diff options
| -rw-r--r-- | arch/x86/mm/pgtable_32.c | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c index f85ee44720d..33ddddfc26b 100644 --- a/arch/x86/mm/pgtable_32.c +++ b/arch/x86/mm/pgtable_32.c @@ -294,6 +294,70 @@ static void pgd_dtor(void *pgd) #define UNSHARED_PTRS_PER_PGD \ (SHARED_KERNEL_PMD ? USER_PTRS_PER_PGD : PTRS_PER_PGD) +#ifdef CONFIG_X86_PAE +/* + * Mop up any pmd pages which may still be attached to the pgd. + * Normally they will be freed by munmap/exit_mmap, but any pmd we + * preallocate which never got a corresponding vma will need to be + * freed manually. + */ +static void pgd_mop_up_pmds(pgd_t *pgdp) +{ + int i; + + for(i = 0; i < USER_PTRS_PER_PGD; i++) { + pgd_t pgd = pgdp[i]; + + if (pgd_val(pgd) != 0) { + pmd_t *pmd = (pmd_t *)pgd_page_vaddr(pgd); + + pgdp[i] = native_make_pgd(0); + + paravirt_release_pd(pgd_val(pgd) >> PAGE_SHIFT); + pmd_free(pmd); + } + } +} + +/* + * In PAE mode, we need to do a cr3 reload (=tlb flush) when + * updating the top-level pagetable entries to guarantee the + * processor notices the update. Since this is expensive, and + * all 4 top-level entries are used almost immediately in a + * new process's life, we just pre-populate them here. + */ +static int pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd) +{ + pud_t *pud; + unsigned long addr; + int i; + + pud = pud_offset(pgd, 0); + for (addr = i = 0; i < USER_PTRS_PER_PGD; i++, pud++, addr += PUD_SIZE) { + pmd_t *pmd = pmd_alloc_one(mm, addr); + + if (!pmd) { + pgd_mop_up_pmds(pgd); + return 0; + } + + pud_populate(mm, pud, pmd); + } + + return 1; +} +#else /* !CONFIG_X86_PAE */ +/* No need to prepopulate any pagetable entries in non-PAE modes. */ +static int pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd) +{ + return 1; +} + +static void pgd_mop_up_pmds(pgd_t *pgd) +{ +} +#endif /* CONFIG_X86_PAE */ + /* If we allocate a pmd for part of the kernel address space, then make sure its initialized with the appropriate kernel mappings. Otherwise use a cached zeroed pmd. */ @@ -341,6 +405,11 @@ pgd_t *pgd_alloc(struct mm_struct *mm) paravirt_alloc_pd(mm, __pa(pmd) >> PAGE_SHIFT); set_pgd(&pgd[i], __pgd(1 + __pa(pmd))); } + if (pgd && !pgd_prepopulate_pmd(mm, pgd)) { + quicklist_free(0, pgd_dtor, pgd); + pgd = NULL; + } + return pgd; out_oom: @@ -367,6 +436,7 @@ void pgd_free(pgd_t *pgd) pmd_cache_free(pmd, i); } /* in the non-PAE case, free_pgtables() clears user pgd entries */ + pgd_mop_up_pmds(pgd); quicklist_free(0, pgd_dtor, pgd); } |