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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/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 phys_addr_t __init kasan_alloc_zeroed_page(int node)
{
void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
__pa(MAX_DMA_ADDRESS),
MEMBLOCK_ALLOC_ACCESSIBLE, 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_zero_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_zero_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_zero_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_zero_page)
: kasan_alloc_zeroed_page(node);
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_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;
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_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");
}
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