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