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/abs_lowcore.h>
  12 #include <asm/nospec-branch.h>
  13 #include <asm/sections.h>
  14 #include <asm/maccess.h>
  15
  16 static unsigned long max_addr;
  17
  18 struct addr_marker {
  19         unsigned long start_address;
  20         const char *name;
  21 };
  22
  23 enum address_markers_idx {
  24         IDENTITY_BEFORE_NR = 0,
  25         IDENTITY_BEFORE_END_NR,
  26         AMODE31_START_NR,
  27         AMODE31_END_NR,
  28         KERNEL_START_NR,
  29         KERNEL_END_NR,
  30 #ifdef CONFIG_KFENCE
  31         KFENCE_START_NR,
  32         KFENCE_END_NR,
  33 #endif
  34         IDENTITY_AFTER_NR,
  35         IDENTITY_AFTER_END_NR,
  36         VMEMMAP_NR,
  37         VMEMMAP_END_NR,
  38         VMALLOC_NR,
  39         VMALLOC_END_NR,
  40         MODULES_NR,
  41         MODULES_END_NR,
  42         ABS_LOWCORE_NR,
  43         ABS_LOWCORE_END_NR,
  44         MEMCPY_REAL_NR,
  45         MEMCPY_REAL_END_NR,
  46 #ifdef CONFIG_KASAN
  47         KASAN_SHADOW_START_NR,
  48         KASAN_SHADOW_END_NR,
  49 #endif
  50 };
  51
  52 static struct addr_marker address_markers[] = {
  53         [IDENTITY_BEFORE_NR]    = {0, "Identity Mapping Start"},
  54         [IDENTITY_BEFORE_END_NR] = {(unsigned long)_stext, "Identity Mapping End"},
  55         [AMODE31_START_NR]      = {0, "Amode31 Area Start"},
  56         [AMODE31_END_NR]        = {0, "Amode31 Area End"},
  57         [KERNEL_START_NR]       = {(unsigned long)_stext, "Kernel Image Start"},
  58         [KERNEL_END_NR]         = {(unsigned long)_end, "Kernel Image End"},
  59 #ifdef CONFIG_KFENCE
  60         [KFENCE_START_NR]       = {0, "KFence Pool Start"},
  61         [KFENCE_END_NR]         = {0, "KFence Pool End"},
  62 #endif
  63         [IDENTITY_AFTER_NR]     = {(unsigned long)_end, "Identity Mapping Start"},
  64         [IDENTITY_AFTER_END_NR] = {0, "Identity Mapping End"},
  65         [VMEMMAP_NR]            = {0, "vmemmap Area Start"},
  66         [VMEMMAP_END_NR]        = {0, "vmemmap Area End"},
  67         [VMALLOC_NR]            = {0, "vmalloc Area Start"},
  68         [VMALLOC_END_NR]        = {0, "vmalloc Area End"},
  69         [MODULES_NR]            = {0, "Modules Area Start"},
  70         [MODULES_END_NR]        = {0, "Modules Area End"},
  71         [ABS_LOWCORE_NR]        = {0, "Lowcore Area Start"},
  72         [ABS_LOWCORE_END_NR]    = {0, "Lowcore Area End"},
  73         [MEMCPY_REAL_NR]        = {0, "Real Memory Copy Area Start"},
  74         [MEMCPY_REAL_END_NR]    = {0, "Real Memory Copy Area End"},
  75 #ifdef CONFIG_KASAN
  76         [KASAN_SHADOW_START_NR] = {KASAN_SHADOW_START, "Kasan Shadow Start"},
  77         [KASAN_SHADOW_END_NR]   = {KASAN_SHADOW_END, "Kasan Shadow End"},
  78 #endif
  79         { -1, NULL }
  80 };
  81
  82 struct pg_state {
  83         struct ptdump_state ptdump;
  84         struct seq_file *seq;
  85         int level;
  86         unsigned int current_prot;
  87         bool check_wx;
  88         unsigned long wx_pages;
  89         unsigned long start_address;
  90         const struct addr_marker *marker;
  91 };
  92
  93 #define pt_dump_seq_printf(m, fmt, args...)     \
  94 ({                                              \
  95         struct seq_file *__m = (m);             \
  96                                                 \
  97         if (__m)                                \
  98                 seq_printf(__m, fmt, ##args);   \
  99 })
 100
 101 #define pt_dump_seq_puts(m, fmt)                \
 102 ({                                              \
 103         struct seq_file *__m = (m);             \
 104                                                 \
 105         if (__m)                                \
 106                 seq_printf(__m, fmt);           \
 107 })
 108
 109 static void print_prot(struct seq_file *m, unsigned int pr, int level)
 110 {
 111         static const char * const level_name[] =
 112                 { "ASCE", "PGD", "PUD", "PMD", "PTE" };
 113
 114         pt_dump_seq_printf(m, "%s ", level_name[level]);
 115         if (pr & _PAGE_INVALID) {
 116                 pt_dump_seq_printf(m, "I\n");
 117                 return;
 118         }
 119         pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW ");
 120         pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
 121 }
 122
 123 static void note_prot_wx(struct pg_state *st, unsigned long addr)
 124 {
 125 #ifdef CONFIG_DEBUG_WX
