1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/set_memory.h> 3 #include <linux/ptdump.h> 4 #include <linux/seq_file.h> 5 #include <linux/debugfs.h> 6 #include <linux/mm.h> 7 #include <linux/kfence.h> 8 #include <linux/kasan.h> 9 #include <asm/ptdump.h> 10 #include <asm/kasan.h> 11 #include <asm/sections.h> 12 13 static unsigned long max_addr; 14 15 struct addr_marker { 16 unsigned long start_address; 17 const char *name; 18 }; 19 20 enum address_markers_idx { 21 IDENTITY_BEFORE_NR = 0, 22 IDENTITY_BEFORE_END_NR, 23 KERNEL_START_NR, 24 KERNEL_END_NR, 25 #ifdef CONFIG_KFENCE 26 KFENCE_START_NR, 27 KFENCE_END_NR, 28 #endif 29 IDENTITY_AFTER_NR, 30 IDENTITY_AFTER_END_NR, 31 #ifdef CONFIG_KASAN 32 KASAN_SHADOW_START_NR, 33 KASAN_SHADOW_END_NR, 34 #endif 35 VMEMMAP_NR, 36 VMEMMAP_END_NR, 37 VMALLOC_NR, 38 VMALLOC_END_NR, 39 MODULES_NR, 40 MODULES_END_NR, 41 }; 42 43 static struct addr_marker address_markers[] = { 44 [IDENTITY_BEFORE_NR] = {0, "Identity Mapping Start"}, 45 [IDENTITY_BEFORE_END_NR] = {(unsigned long)_stext, "Identity Mapping End"}, 46 [KERNEL_START_NR] = {(unsigned long)_stext, "Kernel Image Start"}, 47 [KERNEL_END_NR] = {(unsigned long)_end, "Kernel Image End"}, 48 #ifdef CONFIG_KFENCE 49 [KFENCE_START_NR] = {0, "KFence Pool Start"}, 50 [KFENCE_END_NR] = {0, "KFence Pool End"}, 51 #endif 52 [IDENTITY_AFTER_NR] = {(unsigned long)_end, "Identity Mapping Start"}, 53 [IDENTITY_AFTER_END_NR] = {0, "Identity Mapping End"}, 54 #ifdef CONFIG_KASAN 55 [KASAN_SHADOW_START_NR] = {KASAN_SHADOW_START, "Kasan Shadow Start"}, 56 [KASAN_SHADOW_END_NR] = {KASAN_SHADOW_END, "Kasan Shadow End"}, 57 #endif 58 [VMEMMAP_NR] = {0, "vmemmap Area Start"}, 59 [VMEMMAP_END_NR] = {0, "vmemmap Area End"}, 60 [VMALLOC_NR] = {0, "vmalloc Area Start"}, 61 [VMALLOC_END_NR] = {0, "vmalloc Area End"}, 62 [MODULES_NR] = {0, "Modules Area Start"}, 63 [MODULES_END_NR] = {0, "Modules Area End"}, 64 { -1, NULL } 65 }; 66 67 struct pg_state { 68 struct ptdump_state ptdump; 69 struct seq_file *seq; 70 int level; 71 unsigned int current_prot; 72 bool check_wx; 73 unsigned long wx_pages; 74 unsigned long start_address; 75 const struct addr_marker *marker; 76 }; 77 78 #define pt_dump_seq_printf(m, fmt, args...) \ 79 ({ \ 80 struct seq_file *__m = (m); \ 81 \ 82 if (__m) \ 83 seq_printf(__m, fmt, ##args); \ 84 }) 85 86 #define pt_dump_seq_puts(m, fmt) \ 87 ({ \ 88 struct seq_file *__m = (m); \ 89 \ 90 if (__m) \ 91 seq_printf(__m, fmt); \ 92 }) 93 94 static void print_prot(struct seq_file *m, unsigned int pr, int level) 95 { 96 static const char * const level_name[] = 97 { "ASCE", "PGD", "PUD", "PMD", "PTE" }; 98 99 pt_dump_seq_printf(m, "%s ", level_name[level]); 100 if (pr & _PAGE_INVALID) { 101 pt_dump_seq_printf(m, "I\n"); 102 return; 103 } 104 pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW "); 105 pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n"); 106 } 107 108 static void note_prot_wx(struct pg_state *st, unsigned long addr) 109 { 110 #ifdef CONFIG_DEBUG_WX 111 if (!st->check_wx) 112 return; 113 if (st->current_prot & _PAGE_INVALID) 114 return; 115 if (st->current_prot & _PAGE_PROTECT) 116 return; 117 if (st->current_prot & _PAGE_NOEXEC) 118 return; 119 /* The first lowcore page is currently still W+X. */ 120 if (addr == PAGE_SIZE) 121 return; 122 WARN_ONCE(1, "s390/mm: Found insecure W+X mapping at address %pS\n", 123 (void *)st->start_address); 124 st->wx_pages += (addr - st->start_address) / PAGE_SIZE; 125 #endif /* CONFIG_DEBUG_WX */ 126 } 127 128 static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val) 129 { 130 int width = sizeof(unsigned long) * 2; 131 static const char units[] = "KMGTPE"; 132 const char *unit = units; 133 unsigned long delta; 134 struct pg_state *st; 135 struct seq_file *m; 136 unsigned int prot; 137 138 st = container_of(pt_st, struct pg_state, ptdump); 139 m = st->seq; 140 prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC); 141 if (level == 4 && (val & _PAGE_INVALID)) 142 prot = _PAGE_INVALID; 143 /* For pmd_none() & friends val gets passed as zero. */ 144 if (level != 4 && !val) 145 prot = _PAGE_INVALID; 146 /* Final flush from generic code. */ 147 if (level == -1) 148 addr = max_addr; 149 if (st->level == -1) { 150 pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name); 151 st->start_address = addr; 152 st->current_prot = prot; 153 st->level = level; 154 } else if (prot != st->current_prot || level != st->level || 155 addr >= st->marker[1].start_address) { 156 note_prot_wx(st, addr); 157 pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ", 158 width, st->start_address, 159 width, addr); 160 delta = (addr - st->start_address) >> 10; 161 while (!