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-rw-r--r--arch/x86/mm/pgtable_32.c70
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);
}