 126         if (!st->check_wx)
 127                 return;
 128         if (st->current_prot & _PAGE_INVALID)
 129                 return;
 130         if (st->current_prot & _PAGE_PROTECT)
 131                 return;
 132         if (st->current_prot & _PAGE_NOEXEC)
 133                 return;
 134         /*
 135          * The first lowcore page is W+X if spectre mitigations are using
 136          * trampolines or the BEAR enhancements facility is not installed,
 137          * in which case we have two lpswe instructions in lowcore that need
 138          * to be executable.
 139          */
 140         if (addr == PAGE_SIZE && (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)))
 141                 return;
 142         WARN_ONCE(1, "s390/mm: Found insecure W+X mapping at address %pS\n",
 143                   (void *)st->start_address);
 144         st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
 145 #endif /* CONFIG_DEBUG_WX */
 146 }
 147
 148 static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val)
 149 {
 150         int width = sizeof(unsigned long) * 2;
 151         static const char units[] = "KMGTPE";
 152         const char *unit = units;
 153         unsigned long delta;
 154         struct pg_state *st;
 155         struct seq_file *m;
 156         unsigned int prot;
 157
 158         st = container_of(pt_st, struct pg_state, ptdump);
 159         m = st->seq;
 160         prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC);
 161         if (level == 4 && (val & _PAGE_INVALID))
 162                 prot = _PAGE_INVALID;
 163         /* For pmd_none() & friends val gets passed as zero. */
 164         if (level != 4 && !val)
 165                 prot = _PAGE_INVALID;
 166         /* Final flush from generic code. */
 167         if (level == -1)
 168                 addr = max_addr;
 169         if (st->level == -1) {
 170                 pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
 171                 st->start_address = addr;
 172                 st->current_prot = prot;
 173                 st->level = level;
 174         } else if (prot != st->current_prot || level != st->level ||
 175                    addr >= st->marker[1].start_address) {
 176                 note_prot_wx(st, addr);
 177                 pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ",
 178                                    width, st->start_address,
 179                                    width, addr);
 180                 delta = (addr - st->start_address) >> 10;
 181                 while (!(delta & 0x3ff) && unit[1]) {
 182                         delta >>= 10;
 183                         unit++;
 184                 }
 185                 pt_dump_seq_printf(m, "%9lu%c ", delta, *unit);
 186                 print_prot(m, st->current_prot, st->level);
 187                 while (addr >= st->marker[1].start_address) {
 188                         st->marker++;
 189                         pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
 190                 }
 191                 st->start_address = addr;
 192                 st->current_prot = prot;
 193                 st->level = level;
 194         }
 195 }
 196
 197 #ifdef CONFIG_DEBUG_WX
 198 void ptdump_check_wx(void)
 199 {
 200         struct pg_state st = {
 201                 .ptdump = {
 202                         .note_page = note_page,
 203                         .range = (struct ptdump_range[]) {
 204                                 {.start = 0, .end = max_addr},
 205                                 {.start = 0, .end = 0},
 206                         }
 207                 },
 208                 .seq = NULL,
 209                 .level = -1,
 210                 .current_prot = 0,
 211                 .check_wx = true,
 212                 .wx_pages = 0,
 213                 .start_address = 0,
 214                 .marker = (struct addr_marker[]) {
 215                         { .start_address =  0, .name = NULL},
 216                         { .start_address = -1, .name = NULL},
 217                 },
 218         };
 219
 220         if (!MACHINE_HAS_NX)
 221                 return;
 222         ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
 223         if (st.wx_pages)
 224                 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages);
 225         else
 226                 pr_info("Checked W+X mappings: passed, no %sW+X pages found\n",
 227                         (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)) ?
