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 "dso.h" 9 #include "unwind.h" 10 #include "unwind-libdw.h" 11 #include "machine.h" 12 #include "map.h" 13 #include "symbol.h" 14 #include "thread.h" 15 #include <linux/types.h> 16 #include <linux/zalloc.h> 17 #include "event.h" 18 #include "perf_regs.h" 19 #include "callchain.h" 20 21 static char *debuginfo_path; 22 23 static const Dwfl_Callbacks offline_callbacks = { 24 .find_debuginfo = dwfl_standard_find_debuginfo, 25 .debuginfo_path = &debuginfo_path, 26 .section_address = dwfl_offline_section_address, 27 }; 28 29 static int __report_module(struct addr_location *al, u64 ip, 30 struct unwind_info *ui) 31 { 32 Dwfl_Module *mod; 33 struct dso *dso = NULL; 34 /* 35 * Some callers will use al->sym, so we can't just use the 36 * cheaper thread__find_map() here. 37 */ 38 thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al); 39 40 if (al->map) 41 dso = al->map->dso; 42 43 if (!dso) 44 return 0; 45 46 mod = dwfl_addrmodule(ui->dwfl, ip); 47 if (mod) { 48 Dwarf_Addr s; 49 50 dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL); 51 if (s != al->map->start - al->map->pgoff) 52 mod = 0; 53 } 54 55 if (!mod) 56 mod = dwfl_report_elf(ui->dwfl, dso->short_name, 57 (dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start - al->map->pgoff, 58 false); 59 60 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; 61 } 62 63 static int report_module(u64 ip, struct unwind_info *ui) 64 { 65 struct addr_location al; 66 67 return __report_module(&al, ip, ui); 68 } 69 70 /* 71 * Store all entries within entries array, 72 * we will process it after we finish unwind. 73 */ 74 static int entry(u64 ip, struct unwind_info *ui) 75 76 { 77 struct unwind_entry *e = &ui->entries[ui->idx++]; 78 struct addr_location al; 79 80 if (__report_module(&al, ip, ui)) 81 return -1; 82 83 e->ip = ip; 84 e->map = al.map; 85 e->sym = al.sym; 86 87 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n", 88 al.sym ? al.sym->name : "''", 89 ip, 90 al.map ? al.map->map_ip(al.map, ip) : (u64) 0); 91 return 0; 92 } 93 94 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp) 95 { 96 /* We want only single thread to be processed. */ 97 if (*thread_argp != NULL) 98 return 0; 99 100 *thread_argp = arg; 101 return dwfl_pid(dwfl); 102 } 103 104 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr, 105 Dwarf_Word *data) 106 { 107 struct addr_location al; 108 ssize_t size; 109 110 if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) { 111 pr_debug("unwind: no map for %lx\n", (unsigned long)addr); 112 return -1; 113 } 114 115 if (!al.map->dso) 116 return -1; 117 118 size = dso__data_read_addr(al.map->dso, al.map, ui->machine, 119 addr, (u8 *) data, sizeof(*data)); 120 121 return !(size == sizeof(*data)); 122 } 123 124 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result, 125 void *arg) 126 { 127 struct unwind_info *ui = arg; 128 struct stack_dump *stack = &ui->sample->user_stack; 129 u64 start, end; 130 int offset; 131 int ret; 132 133 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP); 134 if (ret) 135 return false; 136 137 end = start + stack->size; 138 139 /* Check overflow. */ 140 if (addr + sizeof(Dwarf_Word) < addr) 141 return false; 142 143 if (addr < start || addr + sizeof(Dwarf_Word) > end) { 144 ret = access_dso_mem(ui, addr, result); 145 if (ret) { 146 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range" 147 " 0x%" PRIx64 "-0x%" PRIx64 "\n", 148 addr, start, end); 149 return false; 150 } 151 return true; 152 } 153 154 offset = addr - start; 155 *result = *(Dwarf_Word *)&stack->data[offset]; 156 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n", 157 addr, (unsigned long)*result, offset); 158 return true; 159 } 160 161 static const Dwfl_Thread_Callbacks callbacks = { 162 .next_thread = next_thread, 163 .memory_read = memory_read, 164 .set_initial_registers = libdw__arch_set_initial_registers, 165 }; 166 167 static int 168 frame_callback(Dwfl_Frame *state, void *arg) 169 { 170 struct unwind_info *ui = arg; 171 Dwarf_Addr pc; 172 bool isactivation; 173 174 if (!dwfl_frame_pc(state, &pc, NULL)) { 175 pr_err("%s", dwfl_errmsg(-1)); 176 return DWARF_CB_ABORT; 177 } 178 179 // report the module before we query for isactivation 180 report_module(pc, ui); 181 182 if (!dwfl_frame_pc(state, &pc, &isactivation)) { 183 pr_err("%s", dwfl_errmsg(-1)); 184 return DWARF_CB_ABORT; 185 } 186 187 if (!isactivation) 188 --pc; 189 190 return entry(pc, ui) || !(--ui->max_stack) ? 191 DWARF_CB_ABORT : DWARF_CB_OK; 192 } 193 194 int unwind__get_entries(unwind_entry_cb_t cb, void *arg, 195 struct thread *thread, 196 struct perf_sample *data, 197 int max_stack) 198 { 199 struct unwind_info *ui, ui_buf = { 200 .sample = data, 201 .thread = thread, 202 .machine = thread->mg->machine, 203 .cb = cb, 204 .arg = arg, 205 .max_stack = max_stack, 206 }; 207 Dwarf_Word ip; 208 int err = -EINVAL, i; 209 210 if (!data->user_regs.regs) 211 return -EINVAL; 212 213 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack); 214 if (!ui) 215 return -ENOMEM; 216 217 *ui = ui_buf; 218 219 ui->dwfl = dwfl_begin(&offline_callbacks); 220 if (!ui->dwfl) 221 goto out; 222 223 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP); 224 if (err) 225 goto out; 226 227 err = report_module(ip, ui); 228 if (err) 229 goto out; 230 231 err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui); 232 if (err) 233 goto out; 234 235 err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui); 236 237 if (err && ui->max_stack != max_stack) 238 err = 0; 239 240 /* 241 * Display what we got based on the order setup. 242 */ 243 for (i = 0; i < ui->idx && !err; i++) { 244 int j = i; 245 246 if (callchain_param.order == ORDER_CALLER) 247 j = ui->idx - i - 1; 248 249 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0; 250 } 251 252 out: 253 if (err) 254 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1)); 255 256 dwfl_end(ui->dwfl); 257 free(ui); 258 return 0; 259 } 260