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// SPDX-License-Identifier: GPL-2.0
/*
* This file contains KASAN shadow initialization code.
*
* Copyright (c) 2015 Samsung Electronics Co., Ltd.
* Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
*/
#include <linux/memblock.h>
#include <linux/init.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/pfn.h>
#include <linux/slab.h>
#include <linux/pgalloc.h>
#include <asm/page.h>
#include "kasan.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_early_shadow_page[PAGE_SIZE] __bss_pgtbl;
#if CONFIG_PGTABLE_LEVELS > 4
p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D] __bss_pgtbl;
static inline bool kasan_p4d_table(pgd_t pgd)
{
return pgd_page(pgd) == virt_to_page(lm_alias(kasan_early_shadow_p4d));
}
#else
static inline bool kasan_p4d_table(pgd_t pgd)
{
return false;
}
#endif
#if CONFIG_PGTABLE_LEVELS > 3
pud_t kasan_early_shadow_pud[MAX_PTRS_PER_PUD] __bss_pgtbl;
static inline bool kasan_pud_table(p4d_t p4d)
{
return p4d_page(p4d) == virt_to_page(lm_alias(kasan_early_shadow_pud));
}
#else
static inline bool kasan_pud_table(p4d_t p4d)
{
return false;
}
#endif
#if CONFIG_PGTABLE_LEVELS > 2
pmd_t kasan_early_shadow_pmd[MAX_PTRS_PER_PMD] __bss_pgtbl;
static inline bool kasan_pmd_table(pud_t pud)
{
return pud_page(pud) == virt_to_page(lm_alias(kasan_early_shadow_pmd));
}
#else
static inline bool kasan_pmd_table(pud_t pud)
{
return false;
}
#endif
pte_t kasan_early_shadow_pte[MAX_PTRS_PER_PTE + PTE_HWTABLE_PTRS]
__bss_pgtbl;
static inline bool kasan_pte_table(pmd_t pmd)
{
return pmd_page(pmd) == virt_to_page(lm_alias(kasan_early_shadow_pte));
}
static inline bool kasan_early_shadow_page_entry(pte_t pte)
{
return pte_page(pte) == virt_to_page(lm_alias(kasan_early_shadow_page));
}
static __init void *early_alloc(size_t size, int node)
{
void *ptr = memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
MEMBLOCK_ALLOC_ACCESSIBLE, node);
if (!ptr)
panic("%s: Failed to allocate %zu bytes align=%zx nid=%d from=%llx\n",
__func__, size, size, node, (u64)__pa(MAX_DMA_ADDRESS));
return ptr;
}
static void __ref 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_early_shadow_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 int __ref 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_early_shadow_pte));
continue;
}
if (pmd_none(*pmd)) {
pte_t *p;
if (slab_is_available())
p = pte_alloc_one_kernel(&init_mm);
else {
p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
kernel_pte_init(p);
}
if (!p)
return -ENOMEM;
pmd_populate_kernel(&init_mm, pmd, p);
}
zero_pte_populate(pmd, addr, next);
} while (pmd++, addr = next, addr != end);
return 0;
}
static int __ref 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_early_shadow_pmd));
pmd = pmd_offset(pud, addr);
pmd_populate_kernel(&init_mm, pmd,
lm_alias(kasan_early_shadow_pte));
continue;
}
if (pud_none(*pud)) {
pmd_t *p;
if (slab_is_available()) {
p = pmd_alloc(&init_mm, pud, addr);
if (!p)
return -ENOMEM;
} else {
p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
pmd_init(p);
pud_populate(&init_mm, pud, p);
}
}
zero_pmd_populate(pud, addr, next);
} while (pud++, addr = next, addr != end);
return 0;
}
static int __ref 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_kernel(addr, p4d,
lm_alias(kasan_early_shadow_pud));
pud = pud_offset(p4d, addr);
pud_populate(&init_mm, pud,
lm_alias(kasan_early_shadow_pmd));
pmd = pmd_offset(pud, addr);
pmd_populate_kernel(&init_mm, pmd,
lm_alias(kasan_early_shadow_pte));
continue;
}
if (p4d_none(*p4d)) {
pud_t *p;
if (slab_is_available()) {
p = pud_alloc(&init_mm, p4d, addr);
if (!p)
return -ENOMEM;
} else {
p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
pud_init(p);
p4d_populate_kernel(addr, p4d, p);
}
}
zero_pud_populate(p4d, addr, next);
} while (p4d++, addr = next, addr != end);
return 0;
}
/**
* kasan_populate_early_shadow - populate shadow memory region with
* kasan_early_shadow_page
* @shadow_start: start of the memory range to populate
* @shadow_end: end of the memory range to populate
*/
int __ref kasan_populate_early_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_early_shadow_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.
