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 pr_debug("%s: %p - %p\n", __func__, start, end); 49 50 for (i = j = 0; i < n_pmds; ++i) { 51 int k; 52 53 for (k = 0; k < PTRS_PER_PTE; ++k, ++j) { 54 phys_addr_t phys = 55 memblock_alloc_base(PAGE_SIZE, PAGE_SIZE, 56 MEMBLOCK_ALLOC_ANYWHERE); 57 58 set_pte(pte + j, pfn_pte(PHYS_PFN(phys), PAGE_KERNEL)); 59 } 60 } 61 62 for (i = 0; i < n_pmds ; ++i, pte += PTRS_PER_PTE) 63 set_pmd(pmd + i, __pmd((unsigned long)pte)); 64 65 local_flush_tlb_all(); 66 memset(start, 0, end - start); 67 } 68 69 void __init kasan_init(void) 70 { 71 int i; 72 73 BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_START - 74 (KASAN_START_VADDR >> KASAN_SHADOW_SCALE_SHIFT)); 75 BUILD_BUG_ON(VMALLOC_START < KASAN_START_VADDR); 76 77 /* 78 * Replace shadow map pages that cover addresses from VMALLOC area 79 * start to the end of KSEG with clean writable pages. 80 */ 81 populate(kasan_mem_to_shadow((void *)VMALLOC_START), 82 kasan_mem_to_shadow((void *)XCHAL_KSEG_BYPASS_VADDR)); 83 84 /* 85 * Write protect kasan_early_shadow_page and zero-initialize it again. 86 */ 87 for (i = 0; i < PTRS_PER_PTE; ++i) 88 set_pte(kasan_early_shadow_pte + i, 89 mk_pte(virt_to_page(kasan_early_shadow_page), 90 PAGE_KERNEL_RO)); 91 92 local_flush_tlb_all(); 93 memset(kasan_early_shadow_page, 0, PAGE_SIZE); 94 95 /* At this point kasan is fully initialized. Enable error messages. */ 96 current->kasan_depth = 0; 97 pr_info("KernelAddressSanitizer initialized\n"); 98 } 99