diff options
Diffstat (limited to 'arch/arm64/mm/kasan_init.c')
| -rw-r--r-- | arch/arm64/mm/kasan_init.c | 159 |
1 files changed, 127 insertions, 32 deletions
diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c index 4c7ad574b946..fbddbf9faf19 100644 --- a/arch/arm64/mm/kasan_init.c +++ b/arch/arm64/mm/kasan_init.c @@ -23,7 +23,7 @@ #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) -static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE); +static pgd_t tmp_pg_dir[PTRS_PER_PTE] __initdata __aligned(PAGE_SIZE); /* * The p*d_populate functions call virt_to_phys implicitly so they can't be used @@ -99,6 +99,19 @@ static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node, return early ? pud_offset_kimg(p4dp, addr) : pud_offset(p4dp, addr); } +static p4d_t *__init kasan_p4d_offset(pgd_t *pgdp, unsigned long addr, int node, + bool early) +{ + if (pgd_none(READ_ONCE(*pgdp))) { + phys_addr_t p4d_phys = early ? + __pa_symbol(kasan_early_shadow_p4d) + : kasan_alloc_zeroed_page(node); + __pgd_populate(pgdp, p4d_phys, PGD_TYPE_TABLE); + } + + return early ? p4d_offset_kimg(pgdp, addr) : p4d_offset(pgdp, addr); +} + static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, unsigned long end, int node, bool early) { @@ -144,12 +157,12 @@ static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr, unsigned long end, int node, bool early) { unsigned long next; - p4d_t *p4dp = p4d_offset(pgdp, addr); + p4d_t *p4dp = kasan_p4d_offset(pgdp, addr, node, early); do { next = p4d_addr_end(addr, end); kasan_pud_populate(p4dp, addr, next, node, early); - } while (p4dp++, addr = next, addr != end); + } while (p4dp++, addr = next, addr != end && p4d_none(READ_ONCE(*p4dp))); } static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, @@ -165,19 +178,48 @@ static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, } while (pgdp++, addr = next, addr != end); } +#if defined(CONFIG_ARM64_64K_PAGES) || CONFIG_PGTABLE_LEVELS > 4 +#define SHADOW_ALIGN P4D_SIZE +#else +#define SHADOW_ALIGN PUD_SIZE +#endif + +/* + * Return whether 'addr' is aligned to the size covered by a root level + * descriptor. + */ +static bool __init root_level_aligned(u64 addr) +{ + int shift = (ARM64_HW_PGTABLE_LEVELS(vabits_actual) - 1) * (PAGE_SHIFT - 3); + + return (addr % (PAGE_SIZE << shift)) == 0; +} + /* The early shadow maps everything to a single page of zeroes */ asmlinkage void __init kasan_early_init(void) { BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); - /* - * We cannot check the actual value of KASAN_SHADOW_START during build, - * as it depends on vabits_actual. As a best-effort approach, check - * potential values calculated based on VA_BITS and VA_BITS_MIN. - */ - BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), PGDIR_SIZE)); - BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), PGDIR_SIZE)); - BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); + BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), SHADOW_ALIGN)); + BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), SHADOW_ALIGN)); + BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, SHADOW_ALIGN)); + + if (!root_level_aligned(KASAN_SHADOW_START)) { + /* + * The start address is misaligned, and so the next level table + * will be shared with the linear region. This can happen with + * 4 or 5 level paging, so install a generic pte_t[] as the + * next level. This prevents the kasan_pgd_populate call below + * from inserting an entry that refers to the shared KASAN zero + * shadow pud_t[]/p4d_t[], which could end up getting corrupted + * when the linear region is mapped. + */ + static pte_t tbl[PTRS_PER_PTE] __page_aligned_bss; + pgd_t *pgdp = pgd_offset_k(KASAN_SHADOW_START); + + set_pgd(pgdp, __pgd(__pa_symbol(tbl) | PGD_TYPE_TABLE)); + } + kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, true); } @@ -190,34 +232,74 @@ static void __init kasan_map_populate(unsigned long start, unsigned long end, } /* - * Copy the current shadow region into a new pgdir. + * Return the descriptor index of 'addr' in the root level table */ -void __init kasan_copy_shadow(pgd_t *pgdir) +static int __init root_level_idx(u64 