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