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 pr_debug("unwind: no map for %lx\n", (unsigned long)addr); 100 return -1; 101 } 102 103 if (!al.map->dso) 104 return -1; 105 106 size = dso__data_read_addr(al.map->dso, al.map, ui->machine, 107 addr, (u8 *) data, sizeof(*data)); 108 109 return !(size == sizeof(*data)); 110 } 111 112 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result, 113 void *arg) 114 { 115 struct unwind_info *ui = arg; 116 struct stack_dump *stack = &ui->sample->user_stack; 117 u64 start, end; 118 int offset; 119 int ret; 120 121 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP); 122 if (ret) 123 return false; 124 125 end = start + stack->size; 126 127 /* Check overflow. */ 128 if (addr + sizeof(Dwarf_Word) < addr) 129 return false; 130 131 if (addr < start || addr + sizeof(Dwarf_Word) > end) { 132 ret = access_dso_mem(ui, addr, result); 133 if (ret) { 134 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range" 135 " 0x%" PRIx64 "-0x%" PRIx64 "\n", 136 addr, start, end); 137 return false; 138 } 139 return true; 140 } 141 142 offset = addr - start; 143 *result = *(Dwarf_Word *)&stack->data[offset]; 144 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n", 145 addr, (unsigned long)*result, offset); 146 return true; 147 } 148 149 static const Dwfl_Thread_Callbacks callbacks = { 150 .next_thread = next_thread, 151 .memory_read = memory_read, 152 .set_initial_registers = libdw__arch_set_initial_registers, 153 }; 154 155 static int 156 frame_callback(Dwfl_Frame *state, void *arg) 157 { 158 struct unwind_info *ui = arg; 159 Dwarf_Addr pc; 160 161 if (!dwfl_frame_pc(state, &pc, NULL)) { 162 pr_err("%s", dwfl_errmsg(-1)); 163 return DWARF_CB_ABORT; 164 } 165 166 return entry(pc, ui) || !(--ui->max_stack) ? 167 DWARF_CB_ABORT : DWARF_CB_OK; 168 } 169 170 int unwind__get_entries(unwind_entry_cb_t cb, void *arg, 171 struct thread *thread, 172 struct perf_sample *data, 173 int max_stack) 174 { 175 struct unwind_info *ui, ui_buf = { 176 .sample = data, 177 .thread = thread, 178 .machine = thread->mg->machine, 179 .cb = cb, 180 .arg = arg, 181 .max_stack = max_stack, 182 }; 183 Dwarf_Word ip; 184 int err = -EINVAL, i; 185 186 if (!data->user_regs.regs) 187 return -EINVAL; 188 189 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack); 190 if (!ui) 191 return -ENOMEM; 192 193 *ui = ui_buf; 194 195 ui->dwfl = dwfl_begin(&offline_callbacks); 196 if (!ui->dwfl) 197 goto out; 198 199 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP); 200 if (err) 201 goto out; 202 203 err = report_module(ip, ui); 204 if (err) 205 goto out; 206 207 if (!dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui)) 208 goto out; 209 210 err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui); 211 212 if (err && !ui->max_stack) 213 err = 0; 214 215 /* 216 * Display what we got based on the order setup. 217 */ 218 for (i = 0; i < ui->idx && !err; i++) { 219 int j = i; 220 221 if (callchain_param.order == ORDER_CALLER) 222 j = ui->idx - i - 1; 223 224 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0; 225 } 226 227 out: 228 if (err) 229 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1)); 230 231 dwfl_end(ui->dwfl); 232 free(ui); 233 return 0; 234 } 235