diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/mm/pgtable.c | 100 |
1 files changed, 81 insertions, 19 deletions
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index db6fb7740bf7..8e4e63d46d81 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -182,6 +182,14 @@ static void pgd_dtor(pgd_t *pgd) */ #define PREALLOCATED_PMDS UNSHARED_PTRS_PER_PGD +/* + * We allocate separate PMDs for the kernel part of the user page-table + * when PTI is enabled. We need them to map the per-process LDT into the + * user-space page-table. + */ +#define PREALLOCATED_USER_PMDS (static_cpu_has(X86_FEATURE_PTI) ? \ + KERNEL_PGD_PTRS : 0) + void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd) { paravirt_alloc_pmd(mm, __pa(pmd) >> PAGE_SHIFT); @@ -202,14 +210,14 @@ void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd) /* No need to prepopulate any pagetable entries in non-PAE modes. */ #define PREALLOCATED_PMDS 0 - +#define PREALLOCATED_USER_PMDS 0 #endif /* CONFIG_X86_PAE */ -static void free_pmds(struct mm_struct *mm, pmd_t *pmds[]) +static void free_pmds(struct mm_struct *mm, pmd_t *pmds[], int count) { int i; - for(i = 0; i < PREALLOCATED_PMDS; i++) + for (i = 0; i < count; i++) if (pmds[i]) { pgtable_pmd_page_dtor(virt_to_page(pmds[i])); free_page((unsigned long)pmds[i]); @@ -217,7 +225,7 @@ static void free_pmds(struct mm_struct *mm, pmd_t *pmds[]) } } -static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[]) +static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[], int count) { int i; bool failed = false; @@ -226,7 +234,7 @@ static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[]) if (mm == &init_mm) gfp &= ~__GFP_ACCOUNT; - for(i = 0; i < PREALLOCATED_PMDS; i++) { + for (i = 0; i < count; i++) { pmd_t *pmd = (pmd_t *)__get_free_page(gfp); if (!pmd) failed = true; @@ -241,7 +249,7 @@ static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[]) } if (failed) { - free_pmds(mm, pmds); + free_pmds(mm, pmds, count); return -ENOMEM; } @@ -254,23 +262,38 @@ static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[]) * preallocate which never got a corresponding vma will need to be * freed manually. */ +static void mop_up_one_pmd(struct mm_struct *mm, pgd_t *pgdp) +{ + pgd_t pgd = *pgdp; + + if (pgd_val(pgd) != 0) { + pmd_t *pmd = (pmd_t *)pgd_page_vaddr(pgd); + + *pgdp = native_make_pgd(0); + + paravirt_release_pmd(pgd_val(pgd) >> PAGE_SHIFT); + pmd_free(mm, pmd); + mm_dec_nr_pmds(mm); + } +} + static void pgd_mop_up_pmds(struct mm_struct *mm, pgd_t *pgdp) { int i; - for(i = 0; i < PREALLOCATED_PMDS; i++) { - pgd_t pgd = pgdp[i]; + for (i = 0; i < PREALLOCATED_PMDS; i++) + mop_up_one_pmd(mm, &pgdp[i]); - if (pgd_val(pgd) != 0) { - pmd_t *pmd = (pmd_t *)pgd_page_vaddr(pgd); +#ifdef CONFIG_PAGE_TABLE_ISOLATION - pgdp[i] = native_make_pgd(0); + if (!static_cpu_has(X86_FEATURE_PTI)) + return; - paravirt_release_pmd(pgd_val(pgd) >> PAGE_SHIFT); - pmd_free(mm, pmd); - mm_dec_nr_pmds(mm); - } - } + pgdp = kernel_to_user_pgdp(pgdp); + + for (i = 0; i < PREALLOCATED_USER_PMDS; i++) + mop_up_one_pmd(mm, &pgdp[i + KERNEL_PGD_BOUNDARY]); +#endif } static void pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmds[]) @@ -296,6 +319,38 @@ static void pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmds[]) } } +#ifdef CONFIG_PAGE_TABLE_ISOLATION +static void pgd_prepopulate_user_pmd(struct mm_struct *mm, + pgd_t *k_pgd, pmd_t *pmds[]) +{ + pgd_t *s_pgd = kernel_to_user_pgdp(swapper_pg_dir); + pgd_t *u_pgd = kernel_to_user_pgdp(k_pgd); + p4d_t *u_p4d; + pud_t *u_pud; + int i; + + u_p4d = p4d_offset(u_pgd, 0); + u_pud = pud_offset(u_p4d, 0); + + s_pgd += KERNEL_PGD_BOUNDARY; + u_pud += KERNEL_PGD_BOUNDARY; + + for (i = 0; i < PREALLOCATED_USER_PMDS; i++, u_pud++, s_pgd++) { + pmd_t *pmd = pmds[i]; + + memcpy(pmd, (pmd_t *)pgd_page_vaddr(*s_pgd), + sizeof(pmd_t) * PTRS_PER_PMD); + + pud_populate(mm, u_pud, pmd); + } + +} +#else +static void pgd_prepopulate_user_pmd(struct mm_struct *mm, + pgd_t *k_pgd, pmd_t *pmds[]) +{ +} +#endif /* * Xen paravirt assumes pgd table should be in one page. 64 bit kernel also * assumes that pgd should be in one page. @@ -376,6 +431,7 @@ static inline void _pgd_free(pgd_t *pgd) pgd_t *pgd_alloc(struct mm_struct *mm) { pgd_t *pgd; + pmd_t *u_pmds[PREALLOCATED_USER_PMDS]; pmd_t *pmds[PREALLOCATED_PMDS]; pgd = _pgd_alloc(); @@ -385,12 +441,15 @@ pgd_t *pgd_alloc(struct mm_struct *mm) mm->pgd = pgd; - if (preallocate_pmds(mm, pmds) != 0) + if (preallocate_pmds(mm, pmds, PREALLOCATED_PMDS) != 0) goto out_free_pgd; - if (paravirt_pgd_alloc(mm) != 0) + if (preallocate_pmds(mm, u_pmds, PREALLOCATED_USER_PMDS) != 0) goto out_free_pmds; + if (paravirt_pgd_alloc(mm) != 0) + goto out_free_user_pmds; + /* * Make sure that pre-populating the pmds is atomic with * respect to anything walking the pgd_list, so that they @@ -400,13 +459,16 @@ pgd_t *pgd_alloc(struct mm_struct *mm) pgd_ctor(mm, pgd); pgd_prepopulate_pmd(mm, pgd, pmds); + pgd_prepopulate_user_pmd(mm, pgd, u_pmds); spin_unlock(&pgd_lock); return pgd; +out_free_user_pmds: + free_pmds(mm, u_pmds, PREALLOCATED_USER_PMDS); out_free_pmds: - free_pmds(mm, pmds); + free_pmds(mm, pmds, PREALLOCATED_PMDS); out_free_pgd: _pgd_free(pgd); out: |