tools/perf/tests/vmlinux-kallsyms.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/compiler.h>
   3 #include <linux/rbtree.h>
   4 #include <inttypes.h>
   5 #include <string.h>
   6 #include <ctype.h>
   7 #include <stdlib.h>
   8 #include "dso.h"
   9 #include "map.h"
  10 #include "symbol.h"
  11 #include <internal/lib.h> // page_size
  12 #include "tests.h"
  13 #include "debug.h"
  14 #include "machine.h"
  15
  16 #define UM(x) map__unmap_ip(kallsyms_map, (x))
  17
  18 static bool is_ignored_symbol(const char *name, char type)
  19 {
  20         /* Symbol names that exactly match to the following are ignored.*/
  21         static const char * const ignored_symbols[] = {
  22                 /*
  23                  * Symbols which vary between passes. Passes 1 and 2 must have
  24                  * identical symbol lists. The kallsyms_* symbols below are
  25                  * only added after pass 1, they would be included in pass 2
  26                  * when --all-symbols is specified so exclude them to get a
  27                  * stable symbol list.
  28                  */
  29                 "kallsyms_offsets",
  30                 "kallsyms_relative_base",
  31                 "kallsyms_num_syms",
  32                 "kallsyms_names",
  33                 "kallsyms_markers",
  34                 "kallsyms_token_table",
  35                 "kallsyms_token_index",
  36                 /* Exclude linker generated symbols which vary between passes */
  37                 "_SDA_BASE_",           /* ppc */
  38                 "_SDA2_BASE_",          /* ppc */
  39                 NULL
  40         };
  41
  42         /* Symbol names that begin with the following are ignored.*/
  43         static const char * const ignored_prefixes[] = {
  44                 "$",                    /* local symbols for ARM, MIPS, etc. */
  45                 ".L",                   /* local labels, .LBB,.Ltmpxxx,.L__unnamed_xx,.LASANPC, etc. */
  46                 "__crc_",               /* modversions */
  47                 "__efistub_",           /* arm64 EFI stub namespace */
  48                 "__kvm_nvhe_$",         /* arm64 local symbols in non-VHE KVM namespace */
  49                 "__kvm_nvhe_.L",        /* arm64 local symbols in non-VHE KVM namespace */
  50                 "__AArch64ADRPThunk_",  /* arm64 lld */
  51                 "__ARMV5PILongThunk_",  /* arm lld */
  52                 "__ARMV7PILongThunk_",
  53                 "__ThumbV7PILongThunk_",
  54                 "__LA25Thunk_",         /* mips lld */
  55                 "__microLA25Thunk_",
  56                 NULL
  57         };
  58
  59         /* Symbol names that end with the following are ignored.*/
  60         static const char * const ignored_suffixes[] = {
  61                 "_from_arm",            /* arm */
  62                 "_from_thumb",          /* arm */
  63                 "_veneer",              /* arm */
  64                 NULL
  65         };
  66
  67         /* Symbol names that contain the following are ignored.*/
  68         static const char * const ignored_matches[] = {
  69                 ".long_branch.",        /* ppc stub */
  70                 ".plt_branch.",         /* ppc stub */
  71                 NULL
  72         };
  73
  74         const char * const *p;
  75
  76         for (p = ignored_symbols; *p; p++)
  77                 if (!strcmp(name, *p))
  78                         return true;
  79
  80         for (p = ignored_prefixes; *p; p++)
  81                 if (!strncmp(name, *p, strlen(*p)))
  82                         return true;
  83
  84         for (p = ignored_suffixes; *p; p++) {
  85                 int l = strlen(name) - strlen(*p);
  86
  87                 if (l >= 0 && !strcmp(name + l, *p))
  88                         return true;
  89         }
  90
  91         for (p = ignored_matches; *p; p++) {
  92                 if (strstr(name, *p))
  93                         return true;
  94         }
  95
  96         if (type == 'U' || type == 'u')
  97                 return true;
  98         /* exclude debugging symbols */
  99         if (type == 'N' || type == 'n')
 100                 return true;
 101
 102         if (toupper(type) == 'A') {
 103                 /* Keep these useful absolute symbols */
 104                 if (strcmp(name, "__kernel_syscall_via_break") &&
 105                     strcmp(name, "__kernel_syscall_via_epc") &&
 106                     strcmp(name, "__kernel_sigtramp") &&
 107                     strcmp(name, "__gp"))
 108                         return true;
 109         }
 110
 111         return false;
 112 }
 113
 114 struct test__vmlinux_matches_kallsyms_cb_args {
 115         struct machine kallsyms;
 116         struct map *vmlinux_map;
 117         bool header_printed;
 118 };
 119
 120 static int test__vmlinux_matches_kallsyms_cb1(struct map *map, void *data)
 121 {
 122         struct test__vmlinux_matches_kallsyms_cb_args *args = data;
 123         struct dso *dso = map__dso(map);
 124         /*
 125          * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
 126          * the kernel will have the path for the vmlinux file being used, so use
 127          * the short name, less descriptive but the same ("[kernel]" in both
 128          * cases.
