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