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 mod = dwfl_report_elf(ui->dwfl, dso->short_name, 44 dso->long_name, -1, al->map->start, 45 false); 46 47 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; 48 } 49 50 static int report_module(u64 ip, struct unwind_info *ui) 51 { 52 struct addr_location al; 53 54 return __report_module(&al, ip, ui); 55 } 56 57 /* 58 * Store all entries within entries array, 59 * we will process it after we finish unwind. 60 */ 61 static int entry(u64 ip, struct unwind_info *ui) 62 63 { 64 struct unwind_entry *e = &ui->entries[ui->idx++]; 65 struct addr_location al; 66 67 if (__report_module(&al, ip, ui)) 68 return -1; 69 70 e->ip = al.addr; 71 e->map = al.map; 72 e->sym = al.sym; 73 74 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n", 75 al.sym ? al.sym->name : "''", 76 ip, 77 al.map ? al.map->map_ip(al.map, ip) : (u64) 0); 78 return 0; 79 } 80 81 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp) 82 { 83 /* We want only single thread to be processed. */ 84 if (*thread_argp != NULL) 85 return 0; 86 87 *thread_argp = arg; 88 return dwfl_pid(dwfl); 89 } 90 91 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr, 92 Dwarf_Word *data) 93 { 94 struct addr_location al; 95 ssize_t size; 96 97 thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER, 98 MAP__FUNCTION, addr, &al); 99 if (!al.map) { 100 /* 101 * We've seen cases (softice) where DWARF unwinder went 102 * through non executable mmaps, which we need to lookup 103 * in MAP__VARIABLE tree. 104 */ 105 thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER, 106 MAP__VARIABLE, addr, &al); 107 } 108 109 if (!al.map) { 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, &isactivation)) { 174 pr_err("%s", dwfl_errmsg(-1)); 175 return DWARF_CB_ABORT; 176 } 177 178 if (!isactivation) 179 --pc; 180 181 return entry(pc, ui) || !(--ui->max_stack) ? 182 DWARF_CB_ABORT : DWARF_CB_OK; 183 } 184 185 int unwind__get_entries(unwind_entry_cb_t cb, void *arg, 186 struct thread *thread, 187 struct perf_sample *data, 188 int max_stack) 189 { 190 struct unwind_info *ui, ui_buf = { 191 .sample = data, 192 .thread = thread, 193 .machine = thread->mg->machine, 194 .cb = cb, 195 .arg = arg, 196 .max_stack = max_stack, 197 }; 198 Dwarf_Word ip; 199 int err = -EINVAL, i; 200 201 if (!data->user_regs.regs) 202 return -EINVAL; 203 204 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack); 205 if (!ui) 206 return -ENOMEM; 207 208 *ui = ui_buf; 209 210 ui->dwfl = dwfl_begin(&offline_callbacks); 211 if (!ui->dwfl) 212 goto out; 213 214 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP); 215 if (err) 216 goto out; 217 218 err = report_module(ip, ui); 219 if (err) 220 goto out; 221 222 if (!dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui)) 223 goto out; 224 225 err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui); 226 227 if (err && !ui->max_stack) 228 err = 0; 229 230 /* 231 * Display what we got based on the order setup. 232 */ 233 for (i = 0; i < ui->idx && !err; i++) { 234 int j = i; 235 236 if (callchain_param.order == ORDER_CALLER) 237 j = ui->idx - i - 1; 238 239 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0; 240 } 241 242 out: 243 if (err) 244 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1)); 245 246 dwfl_end(ui->dwfl); 247 free(ui); 248 return 0; 249 } 250