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/kfence.h>
   8 #include <linux/kasan.h>
   9 #include <asm/ptdump.h>
  10 #include <asm/kasan.h>
  11 #include <asm/sections.h>
  12
  13 static unsigned long max_addr;
  14
  15 struct addr_marker {
  16         unsigned long start_address;
  17         const char *name;
  18 };
  19
  20 enum address_markers_idx {
  21         IDENTITY_BEFORE_NR = 0,
  22         IDENTITY_BEFORE_END_NR,
  23         KERNEL_START_NR,
  24         KERNEL_END_NR,
  25 #ifdef CONFIG_KFENCE
  26         KFENCE_START_NR,
  27         KFENCE_END_NR,
  28 #endif
  29         IDENTITY_AFTER_NR,
  30         IDENTITY_AFTER_END_NR,
  31 #ifdef CONFIG_KASAN
  32         KASAN_SHADOW_START_NR,
  33         KASAN_SHADOW_END_NR,
  34 #endif
  35         VMEMMAP_NR,
  36         VMEMMAP_END_NR,
  37         VMALLOC_NR,
  38         VMALLOC_END_NR,
  39         MODULES_NR,
  40         MODULES_END_NR,
  41 };
  42
  43 static struct addr_marker address_markers[] = {
  44         [IDENTITY_BEFORE_NR]    = {0, "Identity Mapping Start"},
  45         [IDENTITY_BEFORE_END_NR] = {(unsigned long)_stext, "Identity Mapping End"},
  46         [KERNEL_START_NR]       = {(unsigned long)_stext, "Kernel Image Start"},
  47         [KERNEL_END_NR]         = {(unsigned long)_end, "Kernel Image End"},
  48 #ifdef CONFIG_KFENCE
  49         [KFENCE_START_NR]       = {0, "KFence Pool Start"},
  50         [KFENCE_END_NR]         = {0, "KFence Pool End"},
  51 #endif
  52         [IDENTITY_AFTER_NR]     = {(unsigned long)_end, "Identity Mapping Start"},
  53         [IDENTITY_AFTER_END_NR] = {0, "Identity Mapping End"},
  54 #ifdef CONFIG_KASAN
  55         [KASAN_SHADOW_START_NR] = {KASAN_SHADOW_START, "Kasan Shadow Start"},
  56         [KASAN_SHADOW_END_NR]   = {KASAN_SHADOW_END, "Kasan Shadow End"},
  57 #endif
  58         [VMEMMAP_NR]            = {0, "vmemmap Area Start"},
  59         [VMEMMAP_END_NR]        = {0, "vmemmap Area End"},
  60         [VMALLOC_NR]            = {0, "vmalloc Area Start"},
  61         [VMALLOC_END_NR]        = {0, "vmalloc Area End"},
  62         [MODULES_NR]            = {0, "Modules Area Start"},
  63         [MODULES_END_NR]        = {0, "Modules Area End"},
  64         { -1, NULL }
  65 };
  66
  67 struct pg_state {
  68         struct ptdump_state ptdump;
  69         struct seq_file *seq;
  70         int level;
  71         unsigned int current_prot;
  72         bool check_wx;
  73         unsigned long wx_pages;
  74         unsigned long start_address;
  75         const struct addr_marker *marker;
  76 };
  77
  78 #define pt_dump_seq_printf(m, fmt, args...)     \
  79 ({                                              \
  80         struct seq_file *__m = (m);             \
  81                                                 \
  82         if (__m)                                \
  83                 seq_printf(__m, fmt, ##args);   \
  84 })
  85
  86 #define pt_dump_seq_puts(m, fmt)                \
  87 ({                                              \
  88         struct seq_file *__m = (m);             \
  89                                                 \
  90         if (__m)                                \
  91                 seq_printf(__m, fmt);           \
  92 })
  93
  94 static void print_prot(struct seq_file *m, unsigned int pr, int level)
  95 {
  96         static const char * const level_name[] =
  97                 { "ASCE", "PGD", "PUD", "PMD", "PTE" };
  98
  99         pt_dump_seq_printf(m, "%s ", level_name[level]);
 100         if (pr & _PAGE_INVALID) {
 101                 pt_dump_seq_printf(m, "I\n");
 102                 return;
 103         }
 104         pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW ");
 105         pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
 106 }
 107
 108 static void note_prot_wx(struct pg_state *st, unsigned long addr)
 109 {
 110 #ifdef CONFIG_DEBUG_WX
 111         if (!st->check_wx)
 112                 return;
 113         if (st->current_prot & _PAGE_INVALID)
 114                 return;
 115         if (st->current_prot & _PAGE_PROTECT)
 116                 return;
 117         if (st->current_prot & _PAGE_NOEXEC)
 118                 return;
 119         /* The first lowcore page is currently still W+X. */
 120         if (addr == PAGE_SIZE)
 121                 return;
 122         WARN_ONCE(1, "s390/mm: Found insecure W+X mapping at address %pS\n",
 123                   (void *)st->start_address);
 124         st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
 125 #endif /* CONFIG_DEBUG_WX */
 126 }
 127
 128 static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val)
 129 {
 130         int width = sizeof(unsigned long) * 2;
 131         static const char units[] = "KMGTPE";
 132         const char *unit = units;
 133         unsigned long delta;
 134         struct pg_state *st;
 135         struct seq_file *m;
 136         unsigned int prot;
 137
 138         st = container_of(pt_st, struct pg_state, ptdump);
 139         m = st->seq;
 140         prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC);
 141         if (level == 4 && (val & _PAGE_INVALID))
 142                 prot = _PAGE_INVALID;
 143         /* For pmd_none() & friends val gets passed as zero. */
 144         if (level != 4 && !val)
 145                 prot = _PAGE_INVALID;
 146         /* Final flush from generic code. */
 147         if (level == -1)
 148                 addr = max_addr;
 149         if (st->level == -1) {
 150                 pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
 151                 st->start_address = addr;
 152                 st->current_prot = prot;
