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_zero_pte + i, 28 mk_pte(virt_to_page(kasan_zero_page), PAGE_KERNEL)); 29 30 for (vaddr = 0; vaddr < KASAN_SHADOW_SIZE; vaddr += PMD_SIZE, ++pmd) { 31 BUG_ON(!pmd_none(*pmd)); 32 set_pmd(pmd, __pmd((unsigned long)kasan_zero_pte)); 33 } 34 early_trap_init(); 35 } 36 37 static void __init populate(void *start, void *end) 38 { 39 unsigned long n_pages = (end - start) / PAGE_SIZE; 40 unsigned long n_pmds = n_pages / PTRS_PER_PTE; 41 unsigned long i, j; 42 unsigned long vaddr = (unsigned long)start; 43 pgd_t *pgd = pgd_offset_k(vaddr); 44 pmd_t *pmd = pmd_offset(pgd, vaddr); 45 pte_t *pte = memblock_alloc(n_pages * sizeof(pte_t), PAGE_SIZE); 46 47 pr_debug("%s: %p - %p\n", __func__, start, end); 48 49 for (i = j = 0; i < n_pmds; ++i) { 50 int k; 51 52 for (k = 0; k < PTRS_PER_PTE; ++k, ++j) { 53 phys_addr_t phys = 54 memblock_alloc_base(PAGE_SIZE, PAGE_SIZE, 55 MEMBLOCK_ALLOC_ANYWHERE); 56 57 set_pte(pte + j, pfn_pte(PHYS_PFN(phys), PAGE_KERNEL)); 58 } 59 } 60 61 for (i = 0; i < n_pmds ; ++i, pte += PTRS_PER_PTE) 62 set_pmd(pmd + i, __pmd((unsigned long)pte)); 63 64 local_flush_tlb_all(); 65 memset(start, 0, end - start); 66 } 67 68 void __init kasan_init(void) 69 { 70 int i; 71 72 BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_START - 73 (KASAN_START_VADDR >> KASAN_SHADOW_SCALE_SHIFT)); 74 BUILD_BUG_ON(VMALLOC_START < KASAN_START_VADDR); 75 76 /* 77 * Replace shadow map pages that cover addresses from VMALLOC area 78 * start to the end of KSEG with clean writable pages. 79 */ 80 populate(kasan_mem_to_shadow((void *)VMALLOC_START), 81 kasan_mem_to_shadow((void *)XCHAL_KSEG_BYPASS_VADDR)); 82 83 /* Write protect kasan_zero_page and zero-initialize it again. */ 84 for (i = 0; i < PTRS_PER_PTE; ++i) 85 set_pte(kasan_zero_pte + i, 86 mk_pte(virt_to_page(kasan_zero_page), PAGE_KERNEL_RO)); 87 88 local_flush_tlb_all(); 89 memset(kasan_zero_page, 0, PAGE_SIZE); 90 91 /* At this point kasan is fully initialized. Enable error messages. */ 92 current->kasan_depth = 0; 93 pr_info("KernelAddressSanitizer initialized\n"); 94 } 95