diff options
| author | Eugene Surovegin <ebs@ebshome.net> | 2006-03-28 10:13:12 -0800 |
|---|---|---|
| committer | Paul Mackerras <paulus@samba.org> | 2006-03-29 13:44:15 +1100 |
| commit | bab70a4af737f623de5b034976a311055308ab86 (patch) | |
| tree | f8c0e9463de01323db2cb1a62f4eb83adb5ce7ca /arch/ppc/mm/fault.c | |
| parent | bac30d1a78d0f11c613968fc8b351a91ed465386 (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/mm/fault.c')
| -rw-r--r-- | arch/ppc/mm/fault.c | 30 |
1 files changed, 17 insertions, 13 deletions
diff --git a/arch/ppc/mm/fault.c b/arch/ppc/mm/fault.c index 0217188ef46..8e08ca32531 100644 --- a/arch/ppc/mm/fault.c +++ b/arch/ppc/mm/fault.c @@ -202,6 +202,7 @@ good_area: /* an exec - 4xx/Book-E allows for per-page execute permission */ } else if (TRAP(regs) == 0x400) { pte_t *ptep; + pmd_t *pmdp; #if 0 /* It would be nice to actually enforce the VM execute @@ -215,21 +216,24 @@ good_area: /* Since 4xx/Book-E supports per-page execute permission, * we lazily flush dcache to icache. */ ptep = NULL; - if (get_pteptr(mm, address, &ptep) && pte_present(*ptep)) { - struct page *page = pte_page(*ptep); - - if (! test_bit(PG_arch_1, &page->flags)) { - flush_dcache_icache_page(page); - set_bit(PG_arch_1, &page->flags); + if (get_pteptr(mm, address, &ptep, &pmdp)) { + spinlock_t *ptl = pte_lockptr(mm, pmdp); + spin_lock(ptl); + if (pte_present(*ptep)) { + struct page *page = pte_page(*ptep); + + if (!test_bit(PG_arch_1, &page->flags)) { + flush_dcache_icache_page(page); + set_bit(PG_arch_1, &page->flags); + } + pte_update(ptep, 0, _PAGE_HWEXEC); + _tlbie(address); + pte_unmap_unlock(ptep, ptl); + up_read(&mm->mmap_sem); + return 0; } - pte_update(ptep, 0, _PAGE_HWEXEC); - _tlbie(address); - pte_unmap(ptep); - up_read(&mm->mmap_sem); - return 0; + pte_unmap_unlock(ptep, ptl); } - if (ptep != NULL) - pte_unmap(ptep); #endif /* a read */ } else { |