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/kasan.h> 10 #include <asm/abs_lowcore.h> 11 #include <asm/nospec-branch.h> 12 #include <asm/sections.h> 13 #include <asm/maccess.h> 14 15 static unsigned long max_addr; 16 17 struct addr_marker { 18 unsigned long start_address; 19 const char *name; 20 }; 21 22 enum address_markers_idx { 23 IDENTITY_BEFORE_NR = 0, 24 IDENTITY_BEFORE_END_NR, 25 AMODE31_START_NR, 26 AMODE31_END_NR, 27 KERNEL_START_NR, 28 KERNEL_END_NR, 29 #ifdef CONFIG_KFENCE 30 KFENCE_START_NR, 31 KFENCE_END_NR, 32 #endif 33 IDENTITY_AFTER_NR, 34 IDENTITY_AFTER_END_NR, 35 VMEMMAP_NR, 36 VMEMMAP_END_NR, 37 VMALLOC_NR, 38 VMALLOC_END_NR, 39 MODULES_NR, 40 MODULES_END_NR, 41 ABS_LOWCORE_NR, 42 ABS_LOWCORE_END_NR, 43 MEMCPY_REAL_NR, 44 MEMCPY_REAL_END_NR, 45 #ifdef CONFIG_KASAN 46 KASAN_SHADOW_START_NR, 47 KASAN_SHADOW_END_NR, 48 #endif 49 }; 50 51 static struct addr_marker address_markers[] = { 52 [IDENTITY_BEFORE_NR] = {0, "Identity Mapping Start"}, 53 [IDENTITY_BEFORE_END_NR] = {(unsigned long)_stext, "Identity Mapping End"}, 54 [AMODE31_START_NR] = {0, "Amode31 Area Start"}, 55 [AMODE31_END_NR] = {0, "Amode31 Area End"}, 56 [KERNEL_START_NR] = {(unsigned long)_stext, "Kernel Image Start"}, 57 [KERNEL_END_NR] = {(unsigned long)_end, "Kernel Image End"}, 58 #ifdef CONFIG_KFENCE 59 [KFENCE_START_NR] = {0, "KFence Pool Start"}, 60 [KFENCE_END_NR] = {0, "KFence Pool End"}, 61 #endif 62 [IDENTITY_AFTER_NR] = {(unsigned long)_end, "Identity Mapping Start"}, 63 [IDENTITY_AFTER_END_NR] = {0, "Identity Mapping End"}, 64 [VMEMMAP_NR] = {0, "vmemmap Area Start"}, 65 [VMEMMAP_END_NR] = {0, "vmemmap Area End"}, 66 [VMALLOC_NR] = {0, "vmalloc Area Start"}, 67 [VMALLOC_END_NR] = {0, "vmalloc Area End"}, 68 [MODULES_NR] = {0, "Modules Area Start"}, 69 [MODULES_END_NR] = {0, "Modules Area End"}, 70 [ABS_LOWCORE_NR] = {0, "Lowcore Area Start"}, 71 [ABS_LOWCORE_END_NR] = {0, "Lowcore Area End"}, 72 [MEMCPY_REAL_NR] = {0, "Real Memory Copy Area Start"}, 73 [MEMCPY_REAL_END_NR] = {0, "Real Memory Copy Area End"}, 74 #ifdef CONFIG_KASAN 75 [KASAN_SHADOW_START_NR] = {KASAN_SHADOW_START, "Kasan Shadow Start"}, 76 [KASAN_SHADOW_END_NR] = {KASAN_SHADOW_END, "Kasan Shadow End"}, 77 #endif 78 { -1, NULL } 79 }; 80 81 struct pg_state { 82 struct ptdump_state ptdump; 83 struct seq_file *seq; 84 int level; 85 unsigned int current_prot; 86 bool check_wx; 87 unsigned long wx_pages; 88 unsigned long start_address; 89 const struct addr_marker *marker; 90 }; 91 92 #define pt_dump_seq_printf(m, fmt, args...) \ 93 ({ \ 94 struct seq_file *__m = (m); \ 95 \ 96 if (__m) \ 97 seq_printf(__m, fmt, ##args); \ 98 }) 99 100 #define pt_dump_seq_puts(m, fmt) \ 101 ({ \ 102 struct seq_file *__m = (m); \ 103 \ 104 if (__m) \ 105 seq_printf(__m, fmt); \ 106 }) 107 108 static void print_prot(struct seq_file *m, unsigned int pr, int level) 109 { 110 static const char * const level_name[] = 111 { "ASCE", "PGD", "PUD", "PMD", "PTE" }; 112 113 pt_dump_seq_printf(m, "%s ", level_name[level]); 114 if (pr & _PAGE_INVALID) { 115 pt_dump_seq_printf(m, "I\n"); 116 return; 117 } 118 pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW "); 119 pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n"); 