arch/s390/mm/dump_pagetables.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/set_memory.h>
   3 #include <linux/ptdump.h>
   4 #include <linux/seq_file.h>
   5 #include <linux/debugfs.h>
   6 #include <linux/mm.h>
   7 #include <linux/kasan.h>
   8 #include <asm/ptdump.h>
   9 #include <asm/kasan.h>
  10 #include <asm/sections.h>
  11
  12 static unsigned long max_addr;
  13
  14 struct addr_marker {
  15         unsigned long start_address;
  16         const char *name;
  17 };
  18
  19 enum address_markers_idx {
  20         IDENTITY_BEFORE_NR = 0,
  21         IDENTITY_BEFORE_END_NR,
  22         KERNEL_START_NR,
  23         KERNEL_END_NR,
  24         IDENTITY_AFTER_NR,
  25         IDENTITY_AFTER_END_NR,
  26 #ifdef CONFIG_KASAN
  27         KASAN_SHADOW_START_NR,
  28         KASAN_SHADOW_END_NR,
  29 #endif
  30         VMEMMAP_NR,
  31         VMEMMAP_END_NR,
  32         VMALLOC_NR,
  33         VMALLOC_END_NR,
  34         MODULES_NR,
  35         MODULES_END_NR,
  36 };
  37
  38 static struct addr_marker address_markers[] = {
  39         [IDENTITY_BEFORE_NR]    = {0, "Identity Mapping Start"},
  40         [IDENTITY_BEFORE_END_NR] = {(unsigned long)_stext, "Identity Mapping End"},
  41         [KERNEL_START_NR]       = {(unsigned long)_stext, "Kernel Image Start"},
  42         [KERNEL_END_NR]         = {(unsigned long)_end, "Kernel Image End"},
  43         [IDENTITY_AFTER_NR]     = {(unsigned long)_end, "Identity Mapping Start"},
  44         [IDENTITY_AFTER_END_NR] = {0, "Identity Mapping End"},
  45 #ifdef CONFIG_KASAN
  46         [KASAN_SHADOW_START_NR] = {KASAN_SHADOW_START, "Kasan Shadow Start"},
  47         [KASAN_SHADOW_END_NR]   = {KASAN_SHADOW_END, "Kasan Shadow End"},
  48 #endif
  49         [VMEMMAP_NR]            = {0, "vmemmap Area Start"},
  50         [VMEMMAP_END_NR]        = {0, "vmemmap Area End"},
  51         [VMALLOC_NR]            = {0, "vmalloc Area Start"},
  52         [VMALLOC_END_NR]        = {0, "vmalloc Area End"},
  53         [MODULES_NR]            = {0, "Modules Area Start"},
  54         [MODULES_END_NR]        = {0, "Modules Area End"},
  55         { -1, NULL }
  56 };
  57
  58 struct pg_state {
  59         struct ptdump_state ptdump;
  60         struct seq_file *seq;
  61         int level;
  62         unsigned int current_prot;
  63         bool check_wx;
  64         unsigned long wx_pages;
  65         unsigned long start_address;
  66         const struct addr_marker *marker;
  67 };
  68
  69 #define pt_dump_seq_printf(m, fmt, args...)     \
  70 ({                                              \
  71         struct seq_file *__m = (m);             \
  72                                                 \
  73         if (__m)                                \
  74                 seq_printf(__m, fmt, ##args);   \
  75 })
  76
  77 #define pt_dump_seq_puts(m, fmt)                \
  78 ({                                              \
  79         struct seq_file *__m = (m);             \
  80                                                 \
  81         if (__m)                                \
  82                 seq_printf(__m, fmt);           \
  83 })
  84
  85 static void print_prot(struct seq_file *m, unsigned int pr, int level)
  86 {
  87         static const char * const level_name[] =
  88                 { "ASCE", "PGD", "PUD", "PMD", "PTE" };
  89
  90         pt_dump_seq_printf(m, "%s ", level_name[level]);
  91         if (pr & _PAGE_INVALID) {
  92                 pt_dump_seq_printf(m, "I\n");
  93                 return;
  94         }
  95         pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW ");
  96         pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
  97 }
  98
  99 static void note_prot_wx(struct pg_state *st, unsigned long addr)
 100 {
 101 #ifdef CONFIG_DEBUG_WX
 102         if (!st->check_wx)
 103                 return;
 104         if (st->current_prot & _PAGE_INVALID)
 105                 return;
 106         if (st->current_prot & _PAGE_PROTECT)
 107                 return;
 108         if (st->current_prot & _PAGE_NOEXEC)
 109                 return;
 110         /* The first lowcore page is currently still W+X. */
 111         if (addr == PAGE_SIZE)
 112                 return;
 113         WARN_ONCE(1, "s390/mm: Found insecure W+X mapping at address %pS\n",
 114                   (void *)st->start_address);
 115         st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
 116 #endif /* CONFIG_DEBUG_WX */
 117 }
 118
 119 static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val)
 120 {
 121         int width = sizeof(unsigned long) * 2;
 122         static const char units[] = "KMGTPE";
 123         const char *unit = units;
 124         unsigned long delta;
 125         struct pg_state *st;
 126         struct seq_file *m;
 127         unsigned int prot;
 128
 129         st = container_of(pt_st, struct pg_state, ptdump);
 130         m = st->seq;
 131         prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC);
 132         if (level == 4 && (val & _PAGE_INVALID))
 133                 prot = _PAGE_INVALID;
 134         /* For pmd_none() & friends val gets passed as zero. */
 135         if (level != 4 && !val)
 136                 prot = _PAGE_INVALID;
 137         /* Final flush from generic code. */
 138         if (level == -1)
 139                 addr = max_addr;
 140         if (st->level == -1) {
 141                 pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
