arch/s390/mm/dump_pagetables.c

   1 #include <linux/seq_file.h>
   2 #include <linux/debugfs.h>
   3 #include <linux/module.h>
   4 #include <linux/mm.h>
   5 #include <asm/sections.h>
   6 #include <asm/pgtable.h>
   7
   8 static unsigned long max_addr;
   9
  10 struct addr_marker {
  11         unsigned long start_address;
  12         const char *name;
  13 };
  14
  15 enum address_markers_idx {
  16         IDENTITY_NR = 0,
  17         KERNEL_START_NR,
  18         KERNEL_END_NR,
  19         VMEMMAP_NR,
  20         VMALLOC_NR,
  21 #ifdef CONFIG_64BIT
  22         MODULES_NR,
  23 #endif
  24 };
  25
  26 static struct addr_marker address_markers[] = {
  27         [IDENTITY_NR]     = {0, "Identity Mapping"},
  28         [KERNEL_START_NR] = {(unsigned long)&_stext, "Kernel Image Start"},
  29         [KERNEL_END_NR]   = {(unsigned long)&_end, "Kernel Image End"},
  30         [VMEMMAP_NR]      = {0, "vmemmap Area"},
  31         [VMALLOC_NR]      = {0, "vmalloc Area"},
  32 #ifdef CONFIG_64BIT
  33         [MODULES_NR]      = {0, "Modules Area"},
  34 #endif
  35         { -1, NULL }
  36 };
  37
  38 struct pg_state {
  39         int level;
  40         unsigned int current_prot;
  41         unsigned long start_address;
  42         unsigned long current_address;
  43         const struct addr_marker *marker;
  44 };
  45
  46 static void print_prot(struct seq_file *m, unsigned int pr, int level)
  47 {
  48         static const char * const level_name[] =
  49                 { "ASCE", "PGD", "PUD", "PMD", "PTE" };
  50
  51         seq_printf(m, "%s ", level_name[level]);
  52         if (pr & _PAGE_INVALID) {
  53                 seq_printf(m, "I\n");
  54                 return;
  55         }
  56         seq_printf(m, "%s", pr & _PAGE_RO ? "RO " : "RW ");
  57         seq_printf(m, "%s", pr & _PAGE_CO ? "CO " : "   ");
  58         seq_putc(m, '\n');
  59 }
  60
  61 static void note_page(struct seq_file *m, struct pg_state *st,
  62                      unsigned int new_prot, int level)
  63 {
  64         static const char units[] = "KMGTPE";
  65         int width = sizeof(unsigned long) * 2;
  66         const char *unit = units;
  67         unsigned int prot, cur;
  68         unsigned long delta;
  69
  70         /*
  71          * If we have a "break" in the series, we need to flush the state
  72          * that we have now. "break" is either changing perms, levels or
  73          * address space marker.
  74          */
  75         prot = new_prot;
  76         cur = st->current_prot;
  77
  78         if (!st->level) {
  79                 /* First entry */
  80                 st->current_prot = new_prot;
  81                 st->level = level;
  82                 st->marker = address_markers;
  83                 seq_printf(m, "---[ %s ]---\n", st->marker->name);
  84         } else if (prot != cur || level != st->level ||
  85                    st->current_address >= st->marker[1].start_address) {
  86                 /* Print the actual finished series */
  87                 seq_printf(m, "0x%0*lx-0x%0*lx",
  88                            width, st->start_address,
  89                            width, st->current_address);
  90                 delta = (st->current_address - st->start_address) >> 10;
  91                 while (!(delta & 0x3ff) && unit[1]) {
  92                         delta >>= 10;
  93                         unit++;
  94                 }
  95                 seq_printf(m, "%9lu%c ", delta, *unit);
  96                 print_prot(m, st->current_prot, st->level);
  97                 if (st->current_address >= st->marker[1].start_address) {
  98                         st->marker++;
  99                         seq_printf(m, "---[ %s ]---\n", st->marker->name);
 100                 }
 101                 st->start_address = st->current_address;
 102                 st->current_prot = new_prot;
 103                 st->level = level;
 104         }
 105 }
 106
 107 /*
 108  * The actual page table walker functions. In order to keep the implementation
 109  * of print_prot() short, we only check and pass _PAGE_INVALID and _PAGE_RO
 110  * flags to note_page() if a region, segment or page table entry is invalid or
 111  * read-only.
 112  * After all it's just a hint that the current level being walked contains an
 113  * invalid or read-only entry.
