diff options
Diffstat (limited to 'include/asm-x86/pgtable-3level.h')
| -rw-r--r-- | include/asm-x86/pgtable-3level.h | 26 |
1 files changed, 11 insertions, 15 deletions
diff --git a/include/asm-x86/pgtable-3level.h b/include/asm-x86/pgtable-3level.h index a195c3e757b9..1d763eec740f 100644 --- a/include/asm-x86/pgtable-3level.h +++ b/include/asm-x86/pgtable-3level.h @@ -93,26 +93,22 @@ static inline void native_pmd_clear(pmd_t *pmd) static inline void pud_clear(pud_t *pudp) { + unsigned long pgd; + set_pud(pudp, __pud(0)); /* - * In principle we need to do a cr3 reload here to make sure - * the processor recognizes the changed pgd. In practice, all - * the places where pud_clear() gets called are followed by - * full tlb flushes anyway, so we can defer the cost here. - * - * Specifically: - * - * mm/memory.c:free_pmd_range() - immediately after the - * pud_clear() it does a pmd_free_tlb(). We change the - * mmu_gather structure to do a full tlb flush (which has the - * effect of reloading cr3) when the pagetable free is - * complete. + * According to Intel App note "TLBs, Paging-Structure Caches, + * and Their Invalidation", April 2007, document 317080-001, + * section 8.1: in PAE mode we explicitly have to flush the + * TLB via cr3 if the top-level pgd is changed... * - * arch/x86/mm/hugetlbpage.c:huge_pmd_unshare() - the call to - * this is followed by a flush_tlb_range, which on x86 does a - * full tlb flush. + * Make sure the pud entry we're updating is within the + * current pgd to avoid unnecessary TLB flushes. */ + pgd = read_cr3(); + if (__pa(pudp) >= pgd && __pa(pudp) < (pgd + sizeof(pgd_t)*PTRS_PER_PGD)) + write_cr3(pgd); } #define pud_page(pud) \ |