| 1 | /* |
| 2 | * Copyright 2016, Rashmica Gupta, IBM Corp. |
| 3 | * |
| 4 | * This traverses the kernel pagetables and dumps the |
| 5 | * information about the used sections of memory to |
| 6 | * /sys/kernel/debug/kernel_pagetables. |
| 7 | * |
| 8 | * Derived from the arm64 implementation: |
| 9 | * Copyright (c) 2014, The Linux Foundation, Laura Abbott. |
| 10 | * (C) Copyright 2008 Intel Corporation, Arjan van de Ven. |
| 11 | * |
| 12 | * This program is free software; you can redistribute it and/or |
| 13 | * modify it under the terms of the GNU General Public License |
| 14 | * as published by the Free Software Foundation; version 2 |
| 15 | * of the License. |
| 16 | */ |
| 17 | #include <linux/debugfs.h> |
| 18 | #include <linux/fs.h> |
| 19 | #include <linux/hugetlb.h> |
| 20 | #include <linux/io.h> |
| 21 | #include <linux/mm.h> |
| 22 | #include <linux/highmem.h> |
| 23 | #include <linux/sched.h> |
| 24 | #include <linux/seq_file.h> |
| 25 | #include <asm/fixmap.h> |
| 26 | #include <asm/pgtable.h> |
| 27 | #include <linux/const.h> |
| 28 | #include <asm/page.h> |
| 29 | #include <asm/pgalloc.h> |
| 30 | |
| 31 | #include "ptdump.h" |
| 32 | |
| 33 | #ifdef CONFIG_PPC32 |
| 34 | #define KERN_VIRT_START 0 |
| 35 | #endif |
| 36 | |
| 37 | /* |
| 38 | * To visualise what is happening, |
| 39 | * |
| 40 | * - PTRS_PER_P** = how many entries there are in the corresponding P** |
| 41 | * - P**_SHIFT = how many bits of the address we use to index into the |
| 42 | * corresponding P** |
| 43 | * - P**_SIZE is how much memory we can access through the table - not the |
| 44 | * size of the table itself. |
| 45 | * P**={PGD, PUD, PMD, PTE} |
| 46 | * |
| 47 | * |
| 48 | * Each entry of the PGD points to a PUD. Each entry of a PUD points to a |
| 49 | * PMD. Each entry of a PMD points to a PTE. And every PTE entry points to |
| 50 | * a page. |
| 51 | * |
| 52 | * In the case where there are only 3 levels, the PUD is folded into the |
| 53 | * PGD: every PUD has only one entry which points to the PMD. |
| 54 | * |
| 55 | * The page dumper groups page table entries of the same type into a single |
| 56 | * description. It uses pg_state to track the range information while |
| 57 | * iterating over the PTE entries. When the continuity is broken it then |
| 58 | * dumps out a description of the range - ie PTEs that are virtually contiguous |
| 59 | * with the same PTE flags are chunked together. This is to make it clear how |
| 60 | * different areas of the kernel virtual memory are used. |
| 61 | * |
| 62 | */ |
| 63 | struct pg_state { |
| 64 | struct seq_file *seq; |
| 65 | const struct addr_marker *marker; |
| 66 | unsigned long start_address; |
| 67 | unsigned long start_pa; |
| 68 | unsigned long last_pa; |
| 69 | unsigned int level; |
| 70 | u64 current_flags; |
| 71 | }; |
| 72 | |
| 73 | struct addr_marker { |
| 74 | unsigned long start_address; |
| 75 | const char *name; |
| 76 | }; |
| 77 | |
| 78 | static struct addr_marker address_markers[] = { |
| 79 | { 0, "Start of kernel VM" }, |
| 80 | { 0, "vmalloc() Area" }, |
| 81 | { 0, "vmalloc() End" }, |
| 82 | #ifdef CONFIG_PPC64 |
| 83 | { 0, "isa I/O start" }, |
| 84 | { 0, "isa I/O end" }, |
| 85 | { 0, "phb I/O start" }, |
| 86 | { 0, "phb I/O end" }, |
