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