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 "unwind.h" 9 #include "unwind-libdw.h" 10 #include "machine.h" 11 #include "map.h" 12 #include "symbol.h" 13 #include "thread.h" 14 #include <linux/types.h> 15 #include "event.h" 16 #include "perf_regs.h" 17 #include "callchain.h" 18 #include "util.h" 19 20 static char *debuginfo_path; 21 22 static const Dwfl_Callbacks offline_callbacks = { 23 .find_debuginfo = dwfl_standard_find_debuginfo, 24 .debuginfo_path = &debuginfo_path, 25 .section_address = dwfl_offline_section_address, 26 }; 27 28 static int __report_module(struct addr_location *al, u64 ip, 29 struct unwind_info *ui) 30 { 31 Dwfl_Module *mod; 32 struct dso *dso = NULL; 33 /* 34 * Some callers will use al->sym, so we can't just use the 35 * cheaper thread__find_map() here. 36 */ 37 thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al); 38 39 if (al->map) 40 dso = al->map->dso; 41 42 if (!dso) 43 return 0; 44 45 mod = dwfl_addrmodule(ui->dwfl, ip); 46 if (mod) { 47 Dwarf_Addr s; 48 49 dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL); 50 if (s != al->map->start - al->map->pgoff) 51 mod = 0; 52 } 53 54 if (!mod) 55 mod = dwfl_report_elf(ui->dwfl, dso->short_name, 56 (dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start - al->map->pgoff, 57 false); 58 59 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; 60 } 61 62 static int report_module(u64 ip, struct unwind_info *ui) 63 { 64 struct addr_location al; 65 66 return __report_module(&al, ip, ui); 67 } 68 69 /* 70 * Store all entries within entries array, 71 * we will process it after we finish unwind. 72 */ 73 static int entry(u64 ip, struct unwind_info *ui) 74 75 { 76 struct unwind_entry *e = &ui->entries[ui->idx++]; 77 struct addr_location al; 78 79 if (__report_module(&al, ip, ui)) 80 return -1; 81 82 e->ip = ip; 83 e->map = al.map; 84 e->sym = al.sym; 85 86 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n", 87 al.sym ? al.sym->name : "''", 88 ip, 89 al.map ? al.map->map_ip(al.map, ip) : (u64) 0); 90 return 0; 91 } 92 93 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp) 94 { 95 /* We want only single thread to be processed. */ 96 if (*thread_argp != NULL) 97 return 0; 98 99 *thread_argp = arg; 100 return dwfl_pid(dwfl); 101 } 102 103 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr, 104 Dwarf_Word *data) 105 { 106 struct addr_location al; 107 ssize_t size; 108 109 if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) { 110 pr_debug("unwind: no map for %lx\n", (unsigned long)addr); 111 return -1; 112 } 113 114 if (!al.map->dso) 115 return -1; 116 117 size = dso__data_read_addr(al.map->dso, al.map, ui->machine, 118 addr, (u8 *) data, sizeof(*data)); 119 120 return !(size == sizeof(*data)); 121 } 122 123 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result, 124 void *arg) 125 { 126 struct unwind_info *ui = arg; 127 struct stack_dump *stack = &ui->sample->user_stack; 128 u64 start, end; 129 int offset; 130 int ret; 131 132 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP); 133 if (ret) 134 return false; 135 136 end = start + stack->size; 137 138 /* Check overflow. */ 139 if (addr + sizeof(Dwarf_Word) < addr) 140 return false; 141 142 if (addr < start || addr + sizeof(Dwarf_Word) > end) { 143 ret = access_dso_mem(ui, addr, result); 144 if (ret) { 145 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range" 146 " 0x%" PRIx64 "-0x%" PRIx64 "\n", 147 addr, start, end); 148 return false; 149 } 150 return true; 151 } 152 153 offset = addr - start; 154 *result = *(Dwarf_Word *)&stack->data[offset]; 155 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n", 156 addr, (unsigned long)*result, offset); 157 return true; 158 } 159 160 static const Dwfl_Thread_Callbacks callbacks = { 161 .next_thread = next_thread, 162 .memory_read = memory_read, 163 .set_initial_registers = libdw__arch_set_initial_registers, 164 }; 165 166 static int 167 frame_callback(Dwfl_Frame *state, void *arg) 168 { 169 struct unwind_info *ui = arg; 170 Dwarf_Addr pc; 171 bool isactivation; 172 173 if (!dwfl_frame_pc(state, &pc, NULL)) { 174 pr_err("%s", dwfl_errmsg(-1)); 175 return DWARF_CB_ABORT; 176 } 177 178 // report the module before we query for isactivation 179 report_module(pc, ui); 180 181 if (!dwfl_frame_pc(state, &pc, &isactivation)) { 182 pr_err("%s", dwfl_errmsg(-1)); 183 return DWARF_CB_ABORT; 184 } 185 186 if (!isactivation) 187 --pc; 188 189 return entry(pc, ui) || !(--ui->max_stack) ? 190 DWARF_CB_ABORT : DWARF_CB_OK; 191 } 192 193 int unwind__get_entries(unwind_entry_cb_t cb, void *arg, 194 struct thread *thread, 195 struct perf_sample *data, 196 int max_stack) 197 { 198 struct unwind_info *ui, ui_buf = { 199 .sample = data, 200 .thread = thread, 201 .machine = thread->mg->machine, 202 .cb = cb, 203 .arg = arg, 204 .max_stack = max_stack, 205 }; 206 Dwarf_Word ip; 207 int err = -EINVAL, i; 208 209 if (!data->user_regs.regs) 210 return -EINVAL; 211 212 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack); 213 if (!ui) 214 return -ENOMEM; 215 216 *ui = ui_buf; 217 218 ui->dwfl = dwfl_begin(&offline_callbacks); 219 if (!ui->dwfl) 220 goto out; 221 222 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP); 223 if (err) 224 goto out; 225 226 err = report_module(ip, ui); 227 if (err) 228 goto out; 229 230 err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui); 231 if (err) 232 goto out; 233 234 err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui); 235 236 if (err && ui->max_stack != max_stack) 237 err = 0; 238 239 /* 240 * Display what we got based on the order setup. 241 */ 242 for (i = 0; i < ui->idx && !err; i++) { 243 int j = i; 244 245 if (callchain_param.order == ORDER_CALLER) 246 j = ui->idx - i - 1; 247 248 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0; 249 } 250 251 out: 252 if (err) 253 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1)); 254 255 dwfl_end(ui->dwfl); 256 free(ui); 257 return 0; 258 } 259