1 #include <linux/compiler.h> 2 #include <linux/rbtree.h> 3 #include <string.h> 4 #include "map.h" 5 #include "symbol.h" 6 #include "util.h" 7 #include "tests.h" 8 #include "debug.h" 9 #include "machine.h" 10 11 static int vmlinux_matches_kallsyms_filter(struct map *map __maybe_unused, 12 struct symbol *sym) 13 { 14 bool *visited = symbol__priv(sym); 15 *visited = true; 16 return 0; 17 } 18 19 #define UM(x) kallsyms_map->unmap_ip(kallsyms_map, (x)) 20 21 int test__vmlinux_matches_kallsyms(void) 22 { 23 int err = -1; 24 struct rb_node *nd; 25 struct symbol *sym; 26 struct map *kallsyms_map, *vmlinux_map; 27 struct machine kallsyms, vmlinux; 28 enum map_type type = MAP__FUNCTION; 29 struct ref_reloc_sym ref_reloc_sym = { .name = "_stext", }; 30 u64 mem_start, mem_end; 31 32 /* 33 * Step 1: 34 * 35 * Init the machines that will hold kernel, modules obtained from 36 * both vmlinux + .ko files and from /proc/kallsyms split by modules. 37 */ 38 machine__init(&kallsyms, "", HOST_KERNEL_ID); 39 machine__init(&vmlinux, "", HOST_KERNEL_ID); 40 41 /* 42 * Step 2: 43 * 44 * Create the kernel maps for kallsyms and the DSO where we will then 45 * load /proc/kallsyms. Also create the modules maps from /proc/modules 46 * and find the .ko files that match them in /lib/modules/`uname -r`/. 47 */ 48 if (machine__create_kernel_maps(&kallsyms) < 0) { 49 pr_debug("machine__create_kernel_maps "); 50 goto out; 51 } 52 53 /* 54 * Step 3: 55 * 56 * Load and split /proc/kallsyms into multiple maps, one per module. 57 */ 58 if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms", type, NULL) <= 0) { 59 pr_debug("dso__load_kallsyms "); 60 goto out; 61 } 62 63 /* 64 * Step 4: 65 * 66 * kallsyms will be internally on demand sorted by name so that we can 67 * find the reference relocation * symbol, i.e. the symbol we will use 68 * to see if the running kernel was relocated by checking if it has the 69 * same value in the vmlinux file we load. 70 */ 71 kallsyms_map = machine__kernel_map(&kallsyms, type); 72 73 sym = map__find_symbol_by_name(kallsyms_map, ref_reloc_sym.name, NULL); 74 if (sym == NULL) { 75 pr_debug("dso__find_symbol_by_name "); 76 goto out; 77 } 78 79 ref_reloc_sym.addr = UM(sym->start); 80 81 /* 82 * Step 5: 83 * 84 * Now repeat step 2, this time for the vmlinux file we'll auto-locate. 85 */ 86 if (machine__create_kernel_maps(&vmlinux) < 0) { 87 pr_debug("machine__create_kernel_maps "); 88 goto out; 89 } 90 91 vmlinux_map = machine__kernel_map(&vmlinux, type); 92 map__kmap(vmlinux_map)->ref_reloc_sym = &ref_reloc_sym; 93 94 /* 95 * Step 6: 96 * 97 * Locate a vmlinux file in the vmlinux path that has a buildid that 98 * matches the one of the running kernel. 99 * 100 * While doing that look if we find the ref reloc symbol, if we find it 101 * we'll have its ref_reloc_symbol.unrelocated_addr and then 102 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines 103 * to fixup the symbols. 104 */ 105 if (machine__load_vmlinux_path(&vmlinux, type, 106 vmlinux_matches_kallsyms_filter) <= 0) { 107 pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n"); 108 err = TEST_SKIP; 109 goto out; 110 } 111 112 err = 0; 113 /* 114 * Step 7: 115 * 116 * Now look at the symbols in the vmlinux DSO and check if we find all of them 117 * in the kallsyms dso. For the ones that are in both, check its names and 118 * end addresses too. 119 */ 120 for (nd = rb_first(&vmlinux_map->dso->symbols[type]); nd; nd = rb_next(nd)) { 121 struct symbol *pair, *first_pair; 122 bool backwards = true; 123 124 sym = rb_entry(nd, struct symbol, rb_node); 125 126 if (sym->start == sym->end) 127 continue; 128 129 mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start); 130 mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end); 131 132 first_pair = machine__find_kernel_symbol(&kallsyms, type, 133 mem_start, NULL, NULL); 134 pair = first_pair; 135 136 if (pair && UM(pair->start) == mem_start) { 137 next_pair: 138 if (strcmp(sym->name, pair->name) == 0) { 139 /* 140 * kallsyms don't have the symbol end, so we 141 * set that by using the next symbol start - 1, 142 * in some cases we get this up to a page 143 * wrong, trace_kmalloc when I was developing 144 * this code was one such example, 2106 bytes 145 * off the real size. More than that and we 146 * _really_ have a problem. 147 */ 148 s64 skew = mem_end - UM(pair->end); 149 if (llabs(skew) >= page_size) 150 pr_debug("%#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n", 151 mem_start, sym->name, mem_end, 152 UM(pair->end)); 153 154 /* 155 * Do not count this as a failure, because we 156 * could really find a case where it's not 157 * possible to get proper function end from 158 * kallsyms. 159 */ 160 continue; 161 162 } else { 163 struct rb_node *nnd; 164 detour: 165 nnd = backwards ? rb_prev(&pair->rb_node) : 166 rb_next(&pair->rb_node); 167 if (nnd) { 168 struct symbol *next = rb_entry(nnd, struct symbol, rb_node); 169 170 if (UM(next->start) == mem_start) { 171 pair = next; 172 goto next_pair; 173 } 174 } 175 176 if (backwards) { 177 backwards = false; 178 pair = first_pair; 179 goto detour; 180 } 181 182 pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n", 183 mem_start, sym->name, pair->name); 184 } 185 } else 186 pr_debug("%#" PRIx64 ": %s not on kallsyms\n", 187 mem_start, sym->name); 188 189 err = -1; 190 } 191 192 if (!verbose) 193 goto out; 194 195 pr_info("Maps only in vmlinux:\n"); 196 197 for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) { 198 struct map *pos = rb_entry(nd, struct map, rb_node), *pair; 199 /* 200 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while 201 * the kernel will have the path for the vmlinux file being used, 202 * so use the short name, less descriptive but the same ("[kernel]" in 203 * both cases. 204 */ 205 pair = map_groups__find_by_name(&kallsyms.kmaps, type, 206 (pos->dso->kernel ? 207 pos->dso->short_name : 208 pos->dso->name)); 209 if (pair) 210 pair->priv = 1; 211 else 212 map__fprintf(pos, stderr); 213 } 214 215 pr_info("Maps in vmlinux with a different name in kallsyms:\n"); 216 217 for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) { 218 struct map *pos = rb_entry(nd, struct map, rb_node), *pair; 219 220 mem_start = vmlinux_map->unmap_ip(vmlinux_map, pos->start); 221 mem_end = vmlinux_map->unmap_ip(vmlinux_map, pos->end); 222 223 pair = map_groups__find(&kallsyms.kmaps, type, mem_start); 224 if (pair == NULL || pair->priv) 225 continue; 226 227 if (pair->start == mem_start) { 228 pair->priv = 1; 229 pr_info(" %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as", 230 pos->start, pos->end, pos->pgoff, pos->dso->name); 231 if (mem_end != pair->end) 232 pr_info(":\n*%" PRIx64 "-%" PRIx64 " %" PRIx64, 233 pair->start, pair->end, pair->pgoff); 234 pr_info(" %s\n", pair->dso->name); 235 pair->priv = 1; 236 } 237 } 238 239 pr_info("Maps only in kallsyms:\n"); 240 241 for (nd = rb_first(&kallsyms.kmaps.maps[type]); 242 nd; nd = rb_next(nd)) { 243 struct map *pos = rb_entry(nd, struct map, rb_node); 244 245 if (!pos->priv) 246 map__fprintf(pos, stderr); 247 } 248 out: 249 machine__exit(&kallsyms); 250 machine__exit(&vmlinux); 251 return err; 252 } 253