 129          */
 130         struct map *pair = maps__find_by_name(args->kallsyms.kmaps,
 131                                         (dso__kernel(dso) ? dso__short_name(dso) : dso__name(dso)));
 132
 133         if (pair) {
 134                 map__set_priv(pair);
 135                 map__put(pair);
 136         } else {
 137                 if (!args->header_printed) {
 138                         pr_info("WARN: Maps only in vmlinux:\n");
 139                         args->header_printed = true;
 140                 }
 141                 map__fprintf(map, stderr);
 142         }
 143         return 0;
 144 }
 145
 146 static int test__vmlinux_matches_kallsyms_cb2(struct map *map, void *data)
 147 {
 148         struct test__vmlinux_matches_kallsyms_cb_args *args = data;
 149         struct map *pair;
 150         u64 mem_start = map__unmap_ip(args->vmlinux_map, map__start(map));
 151         u64 mem_end = map__unmap_ip(args->vmlinux_map, map__end(map));
 152
 153         pair = maps__find(args->kallsyms.kmaps, mem_start);
 154
 155         if (pair != NULL && !map__priv(pair) && map__start(pair) == mem_start) {
 156                 struct dso *dso = map__dso(map);
 157
 158                 if (!args->header_printed) {
 159                         pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
 160                         args->header_printed = true;
 161                 }
 162
 163                 pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
 164                         map__start(map), map__end(map), map__pgoff(map), dso__name(dso));
 165                 if (mem_end != map__end(pair))
 166                         pr_info(":\nWARN: *%" PRIx64 "-%" PRIx64 " %" PRIx64,
 167                                 map__start(pair), map__end(pair), map__pgoff(pair));
 168                 pr_info(" %s\n", dso__name(dso));
 169                 map__set_priv(pair);
 170         }
 171         map__put(pair);
 172         return 0;
 173 }
 174
 175 static int test__vmlinux_matches_kallsyms_cb3(struct map *map, void *data)
 176 {
 177         struct test__vmlinux_matches_kallsyms_cb_args *args = data;
 178
 179         if (!map__priv(map)) {
 180                 if (!args->header_printed) {
 181                         pr_info("WARN: Maps only in kallsyms:\n");
 182                         args->header_printed = true;
 183                 }
 184                 map__fprintf(map, stderr);
 185         }
 186         return 0;
 187 }
 188
 189 static int test__vmlinux_matches_kallsyms(struct test_suite *test __maybe_unused,
 190                                         int subtest __maybe_unused)
 191 {
 192         int err = TEST_FAIL;
 193         struct rb_node *nd;
 194         struct symbol *sym;
 195         struct map *kallsyms_map;
 196         struct machine vmlinux;
 197         struct maps *maps;
 198         u64 mem_start, mem_end;
 199         struct test__vmlinux_matches_kallsyms_cb_args args;
 200
 201         /*
 202          * Step 1:
 203          *
 204          * Init the machines that will hold kernel, modules obtained from
 205          * both vmlinux + .ko files and from /proc/kallsyms split by modules.
 206          */
 207         machine__init(&args.kallsyms, "", HOST_KERNEL_ID);
 208         machine__init(&vmlinux, "", HOST_KERNEL_ID);
 209
 210         maps = machine__kernel_maps(&vmlinux);
 211
 212         /*
 213          * Step 2:
 214          *
 215          * Create the kernel maps for kallsyms and the DSO where we will then
 216          * load /proc/kallsyms. Also create the modules maps from /proc/modules
 217          * and find the .ko files that match them in /lib/modules/`uname -r`/.
 218          */
 219         if (machine__create_kernel_maps(&args.kallsyms) < 0) {
 220                 pr_debug("machine__create_kernel_maps failed");
 221                 err = TEST_SKIP;
 222                 goto out;
 223         }
 224
 225         /*
 226          * Step 3:
 227          *
 228          * Load and split /proc/kallsyms into multiple maps, one per module.
 229          * Do not use kcore, as this test was designed before kcore support
 230          * and has parts that only make sense if using the non-kcore code.
 231          * XXX: extend it to stress the kcorre code as well, hint: the list
 232          * of modules extracted from /proc/kcore, in its current form, can't
 233          * be compacted against the list of modules found in the "vmlinux"
 234          * code and with the one got from /proc/modules from the "kallsyms" code.
 235          */
 236         if (machine__load_kallsyms(&args.kallsyms, "/proc/kallsyms") <= 0) {
 237                 pr_debug("machine__load_kallsyms failed");
 238                 err = TEST_SKIP;
 239                 goto out;
 240         }
 241
 242         /*
 243          * Step 4:
 244          *
 245          * kallsyms will be internally on demand sorted by name so that we can
 246          * find the reference relocation * symbol, i.e. the symbol we will use
 247          * to see if the running kernel was relocated by checking if it has the
 248          * same value in the vmlinux file we load.
