1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * KASAN for 64-bit Book3S powerpc 4 * 5 * Copyright 2019-2022, Daniel Axtens, IBM Corporation. 6 */ 7 8 /* 9 * ppc64 turns on virtual memory late in boot, after calling into generic code 10 * like the device-tree parser, so it uses this in conjunction with a hook in 11 * outline mode to avoid invalid access early in boot. 12 */ 13 14 #define DISABLE_BRANCH_PROFILING 15 16 #include <linux/kasan.h> 17 #include <linux/printk.h> 18 #include <linux/sched/task.h> 19 #include <linux/memblock.h> 20 #include <asm/pgalloc.h> 21 22 DEFINE_STATIC_KEY_FALSE(powerpc_kasan_enabled_key); 23 24 static void __init kasan_init_phys_region(void *start, void *end) 25 { 26 unsigned long k_start, k_end, k_cur; 27 void *va; 28 29 if (start >= end) 30 return; 31 32 k_start = ALIGN_DOWN((unsigned long)kasan_mem_to_shadow(start), PAGE_SIZE); 33 k_end = ALIGN((unsigned long)kasan_mem_to_shadow(end), PAGE_SIZE); 34 35 va = memblock_alloc(k_end - k_start, PAGE_SIZE); 36 for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE, va += PAGE_SIZE) 37 map_kernel_page(k_cur, __pa(va), PAGE_KERNEL); 38 } 39 40 void __init kasan_init(void) 41 { 42 /* 43 * We want to do the following things: 44 * 1) Map real memory into the shadow for all physical memblocks 45 * This takes us from c000... to c008... 46 * 2) Leave a hole over the shadow of vmalloc space. KASAN_VMALLOC 47 * will manage this for us. 48 * This takes us from c008... to c00a... 49 * 3) Map the 'early shadow'/zero page over iomap and vmemmap space. 50 * This takes us up to where we start at c00e... 51 */ 52 53 void *k_start = kasan_mem_to_shadow((void *)RADIX_VMALLOC_END); 54 void *k_end = kasan_mem_to_shadow((void *)RADIX_VMEMMAP_END); 55 phys_addr_t start, end; 56 u64 i; 57 pte_t zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL); 58 59 if (!early_radix_enabled()) { 60 pr_warn("KASAN not enabled as it requires radix!"); 61 return; 62 } 63 64 for_each_mem_range(i, &start, &end) 65 kasan_init_phys_region((void *)start, (void *)end); 66 67 for (i = 0; i < PTRS_PER_PTE; i++) 68 __set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page, 69 &kasan_early_shadow_pte[i], zero_pte, 0); 70 71 for (i = 0; i < PTRS_PER_PMD; i++) 72 pmd_populate_kernel(&init_mm, &kasan_early_shadow_pmd[i], 73 kasan_early_shadow_pte); 74 75 for (i = 0; i < PTRS_PER_PUD; i++) 76 pud_populate(&init_mm, &kasan_early_shadow_pud[i], 77 kasan_early_shadow_pmd); 78 79 /* map the early shadow over the iomap and vmemmap space */ 80 kasan_populate_early_shadow(k_start, k_end); 81 82 /* mark early shadow region as RO and wipe it */ 83 zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL_RO); 84 for (i = 0; i < PTRS_PER_PTE; i++) 85 __set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page, 86 &kasan_early_shadow_pte[i], zero_pte, 0); 87 88 /* 89 * clear_page relies on some cache info that hasn't been set up yet. 90 * It ends up looping ~forever and blows up other data. 91 * Use memset instead. 92 */ 93 memset(kasan_early_shadow_page, 0, PAGE_SIZE); 94 95 static_branch_inc(&powerpc_kasan_enabled_key); 96 97 /* Enable error messages */ 98 init_task.kasan_depth = 0; 99 pr_info("KASAN init done\n"); 100 } 101 102 void __init kasan_late_init(void) { } 103