cregit-Linux how code gets into the kernel

Release 4.14 arch/arm64/mm/kasan_init.c

Directory: arch/arm64/mm
/*
 * This file contains kasan initialization code for ARM64.
 *
 * 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.
 *
 */


#define pr_fmt(fmt) "kasan: " fmt
#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/sched/task.h>
#include <linux/memblock.h>
#include <linux/start_kernel.h>
#include <linux/mm.h>

#include <asm/mmu_context.h>
#include <asm/kernel-pgtable.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>

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)); }

Contributors

PersonTokensPropCommitsCommitProp
Andrey Ryabinin9292.00%133.33%
Laura Abbott77.00%133.33%
Ard Biesheuvel11.00%133.33%
Total100100.00%3100.00%


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)); }

Contributors

PersonTokensPropCommitsCommitProp
Andrey Ryabinin9092.78%133.33%
Laura Abbott66.19%133.33%
Ard Biesheuvel11.03%133.33%
Total97100.00%3100.00%


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)); }

Contributors

PersonTokensPropCommitsCommitProp
Andrey Ryabinin9092.78%133.33%
Laura Abbott66.19%133.33%
Ard Biesheuvel11.03%133.33%
Total97100.00%3100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Andrey Ryabinin71100.00%1100.00%
Total71100.00%1100.00%


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(); }

Contributors

PersonTokensPropCommitsCommitProp
Andrey Ryabinin4697.87%150.00%
Will Deacon12.13%150.00%
Total47100.00%2100.00%

/* * 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); }

Contributors

PersonTokensPropCommitsCommitProp
Mark Rutland67100.00%1100.00%
Total67100.00%1100.00%


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)); }

Contributors

PersonTokensPropCommitsCommitProp
Andrey Ryabinin40100.00%1100.00%
Total40100.00%1100.00%


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; vmemmap_populate((unsigned long)kasan_mem_to_shadow(start), (unsigned long)kasan_mem_to_shadow(end), 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"); }

Contributors

PersonTokensPropCommitsCommitProp
Ard Biesheuvel15947.04%333.33%
Andrey Ryabinin15545.86%111.11%
Mark Rutland92.66%222.22%
Catalin Marinas82.37%222.22%
Laura Abbott72.07%111.11%
Total338100.00%9100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
Andrey Ryabinin62868.41%18.33%
Ard Biesheuvel16818.30%325.00%
Mark Rutland808.71%325.00%
Laura Abbott303.27%18.33%
Catalin Marinas80.87%216.67%
Ingo Molnar30.33%18.33%
Will Deacon10.11%18.33%
Total918100.00%12100.00%
Directory: arch/arm64/mm
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