120 } 121 122 static void note_prot_wx(struct pg_state *st, unsigned long addr) 123 { 124 if (!st->check_wx) 125 return; 126 if (st->current_prot & _PAGE_INVALID) 127 return; 128 if (st->current_prot & _PAGE_PROTECT) 129 return; 130 if (st->current_prot & _PAGE_NOEXEC) 131 return; 132 /* 133 * The first lowcore page is W+X if spectre mitigations are using 134 * trampolines or the BEAR enhancements facility is not installed, 135 * in which case we have two lpswe instructions in lowcore that need 136 * to be executable. 137 */ 138 if (addr == PAGE_SIZE && (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear))) 139 return; 140 WARN_ONCE(IS_ENABLED(CONFIG_DEBUG_WX), 141 "s390/mm: Found insecure W+X mapping at address %pS\n", 142 (void *)st->start_address); 143 st->wx_pages += (addr - st->start_address) / PAGE_SIZE; 144 } 145 146 static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val) 147 { 148 int width = sizeof(unsigned long) * 2; 149 static const char units[] = "KMGTPE"; 150 const char *unit = units; 151 unsigned long delta; 152 struct pg_state *st; 153 struct seq_file *m; 154 unsigned int prot; 155 156 st = container_of(pt_st, struct pg_state, ptdump); 157 m = st->seq; 158 prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC); 159 if (level == 4 && (val & _PAGE_INVALID)) 160 prot = _PAGE_INVALID; 161 /* For pmd_none() & friends val gets passed as zero. */ 162 if (level != 4 && !val) 163 prot = _PAGE_INVALID; 164 /* Final flush from generic code. */ 165 if (level == -1) 166 addr = max_addr; 167 if (st->level == -1) { 168 pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name); 169 st->start_address = addr; 170 st->current_prot = prot; 171 st->level = level; 172 } else if (prot != st->current_prot || level != st->level || 173 addr >= st->marker[1].start_address) { 174 note_prot_wx(st, addr); 175 pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ", 176 width, st->start_address, 177 width, addr); 178 delta = (addr - st->start_address) >> 10; 179 while (!(delta & 0x3ff) && unit[1]) { 180 delta >>= 10; 181 unit++; 182 } 183 pt_dump_seq_printf(m, "%9lu%c ", delta, *unit); 184 print_prot(m, st->current_prot, st->level); 185 while (addr >= st->marker[1].start_address) { 186 st->marker++; 187 pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name); 188 } 189 st->start_address = addr; 190 st->current_prot = prot; 191 st->level = level; 192 } 193 } 194 195 bool ptdump_check_wx(void) 196 { 197 struct pg_state st = { 198 .ptdump = { 199 .note_page = note_page, 200 .range = (struct ptdump_range[]) { 201 {.start = 0, .end = max_addr}, 202 {.start = 0, .end = 0}, 203 } 204 }, 205 .seq = NULL, 206 .level = -1, 207 .current_prot = 0, 208 .check_wx = true, 209 .wx_pages = 0, 210 .start_address = 0, 211 .marker = (struct addr_marker[]) { 212 { .start_address = 0, .name = NULL}, 213 { .start_address = -1, .name = NULL}, 214 }, 215 }; 216 217 if (!MACHINE_HAS_NX) 218 return true; 219 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); 220 if (st.wx_pages) { 221 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages); 222 223 return false; 224 } else { 225 pr_info("Checked W+X mappings: passed, no %sW+X pages found\n", 226 (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)) ? 