diff options
| -rw-r--r-- | arch/x86/mm/pgtable.c | 169 |
1 files changed, 101 insertions, 68 deletions
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 418c4432fb3..557b2abceef 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -66,12 +66,6 @@ static inline void pgd_list_del(pgd_t *pgd) static void pgd_ctor(void *p) { pgd_t *pgd = p; - unsigned long flags; - - /* Clear usermode parts of PGD */ - memset(pgd, 0, KERNEL_PGD_BOUNDARY*sizeof(pgd_t)); - - spin_lock_irqsave(&pgd_lock, flags); /* If the pgd points to a shared pagetable level (either the ptes in non-PAE, or shared PMD in PAE), then just copy the @@ -91,8 +85,6 @@ static void pgd_ctor(void *p) /* list required to sync kernel mapping updates */ if (!SHARED_KERNEL_PMD) pgd_list_add(pgd); - - spin_unlock_irqrestore(&pgd_lock, flags); } static void pgd_dtor(void *pgd) @@ -120,6 +112,72 @@ static void pgd_dtor(void *pgd) #ifdef CONFIG_X86_PAE /* + * 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. + * + * Also, if we're in a paravirt environment where the kernel pmd is + * not shared between pagetables (!SHARED_KERNEL_PMDS), we allocate + * and initialize the kernel pmds here. + */ +#define PREALLOCATED_PMDS UNSHARED_PTRS_PER_PGD + +void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd) +{ + paravirt_alloc_pmd(mm, __pa(pmd) >> PAGE_SHIFT); + + /* Note: almost everything apart from _PAGE_PRESENT is + reserved at the pmd (PDPT) level. */ + set_pud(pudp, __pud(__pa(pmd) | _PAGE_PRESENT)); + + /* + * 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... + */ + if (mm == current->active_mm) + write_cr3(read_cr3()); +} +#else /* !CONFIG_X86_PAE */ + +/* No need to prepopulate any pagetable entries in non-PAE modes. */ +#define PREALLOCATED_PMDS 0 + +#endif /* CONFIG_X86_PAE */ + +static void free_pmds(pmd_t *pmds[]) +{ + int i; + + for(i = 0; i < PREALLOCATED_PMDS; i++) + if (pmds[i]) + free_page((unsigned long)pmds[i]); +} + +static int preallocate_pmds(pmd_t *pmds[]) +{ + int i; + bool failed = false; + + for(i = 0; i < PREALLOCATED_PMDS; i++) { + pmd_t *pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL|__GFP_REPEAT); + if (pmd == NULL) + failed = true; + pmds[i] = pmd; + } + + if (failed) { + free_pmds(pmds); + return -ENOMEM; + } + + return 0; +} + +/* * 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 @@ -129,7 +187,7 @@ static void pgd_mop_up_pmds(struct mm_struct *mm, pgd_t *pgdp) { int i; - for(i = 0; i < UNSHARED_PTRS_PER_PGD; i++) { + for(i = 0; i < PREALLOCATED_PMDS; i++) { pgd_t pgd = pgdp[i]; if (pgd_val(pgd) != 0) { @@ -143,32 +201,17 @@ static void pgd_mop_up_pmds(struct mm_struct *mm, pgd_t *pgdp) } } -/* - * 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. - * - * Also, if we're in a paravirt environment where the kernel pmd is - * not shared between pagetables (!SHARED_KERNEL_PMDS), we allocate - * and initialize the kernel pmds here. - */ -static int pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd) +static void pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmds[]) { pud_t *pud; unsigned long addr; int i; pud = pud_offset(pgd, 0); - for (addr = i = 0; i < UNSHARED_PTRS_PER_PGD; - i++, pud++, addr += PUD_SIZE) { - pmd_t *pmd = pmd_alloc_one(mm, addr); - if (!pmd) { - pgd_mop_up_pmds(mm, pgd); - return 0; - } + for (addr = i = 0; i < PREALLOCATED_PMDS; + i++, pud++, addr += PUD_SIZE) { + pmd_t *pmd = pmds[i]; if (i >= KERNEL_PGD_BOUNDARY) memcpy(pmd, (pmd_t *)pgd_page_vaddr(swapper_pg_dir[i]), @@ -176,57 +219,47 @@ static int pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd) pud_populate(mm, pud, pmd); } - - return 1; } -void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd) +pgd_t *pgd_alloc(struct mm_struct *mm) { - paravirt_alloc_pmd(mm, __pa(pmd) >> PAGE_SHIFT); + pgd_t *pgd; + pmd_t *pmds[PREALLOCATED_PMDS]; + unsigned long flags; - /* Note: almost everything apart from _PAGE_PRESENT is - reserved at the pmd (PDPT) level. */ - set_pud(pudp, __pud(__pa(pmd) | _PAGE_PRESENT)); + pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO); + + if (pgd == NULL) + goto out; + + mm->pgd = pgd; + + if (preallocate_pmds(pmds) != 0) + goto out_free_pgd; + + if (paravirt_pgd_alloc(mm) != 0) + goto out_free_pmds; /* - * 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... + * Make sure that pre-populating the pmds is atomic with + * respect to anything walking the pgd_list, so that they + * never see a partially populated pgd. */ - if (mm == current->active_mm) - write_cr3(read_cr3()); -} -#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(struct mm_struct *mm, pgd_t *pgd) -{ -} -#endif /* CONFIG_X86_PAE */ + spin_lock_irqsave(&pgd_lock, flags); -pgd_t *pgd_alloc(struct mm_struct *mm) -{ - pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO); + pgd_ctor(pgd); + pgd_prepopulate_pmd(mm, pgd, pmds); - /* so that alloc_pmd can use it */ - mm->pgd = pgd; - if (pgd) { - pgd_ctor(pgd); - - if (paravirt_pgd_alloc(mm) != 0 || - !pgd_prepopulate_pmd(mm, pgd)) { - pgd_dtor(pgd); - free_page((unsigned long)pgd); - pgd = NULL; - } - } + spin_unlock_irqrestore(&pgd_lock, flags); return pgd; + +out_free_pmds: + free_pmds(pmds); +out_free_pgd: + free_page((unsigned long)pgd); +out: + return NULL; } void pgd_free(struct mm_struct *mm, pgd_t *pgd) |