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 21 static char *debuginfo_path; 22 23 static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata, 24 const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused, 25 const char *file_name, const char *debuglink_file __maybe_unused, 26 GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name) 27 { 28 const struct dso *dso = *userdata; 29 30 assert(dso); 31 if (dso->symsrc_filename && strcmp (file_name, dso->symsrc_filename)) 32 *debuginfo_file_name = strdup(dso->symsrc_filename); 33 return -1; 34 } 35 36 static const Dwfl_Callbacks offline_callbacks = { 37 .find_debuginfo = __find_debuginfo, 38 .debuginfo_path = &debuginfo_path, 39 .section_address = dwfl_offline_section_address, 40 // .find_elf is not set as we use dwfl_report_elf() instead. 41 }; 42 43 static int __report_module(struct addr_location *al, u64 ip, 44 struct unwind_info *ui) 45 { 46 Dwfl_Module *mod; 47 struct dso *dso = NULL; 48 /* 49 * Some callers will use al->sym, so we can't just use the 50 * cheaper thread__find_map() here. 51 */ 52 thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al); 53 54 if (al->map) 55 dso = al->map->dso; 56 57 if (!dso) 58 return 0; 59 60 mod = dwfl_addrmodule(ui->dwfl, ip); 61 if (mod) { 62 Dwarf_Addr s; 63 void **userdatap; 64 65 dwfl_module_info(mod, &userdatap, &s, NULL, NULL, NULL, NULL, NULL); 66 *userdatap = dso; 67 if (s != al->map->start - al->map->pgoff) 68 mod = 0; 69 } 70 71 if (!mod) 72 mod = dwfl_report_elf(ui->dwfl, dso->short_name, dso->long_name, -1, 73 al->map->start - al->map->pgoff, false); 74 if (!mod) { 75 char filename[PATH_MAX]; 76 77 if (dso__build_id_filename(dso, filename, sizeof(filename), false)) 78 mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1, 79 al->map->start - al->map->pgoff, false); 80 } 81 82 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; 83 } 84 85 static int report_module(u64 ip, struct unwind_info *ui) 86 { 87 struct addr_location al; 88 89 return __report_module(&al, ip, ui); 90 } 91 92 /* 93 * Store all entries within entries array, 94 * we will process it after we finish unwind. 95 */ 96 static int entry(u64 ip, struct unwind_info *ui) 97 98 { 99 struct unwind_entry *e = &ui->entries[ui->idx++]; 100 struct addr_location al; 101 102 if (__report_module(&al, ip, ui)) 103 return -1; 104 105 e->ip = ip; 106 e->ms.maps = al.maps; 107 e->ms.map = al.map; 108 e->ms.sym = al.sym; 109 110 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n", 111 al.sym ? al.sym->name : "''", 112 ip, 113 al.map ? al.map->map_ip(al.map, ip) : (u64) 0); 114 return 0; 115 } 116 117 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp) 118 { 119 /* We want only single thread to be processed. */ 120 if (*thread_argp != NULL) 121 return 0; 122 123 *thread_argp = arg; 124 return dwfl_pid(dwfl); 125 } 126 127 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr, 128 Dwarf_Word *data) 129 { 130 struct addr_location al; 131 ssize_t size; 132 133 if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) { 134 pr_debug("unwind: no map for %lx\n", (unsigned long)addr); 135 return -1; 136 } 137 138 if (!al.map->dso) 139 return -1; 140 141 size = dso__data_read_addr(al.map->dso, al.map, ui->machine, 142 addr, (u8 *) data, sizeof(*data)); 143 144 return !(size == sizeof(*data)); 145 } 146 147 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result, 148 void *arg) 149 { 150 struct unwind_info *ui = arg; 151 struct stack_dump *stack = &ui->sample->user_stack; 152 u64 start, end; 153 int offset; 154 int ret; 155 156 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP); 157 if (ret) 158 return false; 159 160 end = start + stack->size; 161 162 /* Check overflow. */ 163 if (addr + sizeof(Dwarf_Word) < addr) 164 return false; 165 166 if (addr < start || addr + sizeof(Dwarf_Word) > end) { 167 ret = access_dso_mem(ui, addr, result); 168 if (ret) { 169 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range" 170 " 0x%" PRIx64 "-0x%" PRIx64 "\n", 171 addr, start, end); 172 return false; 173 } 174 return true; 175 } 176 177 offset = addr - start; 178 *result = *(Dwarf_Word *)&stack->data[offset]; 179 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n", 180 addr, (unsigned long)*result, offset); 181 return true; 182 } 183 184 static const Dwfl_Thread_Callbacks callbacks = { 185 .next_thread = next_thread, 186 .memory_read = memory_read, 187 .set_initial_registers = libdw__arch_set_initial_registers, 188 }; 189 190 static int 191 frame_callback(Dwfl_Frame *state, void *arg) 192 { 193 struct unwind_info *ui = arg; 194 Dwarf_Addr pc; 195 bool isactivation; 196 197 if (!dwfl_frame_pc(state, &pc, NULL)) { 198 pr_err("%s", dwfl_errmsg(-1)); 199 return DWARF_CB_ABORT; 200 } 201 202 // report the module before we query for isactivation 203 report_module(pc, ui); 204 205 if (!dwfl_frame_pc(state, &pc, &isactivation)) { 206 pr_err("%s", dwfl_errmsg(-1)); 207 return DWARF_CB_ABORT; 208 } 209 210 if (!isactivation) 211 --pc; 212 213 return entry(pc, ui) || !(--ui->max_stack) ? 214 DWARF_CB_ABORT : DWARF_CB_OK; 215 } 216 217 int unwind__get_entries(unwind_entry_cb_t cb, void *arg, 218 struct thread *thread, 219 struct perf_sample *data, 220 int max_stack) 221 { 222 struct unwind_info *ui, ui_buf = { 223 .sample = data, 224 .thread = thread, 225 .machine = thread->maps->machine, 226 .cb = cb, 227 .arg = arg, 228 .max_stack = max_stack, 229 }; 230 Dwarf_Word ip; 231 int err = -EINVAL, i; 232 233 if (!data->user_regs.regs) 234 return -EINVAL; 235 236 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack); 237 if (!ui) 238 return -ENOMEM; 239 240 *ui = ui_buf; 241 242 ui->dwfl = dwfl_begin(&offline_callbacks); 243 if (!ui->dwfl) 244 goto out; 245 246 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP); 247 if (err) 248 goto out; 249 250 err = report_module(ip, ui); 251 if (err) 252 goto out; 253 254 err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui); 255 if (err) 256 goto out; 257 258 err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui); 259 260 if (err && ui->max_stack != max_stack) 261 err = 0; 262 263 /* 264 * Display what we got based on the order setup. 265 */ 266 for (i = 0; i < ui->idx && !err; i++) { 267 int j = i; 268 269 if (callchain_param.order == ORDER_CALLER) 270 j = ui->idx - i - 1; 271 272 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0; 273 } 274 275 out: 276 if (err) 277 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1)); 278 279 dwfl_end(ui->dwfl); 280 free(ui); 281 return 0; 282 } 283