227 "unexpected " : ""); 228 229 return true; 230 } 231 } 232 233 #ifdef CONFIG_PTDUMP_DEBUGFS 234 static int ptdump_show(struct seq_file *m, void *v) 235 { 236 struct pg_state st = { 237 .ptdump = { 238 .note_page = note_page, 239 .range = (struct ptdump_range[]) { 240 {.start = 0, .end = max_addr}, 241 {.start = 0, .end = 0}, 242 } 243 }, 244 .seq = m, 245 .level = -1, 246 .current_prot = 0, 247 .check_wx = false, 248 .wx_pages = 0, 249 .start_address = 0, 250 .marker = address_markers, 251 }; 252 253 get_online_mems(); 254 mutex_lock(&cpa_mutex); 255 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); 256 mutex_unlock(&cpa_mutex); 257 put_online_mems(); 258 return 0; 259 } 260 DEFINE_SHOW_ATTRIBUTE(ptdump); 261 #endif /* CONFIG_PTDUMP_DEBUGFS */ 262 263 /* 264 * Heapsort from lib/sort.c is not a stable sorting algorithm, do a simple 265 * insertion sort to preserve the original order of markers with the same 266 * start address. 267 */ 268 static void sort_address_markers(void) 269 { 270 struct addr_marker tmp; 271 int i, j; 272 273 for (i = 1; i < ARRAY_SIZE(address_markers) - 1; i++) { 274 tmp = address_markers[i]; 275 for (j = i - 1; j >= 0 && address_markers[j].start_address > tmp.start_address; j--) 276 address_markers[j + 1] = address_markers[j]; 277 address_markers[j + 1] = tmp; 278 } 279 } 280 281 static int pt_dump_init(void) 282 { 283 #ifdef CONFIG_KFENCE 284 unsigned long kfence_start = (unsigned long)__kfence_pool; 285 #endif 286 /* 287 * Figure out the maximum virtual address being accessible with the 288 * kernel ASCE. We need this to keep the page table walker functions 289 * from accessing non-existent entries. 290 */ 291 max_addr = (S390_lowcore.kernel_asce.val & _REGION_ENTRY_TYPE_MASK) >> 2; 292 max_addr = 1UL << (max_addr * 11 + 31); 293 address_markers[IDENTITY_AFTER_END_NR].start_address = ident_map_size; 294 address_markers[AMODE31_START_NR].start_address = (unsigned long)__samode31; 295 address_markers[AMODE31_END_NR].start_address = (unsigned long)__eamode31; 296 address_markers[MODULES_NR].start_address = MODULES_VADDR; 297 address_markers[MODULES_END_NR].start_address = MODULES_END; 298 address_markers[ABS_LOWCORE_NR].start_address = __abs_lowcore; 299 address_markers[ABS_LOWCORE_END_NR].start_address = __abs_lowcore + ABS_LOWCORE_MAP_SIZE; 300 address_markers[MEMCPY_REAL_NR].start_address = __memcpy_real_area; 301 address_markers[MEMCPY_REAL_END_NR].start_address = __memcpy_real_area + MEMCPY_REAL_SIZE; 302 address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap; 303 address_markers[VMEMMAP_END_NR].start_address = (unsigned long)vmemmap + vmemmap_size; 304 address_markers[VMALLOC_NR].start_address = VMALLOC_START; 305 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END; 306 #ifdef CONFIG_KFENCE 307 address_markers[KFENCE_START_NR].start_address = kfence_start; 308 address_markers[KFENCE_END_NR].start_address = kfence_start + KFENCE_POOL_SIZE; 309 #endif 310 sort_address_markers(); 311 #ifdef CONFIG_PTDUMP_DEBUGFS 312 debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops); 313 #endif /* CONFIG_PTDUMP_DEBUGFS */ 314 return 0; 315 } 316 device_initcall(pt_dump_init); 317