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/abs_lowcore.h> 12 #include <asm/nospec-branch.h> 13 #include <asm/sections.h> 14 #include <asm/maccess.h> 15 16 static unsigned long max_addr; 17 18 struct addr_marker { 19 unsigned long start_address; 20 const char *name; 21 }; 22 23 enum address_markers_idx { 24 IDENTITY_BEFORE_NR = 0, 25 IDENTITY_BEFORE_END_NR, 26 AMODE31_START_NR, 27 AMODE31_END_NR, 28 KERNEL_START_NR, 29 KERNEL_END_NR, 30 #ifdef CONFIG_KFENCE 31 KFENCE_START_NR, 32 KFENCE_END_NR, 33 #endif 34 IDENTITY_AFTER_NR, 35 IDENTITY_AFTER_END_NR, 36 VMEMMAP_NR, 37 VMEMMAP_END_NR, 38 VMALLOC_NR, 39 VMALLOC_END_NR, 40 MODULES_NR, 41 MODULES_END_NR, 42 ABS_LOWCORE_NR, 43 ABS_LOWCORE_END_NR, 44 MEMCPY_REAL_NR, 45 MEMCPY_REAL_END_NR, 46 #ifdef CONFIG_KASAN 47 KASAN_SHADOW_START_NR, 48 KASAN_SHADOW_END_NR, 49 #endif 50 }; 51 52 static struct addr_marker address_markers[] = { 53 [IDENTITY_BEFORE_NR] = {0, "Identity Mapping Start"}, 54 [IDENTITY_BEFORE_END_NR] = {(unsigned long)_stext, "Identity Mapping End"}, 55 [AMODE31_START_NR] = {0, "Amode31 Area Start"}, 56 [AMODE31_END_NR] = {0, "Amode31 Area End"}, 57 [KERNEL_START_NR] = {(unsigned long)_stext, "Kernel Image Start"}, 58 [KERNEL_END_NR] = {(unsigned long)_end, "Kernel Image End"}, 59 #ifdef CONFIG_KFENCE 60 [KFENCE_START_NR] = {0, "KFence Pool Start"}, 61 [KFENCE_END_NR] = {0, "KFence Pool End"}, 62 #endif 63 [IDENTITY_AFTER_NR] = {(unsigned long)_end, "Identity Mapping Start"}, 64 [IDENTITY_AFTER_END_NR] = {0, "Identity Mapping End"}, 65 [VMEMMAP_NR] = {0, "vmemmap Area Start"}, 66 [VMEMMAP_END_NR] = {0, "vmemmap Area End"}, 67 [VMALLOC_NR] = {0, "vmalloc Area Start"}, 68 [VMALLOC_END_NR] = {0, "vmalloc Area End"}, 69 [MODULES_NR] = {0, "Modules Area Start"}, 70 [MODULES_END_NR] = {0, "Modules Area End"}, 71 [ABS_LOWCORE_NR] = {0, "Lowcore Area Start"}, 72 [ABS_LOWCORE_END_NR] = {0, "Lowcore Area End"}, 73 [MEMCPY_REAL_NR] = {0, "Real Memory Copy Area Start"}, 74 [MEMCPY_REAL_END_NR] = {0, "Real Memory Copy Area End"}, 75 #ifdef CONFIG_KASAN 76 [KASAN_SHADOW_START_NR] = {KASAN_SHADOW_START, "Kasan Shadow Start"}, 77 [KASAN_SHADOW_END_NR] = {KASAN_SHADOW_END, "Kasan Shadow End"}, 78 #endif 79 { -1, NULL } 80 }; 81 82 struct pg_state { 83 struct ptdump_state ptdump; 84 struct seq_file *seq; 85 int level; 86 unsigned int current_prot; 87 bool check_wx; 88 unsigned long wx_pages; 89 unsigned long start_address; 90 const struct addr_marker *marker; 91 }; 92 93 #define pt_dump_seq_printf(m, fmt, args...) \ 94 ({ \ 95 struct seq_file *__m = (m); \ 96 \ 97 if (__m) \ 98 seq_printf(__m, fmt, ##args); \ 99 }) 100 101 #define pt_dump_seq_puts(m, fmt) \ 102 ({ \ 103 struct seq_file *__m = (m); \ 104 \ 105 if (__m) \ 106 seq_printf(__m, fmt); \ 107 }) 108 109 static void print_prot(struct seq_file *m, unsigned int pr, int level) 110 { 111 static const char * const level_name[] = 112 { "ASCE", "PGD", "PUD", "PMD", "PTE" }; 113 114 pt_dump_seq_printf(m, "%s ", level_name[level]); 115 if (pr & _PAGE_INVALID) { 116 pt_dump_seq_printf(m, "I\n"); 117 return; 118 } 119 pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW "); 120 pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n"); 121 } 