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/*
* 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/memblock.h>
#include <linux/start_kernel.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);
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_kernel(&init_mm, pmd, kasan_zero_pte);
pte = pte_offset_kimg(pmd, addr);
do {
next = addr + PAGE_SIZE;
set_pte(pte, pfn_pte(virt_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(&init_mm, pud, kasan_zero_pmd);
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(&init_mm, pgd, kasan_zero_pud);
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(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(_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(virt_to_pfn(kasan_zero_page), PAGE_KERNEL_RO));
memset(kasan_zero_page, 0, PAGE_SIZE);
cpu_replace_ttbr1(swapper_pg_dir);
/* At this point kasan is fully initialized. Enable error messages */
init_task.kasan_depth = 0;
pr_info("KernelAddressSanitizer initialized\n");
}
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