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- // 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 <[email protected]>
- * Author: Linus Walleij <[email protected]>
- */
- #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/memory.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;
- }
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