122 123 static void note_prot_wx(struct pg_state *st, unsigned long addr) 124 { 125 #ifdef CONFIG_DEBUG_WX 126 if (!st->check_wx) 127 return; 128 if (st->current_prot & _PAGE_INVALID) 129 return; 130 if (st->current_prot & _PAGE_PROTECT) 131 return; 132 if (st->current_prot & _PAGE_NOEXEC) 133 return; 134 /* 135 * The first lowcore page is W+X if spectre mitigations are using 136 * trampolines or the BEAR enhancements facility is not installed, 137 * in which case we have two lpswe instructions in lowcore that need 138 * to be executable. 139 */ 140 if (addr == PAGE_SIZE && (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear))) 141 return; 142 WARN_ONCE(1, "s390/mm: Found insecure W+X mapping at address %pS\n", 143 (void *)st->start_address); 144 st->wx_pages += (addr - st->start_address) / PAGE_SIZE; 145 #endif /* CONFIG_DEBUG_WX */ 146 } 147 148 static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val) 149 { 150 int width = sizeof(unsigned long) * 2; 151 static const char units[] = "KMGTPE"; 152 const char *unit = units; 153 unsigned long delta; 154 struct pg_state *st; 155 struct seq_file *m; 156 unsigned int prot; 157 158 st = container_of(pt_st, struct pg_state, ptdump); 159 m = st->seq; 160 prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC); 161 if (level == 4 && (val & _PAGE_INVALID)) 162 prot = _PAGE_INVALID; 163 /* For pmd_none() & friends val gets passed as zero. */ 164 if (level != 4 && !val) 165 prot = _PAGE_INVALID; 166 /* Final flush from generic code. */ 167 if (level == -1) 168 addr = max_addr; 169 if (st->level == -1) { 170 pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name); 171 st->start_address = addr; 172 st->current_prot = prot; 173 st->level = level; 174 } else if (prot != st->current_prot || level != st->level || 175 addr >= st->marker[1].start_address) { 176 note_prot_wx(st, addr); 177 pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ", 178 width, st->start_address, 179 width, addr); 180 delta = (addr - st->start_address) >> 10; 181 while (!(delta & 0x3ff) && unit[1]) { 182 delta >>= 10; 183 unit++; 184 } 185 pt_dump_seq_printf(m, "%9lu%c ", delta, *unit); 186 print_prot(m, st->current_prot, st->level); 187 while (addr >= st->marker[1].start_address) { 188 st->marker++; 189 pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name); 190 } 191 st->start_address = addr; 192 st->current_prot = prot; 193 st->level = level; 194 } 195 } 196 197 #ifdef CONFIG_DEBUG_WX 198 void ptdump_check_wx(void) 199 { 200 struct pg_state st = { 201 .ptdump = { 202 .note_page = note_page, 203 .range = (struct ptdump_range[]) { 204 {.start = 0, .end = max_addr}, 205 {.start = 0, .end = 0}, 206 } 207 }, 208 .seq = NULL, 209 .level = -1, 210 .current_prot = 0, 211 .check_wx = true, 212 .wx_pages = 0, 213 .start_address = 0, 214 .marker = (struct addr_marker[]) { 215 { .start_address = 0, .name = NULL}, 216 { .start_address = -1, .name = NULL}, 217 }, 218 }; 219 220 if (!MACHINE_HAS_NX) 221 return; 222 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); 223 if (st.wx_pages) 224 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages); 225 else 226 pr_info("Checked W+X mappings: passed, no %sW+X pages found\n", 227 (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)) ? 