 114  */
 115 static void walk_pte_level(struct seq_file *m, struct pg_state *st,
 116                            pmd_t *pmd, unsigned long addr)
 117 {
 118         unsigned int prot;
 119         pte_t *pte;
 120         int i;
 121
 122         for (i = 0; i < PTRS_PER_PTE && addr < max_addr; i++) {
 123                 st->current_address = addr;
 124                 pte = pte_offset_kernel(pmd, addr);
 125                 prot = pte_val(*pte) & (_PAGE_RO | _PAGE_INVALID);
 126                 note_page(m, st, prot, 4);
 127                 addr += PAGE_SIZE;
 128         }
 129 }
 130
 131 #ifdef CONFIG_64BIT
 132 #define _PMD_PROT_MASK (_SEGMENT_ENTRY_RO | _SEGMENT_ENTRY_CO)
 133 #else
 134 #define _PMD_PROT_MASK 0
 135 #endif
 136
 137 static void walk_pmd_level(struct seq_file *m, struct pg_state *st,
 138                            pud_t *pud, unsigned long addr)
 139 {
 140         unsigned int prot;
 141         pmd_t *pmd;
 142         int i;
 143
 144         for (i = 0; i < PTRS_PER_PMD && addr < max_addr; i++) {
 145                 st->current_address = addr;
 146                 pmd = pmd_offset(pud, addr);
 147                 if (!pmd_none(*pmd)) {
 148                         if (pmd_large(*pmd)) {
 149                                 prot = pmd_val(*pmd) & _PMD_PROT_MASK;
 150                                 note_page(m, st, prot, 3);
 151                         } else
 152                                 walk_pte_level(m, st, pmd, addr);
 153                 } else
 154                         note_page(m, st, _PAGE_INVALID, 3);
 155                 addr += PMD_SIZE;
 156         }
 157 }
 158
 159 #ifdef CONFIG_64BIT
 160 #define _PUD_PROT_MASK (_REGION3_ENTRY_RO | _REGION3_ENTRY_CO)
 161 #else
 162 #define _PUD_PROT_MASK 0
 163 #endif
 164
 165 static void walk_pud_level(struct seq_file *m, struct pg_state *st,
 166                            pgd_t *pgd, unsigned long addr)
 167 {
 168         unsigned int prot;
 169         pud_t *pud;
 170         int i;
 171
 172         for (i = 0; i < PTRS_PER_PUD && addr < max_addr; i++) {
 173                 st->current_address = addr;
 174                 pud = pud_offset(pgd, addr);
 175                 if (!pud_none(*pud))
 176                         if (pud_large(*pud)) {
 177                                 prot = pud_val(*pud) & _PUD_PROT_MASK;
 178                                 note_page(m, st, prot, 2);
 179                         } else
 180                                 walk_pmd_level(m, st, pud, addr);
 181                 else
 182                         note_page(m, st, _PAGE_INVALID, 2);
 183                 addr += PUD_SIZE;
 184         }
 185 }
 186
 187 static void walk_pgd_level(struct seq_file *m)
 188 {
 189         unsigned long addr = 0;
 190         struct pg_state st;
 191         pgd_t *pgd;
 192         int i;
 193
 194         memset(&st, 0, sizeof(st));
 195         for (i = 0; i < PTRS_PER_PGD && addr < max_addr; i++) {
 196                 st.current_address = addr;
 197                 pgd = pgd_offset_k(addr);
 198                 if (!pgd_none(*pgd))
 199                         walk_pud_level(m, &st, pgd, addr);
 200                 else
 201                         note_page(m, &st, _PAGE_INVALID, 1);
 202                 addr += PGDIR_SIZE;
 203         }
 204         /* Flush out the last page */
 205         st.current_address = max_addr;
 206         note_page(m, &st, 0, 0);
 207 }
 208
 209 static int ptdump_show(struct seq_file *m, void *v)
 210 {
 211         walk_pgd_level(m);
 212         return 0;
 213 }
 214
 215 static int ptdump_open(struct inode *inode, struct file *filp)
 216 {
 217         return single_open(filp, ptdump_show, NULL);
 218 }
 219
 220 static const struct file_operations ptdump_fops = {
 221         .open           = ptdump_open,
 222         .read           = seq_read,
 223         .llseek         = seq_lseek,
 224         .release        = single_release,
 225 };
 226
 227 static int pt_dump_init(void)
 228 {
 229         /*
 230          * Figure out the maximum virtual address being accessible with the
 231          * kernel ASCE. We need this to keep the page table walker functions
 232          * from accessing non-existent entries.
 233          */
 234 #ifdef CONFIG_32BIT
 235         max_addr = 1UL << 31;
 236 #else
 237         max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2;
 238         max_addr = 1UL << (max_addr * 11 + 31);
 239         address_markers[MODULES_NR].start_address = MODULES_VADDR;
 240 #endif
 241         address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
 242         address_markers[VMALLOC_NR].start_address = VMALLOC_START;
 243         debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
 244         return 0;
 245 }
 246 device_initcall(pt_dump_init);