/* * This file contains some kasan initialization code. * * Copyright (c) 2015 Samsung Electronics Co., Ltd. * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> * * 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. * */ #include <linux/bootmem.h> #include <linux/init.h> #include <linux/kasan.h> #include <linux/kernel.h> #include <linux/memblock.h> #include <linux/mm.h> #include <linux/pfn.h> #include <asm/page.h> #include <asm/pgalloc.h> /* * This page serves two purposes: * - It used as early shadow memory. The entire shadow region populated * with this page, before we will be able to setup normal shadow memory. * - Latter it reused it as zero shadow to cover large ranges of memory * that allowed to access, but not handled by kasan (vmalloc/vmemmap ...). */ unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss; #if CONFIG_PGTABLE_LEVELS > 4 p4d_t kasan_zero_p4d[PTRS_PER_P4D] __page_aligned_bss; #endif #if CONFIG_PGTABLE_LEVELS > 3 pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss; #endif #if CONFIG_PGTABLE_LEVELS > 2 pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss; #endif pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss; static __init void *early_alloc(size_t size, int node) { return memblock_virt_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS), BOOTMEM_ALLOC_ACCESSIBLE, node); } static void __init zero_pte_populate(pmd_t *pmd, unsigned long addr, unsigned long end) { pte_t *pte = pte_offset_kernel(pmd, addr); pte_t zero_pte; zero_pte = pfn_pte(PFN_DOWN(__pa_symbol(kasan_zero_page)), PAGE_KERNEL); zero_pte = pte_wrprotect(zero_pte); while (addr + PAGE_SIZE <= end) { set_pte_at(&init_mm, addr, pte, zero_pte); addr += PAGE_SIZE; pte = pte_offset_kernel(pmd, addr); } } static void __init zero_pmd_populate(pud_t *pud, unsigned long addr, unsigned long end) { pmd_t *pmd = pmd_offset(pud, addr); unsigned long next; do { next = pmd_addr_end(addr, end); if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) { pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte)); continue; } if (pmd_none(*pmd)) { pmd_populate_kernel(&init_mm, pmd, early_alloc(PAGE_SIZE, NUMA_NO_NODE)); } zero_pte_populate(pmd, addr, next); } while (pmd++, addr = next, addr != end); } static void __init zero_pud_populate(p4d_t *p4d, unsigned long addr, unsigned long end) { pud_t *pud = pud_offset(p4d, addr); unsigned long next; do { next = pud_addr_end(addr, end); if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) { pmd_t *pmd; pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd)); pmd = pmd_offset(pud, addr); pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte)); continue; } if (pud_none(*pud)) { pud_populate(&init_mm, pud, early_alloc(PAGE_SIZE, NUMA_NO_NODE)); } zero_pmd_populate(pud, addr, next); } while (pud++, addr = next, addr != end); } static void __init zero_p4d_populate(pgd_t *pgd, unsigned long addr, unsigned long end) { p4d_t *p4d = p4d_offset(pgd, addr); unsigned long next; do { next = p4d_addr_end(addr, end); if (IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) { pud_t *pud; pmd_t *pmd; p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud)); pud = pud_offset(p4d, addr); pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd)); pmd = pmd_offset(pud, addr); pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte)); continue; } if (p4d_none(*p4d)) { p4d_populate(&init_mm, p4d, early_alloc(PAGE_SIZE, NUMA_NO_NODE)); } zero_pud_populate(p4d, addr, next); } while (p4d++, addr = next, addr != end); } /** * kasan_populate_zero_shadow - populate shadow memory region with * kasan_zero_page * @shadow_start - start of the memory range to populate * @shadow_end - end of the memory range to populate */ void __init kasan_populate_zero_shadow(const void *shadow_start, const void *shadow_end) { unsigned long addr = (unsigned long)shadow_start; unsigned long end = (unsigned long)shadow_end; pgd_t *pgd = pgd_offset_k(addr); unsigned long next; do { next = pgd_addr_end(addr, end); if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) { p4d_t *p4d; pud_t *pud; pmd_t *pmd; /* * kasan_zero_pud should be populated with pmds * at this moment. * [pud,pmd]_populate*() below needed only for * 3,2 - level page tables where we don't have * puds,pmds, so pgd_populate(), pud_populate() * is noops. * * The ifndef is required to avoid build breakage. * * With 5level-fixup.h, pgd_populate() is not nop and * we reference kasan_zero_p4d. It's not defined * unless 5-level paging enabled. * * The ifndef can be dropped once all KASAN-enabled * architectures will switch to pgtable-nop4d.h. */ #ifndef __ARCH_HAS_5LEVEL_HACK pgd_populate(&init_mm, pgd, lm_alias(kasan_zero_p4d)); #endif p4d = p4d_offset(pgd, addr); p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud)); pud = pud_offset(p4d, addr); pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd)); pmd = pmd_offset(pud, addr); pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte)); continue; } if (pgd_none(*pgd)) { pgd_populate(&init_mm, pgd, early_alloc(PAGE_SIZE, NUMA_NO_NODE)); } zero_p4d_populate(pgd, addr, next); } while (pgd++, addr = next, addr != end); }