// SPDX-License-Identifier: GPL-2.0-only
/*
* This file contains kasan initialization code for ARM.
*
* Copyright (c) 2018 Samsung Electronics Co., Ltd.
* Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
* Author: Linus Walleij <linus.walleij@linaro.org>
*/
#define pr_fmt(fmt) "kasan: " fmt
#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/memblock.h>
#include <linux/sched/task.h>
#include <linux/start_kernel.h>
#include <linux/pgtable.h>
#include <asm/cputype.h>
#include <asm/highmem.h>
#include <asm/mach/map.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/procinfo.h>
#include <asm/proc-fns.h>
#include "mm.h"
static pgd_t tmp_pgd_table[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE);
pmd_t tmp_pmd_table[PTRS_PER_PMD] __page_aligned_bss;
static __init void *kasan_alloc_block(size_t size)
{
return memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
MEMBLOCK_ALLOC_NOLEAKTRACE, NUMA_NO_NODE);
}
static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
unsigned long end, bool early)
{
unsigned long next;
pte_t *ptep = pte_offset_kernel(pmdp, addr);
do {
pte_t entry;
void *p;
next = addr + PAGE_SIZE;
if (!early) {
if (!pte_none(READ_ONCE(*ptep)))
continue;
p = kasan_alloc_block(PAGE_SIZE);
if (!p) {
panic("%s failed to allocate shadow page for address 0x%lx\n",
__func__, addr);
return;
}
memset(p, KASAN_SHADOW_INIT, PAGE_SIZE);
entry = pfn_pte(virt_to_pfn(p),
__pgprot(pgprot_val(PAGE_KERNEL)));
} else if (pte_none(READ_ONCE(*ptep))) {
/*
* The early shadow memory is mapping all KASan
* operations to one and the same page in memory,
* "kasan_early_shadow_page" so that the instrumentation
* will work on a scratch area until we can set up the
* proper KASan shadow memory.
*/
entry = pfn_pte(virt_to_pfn(kasan_early_shadow_page),
__pgprot(_L_PTE_DEFAULT | L_PTE_DIRTY | L_PTE_XN));
} else {
/*
* Early shadow mappings are PMD_SIZE aligned, so if the
* first entry is already set, they must all be set.
*/
return;
}
set_pte_at(&init_mm, addr, ptep, entry);
} while (ptep++, addr = next, addr != end);
}
/*
* The pmd (page middle directory) is only used on LPAE
*/
static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
unsigned long end, bool early)
{
unsigned long next;
pmd_t *pmdp = pmd_offset(pudp, addr);
do {
if (pmd_none(*pmdp)) {
/*
* We attempt to allocate a shadow block for the PMDs
* used by the PTEs for this address if it isn't already
* allocated.
*/
void *p = early ? kasan_early_shadow_pte :
kasan_alloc_block(PAGE_SIZE);
if (!p) {
panic("%s failed to allocate shadow block for address 0x%lx\n",
__func__, addr);
return;
}
pmd_populate_kernel(&init_mm, pmdp, p);
flush_pmd_entry(pmdp);
}
next = pmd_addr_end(addr, end);
kasan_pte_populate(pmdp, addr, next, early);
} while (pmdp++, addr = next, addr != end);
}
static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
bool early)
{
unsigned long next;
pgd_t *pgdp;
p4d_t *p4dp;
pud_t *pudp;
pgdp = pgd_offset_k(addr);
do {
/*
* Allocate and populate the shadow block of p4d folded into
* pud folded into pmd if it doesn't already exist
*/
if (!early && pgd_none(*pgdp)) {
void *p = kasan_alloc_block(PAGE_SIZE);
if (!p) {
panic("%s failed to allocate shadow block for address 0x%lx\n",
__func__, addr);
return;
}
pgd_populate(&init_mm, pgdp, p);
}
next = pgd_addr_end(addr, end);
/*
* We just immediately jump over the p4d and pud page
* directories since we believe ARM32 will never gain four
* nor five level page tables.
*/
p4dp = p4d_offset(pgdp, addr);
pudp = pud_offset(p4dp, addr);
kasan_pmd_populate(pudp, addr, next, early);
} while (pgdp++, addr = next, addr != end);
}
extern struct proc_info_list *lookup_processor_type(unsigned int);
void __init kasan_early_init(void)
{
struct proc_info_list *list;
/*
* locate processor in the list of supported processor
* types. The linker builds this table for us from the
* entries in arch/arm/mm/proc-*.S
*/
list = lookup_processor_type(read_cpuid_id());
if (list) {
#ifdef MULTI_CPU
processor = *list->proc;
#endif
}
BUILD_BUG_ON((KASAN_SHADOW_END - (1UL << 29)) != KASAN_SHADOW_OFFSET);
/*
* We walk the page table and set all of the shadow memory to point
* to the scratch page.
