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 <stdlib.h>
   7 #include "dso.h"
   8 #include "map.h"
   9 #include "symbol.h"
  10 #include <internal/lib.h> // page_size
  11 #include "tests.h"
  12 #include "debug.h"
  13 #include "machine.h"
  14
  15 #define UM(x) kallsyms_map->unmap_ip(kallsyms_map, (x))
  16
  17 int test__vmlinux_matches_kallsyms(struct test *test __maybe_unused, int subtest __maybe_unused)
  18 {
  19         int err = -1;
  20         struct rb_node *nd;
  21         struct symbol *sym;
  22         struct map *kallsyms_map, *vmlinux_map, *map;
  23         struct machine kallsyms, vmlinux;
  24         struct maps *maps = machine__kernel_maps(&vmlinux);
  25         u64 mem_start, mem_end;
  26         bool header_printed;
  27
  28         /*
  29          * Step 1:
  30          *
  31          * Init the machines that will hold kernel, modules obtained from
  32          * both vmlinux + .ko files and from /proc/kallsyms split by modules.
  33          */
  34         machine__init(&kallsyms, "", HOST_KERNEL_ID);
  35         machine__init(&vmlinux, "", HOST_KERNEL_ID);
  36
  37         /*
  38          * Step 2:
  39          *
  40          * Create the kernel maps for kallsyms and the DSO where we will then
  41          * load /proc/kallsyms. Also create the modules maps from /proc/modules
  42          * and find the .ko files that match them in /lib/modules/`uname -r`/.
  43          */
  44         if (machine__create_kernel_maps(&kallsyms) < 0) {
  45                 pr_debug("machine__create_kernel_maps ");
  46                 goto out;
  47         }
  48
  49         /*
  50          * Step 3:
  51          *
  52          * Load and split /proc/kallsyms into multiple maps, one per module.
  53          * Do not use kcore, as this test was designed before kcore support
  54          * and has parts that only make sense if using the non-kcore code.
  55          * XXX: extend it to stress the kcorre code as well, hint: the list
  56          * of modules extracted from /proc/kcore, in its current form, can't
  57          * be compacted against the list of modules found in the "vmlinux"
  58          * code and with the one got from /proc/modules from the "kallsyms" code.
  59          */
  60         if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms") <= 0) {
  61                 pr_debug("dso__load_kallsyms ");
  62                 goto out;
  63         }
  64
  65         /*
  66          * Step 4:
  67          *
  68          * kallsyms will be internally on demand sorted by name so that we can
  69          * find the reference relocation * symbol, i.e. the symbol we will use
  70          * to see if the running kernel was relocated by checking if it has the
  71          * same value in the vmlinux file we load.
  72          */
  73         kallsyms_map = machine__kernel_map(&kallsyms);
  74
  75         /*
  76          * Step 5:
  77          *
  78          * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
  79          */
  80         if (machine__create_kernel_maps(&vmlinux) < 0) {
  81                 pr_debug("machine__create_kernel_maps ");
  82                 goto out;
  83         }
  84
  85         vmlinux_map = machine__kernel_map(&vmlinux);
  86
  87         /*
  88          * Step 6:
  89          *
  90          * Locate a vmlinux file in the vmlinux path that has a buildid that
  91          * matches the one of the running kernel.
  92          *
  93          * While doing that look if we find the ref reloc symbol, if we find it
  94          * we'll have its ref_reloc_symbol.unrelocated_addr and then
  95          * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
  96          * to fixup the symbols.
  97          */
  98         if (machine__load_vmlinux_path(&vmlinux) <= 0) {
  99                 pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
 100                 err = TEST_SKIP;
 101                 goto out;
 102         }
 103
 104         err = 0;
 105         /*
 106          * Step 7:
 107          *
 108          * Now look at the symbols in the vmlinux DSO and check if we find all of them
 109          * in the kallsyms dso. For the ones that are in both, check its names and
 110          * end addresses too.