 249          */
 250         kallsyms_map = machine__kernel_map(&args.kallsyms);
 251
 252         /*
 253          * Step 5:
 254          *
 255          * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
 256          */
 257         if (machine__create_kernel_maps(&vmlinux) < 0) {
 258                 pr_info("machine__create_kernel_maps failed");
 259                 goto out;
 260         }
 261
 262         args.vmlinux_map = machine__kernel_map(&vmlinux);
 263
 264         /*
 265          * Step 6:
 266          *
 267          * Locate a vmlinux file in the vmlinux path that has a buildid that
 268          * matches the one of the running kernel.
 269          *
 270          * While doing that look if we find the ref reloc symbol, if we find it
 271          * we'll have its ref_reloc_symbol.unrelocated_addr and then
 272          * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
 273          * to fixup the symbols.
 274          */
 275         if (machine__load_vmlinux_path(&vmlinux) <= 0) {
 276                 pr_info("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
 277                 err = TEST_SKIP;
 278                 goto out;
 279         }
 280
 281         err = 0;
 282         /*
 283          * Step 7:
 284          *
 285          * Now look at the symbols in the vmlinux DSO and check if we find all of them
 286          * in the kallsyms dso. For the ones that are in both, check its names and
 287          * end addresses too.
 288          */
 289         map__for_each_symbol(args.vmlinux_map, sym, nd) {
 290                 struct symbol *pair, *first_pair;
 291
 292                 sym  = rb_entry(nd, struct symbol, rb_node);
 293
 294                 if (sym->start == sym->end)
 295                         continue;
 296
 297                 mem_start = map__unmap_ip(args.vmlinux_map, sym->start);
 298                 mem_end = map__unmap_ip(args.vmlinux_map, sym->end);
 299
 300                 first_pair = machine__find_kernel_symbol(&args.kallsyms, mem_start, NULL);
 301                 pair = first_pair;
 302
 303                 if (pair && UM(pair->start) == mem_start) {
 304 next_pair:
 305                         if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
 306                                 /*
 307                                  * kallsyms don't have the symbol end, so we
 308                                  * set that by using the next symbol start - 1,
 309                                  * in some cases we get this up to a page
 310                                  * wrong, trace_kmalloc when I was developing
 311                                  * this code was one such example, 2106 bytes
 312                                  * off the real size. More than that and we
 313                                  * _really_ have a problem.
 314                                  */
 315                                 s64 skew = mem_end - UM(pair->end);
 316                                 if (llabs(skew) >= page_size)
 317                                         pr_debug("WARN: %#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
 318                                                  mem_start, sym->name, mem_end,
 319                                                  UM(pair->end));
 320
 321                                 /*
 322                                  * Do not count this as a failure, because we
 323                                  * could really find a case where it's not
 324                                  * possible to get proper function end from
 325                                  * kallsyms.
 326                                  */
 327                                 continue;
 328                         } else {
 329                                 pair = machine__find_kernel_symbol_by_name(&args.kallsyms,
 330                                                                            sym->name, NULL);
 331                                 if (pair) {
 332                                         if (UM(pair->start) == mem_start)
 333                                                 goto next_pair;
 334
 335                                         pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
 336                                                  mem_start, sym->name, pair->name);
 337                                 } else {
 338                                         pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
 339                                                  mem_start, sym->name, first_pair->name);
 340                                 }
 341
 342                                 continue;
 343                         }
 344                 } else if (mem_start == map__end(args.kallsyms.vmlinux_map)) {
 345                         /*
 346                          * Ignore aliases to _etext, i.e. to the end of the kernel text area,
 347                          * such as __indirect_thunk_end.
 348                          */
 349                         continue;
 350                 } else if (is_ignored_symbol(sym->name, sym->type)) {
 351                         /*
 352                          * Ignore hidden symbols, see scripts/kallsyms.c for the details
 353                          */
 354                         continue;
 355                 } else {
 356                         pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
 357                                  mem_start, sym->name);
 358                 }
 359
 360                 err = -1;
 361         }
 362
 363         if (verbose <= 0)
 364                 goto out;
 365
 366         args.header_printed = false;
 367         maps__for_each_map(maps, test__vmlinux_matches_kallsyms_cb1, &args);
 368
 369         args.header_printed = false;
 370         maps__for_each_map(maps, test__vmlinux_matches_kallsyms_cb2, &args);
 371
 372         args.header_printed = false;
 373         maps = machine__kernel_maps(&args.kallsyms);
 374         maps__for_each_map(maps, test__vmlinux_matches_kallsyms_cb3, &args);
 375
 376 out:
 377         machine__exit(&args.kallsyms);
 378         machine__exit(&vmlinux);
 379         return err;
 380 }
 381
 382 DEFINE_SUITE("vmlinux symtab matches kallsyms", vmlinux_matches_kallsyms);