*/
kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, true);
}
static void __init clear_pgds(unsigned long start,
unsigned long end)
{
for (; start && start < end; start += PMD_SIZE)
pmd_clear(pmd_off_k(start));
}
static int __init create_mapping(void *start, void *end)
{
void *shadow_start, *shadow_end;
shadow_start = kasan_mem_to_shadow(start);
shadow_end = kasan_mem_to_shadow(end);
pr_info("Mapping kernel virtual memory block: %px-%px at shadow: %px-%px\n",
start, end, shadow_start, shadow_end);
kasan_pgd_populate((unsigned long)shadow_start & PAGE_MASK,
PAGE_ALIGN((unsigned long)shadow_end), false);
return 0;
}
void __init kasan_init(void)
{
phys_addr_t pa_start, pa_end;
u64 i;
/*
* We are going to perform proper setup of shadow memory.
*
* At first we should unmap early shadow (clear_pgds() call bellow).
* However, instrumented code can't execute without shadow memory.
*
* To keep the early shadow memory MMU tables around while setting up
* the proper shadow memory, we copy swapper_pg_dir (the initial page
* table) to tmp_pgd_table and use that to keep the early shadow memory
* mapped until the full shadow setup is finished. Then we swap back
* to the proper swapper_pg_dir.
*/
memcpy(tmp_pgd_table, swapper_pg_dir, sizeof(tmp_pgd_table));
#ifdef CONFIG_ARM_LPAE
/* We need to be in the same PGD or this won't work */
BUILD_BUG_ON(pgd_index(KASAN_SHADOW_START) !=
pgd_index(KASAN_SHADOW_END));
memcpy(tmp_pmd_table,
(void*)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_START)),
sizeof(tmp_pmd_table));
set_pgd(&tmp_pgd_table[pgd_index(KASAN_SHADOW_START)],
__pgd(__pa(tmp_pmd_table) | PMD_TYPE_TABLE | L_PGD_SWAPPER));
#endif
cpu_switch_mm(tmp_pgd_table, &init_mm);
local_flush_tlb_all();
clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
if (!IS_ENABLED(CONFIG_KASAN_VMALLOC))
kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
kasan_mem_to_shadow((void *)VMALLOC_END));
kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_END),
kasan_mem_to_shadow((void *)-1UL) + 1);
for_each_mem_range(i, &pa_start, &pa_end) {
void *start = __va(pa_start);
void *end = __va(pa_end);
/* Do not attempt to shadow highmem */
if (pa_start >= arm_lowmem_limit) {
pr_info("Skip highmem block at %pa-%pa\n", &pa_start, &pa_end);
continue;
}
if (pa_end > arm_lowmem_limit) {
pr_info("Truncating shadow for memory block at %pa-%pa to lowmem region at %pa\n",
&pa_start, &pa_end, &arm_lowmem_limit);
end = __va(arm_lowmem_limit);
}
if (start >= end) {
pr_info("Skipping invalid memory block %pa-%pa (virtual %p-%p)\n",
&pa_start, &pa_end, start, end);
continue;
}
create_mapping(start, end);
}
/*
* 1. The module global variables are in MODULES_VADDR ~ MODULES_END,
* so we need to map this area if CONFIG_KASAN_VMALLOC=n. With
* VMALLOC support KASAN will manage this region dynamically,
* refer to kasan_populate_vmalloc() and ARM's implementation of
* module_alloc().
* 2. PKMAP_BASE ~ PKMAP_BASE+PMD_SIZE's shadow and MODULES_VADDR
* ~ MODULES_END's shadow is in the same PMD_SIZE, so we can't
* use kasan_populate_zero_shadow.
*/
if (!IS_ENABLED(CONFIG_KASAN_VMALLOC) && IS_ENABLED(CONFIG_MODULES))
create_mapping((void *)MODULES_VADDR, (void *)(MODULES_END));
create_mapping((void *)PKMAP_BASE, (void *)(PKMAP_BASE + PMD_SIZE));
/*
* KAsan may reuse the contents of kasan_early_shadow_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_at(&init_mm, KASAN_SHADOW_START + i*PAGE_SIZE,
&kasan_early_shadow_pte[i],
pfn_pte(virt_to_pfn(kasan_early_shadow_page),
__pgprot(pgprot_val(PAGE_KERNEL)
| L_PTE_RDONLY)));
cpu_switch_mm(swapper_pg_dir, &init_mm);
local_flush_tlb_all();
memset(kasan_early_shadow_page, 0, PAGE_SIZE);
pr_info("Kernel address sanitizer initialized\n");
init_task.kasan_depth = 0;
}