--- /dev/null
+// 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/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_KASAN, 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,
+ 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);
+
+ kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
+ 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.
+ * 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.
+ */
+ create_mapping((void *)MODULES_VADDR, (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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