arch/s390/mm/dump_pagetables.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/seq_file.h>
   3 #include <linux/debugfs.h>
   4 #include <linux/sched.h>
   5 #include <linux/mm.h>
   6 #include <linux/kasan.h>
   7 #include <asm/kasan.h>
   8 #include <asm/sections.h>
   9 #include <asm/pgtable.h>
  10
  11 static unsigned long max_addr;
  12
  13 struct addr_marker {
  14         unsigned long start_address;
  15         const char *name;
  16 };
  17
  18 enum address_markers_idx {
  19         IDENTITY_NR = 0,
  20         KERNEL_START_NR,
  21         KERNEL_END_NR,
  22 #ifdef CONFIG_KASAN
  23         KASAN_SHADOW_START_NR,
  24         KASAN_SHADOW_END_NR,
  25 #endif
  26         VMEMMAP_NR,
  27         VMALLOC_NR,
  28         MODULES_NR,
  29 };
  30
  31 static struct addr_marker address_markers[] = {
  32         [IDENTITY_NR]           = {0, "Identity Mapping"},
  33         [KERNEL_START_NR]       = {(unsigned long)_stext, "Kernel Image Start"},
  34         [KERNEL_END_NR]         = {(unsigned long)_end, "Kernel Image End"},
  35 #ifdef CONFIG_KASAN
  36         [KASAN_SHADOW_START_NR] = {KASAN_SHADOW_START, "Kasan Shadow Start"},
  37         [KASAN_SHADOW_END_NR]   = {KASAN_SHADOW_END, "Kasan Shadow End"},
  38 #endif
  39         [VMEMMAP_NR]            = {0, "vmemmap Area"},
  40         [VMALLOC_NR]            = {0, "vmalloc Area"},
  41         [MODULES_NR]            = {0, "Modules Area"},
  42         { -1, NULL }
  43 };
  44
  45 struct pg_state {
  46         int level;
  47         unsigned int current_prot;
  48         unsigned long start_address;
  49         unsigned long current_address;
  50         const struct addr_marker *marker;
  51 };
  52
  53 static void print_prot(struct seq_file *m, unsigned int pr, int level)
  54 {
  55         static const char * const level_name[] =
  56                 { "ASCE", "PGD", "PUD", "PMD", "PTE" };
  57
  58         seq_printf(m, "%s ", level_name[level]);
  59         if (pr & _PAGE_INVALID) {
  60                 seq_printf(m, "I\n");
  61                 return;
  62         }
  63         seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW ");
  64         seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
  65 }
  66
  67 static void note_page(struct seq_file *m, struct pg_state *st,
  68                      unsigned int new_prot, int level)
  69 {
  70         static const char units[] = "KMGTPE";
  71         int width = sizeof(unsigned long) * 2;
  72         const char *unit = units;
  73         unsigned int prot, cur;
  74         unsigned long delta;
  75
  76         /*
  77          * If we have a "break" in the series, we need to flush the state
  78          * that we have now. "break" is either changing perms, levels or
  79          * address space marker.
  80          */
  81         prot = new_prot;
  82         cur = st->current_prot;
  83
  84         if (!st->level) {
  85                 /* First entry */
  86                 st->current_prot = new_prot;
  87                 st->level = level;
  88                 st->marker = address_markers;
  89                 seq_printf(m, "---[ %s ]---\n", st->marker->name);
  90         } else if (prot != cur || level != st->level ||
  91                    st->current_address >= st->marker[1].start_address) {
  92                 /* Print the actual finished series */
  93                 seq_printf(m, "0x%0*lx-0x%0*lx ",
  94                            width, st->start_address,
  95                            width, st->current_address);
  96                 delta = (st->current_address - st->start_address) >> 10;
  97                 while (!(delta & 0x3ff) && unit[1]) {
  98                         delta >>= 10;
  99                         unit++;
 100                 }
 101                 seq_printf(m, "%9lu%c ", delta, *unit);
 102                 print_prot(m, st->current_prot, st->level);
 103                 while (st->current_address >= st->marker[1].start_address) {
 104                         st->marker++;
 105                         seq_printf(m, "---[ %s ]---\n", st->marker->name);
 106                 }
 107                 st->start_address = st->current_address;
 108                 st->current_prot = new_prot;
 109                 st->level = level;
 110         }
 111 }
 112
 113 #ifdef CONFIG_KASAN
 114 static void note_kasan_early_shadow_page(struct seq_file *m,
 115                                                 struct pg_state *st)
 116 {
 117         unsigned int prot;
 118
 119         prot = pte_val(*kasan_early_shadow_pte) &
 120                 (_PAGE_PROTECT | _PAGE_INVALID | _PAGE_NOEXEC);
 121         note_page(m, st, prot, 4);
 122 }
 123 #endif
 124
 125 /*
 126  * The actual page table walker functions. In order to keep the
 127  * implementation of print_prot() short, we only check and pass
 128  * _PAGE_INVALID and _PAGE_PROTECT flags to note_page() if a region,
 129  * segment or page table entry is invalid or read-only.
 130  * After all it's just a hint that the current level being walked
 131  * contains an invalid or read-only entry.