addr) { - pgd_t *pgdp, *pgdp_new, *pgdp_end; + /* + * On 64k pages, the TTBR1 range root tables are extended for 52-bit + * virtual addressing, and TTBR1 will simply point to the pgd_t entry + * that covers the start of the 48-bit addressable VA space if LVA is + * not implemented. This means we need to index the table as usual, + * instead of masking off bits based on vabits_actual. + */ + u64 vabits = IS_ENABLED(CONFIG_ARM64_64K_PAGES) ? VA_BITS + : vabits_actual; + int shift = (ARM64_HW_PGTABLE_LEVELS(vabits) - 1) * (PAGE_SHIFT - 3); - pgdp = pgd_offset_k(KASAN_SHADOW_START); - pgdp_end = pgd_offset_k(KASAN_SHADOW_END); - pgdp_new = pgd_offset_pgd(pgdir, KASAN_SHADOW_START); - do { - set_pgd(pgdp_new, READ_ONCE(*pgdp)); - } while (pgdp++, pgdp_new++, pgdp != pgdp_end); + return (addr & ~_PAGE_OFFSET(vabits)) >> (shift + PAGE_SHIFT); +} + +/* + * Clone a next level table from swapper_pg_dir into tmp_pg_dir + */ +static void __init clone_next_level(u64 addr, pgd_t *tmp_pg_dir, pud_t *pud) +{ + int idx = root_level_idx(addr); + pgd_t pgd = READ_ONCE(swapper_pg_dir[idx]); + pud_t *pudp = (pud_t *)__phys_to_kimg(__pgd_to_phys(pgd)); + + memcpy(pud, pudp, PAGE_SIZE); + tmp_pg_dir[idx] = __pgd(__phys_to_pgd_val(__pa_symbol(pud)) | + PUD_TYPE_TABLE); } -static void __init clear_pgds(unsigned long start, - unsigned long end) +/* + * Return the descriptor index of 'addr' in the next level table + */ +static int __init next_level_idx(u64 addr) { - /* - * Remove references to kasan page tables from - * swapper_pg_dir. pgd_clear() can't be used - * here because it's nop on 2,3-level pagetable setups - */ - for (; start < end; start += PGDIR_SIZE) - set_pgd(pgd_offset_k(start), __pgd(0)); + int shift = (ARM64_HW_PGTABLE_LEVELS(vabits_actual) - 2) * (PAGE_SHIFT - 3); + + return (addr >> (shift + PAGE_SHIFT)) % PTRS_PER_PTE; +} + +/* + * Dereference the table descriptor at 'pgd_idx' and clear the entries from + * 'start' to 'end' (exclusive) from the table. + */ +static void __init clear_next_level(int pgd_idx, int start, int end) +{ + pgd_t pgd = READ_ONCE(swapper_pg_dir[pgd_idx]); + pud_t *pudp = (pud_t *)__phys_to_kimg(__pgd_to_phys(pgd)); + + memset(&pudp[start], 0, (end - start) * sizeof(pud_t)); +} + +static void __init clear_shadow(u64 start, u64 end) +{ + int l = root_level_idx(start), m = root_level_idx(end); + + if (!root_level_aligned(start)) + clear_next_level(l++, next_level_idx(start), PTRS_PER_PTE); + if (!root_level_aligned(end)) + clear_next_level(m, 0, next_level_idx(end)); + memset(&swapper_pg_dir[l], 0, (m - l) * sizeof(pgd_t)); } static void __init kasan_init_shadow(void) { + static pud_t pud[2][PTRS_PER_PUD] __initdata __aligned(PAGE_SIZE); u64 kimg_shadow_start, kimg_shadow_end; u64 mod_shadow_start; u64 vmalloc_shadow_end; @@ -239,10 +321,23 @@ static void __init kasan_init_shadow(void) * setup will be finished. */ memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir)); + + /* + * If the start or end address of the shadow region is not aligned to + * the root level size, we have to allocate a temporary next-level table + * in each case, clone the next level of descriptors, and install the + * table into tmp_pg_dir. Note that with 5 levels of paging, the next + * level will in fact be p4d_t, but that makes no difference in this + * case. + */ + if (!root_level_aligned(KASAN_SHADOW_START)) + clone_next_level(KASAN_SHADOW_START, tmp_pg_dir, pud[0]); + if (!root_level_aligned(KASAN_SHADOW_END)) + clone_next_level(KASAN_SHADOW_END, tmp_pg_dir, pud[1]); dsb(ishst); - cpu_replace_ttbr1(lm_alias(tmp_pg_dir), idmap_pg_dir); + cpu_replace_ttbr1(lm_alias(tmp_pg_dir)); - clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); + clear_shadow(KASAN_SHADOW_START, KASAN_SHADOW_END); kasan_map_populate(kimg_shadow_start, kimg_shadow_end, early_pfn_to_nid(virt_to_pfn(lm_alias(KERNEL_START)))); @@ -276,7 +371,7 @@ static void __init kasan_init_shadow(void) PAGE_KERNEL_RO)); memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE); - cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir); + cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); } static void __init kasan_init_depth(void) |