 228                         "unexpected " : "");
 229 }
 230 #endif /* CONFIG_DEBUG_WX */
 231
 232 #ifdef CONFIG_PTDUMP_DEBUGFS
 233 static int ptdump_show(struct seq_file *m, void *v)
 234 {
 235         struct pg_state st = {
 236                 .ptdump = {
 237                         .note_page = note_page,
 238                         .range = (struct ptdump_range[]) {
 239                                 {.start = 0, .end = max_addr},
 240                                 {.start = 0, .end = 0},
 241                         }
 242                 },
 243                 .seq = m,
 244                 .level = -1,
 245                 .current_prot = 0,
 246                 .check_wx = false,
 247                 .wx_pages = 0,
 248                 .start_address = 0,
 249                 .marker = address_markers,
 250         };
 251
 252         get_online_mems();
 253         mutex_lock(&cpa_mutex);
 254         ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
 255         mutex_unlock(&cpa_mutex);
 256         put_online_mems();
 257         return 0;
 258 }
 259 DEFINE_SHOW_ATTRIBUTE(ptdump);
 260 #endif /* CONFIG_PTDUMP_DEBUGFS */
 261
 262 /*
 263  * Heapsort from lib/sort.c is not a stable sorting algorithm, do a simple
 264  * insertion sort to preserve the original order of markers with the same
 265  * start address.
 266  */
 267 static void sort_address_markers(void)
 268 {
 269         struct addr_marker tmp;
 270         int i, j;
 271
 272         for (i = 1; i < ARRAY_SIZE(address_markers) - 1; i++) {
 273                 tmp = address_markers[i];
 274                 for (j = i - 1; j >= 0 && address_markers[j].start_address > tmp.start_address; j--)
 275                         address_markers[j + 1] = address_markers[j];
 276                 address_markers[j + 1] = tmp;
 277         }
 278 }
 279
 280 static int pt_dump_init(void)
 281 {
 282 #ifdef CONFIG_KFENCE
 283         unsigned long kfence_start = (unsigned long)__kfence_pool;
 284 #endif
 285         /*
 286          * Figure out the maximum virtual address being accessible with the
 287          * kernel ASCE. We need this to keep the page table walker functions
 288          * from accessing non-existent entries.
 289          */
 290         max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2;
 291         max_addr = 1UL << (max_addr * 11 + 31);
 292         address_markers[IDENTITY_AFTER_END_NR].start_address = ident_map_size;
 293         address_markers[AMODE31_START_NR].start_address = __samode31;
 294         address_markers[AMODE31_END_NR].start_address = __eamode31;
 295         address_markers[MODULES_NR].start_address = MODULES_VADDR;
 296         address_markers[MODULES_END_NR].start_address = MODULES_END;
 297         address_markers[ABS_LOWCORE_NR].start_address = __abs_lowcore;
 298         address_markers[ABS_LOWCORE_END_NR].start_address = __abs_lowcore + ABS_LOWCORE_MAP_SIZE;
 299         address_markers[MEMCPY_REAL_NR].start_address = __memcpy_real_area;
 300         address_markers[MEMCPY_REAL_END_NR].start_address = __memcpy_real_area + MEMCPY_REAL_SIZE;
 301         address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
 302         address_markers[VMEMMAP_END_NR].start_address = (unsigned long)vmemmap + vmemmap_size;
 303         address_markers[VMALLOC_NR].start_address = VMALLOC_START;
 304         address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
 305 #ifdef CONFIG_KFENCE
 306         address_markers[KFENCE_START_NR].start_address = kfence_start;
 307         address_markers[KFENCE_END_NR].start_address = kfence_start + KFENCE_POOL_SIZE;
 308 #endif
 309         sort_address_markers();
 310 #ifdef CONFIG_PTDUMP_DEBUGFS
 311         debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
 312 #endif /* CONFIG_PTDUMP_DEBUGFS */
 313         return 0;
 314 }
 315 device_initcall(pt_dump_init);