1 #include <linux/compiler.h> 2 #include <elfutils/libdw.h> 3 #include <elfutils/libdwfl.h> 4 #include <inttypes.h> 5 #include <errno.h> 6 #include "debug.h" 7 #include "unwind.h" 8 #include "unwind-libdw.h" 9 #include "machine.h" 10 #include "thread.h" 11 #include <linux/types.h> 12 #include "event.h" 13 #include "perf_regs.h" 14 #include "callchain.h" 15 #include "util.h" 16 17 static char *debuginfo_path; 18 19 static const Dwfl_Callbacks offline_callbacks = { 20 .find_debuginfo = dwfl_standard_find_debuginfo, 21 .debuginfo_path = &debuginfo_path, 22 .section_address = dwfl_offline_section_address, 23 }; 24 25 static int __report_module(struct addr_location *al, u64 ip, 26 struct unwind_info *ui) 27 { 28 Dwfl_Module *mod; 29 struct dso *dso = NULL; 30 31 thread__find_addr_location(ui->thread, 32 PERF_RECORD_MISC_USER, 33 MAP__FUNCTION, ip, al); 34 35 if (al->map) 36 dso = al->map->dso; 37 38 if (!dso) 39 return 0; 40 41 mod = dwfl_addrmodule(ui->dwfl, ip); 42 if (mod) { 43 Dwarf_Addr s; 44 45 dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL); 46 if (s != al->map->start) 47 mod = 0; 48 } 49 50 if (!mod) 51 mod = dwfl_report_elf(ui->dwfl, dso->short_name, 52 dso->long_name, -1, al->map->start, 53 false); 54 55 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; 56 } 57 58 static int report_module(u64 ip, struct unwind_info *ui) 59 { 60 struct addr_location al; 61 62 return __report_module(&al, ip, ui); 63 } 64 65 /* 66 * Store all entries within entries array, 67 * we will process it after we finish unwind. 68 */ 69 static int entry(u64 ip, struct unwind_info *ui) 70 71 { 72 struct unwind_entry *e = &ui->entries[ui->idx++]; 73 struct addr_location al; 74 75 if (__report_module(&al, ip, ui)) 76 return -1; 77 78 e->ip = al.addr; 79 e->map = al.map; 80 e->sym = al.sym; 81 82 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n", 83 al.sym ? al.sym->name : "''", 84 ip, 85 al.map ? al.map->map_ip(al.map, ip) : (u64) 0); 86 return 0; 87 } 88 89 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp) 90 { 91 /* We want only single thread to be processed. */ 92 if (*thread_argp != NULL) 93 return 0; 94 95 *thread_argp = arg; 96 return dwfl_pid(dwfl); 97 } 98 99 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr, 100 Dwarf_Word *data) 101 { 102 struct addr_location al; 103 ssize_t size; 104 105 thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER, 106 MAP__FUNCTION, addr, &al); 107 if (!al.map) { 108 /* 109 * We've seen cases (softice) where DWARF unwinder went 110 * through non executable mmaps, which we need to lookup 111 * in MAP__VARIABLE tree. 112 */ 113 thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER, 114 MAP__VARIABLE, addr, &al); 115 } 116 117 if (!al.map) { 118 pr_debug("unwind: no map for %lx\n", (unsigned long)addr); 119 return -1; 120 } 121 122 if (!al.map->dso) 123 return -1; 124 125 size = dso__data_read_addr(al.map->dso, al.map, ui->machine, 126 addr, (u8 *) data, sizeof(*data)); 127 128 return !(size == sizeof(*data)); 129 } 130 131 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result, 132 void *arg) 133 { 134 struct unwind_info *ui = arg; 135 struct stack_dump *stack = &ui->sample->user_stack; 136 u64 start, end; 137 int offset; 138 int ret; 139 140 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP); 141 if (ret) 142 return false; 143 144 end = start + stack->size; 145 146 /* Check overflow. */ 147 if (addr + sizeof(Dwarf_Word) < addr) 148 return false; 149 150 if (addr < start || addr + sizeof(Dwarf_Word) > end) { 151 ret = access_dso_mem(ui, addr, result); 152 if (ret) { 153 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range" 154 " 0x%" PRIx64 "-0x%" PRIx64 "\n", 155 addr, start, end); 156 return false; 157 } 158 return true; 159 } 160 161 offset = addr - start; 162 *result = *(Dwarf_Word *)&stack->data[offset]; 163 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n", 164 addr, (unsigned long)*result, offset); 165 return true; 166 } 167 168 static const Dwfl_Thread_Callbacks callbacks = { 169 .next_thread = next_thread, 170 .memory_read = memory_read, 171 .set_initial_registers = libdw__arch_set_initial_registers, 172 }; 173 174 static int 175 frame_callback(Dwfl_Frame *state, void *arg) 176 { 177 struct unwind_info *ui = arg; 178 Dwarf_Addr pc; 179 bool isactivation; 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 if (!dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui)) 231 goto out; 232 233 err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui); 234 235 if (err && ui->max_stack != max_stack) 236 err = 0; 237 238 /* 239 * Display what we got based on the order setup. 240 */ 241 for (i = 0; i < ui->idx && !err; i++) { 242 int j = i; 243 244 if (callchain_param.order == ORDER_CALLER) 245 j = ui->idx - i - 1; 246 247 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0; 248 } 249 250 out: 251 if (err) 252 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1)); 253 254 dwfl_end(ui->dwfl); 255 free(ui); 256 return 0; 257 } 258