte);
426 } 428 }