228 "unexpected " : ""); 229 } 230 #endif /* CONFIG_DEBUG_WX */ 231 232 #ifdef CONFIG_PTDUMP_DEBUGFS 233 static int ptdump_show(struct seq_file *m, void *v) 234 { 235 struct pg_state st = { 236 .ptdump = { 237 .note_page = note_page, 238 .range = (struct ptdump_range[]) { 239 {.start = 0, .end = max_addr}, 240 {.start = 0, .end = 0}, 241 } 242 }, 243 .seq = m, 244 .level = -1, 245 .current_prot = 0, 246 .check_wx = false, 247 .wx_pages = 0, 248 .start_address = 0, 249 .marker = address_markers, 250 }; 251 252 get_online_mems(); 253 mutex_lock(&cpa_mutex); 254 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); 255 mutex_unlock(&cpa_mutex); 256 put_online_mems(); 257 return 0; 258 } 259 DEFINE_SHOW_ATTRIBUTE(ptdump); 260 #endif /* CONFIG_PTDUMP_DEBUGFS */ 261 262 /* 263 * Heapsort from lib/sort.c is not a stable sorting algorithm, do a simple 264 * insertion sort to preserve the original order of markers with the same 265 * start address. 266 */ 267 static void sort_address_markers(void) 268 { 269 struct addr_marker tmp; 270 int i, j; 271 272 for (i = 1; i < ARRAY_SIZE(address_markers) - 1; i++) { 273 tmp = address_markers[i]; 274 for (j = i - 1; j >= 0 && address_markers[j].start_address > tmp.start_address; j--) 275 address_markers[j + 1] = address_markers[j]; 276 address_markers[j + 1] = tmp; 277 } 278 } 279 280 static int pt_dump_init(void) 281 { 282 #ifdef CONFIG_KFENCE 283 unsigned long kfence_start = (unsigned long)__kfence_pool; 284 #endif 285 /* 286 * Figure out the maximum virtual address being accessible with the 287 * kernel ASCE. We need this to keep the page table walker functions 288 * from accessing non-existent entries. 289 */ 290 max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2; 291 max_addr = 1UL << (max_addr * 11 + 31); 292 address_markers[IDENTITY_AFTER_END_NR].start_address = ident_map_size; 293 address_markers[AMODE31_START_NR].start_address = __samode31; 294 address_markers[AMODE31_END_NR].start_address = __eamode31; 295 address_markers[MODULES_NR].start_address = MODULES_VADDR; 296 address_markers[MODULES_END_NR].start_address = MODULES_END; 297 address_markers[ABS_LOWCORE_NR].start_address = __abs_lowcore; 298 address_markers[ABS_LOWCORE_END_NR].start_address = __abs_lowcore + ABS_LOWCORE_MAP_SIZE; 299 address_markers[MEMCPY_REAL_NR].start_address = __memcpy_real_area; 300 address_markers[MEMCPY_REAL_END_NR].start_address = __memcpy_real_area + PAGE_SIZE; 301 address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap; 302 address_markers[VMEMMAP_END_NR].start_address = (unsigned long)vmemmap + vmemmap_size; 303 address_markers[VMALLOC_NR].start_address = VMALLOC_START; 304 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END; 305 #ifdef CONFIG_KFENCE 306 address_markers[KFENCE_START_NR].start_address = kfence_start; 307 address_markers[KFENCE_END_NR].start_address = kfence_start + KFENCE_POOL_SIZE; 308 #endif 309 sort_address_markers(); 310 #ifdef CONFIG_PTDUMP_DEBUGFS 311 debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops); 312 #endif /* CONFIG_PTDUMP_DEBUGFS */ 313 return 0; 314 } 315 device_initcall(pt_dump_init); 316