1 // SPDX-License-Identifier: GPL-2.0 2 3 #include <linux/cpufeature.h> 4 #include <linux/set_memory.h> 5 #include <linux/ptdump.h> 6 #include <linux/seq_file.h> 7 #include <linux/debugfs.h> 8 #include <linux/sort.h> 9 #include <linux/mm.h> 10 #include <linux/kfence.h> 11 #include <linux/kasan.h> 12 #include <asm/kasan.h> 13 #include <asm/abs_lowcore.h> 14 #include <asm/nospec-branch.h> 15 #include <asm/sections.h> 16 #include <asm/maccess.h> 17 18 static unsigned long max_addr; 19 20 struct addr_marker { 21 int is_start; 22 unsigned long start_address; 23 unsigned long size; 24 const char *name; 25 }; 26 27 static struct addr_marker *markers; 28 static unsigned int markers_cnt; 29 30 struct pg_state { 31 struct ptdump_state ptdump; 32 struct seq_file *seq; 33 int level; 34 unsigned int current_prot; 35 bool check_wx; 36 unsigned long wx_pages; 37 unsigned long start_address; 38 const struct addr_marker *marker; 39 }; 40 41 #define pt_dump_seq_printf(m, fmt, args...) \ 42 ({ \ 43 struct seq_file *__m = (m); \ 44 \ 45 if (__m) \ 46 seq_printf(__m, fmt, ##args); \ 47 }) 48 49 #define pt_dump_seq_puts(m, fmt) \ 50 ({ \ 51 struct seq_file *__m = (m); \ 52 \ 53 if (__m) \ 54 seq_printf(__m, fmt); \ 55 }) 56 57 static void print_prot(struct seq_file *m, unsigned int pr, int level) 58 { 59 static const char * const level_name[] = 60 { "ASCE", "PGD", "PUD", "PMD", "PTE" }; 61 62 pt_dump_seq_printf(m, "%s ", level_name[level]); 63 if (pr & _PAGE_INVALID) { 64 pt_dump_seq_printf(m, "I\n"); 65 return; 66 } 67 pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW "); 68 pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n"); 69 } 70 71 static void note_prot_wx(struct pg_state *st, unsigned long addr) 72 { 73 if (!st->check_wx) 74 return; 75 if (st->current_prot & _PAGE_INVALID) 76 return; 77 if (st->current_prot & _PAGE_PROTECT) 78 return; 79 if (st->current_prot & _PAGE_NOEXEC) 80 return; 81 /* 82 * The first lowcore page is W+X if spectre mitigations are using 83 * trampolines or the BEAR enhancements facility is not installed, 84 * in which case we have two lpswe instructions in lowcore that need 85 * to be executable. 86 */ 87 if (addr == PAGE_SIZE && (nospec_uses_trampoline() || !cpu_has_bear())) 88 return; 89 WARN_ONCE(IS_ENABLED(CONFIG_DEBUG_WX), 90 "s390/mm: Found insecure W+X mapping at address %pS\n", 91 (void *)st->start_address); 92 st->wx_pages += (addr - st->start_address) / PAGE_SIZE; 93 } 94 95 static void note_page_update_state(struct pg_state *st, unsigned long addr, unsigned int prot, int level) 96 { 97 struct seq_file *m = st->seq; 98 99 while (addr >= st->marker[1].start_address) { 100 st->marker++; 101 pt_dump_seq_printf(m, "---[ %s %s ]---\n", st->marker->name, 102 st->marker->is_start ? "Start" : "End"); 103 } 104 st->start_address = addr; 105 st->current_prot = prot; 106 st->level = level; 107 } 108 109 static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val) 110 { 111 int width = sizeof(unsigned long) * 2; 112 static const char units[] = "KMGTPE"; 113 const char *unit = units; 114 unsigned long delta; 115 struct pg_state *st; 116 struct seq_file *m; 117 unsigned int prot; 118 119 st = container_of(pt_st, struct pg_state, ptdump); 120 m = st->seq; 121 prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC); 