| 87 | { 0, "I/O remap start" }, |
| 88 | { 0, "I/O remap end" }, |
| 89 | { 0, "vmemmap start" }, |
| 90 | #else |
| 91 | { 0, "Early I/O remap start" }, |
| 92 | { 0, "Early I/O remap end" }, |
| 93 | #ifdef CONFIG_NOT_COHERENT_CACHE |
| 94 | { 0, "Consistent mem start" }, |
| 95 | { 0, "Consistent mem end" }, |
| 96 | #endif |
| 97 | #ifdef CONFIG_HIGHMEM |
| 98 | { 0, "Highmem PTEs start" }, |
| 99 | { 0, "Highmem PTEs end" }, |
| 100 | #endif |
| 101 | { 0, "Fixmap start" }, |
| 102 | { 0, "Fixmap end" }, |
| 103 | #endif |
| 104 | { -1, NULL }, |
| 105 | }; |
| 106 | |
| 107 | static void dump_flag_info(struct pg_state *st, const struct flag_info |
| 108 | *flag, u64 pte, int num) |
| 109 | { |
| 110 | unsigned int i; |
| 111 | |
| 112 | for (i = 0; i < num; i++, flag++) { |
| 113 | const char *s = NULL; |
| 114 | u64 val; |
| 115 | |
| 116 | /* flag not defined so don't check it */ |
| 117 | if (flag->mask == 0) |
| 118 | continue; |
| 119 | /* Some 'flags' are actually values */ |
| 120 | if (flag->is_val) { |
| 121 | val = pte & flag->val; |
| 122 | if (flag->shift) |
| 123 | val = val >> flag->shift; |
| 124 | seq_printf(st->seq, " %s:%llx", flag->set, val); |
| 125 | } else { |
| 126 | if ((pte & flag->mask) == flag->val) |
| 127 | s = flag->set; |
| 128 | else |
| 129 | s = flag->clear; |
| 130 | if (s) |
| 131 | seq_printf(st->seq, " %s", s); |
| 132 | } |
| 133 | st->current_flags &= ~flag->mask; |
| 134 | } |
| 135 | if (st->current_flags != 0) |
| 136 | seq_printf(st->seq, " unknown flags:%llx", st->current_flags); |
| 137 | } |
| 138 | |
| 139 | static void dump_addr(struct pg_state *st, unsigned long addr) |
| 140 | { |
| 141 | static const char units[] = "KMGTPE"; |
| 142 | const char *unit = units; |
| 143 | unsigned long delta; |
| 144 | |
| 145 | #ifdef CONFIG_PPC64 |
| 146 | #define REG "0x%016lx" |
| 147 | #else |
| 148 | #define REG "0x%08lx" |
| 149 | #endif |
| 150 | |
| 151 | seq_printf(st->seq, REG "-" REG " ", st->start_address, addr - 1); |
| 152 | if (st->start_pa == st->last_pa && st->start_address + PAGE_SIZE != addr) { |
| 153 | seq_printf(st->seq, "[" REG "]", st->start_pa); |
| 154 | delta = PAGE_SIZE >> 10; |
| 155 | } else { |
| 156 | seq_printf(st->seq, " " REG " ", st->start_pa); |
| 157 | delta = (addr - st->start_address) >> 10; |
| 158 | } |
| 159 | /* Work out what appropriate unit to use */ |
| 160 | while (!(delta & 1023) && unit[1]) { |
| 161 | delta >>= 10; |
| 162 | unit++; |
| 163 | } |
| 164 | seq_printf(st->seq, "%9lu%c", delta, *unit); |
| 165 | |
| 166 | } |
| 167 | |
| 168 | static void note_page(struct pg_state *st, unsigned long addr, |
| 169 | unsigned int level, u64 val) |
| 170 | { |
| 171 | u64 flag = val & pg_level[level].mask; |
| 172 | u64 pa = val & PTE_RPN_MASK; |
| 173 | |
| 174 | /* At first no level is set */ |
| 175 | if (!st->level) { |
| 176 | st->level = level; |
| 177 | st->current_flags = flag; |
| 178 | st->start_address = addr; |
| 179 | st->start_pa = pa; |
| 180 | st->last_pa = pa; |
| 181 | seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); |
| 182 | /* |
| 183 | * Dump the section of virtual memory when: |
| 184 | * - the PTE flags from one entry to the next differs. |
| 185 | * - we change levels in the tree. |
