1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/compiler.h> 3 #include <elfutils/libdw.h> 4 #include <elfutils/libdwfl.h> 5 #include <inttypes.h> 6 #include <errno.h> 7 #include "debug.h" 8 #include "dso.h" 9 #include "unwind.h" 10 #include "unwind-libdw.h" 11 #include "machine.h" 12 #include "map.h" 13 #include "symbol.h" 14 #include "thread.h" 15 #include <linux/types.h> 16 #include <linux/zalloc.h> 17 #include "event.h" 18 #include "perf_regs.h" 19 #include "callchain.h" 20 #include "util/env.h" 21 22 static char *debuginfo_path; 23 24 static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata, 25 const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused, 26 const char *file_name, const char *debuglink_file __maybe_unused, 27 GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name) 28 { 29 const struct dso *dso = *userdata; 30 31 assert(dso); 32 if (dso__symsrc_filename(dso) && strcmp(file_name, dso__symsrc_filename(dso))) 33 *debuginfo_file_name = strdup(dso__symsrc_filename(dso)); 34 return -1; 35 } 36 37 static const Dwfl_Callbacks offline_callbacks = { 38 .find_debuginfo = __find_debuginfo, 39 .debuginfo_path = &debuginfo_path, 40 .section_address = dwfl_offline_section_address, 41 // .find_elf is not set as we use dwfl_report_elf() instead. 42 }; 43 44 static int __report_module(struct addr_location *al, u64 ip, 45 struct unwind_info *ui) 46 { 47 Dwfl_Module *mod; 48 struct dso *dso = NULL; 49 Dwarf_Addr base; 50 /* 51 * Some callers will use al->sym, so we can't just use the 52 * cheaper thread__find_map() here. 53 */ 54 thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al); 55 56 if (al->map) 57 dso = map__dso(al->map); 58 59 if (!dso) 60 return 0; 61 62 /* 63 * The generated JIT DSO files only map the code segment without 64 * ELF headers. Since JIT codes used to be packed in a memory 65 * segment, calculating the base address using pgoff falls into 66 * a different code in another DSO. So just use the map->start 67 * directly to pick the correct one. 68 */ 69 if (!strncmp(dso__long_name(dso), "/tmp/jitted-", 12)) 70 base = map__start(al->map); 71 else 72 base = map__start(al->map) - map__pgoff(al->map); 73 74 mod = dwfl_addrmodule(ui->dwfl, ip); 75 if (mod) { 76 Dwarf_Addr s; 77 78 dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL); 79 if (s != base) 80 mod = NULL; 81 } 82 83 if (!mod) { 84 char filename[PATH_MAX]; 85 86 __symbol__join_symfs(filename, sizeof(filename), dso__long_name(dso)); 87 /* Don't hang up on device files like /dev/dri/renderD128. */ 88 if (is_regular_file(filename)) { 89 mod = dwfl_report_elf(ui->dwfl, dso__short_name(dso), filename, -1, 90 base, false); 91 } 92 } 93 if (!mod) { 94 char filename[PATH_MAX]; 95 96 if (dso__build_id_filename(dso, filename, sizeof(filename), false)) 97 mod = dwfl_report_elf(ui->dwfl, dso__short_name(dso), filename, -1, 98 base, false); 99 } 100 101 if (mod) { 102 void **userdatap; 103 104 dwfl_module_info(mod, &userdatap, NULL, NULL, NULL, NULL, NULL, NULL); 105 *userdatap = dso; 106 } 107 108 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; 109 } 110 111 static int report_module(u64 ip, struct unwind_info *ui) 112 { 113 struct addr_location al; 114 int res; 115 116 addr_location__init(&al); 117 res = __report_module(&al, ip, ui); 118 addr_location__exit(&al); 119 return res; 120 } 121 122 /* 123 * Store all entries within entries array, 124 * we will process it after we finish unwind. 125 */ 126 static int entry(u64 ip, struct unwind_info *ui) 127 128 { 129 struct unwind_entry *e = &ui->entries[ui->idx++]; 130 struct addr_location al; 131 132 addr_location__init(&al); 133 if (__report_module(&al, ip, ui)) { 134 addr_location__exit(&al); 135 return -1; 136 } 137 138 e->ip = ip; 139 e->ms.maps = al.maps; 140 e->ms.map = al.map; 141 e->ms.sym = al.sym; 142 143 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n", 144 al.sym ? al.sym->name : "''", 145 ip, 146 al.map ? map__map_ip(al.map, ip) : (u64) 0); 147 addr_location__exit(&al); 148 return 0; 149 } 150 151 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp) 152 { 153 /* We want only single thread to be processed. */ 154 if (*thread_argp != NULL) 155 return 0; 156 157 *thread_argp = arg; 158 return dwfl_pid(dwfl); 159 } 160 161 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr, 162 Dwarf_Word *data) 163 { 164 struct addr_location al; 165 ssize_t size; 166 struct dso *dso; 167 168 addr_location__init(&al); 169 if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) { 170 pr_debug("unwind: no map for %lx\n", (unsigned long)addr); 171 goto out_fail; 172 } 173 dso = map__dso(al.map); 174 if (!dso) 175 goto out_fail; 176 177 size = dso__data_read_addr(dso, al.map, ui->machine, addr, (u8 *) data, sizeof(*data)); 178 179 addr_location__exit(&al); 180 return !