 153                 st->level = level;
 154         } else if (prot != st->current_prot || level != st->level ||
 155                    addr >= st->marker[1].start_address) {
 156                 note_prot_wx(st, addr);
 157                 pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ",
 158                                    width, st->start_address,
 159                                    width, addr);
 160                 delta = (addr - st->start_address) >> 10;
 161                 while (!(delta & 0x3ff) && unit[1]) {
 162                         delta >>= 10;
 163                         unit++;
 164                 }
 165                 pt_dump_seq_printf(m, "%9lu%c ", delta, *unit);
 166                 print_prot(m, st->current_prot, st->level);
 167                 while (addr >= st->marker[1].start_address) {
 168                         st->marker++;
 169                         pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
 170                 }
 171                 st->start_address = addr;
 172                 st->current_prot = prot;
 173                 st->level = level;
 174         }
 175 }
 176
 177 #ifdef CONFIG_DEBUG_WX
 178 void ptdump_check_wx(void)
 179 {
 180         struct pg_state st = {
 181                 .ptdump = {
 182                         .note_page = note_page,
 183                         .range = (struct ptdump_range[]) {
 184                                 {.start = 0, .end = max_addr},
 185                                 {.start = 0, .end = 0},
 186                         }
 187                 },
 188                 .seq = NULL,
 189                 .level = -1,
 190                 .current_prot = 0,
 191                 .check_wx = true,
 192                 .wx_pages = 0,
 193                 .start_address = 0,
 194                 .marker = (struct addr_marker[]) {
 195                         { .start_address =  0, .name = NULL},
 196                         { .start_address = -1, .name = NULL},
 197                 },
 198         };
 199
 200         if (!MACHINE_HAS_NX)
 201                 return;
 202         ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
 203         if (st.wx_pages)
 204                 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages);
 205         else
 206                 pr_info("Checked W+X mappings: passed, no unexpected W+X pages found\n");
 207 }
 208 #endif /* CONFIG_DEBUG_WX */
 209
 210 #ifdef CONFIG_PTDUMP_DEBUGFS
 211 static int ptdump_show(struct seq_file *m, void *v)
 212 {
 213         struct pg_state st = {
 214                 .ptdump = {
 215                         .note_page = note_page,
 216                         .range = (struct ptdump_range[]) {
 217                                 {.start = 0, .end = max_addr},
 218                                 {.start = 0, .end = 0},
 219                         }
 220                 },
 221                 .seq = m,
 222                 .level = -1,
 223                 .current_prot = 0,
 224                 .check_wx = false,
 225                 .wx_pages = 0,
 226                 .start_address = 0,
 227                 .marker = address_markers,
 228         };
 229
 230         get_online_mems();
 231         mutex_lock(&cpa_mutex);
 232         ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
 233         mutex_unlock(&cpa_mutex);
 234         put_online_mems();
 235         return 0;
 236 }
 237 DEFINE_SHOW_ATTRIBUTE(ptdump);
 238 #endif /* CONFIG_PTDUMP_DEBUGFS */
 239
 240 /*
 241  * Heapsort from lib/sort.c is not a stable sorting algorithm, do a simple
 242  * insertion sort to preserve the original order of markers with the same
 243  * start address.
 244  */
 245 static void sort_address_markers(void)
 246 {
 247         struct addr_marker tmp;
 248         int i, j;
 249
 250         for (i = 1; i < ARRAY_SIZE(address_markers) - 1; i++) {
 251                 tmp = address_markers[i];
 252                 for (j = i - 1; j >= 0 && address_markers[j].start_address > tmp.start_address; j--)
 253                         address_markers[j + 1] = address_markers[j];
 254                 address_markers[j + 1] = tmp;
 255         }
 256 }
 257
 258 static int pt_dump_init(void)
 259 {
 260 #ifdef CONFIG_KFENCE
 261         unsigned long kfence_start = (unsigned long)__kfence_pool;
 262 #endif
 263         /*
 264          * Figure out the maximum virtual address being accessible with the
 265          * kernel ASCE. We need this to keep the page table walker functions
 266          * from accessing non-existent entries.
 267          */
 268         max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2;
 269         max_addr = 1UL << (max_addr * 11 + 31);
 270         address_markers[IDENTITY_AFTER_END_NR].start_address = ident_map_size;
 271         address_markers[MODULES_NR].start_address = MODULES_VADDR;
 272         address_markers[MODULES_END_NR].start_address = MODULES_END;
 273         address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
 274         address_markers[VMEMMAP_END_NR].start_address = (unsigned long)vmemmap + vmemmap_size;
 275         address_markers[VMALLOC_NR].start_address = VMALLOC_START;
 276         address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
 277 #ifdef CONFIG_KFENCE
 278         address_markers[KFENCE_START_NR].start_address = kfence_start;
 279         address_markers[KFENCE_END_NR].start_address = kfence_start + KFENCE_POOL_SIZE;
 280 #endif
 281         sort_address_markers();
 282 #ifdef CONFIG_PTDUMP_DEBUGFS
 283         debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
 284 #endif /* CONFIG_PTDUMP_DEBUGFS */
 285         return 0;
 286 }
 287 device_initcall(pt_dump_init);