1 /* 2 * Xtensa KASAN shadow map initialization 3 * 4 * This file is subject to the terms and conditions of the GNU General Public 5 * License. See the file "COPYING" in the main directory of this archive 6 * for more details. 7 * 8 * Copyright (C) 2017 Cadence Design Systems Inc. 9 */ 10 11 #include <linux/memblock.h> 12 #include <linux/init_task.h> 13 #include <linux/kasan.h> 14 #include <linux/kernel.h> 15 #include <asm/initialize_mmu.h> 16 #include <asm/tlbflush.h> 17 #include <asm/traps.h> 18 19 void __init kasan_early_init(void) 20 { 21 unsigned long vaddr = KASAN_SHADOW_START; 22 pgd_t *pgd = pgd_offset_k(vaddr); 23 pmd_t *pmd = pmd_offset(pgd, vaddr); 24 int i; 25 26 for (i = 0; i < PTRS_PER_PTE; ++i) 27 set_pte(kasan_early_shadow_pte + i, 28 mk_pte(virt_to_page(kasan_early_shadow_page), 29 PAGE_KERNEL)); 30 31 for (vaddr = 0; vaddr < KASAN_SHADOW_SIZE; vaddr += PMD_SIZE, ++pmd) { 32 BUG_ON(!pmd_none(*pmd)); 33 set_pmd(pmd, __pmd((unsigned long)kasan_early_shadow_pte)); 34 } 35 early_trap_init(); 36 } 37 38 static void __init populate(void *start, void *end) 39 { 40 unsigned long n_pages = (end - start) / PAGE_SIZE; 41 unsigned long n_pmds = n_pages / PTRS_PER_PTE; 42 unsigned long i, j; 43 unsigned long vaddr = (unsigned long)start; 44 pgd_t *pgd = pgd_offset_k(vaddr); 45 pmd_t *pmd = pmd_offset(pgd, vaddr); 46 pte_t *pte = memblock_alloc(n_pages * sizeof(pte_t), PAGE_SIZE); 47 48 if (!pte) 49 panic("%s: Failed to allocate %lu bytes align=0x%lx\n", 50 __func__, n_pages * sizeof(pte_t), PAGE_SIZE); 51 52 pr_debug("%s: %p - %p\n", __func__, start, end); 53 54 for (i = j = 0; i < n_pmds; ++i) { 55 int k; 56 57 for (k = 0; k < PTRS_PER_PTE; ++k, ++j) { 58 phys_addr_t phys = 59 memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE); 60 61 if (!phys) 62 panic("Failed to allocate page table page\n"); 63 64 set_pte(pte + j, pfn_pte(PHYS_PFN(phys), PAGE_KERNEL)); 65 } 66 } 67 68 for (i = 0; i < n_pmds ; ++i, pte += PTRS_PER_PTE) 69 set_pmd(pmd + i, __pmd((unsigned long)pte)); 70 71 local_flush_tlb_all(); 72 memset(start, 0, end - start); 73 } 74 75 void __init kasan_init(void) 76 { 77 int i; 78 79 BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_START - 80 (KASAN_START_VADDR >> KASAN_SHADOW_SCALE_SHIFT)); 81 BUILD_BUG_ON(VMALLOC_START < KASAN_START_VADDR); 82 83 /* 84 * Replace shadow map pages that cover addresses from VMALLOC area 85 * start to the end of KSEG with clean writable pages. 86 */ 87 populate(kasan_mem_to_shadow((void *)VMALLOC_START), 88 kasan_mem_to_shadow((void *)XCHAL_KSEG_BYPASS_VADDR)); 89 90 /* 91 * Write protect kasan_early_shadow_page and zero-initialize it again. 92 */ 93 for (i = 0; i < PTRS_PER_PTE; ++i) 94 set_pte(kasan_early_shadow_pte + i, 95 mk_pte(virt_to_page(kasan_early_shadow_page), 96 PAGE_KERNEL_RO)); 97 98 local_flush_tlb_all(); 99 memset(kasan_early_shadow_page, 0, PAGE_SIZE); 100 101 /* At this point kasan is fully initialized. Enable error messages. */ 102 current->kasan_depth = 0; 103 pr_info("KernelAddressSanitizer initialized\n"); 104 } 105