(size == sizeof(*data)); 181 out_fail: 182 addr_location__exit(&al); 183 return -1; 184 } 185 186 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result, 187 void *arg) 188 { 189 struct unwind_info *ui = arg; 190 const char *arch = perf_env__arch(ui->machine->env); 191 struct stack_dump *stack = &ui->sample->user_stack; 192 u64 start, end; 193 int offset; 194 int ret; 195 196 if (!ui->sample->user_regs) 197 return false; 198 199 ret = perf_reg_value(&start, ui->sample->user_regs, 200 perf_arch_reg_sp(arch)); 201 if (ret) 202 return false; 203 204 end = start + stack->size; 205 206 /* Check overflow. */ 207 if (addr + sizeof(Dwarf_Word) < addr) 208 return false; 209 210 if (addr < start || addr + sizeof(Dwarf_Word) > end) { 211 ret = access_dso_mem(ui, addr, result); 212 if (ret) { 213 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range" 214 " 0x%" PRIx64 "-0x%" PRIx64 "\n", 215 addr, start, end); 216 return false; 217 } 218 return true; 219 } 220 221 offset = addr - start; 222 *result = *(Dwarf_Word *)&stack->data[offset]; 223 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n", 224 addr, (unsigned long)*result, offset); 225 return true; 226 } 227 228 static const Dwfl_Thread_Callbacks callbacks = { 229 .next_thread = next_thread, 230 .memory_read = memory_read, 231 .set_initial_registers = libdw__arch_set_initial_registers, 232 }; 233 234 static int 235 frame_callback(Dwfl_Frame *state, void *arg) 236 { 237 struct unwind_info *ui = arg; 238 Dwarf_Addr pc; 239 bool isactivation; 240 241 if (!dwfl_frame_pc(state, &pc, NULL)) { 242 if (!ui->best_effort) 243 pr_err("%s", dwfl_errmsg(-1)); 244 return DWARF_CB_ABORT; 245 } 246 247 // report the module before we query for isactivation 248 report_module(pc, ui); 249 250 if (!dwfl_frame_pc(state, &pc, &isactivation)) { 251 if (!ui->best_effort) 252 pr_err("%s", dwfl_errmsg(-1)); 253 return DWARF_CB_ABORT; 254 } 255 256 if (!isactivation) 257 --pc; 258 259 return entry(pc, ui) || !(--ui->max_stack) ? 260 DWARF_CB_ABORT : DWARF_CB_OK; 261 } 262 263 int unwind__get_entries(unwind_entry_cb_t cb, void *arg, 264 struct thread *thread, 265 struct perf_sample *data, 266 int max_stack, 267 bool best_effort) 268 { 269 struct unwind_info *ui, ui_buf = { 270 .sample = data, 271 .thread = thread, 272 .machine = maps__machine((thread__maps(thread))), 273 .cb = cb, 274 .arg = arg, 275 .max_stack = max_stack, 276 .best_effort = best_effort 277 }; 278 const char *arch = perf_env__arch(ui_buf.machine->env); 279 Dwarf_Word ip; 280 int err = -EINVAL, i; 281 282 if (!data->user_regs || !data->user_regs->regs) 283 return -EINVAL; 284 285 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack); 286 if (!ui) 287 return -ENOMEM; 288 289 *ui = ui_buf; 290 291 ui->dwfl = dwfl_begin(&offline_callbacks); 292 if (!ui->dwfl) 293 goto out; 294 295 err = perf_reg_value(&ip, data->user_regs, perf_arch_reg_ip(arch)); 296 if (err) 297 goto out; 298 299 err = report_module(ip, ui); 300 if (err) 301 goto out; 302 303 err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread__tid(thread), &callbacks, ui); 304 if (err) 305 goto out; 306 307 err = dwfl_getthread_frames(ui->dwfl, thread__tid(thread), frame_callback, ui); 308 309 if (err && ui->max_stack != max_stack) 310 err = 0; 311 312 /* 313 * Display what we got based on the order setup. 314 */ 315 for (i = 0; i < ui->idx && !err; i++) { 316 int j = i; 317 318 if (callchain_param.order == ORDER_CALLER) 319 j = ui->idx - i - 1; 320 321 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0; 322 } 323 324 out: 325 if (err) 326 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1)); 327 328 dwfl_end(ui->dwfl); 329 free(ui); 330 return 0; 331 } 332