 132  */
 133 static void walk_pte_level(struct seq_file *m, struct pg_state *st,
 134                            pmd_t *pmd, unsigned long addr)
 135 {
 136         unsigned int prot;
 137         pte_t *pte;
 138         int i;
 139
 140         for (i = 0; i < PTRS_PER_PTE && addr < max_addr; i++) {
 141                 st->current_address = addr;
 142                 pte = pte_offset_kernel(pmd, addr);
 143                 prot = pte_val(*pte) &
 144                         (_PAGE_PROTECT | _PAGE_INVALID | _PAGE_NOEXEC);
 145                 note_page(m, st, prot, 4);
 146                 addr += PAGE_SIZE;
 147         }
 148 }
 149
 150 static void walk_pmd_level(struct seq_file *m, struct pg_state *st,
 151                            pud_t *pud, unsigned long addr)
 152 {
 153         unsigned int prot;
 154         pmd_t *pmd;
 155         int i;
 156
 157 #ifdef CONFIG_KASAN
 158         if ((pud_val(*pud) & PAGE_MASK) == __pa(kasan_early_shadow_pmd)) {
 159                 note_kasan_early_shadow_page(m, st);
 160                 return;
 161         }
 162 #endif
 163
 164         pmd = pmd_offset(pud, addr);
 165         for (i = 0; i < PTRS_PER_PMD && addr < max_addr; i++, pmd++) {
 166                 st->current_address = addr;
 167                 if (!pmd_none(*pmd)) {
 168                         if (pmd_large(*pmd)) {
 169                                 prot = pmd_val(*pmd) &
 170                                         (_SEGMENT_ENTRY_PROTECT |
 171                                          _SEGMENT_ENTRY_NOEXEC);
 172                                 note_page(m, st, prot, 3);
 173                         } else
 174                                 walk_pte_level(m, st, pmd, addr);
 175                 } else
 176                         note_page(m, st, _PAGE_INVALID, 3);
 177                 addr += PMD_SIZE;
 178         }
 179 }
 180
 181 static void walk_pud_level(struct seq_file *m, struct pg_state *st,
 182                            p4d_t *p4d, unsigned long addr)
 183 {
 184         unsigned int prot;
 185         pud_t *pud;
 186         int i;
 187
 188 #ifdef CONFIG_KASAN
 189         if ((p4d_val(*p4d) & PAGE_MASK) == __pa(kasan_early_shadow_pud)) {
 190                 note_kasan_early_shadow_page(m, st);
 191                 return;
 192         }
 193 #endif
 194
 195         pud = pud_offset(p4d, addr);
 196         for (i = 0; i < PTRS_PER_PUD && addr < max_addr; i++, pud++) {
 197                 st->current_address = addr;
 198                 if (!pud_none(*pud))
 199                         if (pud_large(*pud)) {
 200                                 prot = pud_val(*pud) &
 201                                         (_REGION_ENTRY_PROTECT |
 202                                          _REGION_ENTRY_NOEXEC);
 203                                 note_page(m, st, prot, 2);
 204                         } else
 205                                 walk_pmd_level(m, st, pud, addr);
 206                 else
 207                         note_page(m, st, _PAGE_INVALID, 2);
 208                 addr += PUD_SIZE;
 209         }
 210 }
 211
 212 static void walk_p4d_level(struct seq_file *m, struct pg_state *st,
 213                            pgd_t *pgd, unsigned long addr)
 214 {
 215         p4d_t *p4d;
 216         int i;
 217
 218 #ifdef CONFIG_KASAN
 219         if ((pgd_val(*pgd) & PAGE_MASK) == __pa(kasan_early_shadow_p4d)) {
 220                 note_kasan_early_shadow_page(m, st);
 221                 return;
 222         }
 223 #endif
 224
 225         p4d = p4d_offset(pgd, addr);
 226         for (i = 0; i < PTRS_PER_P4D && addr < max_addr; i++, p4d++) {
 227                 st->current_address = addr;
 228                 if (!p4d_none(*p4d))
 229                         walk_pud_level(m, st, p4d, addr);
 230                 else
 231                         note_page(m, st, _PAGE_INVALID, 2);
 232                 addr += P4D_SIZE;
 233         }
 234 }
 235
 236 static void walk_pgd_level(struct seq_file *m)
 237 {
 238         unsigned long addr = 0;
 239         struct pg_state st;
 240         pgd_t *pgd;
 241         int i;
 242
 243         memset(&st, 0, sizeof(st));
 244         for (i = 0; i < PTRS_PER_PGD && addr < max_addr; i++) {
 245                 st.current_address = addr;
 246                 pgd = pgd_offset_k(addr);
 247                 if (!pgd_none(*pgd))
 248                         walk_p4d_level(m, &st, pgd, addr);
 249                 else
 250                         note_page(m, &st, _PAGE_INVALID, 1);
 251                 addr += PGDIR_SIZE;
 252                 cond_resched();
 253         }
 254         /* Flush out the last page */
 255         st.current_address = max_addr;
 256         note_page(m, &st, 0, 0);
 257 }
 258
 259 static int ptdump_show(struct seq_file *m, void *v)
 260 {
 261         walk_pgd_level(m);
 262         return 0;
 263 }
 264
 265 static int ptdump_open(struct inode *inode, struct file *filp)
 266 {
 267         return single_open(filp, ptdump_show, NULL);
 268 }
 269
 270 static const struct file_operations ptdump_fops = {
 271         .open           = ptdump_open,
 272         .read           = seq_read,
 273         .llseek         = seq_lseek,
 274         .release        = single_release,
 275 };
 276
 277 static int pt_dump_init(void)
 278 {
 279         /*
 280          * Figure out the maximum virtual address being accessible with the
 281          * kernel ASCE. We need this to keep the page table walker functions
 282          * from accessing non-existent entries.
 283          */
 284         max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2;
 285         max_addr = 1UL << (max_addr * 11 + 31);
 286         address_markers[MODULES_NR].start_address = MODULES_VADDR;
 287         address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
 288         address_markers[VMALLOC_NR].start_address = VMALLOC_START;
 289         debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
 290         return 0;
 291 }
 292 device_initcall(pt_dump_init);