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 && strcmp (file_name, dso->symsrc_filename)) 33 *debuginfo_file_name = strdup(dso->symsrc_filename); 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 /* 50 * Some callers will use al->sym, so we can't just use the 51 * cheaper thread__find_map() here. 52 */ 53 thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al); 54 55 if (al->map) 56 dso = map__dso(al->map); 57 58 if (!dso) 59 return 0; 60 61 mod = dwfl_addrmodule(ui->dwfl, ip); 62 if (mod) { 63 Dwarf_Addr s; 64 65 dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL); 66 if (s != map__start(al->map) - map__pgoff(al->map)) 67 mod = 0; 68 } 69 70 if (!mod) { 71 char filename[PATH_MAX]; 72 73 __symbol__join_symfs(filename, sizeof(filename), dso->long_name); 74 mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1, 75 map__start(al->map) - map__pgoff(al->map), false); 76 } 77 if (!mod) { 78 char filename[PATH_MAX]; 79 80 if (dso__build_id_filename(dso, filename, sizeof(filename), false)) 81 mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1, 82 map__start(al->map) - map__pgoff(al->map), false); 83 } 84 85 if (mod) { 86 void **userdatap; 87 88 dwfl_module_info(mod, &userdatap, NULL, NULL, NULL, NULL, NULL, NULL); 89 *userdatap = dso; 90 } 91 92 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; 93 } 94 95 static int report_module(u64 ip, struct unwind_info *ui) 96 { 97 struct addr_location al; 98 int res; 99 100 addr_location__init(&al); 101 res = __report_module(&al, ip, ui); 102 addr_location__exit(&al); 103 return res; 104 } 105 106 /* 107 * Store all entries within entries array, 108 * we will process it after we finish unwind. 109 */ 110 static int entry(u64 ip, struct unwind_info *ui) 111 112 { 113 struct unwind_entry *e = &ui->entries[ui->idx++]; 114 struct addr_location al; 115 116 addr_location__init(&al); 117 if (__report_module(&al, ip, ui)) { 118 addr_location__exit(&al); 119 return -1; 120 } 121 122 e->ip = ip; 123 e->ms.maps = al.maps; 124 e->ms.map = al.map; 125 e->ms.sym = al.sym; 126 127 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n", 128 al.sym ? al.sym->name : "''", 129 ip, 130 al.map ? map__map_ip(al.map, ip) : (u64) 0); 131 addr_location__exit(&al); 132 return 0; 133 } 134 135 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp) 136 { 137 /* We want only single thread to be processed. */ 138 if (*thread_argp != NULL) 139 return 0; 140 141 *thread_argp = arg; 142 return dwfl_pid(dwfl); 143 } 144 145 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr, 146 Dwarf_Word *data) 147 { 148 struct addr_location al; 149 ssize_t size; 150 struct dso *dso; 151 152 addr_location__init(&al); 153 if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) { 154 pr_debug("unwind: no map for %lx\n", (unsigned long)addr); 155 goto out_fail; 156 } 157 dso = map__dso(al.map); 158 if (!dso) 159 goto out_fail; 160 161 size = dso__data_read_addr(dso, al.map, ui->machine, addr, (u8 *) data, sizeof(*data)); 162 163 addr_location__exit(&al); 164 return !(size == sizeof(*data)); 165 out_fail: 166 addr_location__exit(&al); 167 return -1; 168 } 169 170 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result, 171 void *arg) 172 { 173 struct unwind_info *ui = arg; 174 const char *arch = perf_env__arch(ui->machine->env); 175 struct stack_dump *stack = &ui->sample->user_stack; 176 u64 start, end; 177 int offset; 178 int ret; 179 180 ret = perf_reg_value(&start, &ui->sample->user_regs, 181 perf_arch_reg_sp(arch)); 182 if (ret) 183 return false; 184 185 end = start + stack->size; 186 187 /* Check overflow. */ 188 if (addr + sizeof(Dwarf_Word) < addr) 189 return false; 190 191 if (addr < start || addr + sizeof(Dwarf_Word) > end) { 192 ret = access_dso_mem(ui, addr, result); 193 if (ret) { 194 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range" 195 " 0x%" PRIx64 "-0x%" PRIx64 "\n", 196 addr, start, end); 197 return false; 198 } 199 return true; 200 } 201 202 offset = addr - start; 203 *result = *(Dwarf_Word *)&stack->data[offset]; 204 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n", 205 addr, (unsigned long)*result, offset); 206 return true; 207 } 208 209 static const Dwfl_Thread_Callbacks callbacks = { 210 .next_thread = next_thread, 211 .memory_read = memory_read, 212 .set_initial_registers = libdw__arch_set_initial_registers, 213 }; 214 215 static int 216 frame_callback(Dwfl_Frame *state, void *arg) 217 { 218 struct unwind_info *ui = arg; 219 Dwarf_Addr pc; 220 bool isactivation; 221 222 if (!dwfl_frame_pc(state, &pc, NULL)) { 223 if (!ui->best_effort) 224 pr_err("%s", dwfl_errmsg(-1)); 225 return DWARF_CB_ABORT; 226 } 227 228 // report the module before we query for isactivation 229 report_module(pc, ui); 230 231 if (!dwfl_frame_pc(state, &pc, &isactivation)) { 232 if (!ui->best_effort) 233 pr_err("%s", dwfl_errmsg(-1)); 234 return DWARF_CB_ABORT; 235 } 236 237 if (!isactivation) 238 --pc; 239 240 return entry(pc, ui) || !(--ui->max_stack) ? 241 DWARF_CB_ABORT : DWARF_CB_OK; 242 } 243 244 int unwind__get_entries(unwind_entry_cb_t cb, void *arg, 245 struct thread *thread, 246 struct perf_sample *data, 247 int max_stack, 248 bool best_effort) 249 { 250 struct unwind_info *ui, ui_buf = { 251 .sample = data, 252 .thread = thread, 253 .machine = RC_CHK_ACCESS(thread__maps(thread))->machine, 254 .cb = cb, 255 .arg = arg, 256 .max_stack = max_stack, 257 .best_effort = best_effort 258 }; 259 const char *arch = perf_env__arch(ui_buf.machine->env); 260 Dwarf_Word ip; 261 int err = -EINVAL, i; 262 263 if (!data->user_regs.regs) 264 return -EINVAL; 265 266 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack); 267 if (!ui) 268 return -ENOMEM; 269 270 *ui = ui_buf; 271 272 ui->dwfl = dwfl_begin(&offline_callbacks); 273 if (!ui->dwfl) 274 goto out; 275 276 err = perf_reg_value(&ip, &data->user_regs, perf_arch_reg_ip(arch)); 277 if (err) 278 goto out; 279 280 err = report_module(ip, ui); 281 if (err) 282 goto out; 283 284 err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread__tid(thread), &callbacks, ui); 285 if (err) 286 goto out; 287 288 err = dwfl_getthread_frames(ui->dwfl, thread__tid(thread), frame_callback, ui); 289 290 if (err && ui->max_stack != max_stack) 291 err = 0; 292 293 /* 294 * Display what we got based on the order setup. 295 */ 296 for (i = 0; i < ui->idx && !err; i++) { 297 int j = i; 298 299 if (callchain_param.order == ORDER_CALLER) 300 j = ui->idx - i - 1; 301 302 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0; 303 } 304 305 out: 306 if (err) 307 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1)); 308 309 dwfl_end(ui->dwfl); 310 free(ui); 311 return 0; 312 } 313