122 if (level == 4 && (val & _PAGE_INVALID)) 123 prot = _PAGE_INVALID; 124 /* For pmd_none() & friends val gets passed as zero. */ 125 if (level != 4 && !val) 126 prot = _PAGE_INVALID; 127 /* Final flush from generic code. */ 128 if (level == -1) 129 addr = max_addr; 130 if (st->level == -1) { 131 pt_dump_seq_puts(m, "---[ Kernel Virtual Address Space ]---\n"); 132 note_page_update_state(st, addr, prot, level); 133 } else if (prot != st->current_prot || level != st->level || 134 addr >= st->marker[1].start_address) { 135 note_prot_wx(st, addr); 136 pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ", 137 width, st->start_address, 138 width, addr); 139 delta = (addr - st->start_address) >> 10; 140 while (!(delta & 0x3ff) && unit[1]) { 141 delta >>= 10; 142 unit++; 143 } 144 pt_dump_seq_printf(m, "%9lu%c ", delta, *unit); 145 print_prot(m, st->current_prot, st->level); 146 note_page_update_state(st, addr, prot, level); 147 } 148 } 149 150 bool ptdump_check_wx(void) 151 { 152 struct pg_state st = { 153 .ptdump = { 154 .note_page = note_page, 155 .range = (struct ptdump_range[]) { 156 {.start = 0, .end = max_addr}, 157 {.start = 0, .end = 0}, 158 } 159 }, 160 .seq = NULL, 161 .level = -1, 162 .current_prot = 0, 163 .check_wx = true, 164 .wx_pages = 0, 165 .start_address = 0, 166 .marker = (struct addr_marker[]) { 167 { .start_address = 0, .name = NULL}, 168 { .start_address = -1, .name = NULL}, 169 }, 170 }; 171 172 if (!cpu_has_nx()) 173 return true; 174 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); 175 if (st.wx_pages) { 176 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages); 177 178 return false; 179 } else { 180 pr_info("Checked W+X mappings: passed, no %sW+X pages found\n", 181 (nospec_uses_trampoline() || !cpu_has_bear()) ? 182 "unexpected " : ""); 183 184 return true; 185 } 186 } 187 188 #ifdef CONFIG_PTDUMP_DEBUGFS 189 static int ptdump_show(struct seq_file *m, void *v) 190 { 191 struct pg_state st = { 192 .ptdump = { 193 .note_page = note_page, 194 .range = (struct ptdump_range[]) { 195 {.start = 0, .end = max_addr}, 196 {.start = 0, .end = 0}, 197 } 198 }, 199 .seq = m, 200 .level = -1, 201 .current_prot = 0, 202 .check_wx = false, 203 .wx_pages = 0, 204 .start_address = 0, 205 .marker = markers, 206 }; 207 208 get_online_mems(); 209 mutex_lock(&cpa_mutex); 210 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); 211 mutex_unlock(&cpa_mutex); 212 put_online_mems(); 213 return 0; 214 } 215 DEFINE_SHOW_ATTRIBUTE(ptdump); 216 #endif /* CONFIG_PTDUMP_DEBUGFS */ 217 218 static int ptdump_cmp(const void *a, const void *b) 219 { 220 const struct addr_marker *ama = a; 221 const struct addr_marker *amb = b; 222 223 if (ama->start_address > amb->start_address) 224 return 1; 225 if (ama->start_address < amb->start_address) 226 return -1; 227 /* 228 * If the start addresses of two markers are identical sort markers in an 229 * order that considers areas contained within other areas correctly. 