(delta & 0x3ff) && unit[1]) { 162 delta >>= 10; 163 unit++; 164 } 165 pt_dump_seq_printf(m, "%9lu%c ", delta, *unit); 166 print_prot(m, st->current_prot, st->level); 167 while (addr >= st->marker[1].start_address) { 168 st->marker++; 169 pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name); 170 } 171 st->start_address = addr; 172 st->current_prot = prot; 173 st->level = level; 174 } 175 } 176 177 #ifdef CONFIG_DEBUG_WX 178 void ptdump_check_wx(void) 179 { 180 struct pg_state st = { 181 .ptdump = { 182 .note_page = note_page, 183 .range = (struct ptdump_range[]) { 184 {.start = 0, .end = max_addr}, 185 {.start = 0, .end = 0}, 186 } 187 }, 188 .seq = NULL, 189 .level = -1, 190 .current_prot = 0, 191 .check_wx = true, 192 .wx_pages = 0, 193 .start_address = 0, 194 .marker = (struct addr_marker[]) { 195 { .start_address = 0, .name = NULL}, 196 { .start_address = -1, .name = NULL}, 197 }, 198 }; 199 200 if (!MACHINE_HAS_NX) 201 return; 202 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); 203 if (st.wx_pages) 204 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages); 205 else 206 pr_info("Checked W+X mappings: passed, no unexpected W+X pages found\n"); 207 } 208 #endif /* CONFIG_DEBUG_WX */ 209 210 #ifdef CONFIG_PTDUMP_DEBUGFS 211 static int ptdump_show(struct seq_file *m, void *v) 212 { 213 struct pg_state st = { 214 .ptdump = { 215 .note_page = note_page, 216 .range = (struct ptdump_range[]) { 217 {.start = 0, .end = max_addr}, 218 {.start = 0, .end = 0}, 219 } 220 }, 221 .seq = m, 222 .level = -1, 223 .current_prot = 0, 224 .check_wx = false, 225 .wx_pages = 0, 226 .start_address = 0, 227 .marker = address_markers, 228 }; 229 230 get_online_mems(); 231 mutex_lock(&cpa_mutex); 232 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); 233 mutex_unlock(&cpa_mutex); 234 put_online_mems(); 235 return 0; 236 } 237 DEFINE_SHOW_ATTRIBUTE(ptdump); 238 #endif /* CONFIG_PTDUMP_DEBUGFS */ 239 240 /* 241 * Heapsort from lib/sort.c is not a stable sorting algorithm, do a simple 242 * insertion sort to preserve the original order of markers with the same 243 * start address. 244 */ 245 static void sort_address_markers(void) 246 { 247 struct addr_marker tmp; 248 int i, j; 249 250 for (i = 1; i < ARRAY_SIZE(address_markers) - 1; i++) { 251 tmp = address_markers[i]; 252 for (j = i - 1; j >= 0 && address_markers[j].start_address > tmp.start_address; j--) 253 address_markers[j + 1] = address_markers[j]; 254 address_markers[j + 1] = tmp; 255 } 256 } 257 258 static int pt_dump_init(void) 259 { 260 #ifdef CONFIG_KFENCE 261 unsigned long kfence_start = (unsigned long)__kfence_pool; 262 #endif 263 /* 264 * Figure out the maximum virtual address being accessible with the 265 * kernel ASCE. We need this to keep the page table walker functions 266 * from accessing non-existent entries. 267 */ 268 max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2; 269 max_addr = 1UL << (max_addr * 11 + 31); 270 address_markers[IDENTITY_AFTER_END_NR].start_address = ident_map_size; 271 address_markers[MODULES_NR].start_address = MODULES_VADDR; 272 address_markers[MODULES_END_NR].start_address = MODULES_END; 273 address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap; 274 address_markers[VMEMMAP_END_NR].start_address = (unsigned long)vmemmap + vmemmap_size; 275 address_markers[VMALLOC_NR].start_address = VMALLOC_START; 276 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END; 277 #ifdef CONFIG_KFENCE 278 address_markers[KFENCE_START_NR].start_address = kfence_start; 279 address_markers[KFENCE_END_NR].start_address = kfence_start + KFENCE_POOL_SIZE; 280 #endif 281 sort_address_markers(); 282 #ifdef CONFIG_PTDUMP_DEBUGFS 283 debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops); 284 #endif /* CONFIG_PTDUMP_DEBUGFS */ 285 return 0; 286 } 287 device_initcall(pt_dump_init); 288