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