 111          */
 112         map__for_each_symbol(vmlinux_map, sym, nd) {
 113                 struct symbol *pair, *first_pair;
 114
 115                 sym  = rb_entry(nd, struct symbol, rb_node);
 116
 117                 if (sym->start == sym->end)
 118                         continue;
 119
 120                 mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
 121                 mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
 122
 123                 first_pair = machine__find_kernel_symbol(&kallsyms, mem_start, NULL);
 124                 pair = first_pair;
 125
 126                 if (pair && UM(pair->start) == mem_start) {
 127 next_pair:
 128                         if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
 129                                 /*
 130                                  * kallsyms don't have the symbol end, so we
 131                                  * set that by using the next symbol start - 1,
 132                                  * in some cases we get this up to a page
 133                                  * wrong, trace_kmalloc when I was developing
 134                                  * this code was one such example, 2106 bytes
 135                                  * off the real size. More than that and we
 136                                  * _really_ have a problem.
 137                                  */
 138                                 s64 skew = mem_end - UM(pair->end);
 139                                 if (llabs(skew) >= page_size)
 140                                         pr_debug("WARN: %#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
 141                                                  mem_start, sym->name, mem_end,
 142                                                  UM(pair->end));
 143
 144                                 /*
 145                                  * Do not count this as a failure, because we
 146                                  * could really find a case where it's not
 147                                  * possible to get proper function end from
 148                                  * kallsyms.
 149                                  */
 150                                 continue;
 151                         } else {
 152                                 pair = machine__find_kernel_symbol_by_name(&kallsyms, sym->name, NULL);
 153                                 if (pair) {
 154                                         if (UM(pair->start) == mem_start)
 155                                                 goto next_pair;
 156
 157                                         pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
 158                                                  mem_start, sym->name, pair->name);
 159                                 } else {
 160                                         pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
 161                                                  mem_start, sym->name, first_pair->name);
 162                                 }
 163
 164                                 continue;
 165                         }
 166                 } else if (mem_start == kallsyms.vmlinux_map->end) {
 167                         /*
 168                          * Ignore aliases to _etext, i.e. to the end of the kernel text area,
 169                          * such as __indirect_thunk_end.
 170                          */
 171                         continue;
 172                 } else {
 173                         pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
 174                                  mem_start, sym->name);
 175                 }
 176
 177                 err = -1;
 178         }
 179
 180         if (verbose <= 0)
 181                 goto out;
 182
 183         header_printed = false;
 184
 185         maps__for_each_entry(maps, map) {
 186                 struct map *
 187                 /*
 188                  * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
 189                  * the kernel will have the path for the vmlinux file being used,
 190                  * so use the short name, less descriptive but the same ("[kernel]" in
 191                  * both cases.
 192                  */
 193                 pair = maps__find_by_name(&kallsyms.kmaps, (map->dso->kernel ?
 194                                                                 map->dso->short_name :
 195                                                                 map->dso->name));
 196                 if (pair) {
 197                         pair->priv = 1;
 198                 } else {
 199                         if (!header_printed) {
 200                                 pr_info("WARN: Maps only in vmlinux:\n");
 201                                 header_printed = true;
 202                         }
 203                         map__fprintf(map, stderr);
 204                 }
 205         }
 206
 207         header_printed = false;
 208
 209         maps__for_each_entry(maps, map) {
 210                 struct map *pair;
 211
 212                 mem_start = vmlinux_map->unmap_ip(vmlinux_map, map->start);
 213                 mem_end = vmlinux_map->unmap_ip(vmlinux_map, map->end);
 214
 215                 pair = maps__find(&kallsyms.kmaps, mem_start);
 216                 if (pair == NULL || pair->priv)
 217                         continue;
 218
 219                 if (pair->start == mem_start) {
 220                         if (!header_printed) {
 221                                 pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
 222                                 header_printed = true;
 223                         }
 224
 225                         pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
 226                                 map->start, map->end, map->pgoff, map->dso->name);
 227                         if (mem_end != pair->end)
 228                                 pr_info(":\nWARN: *%" PRIx64 "-%" PRIx64 " %" PRIx64,
 229                                         pair->start, pair->end, pair->pgoff);
 230                         pr_info(" %s\n", pair->dso->name);
 231                         pair->priv = 1;
 232                 }
 233         }
 234
 235         header_printed = false;
 236
 237         maps = machine__kernel_maps(&kallsyms);
 238
 239         maps__for_each_entry(maps, map) {
 240                 if (!map->priv) {
 241                         if (!header_printed) {
 242                                 pr_info("WARN: Maps only in kallsyms:\n");
 243                                 header_printed = true;
 244                         }
 245                         map__fprintf(map, stderr);
 246                 }
 247         }
 248 out:
 249         machine__exit(&kallsyms);
 250         machine__exit(&vmlinux);
 251         return err;
 252 }