230 */ 231 if (ama->is_start && amb->is_start) { 232 if (ama->size > amb->size) 233 return -1; 234 if (ama->size < amb->size) 235 return 1; 236 return 0; 237 } 238 if (!ama->is_start && !amb->is_start) { 239 if (ama->size > amb->size) 240 return 1; 241 if (ama->size < amb->size) 242 return -1; 243 return 0; 244 } 245 if (ama->is_start) 246 return 1; 247 if (amb->is_start) 248 return -1; 249 return 0; 250 } 251 252 static int add_marker(unsigned long start, unsigned long end, const char *name) 253 { 254 size_t oldsize, newsize; 255 256 oldsize = markers_cnt * sizeof(*markers); 257 newsize = oldsize + 2 * sizeof(*markers); 258 if (!oldsize) 259 markers = kvmalloc(newsize, GFP_KERNEL); 260 else 261 markers = kvrealloc(markers, newsize, GFP_KERNEL); 262 if (!markers) 263 goto error; 264 markers[markers_cnt].is_start = 1; 265 markers[markers_cnt].start_address = start; 266 markers[markers_cnt].size = end - start; 267 markers[markers_cnt].name = name; 268 markers_cnt++; 269 markers[markers_cnt].is_start = 0; 270 markers[markers_cnt].start_address = end; 271 markers[markers_cnt].size = end - start; 272 markers[markers_cnt].name = name; 273 markers_cnt++; 274 return 0; 275 error: 276 markers_cnt = 0; 277 return -ENOMEM; 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 unsigned long lowcore = (unsigned long)get_lowcore(); 286 int rc; 287 288 /* 289 * Figure out the maximum virtual address being accessible with the 290 * kernel ASCE. We need this to keep the page table walker functions 291 * from accessing non-existent entries. 292 */ 293 max_addr = (get_lowcore()->kernel_asce.val & _REGION_ENTRY_TYPE_MASK) >> 2; 294 max_addr = 1UL << (max_addr * 11 + 31); 295 /* start + end markers - must be added first */ 296 rc = add_marker(0, -1UL, NULL); 297 rc |= add_marker((unsigned long)_stext, (unsigned long)_end, "Kernel Image"); 298 rc |= add_marker(lowcore, lowcore + sizeof(struct lowcore), "Lowcore"); 299 rc |= add_marker(__identity_base, __identity_base + ident_map_size, "Identity Mapping"); 300 rc |= add_marker((unsigned long)__samode31, (unsigned long)__eamode31, "Amode31 Area"); 301 rc |= add_marker(MODULES_VADDR, MODULES_END, "Modules Area"); 302 rc |= add_marker(__abs_lowcore, __abs_lowcore + ABS_LOWCORE_MAP_SIZE, "Lowcore Area"); 303 rc |= add_marker(__memcpy_real_area, __memcpy_real_area + MEMCPY_REAL_SIZE, "Real Memory Copy Area"); 304 rc |= add_marker((unsigned long)vmemmap, (unsigned long)vmemmap + vmemmap_size, "vmemmap Area"); 305 rc |= add_marker(VMALLOC_START, VMALLOC_END, "vmalloc Area"); 306 #ifdef CONFIG_KFENCE 307 rc |= add_marker(kfence_start, kfence_start + KFENCE_POOL_SIZE, "KFence Pool"); 308 #endif 309 #ifdef CONFIG_KMSAN 310 rc |= add_marker(KMSAN_VMALLOC_SHADOW_START, KMSAN_VMALLOC_SHADOW_END, "Kmsan vmalloc Shadow"); 311 rc |= add_marker(KMSAN_VMALLOC_ORIGIN_START, KMSAN_VMALLOC_ORIGIN_END, "Kmsan vmalloc Origins"); 312 rc |= add_marker(KMSAN_MODULES_SHADOW_START, KMSAN_MODULES_SHADOW_END, "Kmsan Modules Shadow"); 313 rc |= add_marker(KMSAN_MODULES_ORIGIN_START, KMSAN_MODULES_ORIGIN_END, "Kmsan Modules Origins"); 314 #endif 315 #ifdef CONFIG_KASAN 316 rc |= add_marker(KASAN_SHADOW_START, KASAN_SHADOW_END, "Kasan Shadow"); 317 #endif 318 if (rc) 319 goto error; 320 sort(&markers[1], markers_cnt - 1, sizeof(*markers), ptdump_cmp, NULL); 321 #ifdef CONFIG_PTDUMP_DEBUGFS 322 debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops); 323 #endif /* CONFIG_PTDUMP_DEBUGFS */ 324 return 0; 325 error: 326 kvfree(markers); 327 return -ENOMEM; 328 } 329 device_initcall(pt_dump_init); 330