| 186 | * - the address is in a different section of memory and is thus |
| 187 | * used for a different purpose, regardless of the flags. |
| 188 | * - the pa of this page is not adjacent to the last inspected page |
| 189 | */ |
| 190 | } else if (flag != st->current_flags || level != st->level || |
| 191 | addr >= st->marker[1].start_address || |
| 192 | (pa != st->last_pa + PAGE_SIZE && |
| 193 | (pa != st->start_pa || st->start_pa != st->last_pa))) { |
| 194 | |
| 195 | /* Check the PTE flags */ |
| 196 | if (st->current_flags) { |
| 197 | dump_addr(st, addr); |
| 198 | |
| 199 | /* Dump all the flags */ |
| 200 | if (pg_level[st->level].flag) |
| 201 | dump_flag_info(st, pg_level[st->level].flag, |
| 202 | st->current_flags, |
| 203 | pg_level[st->level].num); |
| 204 | |
| 205 | seq_putc(st->seq, '\n'); |
| 206 | } |
| 207 | |
| 208 | /* |
| 209 | * Address indicates we have passed the end of the |
| 210 | * current section of virtual memory |
| 211 | */ |
| 212 | while (addr >= st->marker[1].start_address) { |
| 213 | st->marker++; |
| 214 | seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); |
| 215 | } |
| 216 | st->start_address = addr; |
| 217 | st->start_pa = pa; |
| 218 | st->last_pa = pa; |
| 219 | st->current_flags = flag; |
| 220 | st->level = level; |
| 221 | } else { |
| 222 | st->last_pa = pa; |
| 223 | } |
| 224 | } |
| 225 | |
| 226 | static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start) |
| 227 | { |
| 228 | pte_t *pte = pte_offset_kernel(pmd, 0); |
| 229 | unsigned long addr; |
| 230 | unsigned int i; |
| 231 | |
| 232 | for (i = 0; i < PTRS_PER_PTE; i++, pte++) { |
| 233 | addr = start + i * PAGE_SIZE; |
| 234 | note_page(st, addr, 4, pte_val(*pte)); |
| 235 | |
| 236 | } |
| 237 | } |
| 238 | |
| 239 | static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start) |
| 240 | { |
| 241 | pmd_t *pmd = pmd_offset(pud, 0); |
| 242 | unsigned long addr; |
| 243 | unsigned int i; |
| 244 | |
| 245 | for (i = 0; i < PTRS_PER_PMD; i++, pmd++) { |
| 246 | addr = start + i * PMD_SIZE; |
| 247 | if (!pmd_none(*pmd) && !pmd_huge(*pmd)) |
| 248 | /* pmd exists */ |
| 249 | walk_pte(st, pmd, addr); |
| 250 | else |
| 251 | note_page(st, addr, 3, pmd_val(*pmd)); |
| 252 | } |
| 253 | } |
| 254 | |
| 255 | static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start) |
| 256 | { |
| 257 | pud_t *pud = pud_offset(pgd, 0); |
| 258 | unsigned long addr; |
| 259 | unsigned int i; |
| 260 | |
| 261 | for (i = 0; i < PTRS_PER_PUD; i++, pud++) { |
| 262 | addr = start + i * PUD_SIZE; |
| 263 | if (!pud_none(*pud) && !pud_huge(*pud)) |
| 264 | /* pud exists */ |
| 265 | walk_pmd(st, pud, addr); |
| 266 | else |
| 267 | note_page(st, addr, 2, pud_val(*pud)); |
| 268 | } |
| 269 | } |
| 270 | |
| 271 | static void walk_pagetables(struct pg_state *st) |
| 272 | { |
| 273 | pgd_t *pgd = pgd_offset_k(0UL); |
| 274 | unsigned int i; |
| 275 | unsigned long addr; |
| 276 | |
| 277 | addr = st->start_address; |
| 278 | |
| 279 | /* |
| 280 | * Traverse the linux pagetable structure and dump pages that are in |
| 281 | * the hash pagetable. |
| 282 | */ |
| 283 | for (i = 0; i < PTRS_PER_PGD; i++, pgd++, addr += PGDIR_SIZE) { |
| 284 | if (!pgd_none(*pgd) && !pgd_huge(*pgd)) |
| 285 | /* pgd exists */ |
| 286 | walk_pud(st, pgd, addr); |
