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 mod = dwfl_report_elf(ui->dwfl, dso__short_name(dso), filename, -1, 88 base, false); 89 } 90 if (!mod) { 91 char filename[PATH_MAX]; 92 93 if (dso__build_id_filename(dso, filename, sizeof(filename), false)) 94 mod = dwfl_report_elf(ui->dwfl, dso__short_name(dso), filename, -1, 95 base, false); 96 } 97 98 if (mod) { 99 void **userdatap; 100 101 dwfl_module_info(mod, &userdatap, NULL, NULL, NULL, NULL, NULL, NULL); 102 *userdatap = dso; 103 } 104 105 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; 106 } 107 108 static int report_module(u64 ip, struct unwind_info *ui) 109 { 110 struct addr_location al; 111 int res; 112 113 addr_location__init(&al); 114 res = __report_module(&al, ip, ui); 115 addr_location__exit(&al); 116 return res; 117 } 118 119 /* 120 * Store all entries within entries array, 121 * we will process it after we finish unwind. 122 */ 123 static int entry(u64 ip, struct unwind_info *ui) 124 125 { 126 struct unwind_entry *e = &ui->entries[ui->idx++]; 127 struct addr_location al; 128 129 addr_location__init(&al); 130 if (__report_module(&al, ip, ui)) { 131 addr_location__exit(&al); 132 return -1; 133 } 134 135 e->ip = ip; 136 e->ms.maps = al.maps; 137 e->ms.map = al.map; 138 e->ms.sym = al.sym; 139 140 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n", 141 al.sym ? al.sym->name : "''", 142 ip, 143 al.map ? map__map_ip(al.map, ip) : (u64) 0); 144 addr_location__exit(&al); 145 return 0; 146 } 147 148 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp) 149 { 150 /* We want only single thread to be processed. */ 151 if (*thread_argp != NULL) 152 return 0; 153 154 *thread_argp = arg; 155 return dwfl_pid(dwfl); 156 } 157 158 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr, 159 Dwarf_Word *data) 160 { 161 struct addr_location al; 162 ssize_t size; 163 struct dso *dso; 164 165 addr_location__init(&al); 166 if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) { 167 pr_debug("unwind: no map for %lx\n", (unsigned long)addr); 168 goto out_fail; 169 } 170 dso = map__dso(al.map); 171 if (!dso) 172 goto out_fail; 173 174 size = dso__data_read_addr(dso, al.map, ui->machine, addr, (u8 *) data, sizeof(*data)); 175 176 addr_location__exit(&al); 177 return !(size == sizeof(*data)); 178 out_fail: 179 addr_location__exit(&al); 180 return -1; 181 } 182 183 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result, 184 void *arg) 185 { 186 struct unwind_info *ui = arg; 187 const char *arch = perf_env__arch(ui->machine->env); 188 struct stack_dump *stack = &ui->sample->user_stack; 189 u64 start, end; 190 int offset; 191 int ret; 192 193 ret = perf_reg_value(&start, &ui->sample->user_regs, 194 perf_arch_reg_sp(arch)); 195 if (ret) 196 return false; 197 198 end = start + stack->size; 199 200 /* Check overflow. */ 201 if (addr + sizeof(Dwarf_Word) < addr) 202 return false; 203 204 if (addr < start || addr + sizeof(Dwarf_Word) > end) { 205 ret = access_dso_mem(ui, addr, result); 206 if (ret) { 207 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range" 208 " 0x%" PRIx64 "-0x%" PRIx64 "\n", 209 addr, start, end); 210 return false; 211 } 212 return true; 213 } 214 215 offset = addr - start; 216 *result = *(Dwarf_Word *)&stack->data[offset]; 217 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n", 218 addr, (unsigned long)*result, offset); 219 return true; 220 } 221 222 static const Dwfl_Thread_Callbacks callbacks = { 223 .next_thread = next_thread, 224 .memory_read = memory_read, 225 .set_initial_registers = libdw__arch_set_initial_registers, 226 }; 227 228 static int 229 frame_callback(Dwfl_Frame *state, void *arg) 230 { 231 struct unwind_info *ui = arg; 232 Dwarf_Addr pc; 233 bool isactivation; 234 235 if (!dwfl_frame_pc(state, &pc, NULL)) { 236 if (!ui->best_effort) 237 pr_err("%s", dwfl_errmsg(-1)); 238 return DWARF_CB_ABORT; 239 } 240 241 // report the module before we query for isactivation 242 report_module(pc, ui); 243 244 if (!dwfl_frame_pc(state, &pc, &isactivation)) { 245 if (!ui->best_effort) 246 pr_err("%s", dwfl_errmsg(-1)); 247 return DWARF_CB_ABORT; 248 } 249 250 if (!isactivation) 251 --pc; 252 253 return entry(pc, ui) || !(--ui->max_stack) ? 254 DWARF_CB_ABORT : DWARF_CB_OK; 255 } 256 257 int unwind__get_entries(unwind_entry_cb_t cb, void *arg, 258 struct thread *thread, 259 struct perf_sample *data, 260 int max_stack, 261 bool best_effort) 262 { 263 struct unwind_info *ui, ui_buf = { 264 .sample = data, 265 .thread = thread, 266 .machine = maps__machine((thread__maps(thread))), 267 .cb = cb, 268 .arg = arg, 269 .max_stack = max_stack, 270 .best_effort = best_effort 271 }; 272 const char *arch = perf_env__arch(ui_buf.machine->env); 273 Dwarf_Word ip; 274 int err = -EINVAL, i; 275 276 if (!data->user_regs.regs) 277 return -EINVAL; 278 279 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack); 280 if (!ui) 281 return -ENOMEM; 282 283 *ui = ui_buf; 284 285 ui->dwfl = dwfl_begin(&offline_callbacks); 286 if (!ui->dwfl) 287 goto out; 288 289 err = perf_reg_value(&ip, &data->user_regs, perf_arch_reg_ip(arch)); 290 if (err) 291 goto out; 292 293 err = report_module(ip, ui); 294 if (err) 295 goto out; 296 297 err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread__tid(thread), &callbacks, ui); 298 if (err) 299 goto out; 300 301 err = dwfl_getthread_frames(ui->dwfl, thread__tid(thread), frame_callback, ui); 302 303 if (err && ui->max_stack != max_stack) 304 err = 0; 305 306 /* 307 * Display what we got based on the order setup. 308 */ 309 for (i = 0; i < ui->idx && !err; i++) { 310 int j = i; 311 312 if (callchain_param.order == ORDER_CALLER) 313 j = ui->idx - i - 1; 314 315 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0; 316 } 317 318 out: 319 if (err) 320 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1)); 321 322 dwfl_end(ui->dwfl); 323 free(ui); 324 return 0; 325 } 326