/* * This file contains kasan initialization code for ARM64. * * Copyright (c) 2015 Samsung Electronics Co., Ltd. * Author: Andrey Ryabinin * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * */ #define pr_fmt(fmt) "kasan: " fmt #include #include #include #include #include #include #include #include #include #include #include #include static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE); /* * The p*d_populate functions call virt_to_phys implicitly so they can't be used * directly on kernel symbols (bm_p*d). All the early functions are called too * early to use lm_alias so __p*d_populate functions must be used to populate * with the physical address from __pa_symbol. */ static void __init kasan_early_pte_populate(pmd_t *pmd, unsigned long addr, unsigned long end) { pte_t *pte; unsigned long next; if (pmd_none(*pmd)) __pmd_populate(pmd, __pa_symbol(kasan_zero_pte), PMD_TYPE_TABLE); pte = pte_offset_kimg(pmd, addr); do { next = addr + PAGE_SIZE; set_pte(pte, pfn_pte(sym_to_pfn(kasan_zero_page), PAGE_KERNEL)); } while (pte++, addr = next, addr != end && pte_none(*pte)); } static void __init kasan_early_pmd_populate(pud_t *pud, unsigned long addr, unsigned long end) { pmd_t *pmd; unsigned long next; if (pud_none(*pud)) __pud_populate(pud, __pa_symbol(kasan_zero_pmd), PMD_TYPE_TABLE); pmd = pmd_offset_kimg(pud, addr); do { next = pmd_addr_end(addr, end); kasan_early_pte_populate(pmd, addr, next); } while (pmd++, addr = next, addr != end && pmd_none(*pmd)); } static void __init kasan_early_pud_populate(pgd_t *pgd, unsigned long addr, unsigned long end) { pud_t *pud; unsigned long next; if (pgd_none(*pgd)) __pgd_populate(pgd, __pa_symbol(kasan_zero_pud), PUD_TYPE_TABLE); pud = pud_offset_kimg(pgd, addr); do { next = pud_addr_end(addr, end); kasan_early_pmd_populate(pud, addr, next); } while (pud++, addr = next, addr != end && pud_none(*pud)); } static void __init kasan_map_early_shadow(void) { unsigned long addr = KASAN_SHADOW_START; unsigned long end = KASAN_SHADOW_END; unsigned long next; pgd_t *pgd; pgd = pgd_offset_k(addr); do { next = pgd_addr_end(addr, end); kasan_early_pud_populate(pgd, addr, next); } while (pgd++, addr = next, addr != end); } asmlinkage void __init kasan_early_init(void) { BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_END - (1UL << 61)); BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE)); BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); kasan_map_early_shadow(); } /* * Copy the current shadow region into a new pgdir. */ void __init kasan_copy_shadow(pgd_t *pgdir) { pgd_t *pgd, *pgd_new, *pgd_end; pgd = pgd_offset_k(KASAN_SHADOW_START); pgd_end = pgd_offset_k(KASAN_SHADOW_END); pgd_new = pgd_offset_raw(pgdir, KASAN_SHADOW_START); do { set_pgd(pgd_new, *pgd); } while (pgd++, pgd_new++, pgd != pgd_end); } static void __init clear_pgds(unsigned long start, unsigned long end) { /* * 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)); } void __init kasan_init(void) { u64 kimg_shadow_start, kimg_shadow_end; u64 mod_shadow_start, mod_shadow_end; struct memblock_region *reg; int i; kimg_shadow_start = (u64)kasan_mem_to_shadow(_text); kimg_shadow_end = (u64)kasan_mem_to_shadow(_end); mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR); mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END); /* * We are going to perform proper setup of shadow memory. * At first we should unmap early shadow (clear_pgds() call bellow). * However, instrumented code couldn't execute without shadow memory. * tmp_pg_dir used to keep early shadow mapped until full shadow * setup will be finished. */ memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir)); dsb(ishst); cpu_replace_ttbr1(lm_alias(tmp_pg_dir)); clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); vmemmap_populate(kimg_shadow_start, kimg_shadow_end, pfn_to_nid(virt_to_pfn(lm_alias(_text)))); /* * vmemmap_populate() has populated the shadow region that covers the * kernel image with SWAPPER_BLOCK_SIZE mappings, so we have to round * the start and end addresses to SWAPPER_BLOCK_SIZE as well, to prevent * kasan_populate_zero_shadow() from replacing the page table entries * (PMD or PTE) at the edges of the shadow region for the kernel * image. */ kimg_shadow_start = round_down(kimg_shadow_start, SWAPPER_BLOCK_SIZE); kimg_shadow_end = round_up(kimg_shadow_end, SWAPPER_BLOCK_SIZE); kasan_populate_zero_shadow((void *)KASAN_SHADOW_START, (void *)mod_shadow_start); kasan_populate_zero_shadow((void *)kimg_shadow_end, kasan_mem_to_shadow((void *)PAGE_OFFSET)); if (kimg_shadow_start > mod_shadow_end) kasan_populate_zero_shadow((void *)mod_shadow_end, (void *)kimg_shadow_start); for_each_memblock(memory, reg) { void *start = (void *)__phys_to_virt(reg->base); void *end = (void *)__phys_to_virt(reg->base + reg->size); if (start >= end) break; /* * end + 1 here is intentional. We check several shadow bytes in * advance to slightly speed up fastpath. In some rare cases * we could cross boundary of mapped shadow, so we just map * some more here. */ vmemmap_populate((unsigned long)kasan_mem_to_shadow(start), (unsigned long)kasan_mem_to_shadow(end) + 1, pfn_to_nid(virt_to_pfn(start))); } /* * KAsan may reuse the contents of kasan_zero_pte directly, so we * should make sure that it maps the zero page read-only. */ for (i = 0; i < PTRS_PER_PTE; i++) set_pte(&kasan_zero_pte[i], pfn_pte(sym_to_pfn(kasan_zero_page), PAGE_KERNEL_RO)); memset(kasan_zero_page, 0, PAGE_SIZE); cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); /* At this point kasan is fully initialized. Enable error messages */ init_task.kasan_depth = 0; pr_info("KernelAddressSanitizer initialized\n"); }