/* * 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 #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 phys_addr_t __init kasan_alloc_zeroed_page(int node) { void *p = memblock_virt_alloc_try_nid(PAGE_SIZE, PAGE_SIZE, __pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_KASAN, node); return __pa(p); } static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, bool early) { if (pmd_none(READ_ONCE(*pmdp))) { phys_addr_t pte_phys = early ? __pa_symbol(kasan_early_shadow_pte) : kasan_alloc_zeroed_page(node); __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE); } return early ? pte_offset_kimg(pmdp, addr) : pte_offset_kernel(pmdp, addr); } static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, bool early) { if (pud_none(READ_ONCE(*pudp))) { phys_addr_t pmd_phys = early ? __pa_symbol(kasan_early_shadow_pmd) : kasan_alloc_zeroed_page(node); __pud_populate(pudp, pmd_phys, PMD_TYPE_TABLE); } return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr); } static pud_t *__init kasan_pud_offset(pgd_t *pgdp, unsigned long addr, int node, bool early) { if (pgd_none(READ_ONCE(*pgdp))) { phys_addr_t pud_phys = early ? __pa_symbol(kasan_early_shadow_pud) : kasan_alloc_zeroed_page(node); __pgd_populate(pgdp, pud_phys, PMD_TYPE_TABLE); } return early ? pud_offset_kimg(pgdp, addr) : pud_offset(pgdp, addr); } static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, unsigned long end, int node, bool early) { unsigned long next; pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early); do { phys_addr_t page_phys = early ? __pa_symbol(kasan_early_shadow_page) : kasan_alloc_zeroed_page(node); if (!early) memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE); next = addr + PAGE_SIZE; set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep))); } static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr, unsigned long end, int node, bool early) { unsigned long next; pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early); do { next = pmd_addr_end(addr, end); kasan_pte_populate(pmdp, addr, next, node, early); } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp))); } static void __init kasan_pud_populate(pgd_t *pgdp, unsigned long addr, unsigned long end, int node, bool early) { unsigned long next; pud_t *pudp = kasan_pud_offset(pgdp, addr, node, early); do { next = pud_addr_end(addr, end); kasan_pmd_populate(pudp, addr, next, node, early); } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp))); } static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, int node, bool early) { unsigned long next; pgd_t *pgdp; pgdp = pgd_offset_k(addr); do { next = pgd_addr_end(addr, end); kasan_pud_populate(pgdp, addr, next, node, early); } while (pgdp++, addr = next, addr != end); } /* 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))); BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE)); BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, true); } /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */ static void __init kasan_map_populate(unsigned long start, unsigned long end, int node) { kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false); } /* * Copy the current shadow region into a new pgdir. */ void __init kasan_copy_shadow(pgd_t *pgdir) { pgd_t *pgdp, *pgdp_new, *pgdp_end; pgdp = pgd_offset_k(KASAN_SHADOW_START); pgdp_end = pgd_offset_k(KASAN_SHADOW_END); pgdp_new = pgd_offset_raw(pgdir, KASAN_SHADOW_START); do { set_pgd(pgdp_new, READ_ONCE(*pgdp)); } while (pgdp++, pgdp_new++, pgdp != pgdp_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) & PAGE_MASK; kimg_shadow_end = PAGE_ALIGN((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 below). * 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); kasan_map_populate(kimg_shadow_start, kimg_shadow_end, early_pfn_to_nid(virt_to_pfn(lm_alias(_text)))); kasan_populate_early_shadow((void *)KASAN_SHADOW_START, (void *)mod_shadow_start); kasan_populate_early_shadow((void *)kimg_shadow_end, kasan_mem_to_shadow((void *)PAGE_OFFSET)); if (kimg_shadow_start > mod_shadow_end) kasan_populate_early_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; kasan_map_populate((unsigned long)kasan_mem_to_shadow(start), (unsigned long)kasan_mem_to_shadow(end), early_pfn_to_nid(virt_to_pfn(start))); } /* * KAsan may reuse the contents of kasan_early_shadow_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_early_shadow_pte[i], pfn_pte(sym_to_pfn(kasan_early_shadow_page), PAGE_KERNEL_RO)); memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, 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"); }