| 287 | else |
| 288 | note_page(st, addr, 1, pgd_val(*pgd)); |
| 289 | } |
| 290 | } |
| 291 | |
| 292 | static void populate_markers(void) |
| 293 | { |
| 294 | int i = 0; |
| 295 | |
| 296 | address_markers[i++].start_address = PAGE_OFFSET; |
| 297 | address_markers[i++].start_address = VMALLOC_START; |
| 298 | address_markers[i++].start_address = VMALLOC_END; |
| 299 | #ifdef CONFIG_PPC64 |
| 300 | address_markers[i++].start_address = ISA_IO_BASE; |
| 301 | address_markers[i++].start_address = ISA_IO_END; |
| 302 | address_markers[i++].start_address = PHB_IO_BASE; |
| 303 | address_markers[i++].start_address = PHB_IO_END; |
| 304 | address_markers[i++].start_address = IOREMAP_BASE; |
| 305 | address_markers[i++].start_address = IOREMAP_END; |
| 306 | /* What is the ifdef about? */ |
| 307 | #ifdef CONFIG_PPC_BOOK3S_64 |
| 308 | address_markers[i++].start_address = H_VMEMMAP_START; |
| 309 | #else |
| 310 | address_markers[i++].start_address = VMEMMAP_BASE; |
| 311 | #endif |
| 312 | #else /* !CONFIG_PPC64 */ |
| 313 | address_markers[i++].start_address = ioremap_bot; |
| 314 | address_markers[i++].start_address = IOREMAP_TOP; |
| 315 | #ifdef CONFIG_NOT_COHERENT_CACHE |
| 316 | address_markers[i++].start_address = IOREMAP_TOP; |
| 317 | address_markers[i++].start_address = IOREMAP_TOP + |
| 318 | CONFIG_CONSISTENT_SIZE; |
| 319 | #endif |
| 320 | #ifdef CONFIG_HIGHMEM |
| 321 | address_markers[i++].start_address = PKMAP_BASE; |
| 322 | address_markers[i++].start_address = PKMAP_ADDR(LAST_PKMAP); |
| 323 | #endif |
| 324 | address_markers[i++].start_address = FIXADDR_START; |
| 325 | address_markers[i++].start_address = FIXADDR_TOP; |
| 326 | #endif /* CONFIG_PPC64 */ |
| 327 | } |
| 328 | |
| 329 | static int ptdump_show(struct seq_file *m, void *v) |
| 330 | { |
| 331 | struct pg_state st = { |
| 332 | .seq = m, |
| 333 | .marker = address_markers, |
| 334 | }; |
| 335 | |
| 336 | if (radix_enabled()) |
| 337 | st.start_address = PAGE_OFFSET; |
| 338 | else |
| 339 | st.start_address = KERN_VIRT_START; |
| 340 | |
| 341 | /* Traverse kernel page tables */ |
| 342 | walk_pagetables(&st); |
| 343 | note_page(&st, 0, 0, 0); |
| 344 | return 0; |
| 345 | } |
| 346 | |
| 347 | |
| 348 | static int ptdump_open(struct inode *inode, struct file *file) |
| 349 | { |
| 350 | return single_open(file, ptdump_show, NULL); |
| 351 | } |
| 352 | |
| 353 | static const struct file_operations ptdump_fops = { |
| 354 | .open = ptdump_open, |
| 355 | .read = seq_read, |
| 356 | .llseek = seq_lseek, |
| 357 | .release = single_release, |
| 358 | }; |
| 359 | |
| 360 | static void build_pgtable_complete_mask(void) |
| 361 | { |
| 362 | unsigned int i, j; |
| 363 | |
| 364 | for (i = 0; i < ARRAY_SIZE(pg_level); i++) |
| 365 | if (pg_level[i].flag) |
| 366 | for (j = 0; j < pg_level[i].num; j++) |
| 367 | pg_level[i].mask |= pg_level[i].flag[j].mask; |
| 368 | } |
| 369 | |
| 370 | static int ptdump_init(void) |
| 371 | { |
| 372 | struct dentry *debugfs_file; |
| 373 | |
| 374 | populate_markers(); |
| 375 | build_pgtable_complete_mask(); |
| 376 | debugfs_file = debugfs_create_file("kernel_page_tables", 0400, NULL, |
| 377 | NULL, &ptdump_fops); |
| 378 | return debugfs_file ? 0 : -ENOMEM; |
| 379 | } |
| 380 | device_initcall(ptdump_init); |