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         else
  55                 seq_printf(m, "%s\n", pr & _PAGE_RO ? "RO" : "RW");
  56 }
  57
  58 static void note_page(struct seq_file *m, struct pg_state *st,
  59                      unsigned int new_prot, int level)
  60 {
  61         static const char units[] = "KMGTPE";
  62         int width = sizeof(unsigned long) * 2;
  63         const char *unit = units;
  64         unsigned int prot, cur;
  65         unsigned long delta;
  66
  67         /*
  68          * If we have a "break" in the series, we need to flush the state
  69          * that we have now. "break" is either changing perms, levels or
  70          * address space marker.
  71          */
  72         prot = new_prot;
  73         cur = st->current_prot;
  74
  75         if (!st->level) {
  76                 /* First entry */
  77                 st->current_prot = new_prot;
  78                 st->level = level;
  79                 st->marker = address_markers;
  80                 seq_printf(m, "---[ %s ]---\n", st->marker->name);
  81         } else if (prot != cur || level != st->level ||
  82                    st->current_address >= st->marker[1].start_address) {
  83                 /* Print the actual finished series */
  84                 seq_printf(m, "0x%0*lx-0x%0*lx",
  85                            width, st->start_address,
  86                            width, st->current_address);
  87                 delta = (st->current_address - st->start_address) >> 10;
  88                 while (!(delta & 0x3ff) && unit[1]) {
  89                         delta >>= 10;
  90                         unit++;
  91                 }
  92                 seq_printf(m, "%9lu%c ", delta, *unit);
  93                 print_prot(m, st->current_prot, st->level);
  94                 if (st->current_address >= st->marker[1].start_address) {
  95                         st->marker++;
  96                         seq_printf(m, "---[ %s ]---\n", st->marker->name);
  97                 }
  98                 st->start_address = st->current_address;
  99                 st->current_prot = new_prot;
 100                 st->level = level;
 101         }
 102 }
 103
 104 /*
 105  * The actual page table walker functions. In order to keep the implementation
 106  * of print_prot() short, we only check and pass _PAGE_INVALID and _PAGE_RO
 107  * flags to note_page() if a region, segment or page table entry is invalid or
 108  * read-only.
 109  * After all it's just a hint that the current level being walked contains an
 110  * invalid or read-only entry.
 111  */
 112 static void walk_pte_level(struct seq_file *m, struct pg_state *st,
 113                            pmd_t *pmd, unsigned long addr)
 114 {
 115         unsigned int prot;
 116         pte_t *pte;
 117         int i;
 118
 119         for (i = 0; i < PTRS_PER_PTE && addr < max_addr; i++) {
 120                 st->current_address = addr;
 121                 pte = pte_offset_kernel(pmd, addr);
 122                 prot = pte_val(*pte) & (_PAGE_RO | _PAGE_INVALID);
 123                 note_page(m, st, prot, 4);
 124                 addr += PAGE_SIZE;
 125         }
 126 }
 127
 128 static void walk_pmd_level(struct seq_file *m, struct pg_state *st,
 129                            pud_t *pud, unsigned long addr)
 130 {
 131         unsigned int prot;
 132         pmd_t *pmd;
 133         int i;
 134
 135         for (i = 0; i < PTRS_PER_PMD && addr < max_addr; i++) {
 136                 st->current_address = addr;
 137                 pmd = pmd_offset(pud, addr);
 138                 if (!pmd_none(*pmd)) {
 139                         if (pmd_large(*pmd)) {
 140                                 prot = pmd_val(*pmd) & _SEGMENT_ENTRY_RO;
 141                                 note_page(m, st, prot, 3);
 142                         } else
 143                                 walk_pte_level(m, st, pmd, addr);
 144                 } else
 145                         note_page(m, st, _PAGE_INVALID, 3);
 146                 addr += PMD_SIZE;
 147         }
 148 }
 149
 150 static void walk_pud_level(struct seq_file *m, struct pg_state *st,
 151                            pgd_t *pgd, unsigned long addr)
 152 {
 153         pud_t *pud;
 154         int i;
 155
 156         for (i = 0; i < PTRS_PER_PUD && addr < max_addr; i++) {
 157                 st->current_address = addr;
 158                 pud = pud_offset(pgd, addr);
 159                 if (!pud_none(*pud))
 160                         walk_pmd_level(m, st, pud, addr);
 161                 else
 162                         note_page(m, st, _PAGE_INVALID, 2);
 163                 addr += PUD_SIZE;
 164         }
 165 }
 166
 167 static void walk_pgd_level(struct seq_file *m)
 168 {
 169         unsigned long addr = 0;
 170         struct pg_state st;
 171         pgd_t *pgd;
 172         int i;
 173
 174         memset(&st, 0, sizeof(st));
 175         for (i = 0; i < PTRS_PER_PGD && addr < max_addr; i++) {
 176                 st.current_address = addr;
 177                 pgd = pgd_offset_k(addr);
 178                 if (!pgd_none(*pgd))
 179                         walk_pud_level(m, &st, pgd, addr);
 180                 else
 181                         note_page(m, &st, _PAGE_INVALID, 1);
 182                 addr += PGDIR_SIZE;
 183         }
 184         /* Flush out the last page */
 185         st.current_address = max_addr;
 186         note_page(m, &st, 0, 0);
 187 }
 188
 189 static int ptdump_show(struct seq_file *m, void *v)
 190 {
 191         walk_pgd_level(m);
 192         return 0;
 193 }
 194
 195 static int ptdump_open(struct inode *inode, struct file *filp)
 196 {
 197         return single_open(filp, ptdump_show, NULL);
 198 }
 199
 200 static const struct file_operations ptdump_fops = {
 201         .open           = ptdump_open,
 202         .read           = seq_read,
 203         .llseek         = seq_lseek,
 204         .release        = single_release,
 205 };
 206
 207 static int pt_dump_init(void)
 208 {
 209         /*
 210          * Figure out the maximum virtual address being accessible with the
 211          * kernel ASCE. We need this to keep the page table walker functions
 212          * from accessing non-existent entries.
 213          */
 214 #ifdef CONFIG_32BIT
 215         max_addr = 1UL << 31;
 216 #else
 217         max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2;
 218         max_addr = 1UL << (max_addr * 11 + 31);
 219         address_markers[MODULES_NR].start_address = MODULES_VADDR;
 220 #endif
 221         address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
 222         address_markers[VMALLOC_NR].start_address = VMALLOC_START;
 223         debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
 224         return 0;
 225 }
 226 device_initcall(pt_dump_init);