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