*/
pgd_populate_kernel(addr, pgd,
lm_alias(kasan_early_shadow_p4d));
p4d = p4d_offset(pgd, addr);
p4d_populate_kernel(addr, p4d,
lm_alias(kasan_early_shadow_pud));
pud = pud_offset(p4d, addr);
pud_populate(&init_mm, pud,
lm_alias(kasan_early_shadow_pmd));
pmd = pmd_offset(pud, addr);
pmd_populate_kernel(&init_mm, pmd,
lm_alias(kasan_early_shadow_pte));
continue;
}
if (pgd_none(*pgd)) {
if (slab_is_available()) {
if (!p4d_alloc(&init_mm, pgd, addr))
return -ENOMEM;
} else {
pgd_populate_kernel(addr, pgd,
early_alloc(PAGE_SIZE, NUMA_NO_NODE));
}
}
zero_p4d_populate(pgd, addr, next);
} while (pgd++, addr = next, addr != end);
return 0;
}
static void kasan_free_pte(pte_t *pte_start, pmd_t *pmd)
{
pte_t *pte;
int i;
for (i = 0; i < PTRS_PER_PTE; i++) {
pte = pte_start + i;
if (!pte_none(ptep_get(pte)))
return;
}
pte_free_kernel(&init_mm, pte_start);
pmd_clear(pmd);
}
static void kasan_free_pmd(pmd_t *pmd_start, pud_t *pud)
{
pmd_t *pmd;
int i;
for (i = 0; i < PTRS_PER_PMD; i++) {
pmd = pmd_start + i;
if (!pmd_none(*pmd))
return;
}
pmd_free(&init_mm, pmd_start);
pud_clear(pud);
}
static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d)
{
pud_t *pud;
int i;
for (i = 0; i < PTRS_PER_PUD; i++) {
pud = pud_start + i;
if (!pud_none(*pud))
return;
}
pud_free(&init_mm, pud_start);
p4d_clear(p4d);
}
static void kasan_free_p4d(p4d_t *p4d_start, pgd_t *pgd)
{
p4d_t *p4d;
int i;
for (i = 0; i < PTRS_PER_P4D; i++) {
p4d = p4d_start + i;
if (!p4d_none(*p4d))
return;
}
p4d_free(&init_mm, p4d_start);
pgd_clear(pgd);
}
static void kasan_remove_pte_table(pte_t *pte, unsigned long addr,
unsigned long end)
{
unsigned long next;
pte_t ptent;
for (; addr < end; addr = next, pte++) {
next = (addr + PAGE_SIZE) & PAGE_MASK;
if (next > end)
next = end;
ptent = ptep_get(pte);
if (!pte_present(ptent))
continue;
if (WARN_ON(!kasan_early_shadow_page_entry(ptent)))
continue;
pte_clear(&init_mm, addr, pte);
}
}
static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
unsigned long end)
{
unsigned long next;
for (; addr < end; addr = next, pmd++) {
pte_t *pte;
next = pmd_addr_end(addr, end);
if (!pmd_present(*pmd))
continue;
if (kasan_pte_table(*pmd)) {
if (IS_ALIGNED(addr, PMD_SIZE) &&
IS_ALIGNED(next, PMD_SIZE)) {
pmd_clear(pmd);
continue;
}
}
pte = pte_offset_kernel(pmd, addr);
kasan_remove_pte_table(pte, addr, next);
kasan_free_pte(pte_offset_kernel(pmd, 0), pmd);
}
}
static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
unsigned long end)
{
unsigned long next;
for (; addr < end; addr = next, pud++) {
pmd_t *pmd, *pmd_base;
next = pud_addr_end(addr, end);
if (!pud_present(*pud))
continue;
if (kasan_pmd_table(*pud)) {
if (IS_ALIGNED(addr, PUD_SIZE) &&
IS_ALIGNED(next, PUD_SIZE)) {
pud_clear(pud);
continue;
}
}
pmd = pmd_offset(pud, addr);
pmd_base = pmd_offset(pud, 0);
kasan_remove_pmd_table(pmd, addr, next);
kasan_free_pmd(pmd_base, pud);
}
}
static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
unsigned long end)
{
unsigned long next;
for (; addr < end; addr = next, p4d++) {
pud_t *pud;
next = p4d_addr_end(addr, end);
if (!p4d_present(*p4d))
continue;
if (kasan_pud_table(*p4d)) {
if (IS_ALIGNED(addr, P4D_SIZE) &&
IS_ALIGNED(next, P4D_SIZE)) {
p4d_clear(p4d);
continue;
}
}
pud = pud_offset(p4d, addr);
kasan_remove_pud_table(pud, addr, next);
kasan_free_pud(pud_offset(p4d, 0), p4d);
}
}
void kasan_remove_zero_shadow(void *start, unsigned long size)
{
unsigned long addr, end, next;
pgd_t *pgd;
addr = (unsigned long)kasan_mem_to_shadow(start);
end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);
if (WARN_ON((unsigned long)start % KASAN_MEMORY_PER_SHADOW_PAGE) ||
WARN_ON(size % KASAN_MEMORY_PER_SHADOW_PAGE))
return;
for (; addr < end; addr = next) {
p4d_t *p4d;
next = pgd_addr_end(addr, end);
pgd = pgd_offset_k(addr);
if (!pgd_present(*pgd))
continue;
if (kasan_p4d_table(*pgd)) {
if (IS_ALIGNED(addr, PGDIR_SIZE) &&
IS_ALIGNED(next, PGDIR_SIZE)) {
pgd_clear(pgd);
continue;
}
}
p4d = p4d_offset(pgd, addr);
kasan_remove_p4d_table(p4d, addr, next);
kasan_free_p4d(p4d_offset(pgd, 0), pgd);
}
}
int kasan_add_zero_shadow(void *start, unsigned long size)
{
int ret;
void *shadow_start, *shadow_end;
shadow_start = kasan_mem_to_shadow(start);
shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT);
if (WARN_ON((unsigned long)start % KASAN_MEMORY_PER_SHADOW_PAGE) ||
WARN_ON(size % KASAN_MEMORY_PER_SHADOW_PAGE))
return -EINVAL;
ret = kasan_populate_early_shadow(shadow_start, shadow_end);
if (ret)
kasan_remove_zero_shadow(start, size);
return ret;
}