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