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, *map; 27 struct machine kallsyms, vmlinux; 28 enum map_type type = MAP__FUNCTION; 29 struct maps *maps = &vmlinux.kmaps.maps[type]; 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 /* 74 * Step 5: 75 * 76 * Now repeat step 2, this time for the vmlinux file we'll auto-locate. 77 */ 78 if (machine__create_kernel_maps(&vmlinux) < 0) { 79 pr_debug("machine__create_kernel_maps "); 80 goto out; 81 } 82 83 vmlinux_map = machine__kernel_map(&vmlinux, type); 84 85 /* 86 * Step 6: 87 * 88 * Locate a vmlinux file in the vmlinux path that has a buildid that 89 * matches the one of the running kernel. 90 * 91 * While doing that look if we find the ref reloc symbol, if we find it 92 * we'll have its ref_reloc_symbol.unrelocated_addr and then 93 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines 94 * to fixup the symbols. 95 */ 96 if (machine__load_vmlinux_path(&vmlinux, type, 97 vmlinux_matches_kallsyms_filter) <= 0) { 98 pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n"); 99 err = TEST_SKIP; 100 goto out; 101 } 102 103 err = 0; 104 /* 105 * Step 7: 106 * 107 * Now look at the symbols in the vmlinux DSO and check if we find all of them 108 * in the kallsyms dso. For the ones that are in both, check its names and 109 * end addresses too. 110 */ 111 for (nd = rb_first(&vmlinux_map->dso->symbols[type]); nd; nd = rb_next(nd)) { 112 struct symbol *pair, *first_pair; 113 bool backwards = true; 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, type, 124 mem_start, NULL, NULL); 125 pair = first_pair; 126 127 if (pair && UM(pair->start) == mem_start) { 128 next_pair: 129 if (strcmp(sym->name, pair->name) == 0) { 130 /* 131 * kallsyms don't have the symbol end, so we 132 * set that by using the next symbol start - 1, 133 * in some cases we get this up to a page 134 * wrong, trace_kmalloc when I was developing 135 * this code was one such example, 2106 bytes 136 * off the real size. More than that and we 137 * _really_ have a problem. 138 */ 139 s64 skew = mem_end - UM(pair->end); 140 if (llabs(skew) >= page_size) 141 pr_debug("%#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n", 142 mem_start, sym->name, mem_end, 143 UM(pair->end)); 144 145 /* 146 * Do not count this as a failure, because we 147 * could really find a case where it's not 148 * possible to get proper function end from 149 * kallsyms. 150 */ 151 continue; 152 153 } else { 154 struct rb_node *nnd; 155 detour: 156 nnd = backwards ? rb_prev(&pair->rb_node) : 157 rb_next(&pair->rb_node); 158 if (nnd) { 159 struct symbol *next = rb_entry(nnd, struct symbol, rb_node); 160 161 if (UM(next->start) == mem_start) { 162 pair = next; 163 goto next_pair; 164 } 165 } 166 167 if (backwards) { 168 backwards = false; 169 pair = first_pair; 170 goto detour; 171 } 172 173 pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n", 174 mem_start, sym->name, pair->name); 175 } 176 } else 177 pr_debug("%#" PRIx64 ": %s not on kallsyms\n", 178 mem_start, sym->name); 179 180 err = -1; 181 } 182 183 if (!verbose) 184 goto out; 185 186 pr_info("Maps only in vmlinux:\n"); 187 188 for (map = maps__first(maps); map; map = map__next(map)) { 189 struct map * 190 /* 191 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while 192 * the kernel will have the path for the vmlinux file being used, 193 * so use the short name, less descriptive but the same ("[kernel]" in 194 * both cases. 195 */ 196 pair = map_groups__find_by_name(&kallsyms.kmaps, type, 197 (map->dso->kernel ? 198 map->dso->short_name : 199 map->dso->name)); 200 if (pair) 201 pair->priv = 1; 202 else 203 map__fprintf(map, stderr); 204 } 205 206 pr_info("Maps in vmlinux with a different name in kallsyms:\n"); 207 208 for (map = maps__first(maps); map; map = map__next(map)) { 209 struct map *pair; 210 211 mem_start = vmlinux_map->unmap_ip(vmlinux_map, map->start); 212 mem_end = vmlinux_map->unmap_ip(vmlinux_map, map->end); 213 214 pair = map_groups__find(&kallsyms.kmaps, type, mem_start); 215 if (pair == NULL || pair->priv) 216 continue; 217 218 if (pair->start == mem_start) { 219 pair->priv = 1; 220 pr_info(" %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as", 221 map->start, map->end, map->pgoff, map->dso->name); 222 if (mem_end != pair->end) 223 pr_info(":\n*%" PRIx64 "-%" PRIx64 " %" PRIx64, 224 pair->start, pair->end, pair->pgoff); 225 pr_info(" %s\n", pair->dso->name); 226 pair->priv = 1; 227 } 228 } 229 230 pr_info("Maps only in kallsyms:\n"); 231 232 maps = &kallsyms.kmaps.maps[type]; 233 234 for (map = maps__first(maps); map; map = map__next(map)) { 235 if (!map->priv) 236 map__fprintf(map, stderr); 237 } 238 out: 239 machine__exit(&kallsyms); 240 machine__exit(&vmlinux); 241 return err; 242 } 243