 142                 st->start_address = addr;
 143                 st->current_prot = prot;
 144                 st->level = level;
 145         } else if (prot != st->current_prot || level != st->level ||
 146                    addr >= st->marker[1].start_address) {
 147                 note_prot_wx(st, addr);
 148                 pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ",
 149                                    width, st->start_address,
 150                                    width, addr);
 151                 delta = (addr - st->start_address) >> 10;
 152                 while (!(delta & 0x3ff) && unit[1]) {
 153                         delta >>= 10;
 154                         unit++;
 155                 }
 156                 pt_dump_seq_printf(m, "%9lu%c ", delta, *unit);
 157                 print_prot(m, st->current_prot, st->level);
 158                 while (addr >= st->marker[1].start_address) {
 159                         st->marker++;
 160                         pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
 161                 }
 162                 st->start_address = addr;
 163                 st->current_prot = prot;
 164                 st->level = level;
 165         }
 166 }
 167
 168 #ifdef CONFIG_DEBUG_WX
 169 void ptdump_check_wx(void)
 170 {
 171         struct pg_state st = {
 172                 .ptdump = {
 173                         .note_page = note_page,
 174                         .range = (struct ptdump_range[]) {
 175                                 {.start = 0, .end = max_addr},
 176                                 {.start = 0, .end = 0},
 177                         }
 178                 },
 179                 .seq = NULL,
 180                 .level = -1,
 181                 .current_prot = 0,
 182                 .check_wx = true,
 183                 .wx_pages = 0,
 184                 .start_address = 0,
 185                 .marker = (struct addr_marker[]) {
 186                         { .start_address =  0, .name = NULL},
 187                         { .start_address = -1, .name = NULL},
 188                 },
 189         };
 190
 191         if (!MACHINE_HAS_NX)
 192                 return;
 193         ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
 194         if (st.wx_pages)
 195                 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages);
 196         else
 197                 pr_info("Checked W+X mappings: passed, no unexpected W+X pages found\n");
 198 }
 199 #endif /* CONFIG_DEBUG_WX */
 200
 201 #ifdef CONFIG_PTDUMP_DEBUGFS
 202 static int ptdump_show(struct seq_file *m, void *v)
 203 {
 204         struct pg_state st = {
 205                 .ptdump = {
 206                         .note_page = note_page,
 207                         .range = (struct ptdump_range[]) {
 208                                 {.start = 0, .end = max_addr},
 209                                 {.start = 0, .end = 0},
 210                         }
 211                 },
 212                 .seq = m,
 213                 .level = -1,
 214                 .current_prot = 0,
 215                 .check_wx = false,
 216                 .wx_pages = 0,
 217                 .start_address = 0,
 218                 .marker = address_markers,
 219         };
 220
 221         get_online_mems();
 222         mutex_lock(&cpa_mutex);
 223         ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
 224         mutex_unlock(&cpa_mutex);
 225         put_online_mems();
 226         return 0;
 227 }
 228 DEFINE_SHOW_ATTRIBUTE(ptdump);
 229 #endif /* CONFIG_PTDUMP_DEBUGFS */
 230
 231 /*
 232  * Heapsort from lib/sort.c is not a stable sorting algorithm, do a simple
 233  * insertion sort to preserve the original order of markers with the same
 234  * start address.
 235  */
 236 static void sort_address_markers(void)
 237 {
 238         struct addr_marker tmp;
 239         int i, j;
 240
 241         for (i = 1; i < ARRAY_SIZE(address_markers) - 1; i++) {
 242                 tmp = address_markers[i];
 243                 for (j = i - 1; j >= 0 && address_markers[j].start_address > tmp.start_address; j--)
 244                         address_markers[j + 1] = address_markers[j];
 245                 address_markers[j + 1] = tmp;
 246         }
 247 }
 248
 249 static int pt_dump_init(void)
 250 {
 251         /*
 252          * Figure out the maximum virtual address being accessible with the
 253          * kernel ASCE. We need this to keep the page table walker functions
 254          * from accessing non-existent entries.
 255          */
 256         max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2;
 257         max_addr = 1UL << (max_addr * 11 + 31);
 258         address_markers[IDENTITY_AFTER_END_NR].start_address = ident_map_size;
 259         address_markers[MODULES_NR].start_address = MODULES_VADDR;
 260         address_markers[MODULES_END_NR].start_address = MODULES_END;
 261         address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
 262         address_markers[VMEMMAP_END_NR].start_address = (unsigned long)vmemmap + vmemmap_size;
 263         address_markers[VMALLOC_NR].start_address = VMALLOC_START;
 264         address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
 265         sort_address_markers();
 266 #ifdef CONFIG_PTDUMP_DEBUGFS
 267         debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
 268 #endif /* CONFIG_PTDUMP_DEBUGFS */
 269         return 0;
 270 }
 271 device_initcall(pt_dump_init);