From 1de14c3c5cbc9bb17e9dcc648cda51c0c85d54b9 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 12 Apr 2013 16:23:54 -0700 Subject: x86-32: Fix possible incomplete TLB invalidate with PAE pagetables This patch attempts to fix: https://bugzilla.kernel.org/show_bug.cgi?id=56461 The symptom is a crash and messages like this: chrome: Corrupted page table at address 34a03000 *pdpt = 0000000000000000 *pde = 0000000000000000 Bad pagetable: 000f [#1] PREEMPT SMP Ingo guesses this got introduced by commit 611ae8e3f520 ("x86/tlb: enable tlb flush range support for x86") since that code started to free unused pagetables. On x86-32 PAE kernels, that new code has the potential to free an entire PMD page and will clear one of the four page-directory-pointer-table (aka pgd_t entries). The hardware aggressively "caches" these top-level entries and invlpg does not actually affect the CPU's copy. If we clear one we *HAVE* to do a full TLB flush, otherwise we might continue using a freed pmd page. (note, we do this properly on the population side in pud_populate()). This patch tracks whenever we clear one of these entries in the 'struct mmu_gather', and ensures that we follow up with a full tlb flush. BTW, I disassembled and checked that: if (tlb->fullmm == 0) and if (!tlb->fullmm && !tlb->need_flush_all) generate essentially the same code, so there should be zero impact there to the !PAE case. Signed-off-by: Dave Hansen Cc: Peter Anvin Cc: Ingo Molnar Cc: Artem S Tashkinov Signed-off-by: Linus Torvalds --- arch/x86/include/asm/tlb.h | 2 +- arch/x86/mm/pgtable.c | 7 +++++++ 2 files changed, 8 insertions(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/x86/include/asm/tlb.h b/arch/x86/include/asm/tlb.h index 4fef20773b8f..c7797307fc2b 100644 --- a/arch/x86/include/asm/tlb.h +++ b/arch/x86/include/asm/tlb.h @@ -7,7 +7,7 @@ #define tlb_flush(tlb) \ { \ - if (tlb->fullmm == 0) \ + if (!tlb->fullmm && !tlb->need_flush_all) \ flush_tlb_mm_range(tlb->mm, tlb->start, tlb->end, 0UL); \ else \ flush_tlb_mm_range(tlb->mm, 0UL, TLB_FLUSH_ALL, 0UL); \ diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 193350b51f90..17fda6a8b3c2 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -58,6 +58,13 @@ void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte) void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd) { paravirt_release_pmd(__pa(pmd) >> PAGE_SHIFT); + /* + * NOTE! For PAE, any changes to the top page-directory-pointer-table + * entries need a full cr3 reload to flush. + */ +#ifdef CONFIG_X86_PAE + tlb->need_flush_all = 1; +#endif tlb_remove_page(tlb, virt_to_page(pmd)); } -- cgit v1.2.3