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 | #include "util/env.h" |
21 | |
22 | static char *debuginfo_path; |
23 | |
24 | static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata, |
25 | const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused, |
26 | const char *file_name, const char *debuglink_file __maybe_unused, |
27 | GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name) |
28 | { |
29 | const struct dso *dso = *userdata; |
30 | |
31 | assert(dso); |
32 | if (dso->symsrc_filename && strcmp (file_name, dso->symsrc_filename)) |
33 | *debuginfo_file_name = strdup(dso->symsrc_filename); |
34 | return -1; |
35 | } |
36 | |
37 | static const Dwfl_Callbacks offline_callbacks = { |
38 | .find_debuginfo = __find_debuginfo, |
39 | .debuginfo_path = &debuginfo_path, |
40 | .section_address = dwfl_offline_section_address, |
41 | // .find_elf is not set as we use dwfl_report_elf() instead. |
42 | }; |
43 | |
44 | static int __report_module(struct addr_location *al, u64 ip, |
45 | struct unwind_info *ui) |
46 | { |
47 | Dwfl_Module *mod; |
48 | struct dso *dso = NULL; |
49 | Dwarf_Addr base; |
50 | /* |
51 | * Some callers will use al->sym, so we can't just use the |
52 | * cheaper thread__find_map() here. |
53 | */ |
54 | thread__find_symbol(thread: ui->thread, PERF_RECORD_MISC_USER, addr: ip, al); |
55 | |
56 | if (al->map) |
57 | dso = map__dso(map: al->map); |
58 | |
59 | if (!dso) |
60 | return 0; |
61 | |
62 | /* |
63 | * The generated JIT DSO files only map the code segment without |
64 | * ELF headers. Since JIT codes used to be packed in a memory |
65 | * segment, calculating the base address using pgoff falls into |
66 | * a different code in another DSO. So just use the map->start |
67 | * directly to pick the correct one. |
68 | */ |
69 | if (!strncmp(dso->long_name, "/tmp/jitted-" , 12)) |
70 | base = map__start(al->map); |
71 | else |
72 | base = map__start(al->map) - map__pgoff(al->map); |
73 | |
74 | mod = dwfl_addrmodule(ui->dwfl, ip); |
75 | if (mod) { |
76 | Dwarf_Addr s; |
77 | |
78 | dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL); |
79 | if (s != base) |
80 | mod = NULL; |
81 | } |
82 | |
83 | if (!mod) { |
84 | char filename[PATH_MAX]; |
85 | |
86 | __symbol__join_symfs(bf: filename, size: sizeof(filename), path: dso->long_name); |
87 | mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1, |
88 | base, false); |
89 | } |
90 | if (!mod) { |
91 | char filename[PATH_MAX]; |
92 | |
93 | if (dso__build_id_filename(dso, filename, sizeof(filename), false)) |
94 | mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1, |
95 | base, false); |
96 | } |
97 | |
98 | if (mod) { |
99 | void **userdatap; |
100 | |
101 | dwfl_module_info(mod, &userdatap, NULL, NULL, NULL, NULL, NULL, NULL); |
102 | *userdatap = dso; |
103 | } |
104 | |
105 | return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; |
106 | } |
107 | |
108 | static int report_module(u64 ip, struct unwind_info *ui) |
109 | { |
110 | struct addr_location al; |
111 | int res; |
112 | |
113 | addr_location__init(al: &al); |
114 | res = __report_module(al: &al, ip, ui); |
115 | addr_location__exit(al: &al); |
116 | return res; |
117 | } |
118 | |
119 | /* |
120 | * Store all entries within entries array, |
121 | * we will process it after we finish unwind. |
122 | */ |
123 | static int entry(u64 ip, struct unwind_info *ui) |
124 | |
125 | { |
126 | struct unwind_entry *e = &ui->entries[ui->idx++]; |
127 | struct addr_location al; |
128 | |
129 | addr_location__init(al: &al); |
130 | if (__report_module(al: &al, ip, ui)) { |
131 | addr_location__exit(al: &al); |
132 | return -1; |
133 | } |
134 | |
135 | e->ip = ip; |
136 | e->ms.maps = al.maps; |
137 | e->ms.map = al.map; |
138 | e->ms.sym = al.sym; |
139 | |
140 | pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n" , |
141 | al.sym ? al.sym->name : "''" , |
142 | ip, |
143 | al.map ? map__map_ip(al.map, ip) : (u64) 0); |
144 | addr_location__exit(al: &al); |
145 | return 0; |
146 | } |
147 | |
148 | static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp) |
149 | { |
150 | /* We want only single thread to be processed. */ |
151 | if (*thread_argp != NULL) |
152 | return 0; |
153 | |
154 | *thread_argp = arg; |
155 | return dwfl_pid(dwfl); |
156 | } |
157 | |
158 | static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr, |
159 | Dwarf_Word *data) |
160 | { |
161 | struct addr_location al; |
162 | ssize_t size; |
163 | struct dso *dso; |
164 | |
165 | addr_location__init(al: &al); |
166 | if (!thread__find_map(thread: ui->thread, PERF_RECORD_MISC_USER, addr: addr, al: &al)) { |
167 | pr_debug("unwind: no map for %lx\n" , (unsigned long)addr); |
168 | goto out_fail; |
169 | } |
170 | dso = map__dso(map: al.map); |
171 | if (!dso) |
172 | goto out_fail; |
173 | |
174 | size = dso__data_read_addr(dso, map: al.map, machine: ui->machine, addr: addr, data: (u8 *) data, size: sizeof(*data)); |
175 | |
176 | addr_location__exit(al: &al); |
177 | return !(size == sizeof(*data)); |
178 | out_fail: |
179 | addr_location__exit(al: &al); |
180 | return -1; |
181 | } |
182 | |
183 | static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result, |
184 | void *arg) |
185 | { |
186 | struct unwind_info *ui = arg; |
187 | const char *arch = perf_env__arch(ui->machine->env); |
188 | struct stack_dump *stack = &ui->sample->user_stack; |
189 | u64 start, end; |
190 | int offset; |
191 | int ret; |
192 | |
193 | ret = perf_reg_value(regs: &start, idx: &ui->sample->user_regs, |
194 | perf_arch_reg_sp(arch)); |
195 | if (ret) |
196 | return false; |
197 | |
198 | end = start + stack->size; |
199 | |
200 | /* Check overflow. */ |
201 | if (addr + sizeof(Dwarf_Word) < addr) |
202 | return false; |
203 | |
204 | if (addr < start || addr + sizeof(Dwarf_Word) > end) { |
205 | ret = access_dso_mem(ui, addr, result); |
206 | if (ret) { |
207 | pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range" |
208 | " 0x%" PRIx64 "-0x%" PRIx64 "\n" , |
209 | addr, start, end); |
210 | return false; |
211 | } |
212 | return true; |
213 | } |
214 | |
215 | offset = addr - start; |
216 | *result = *(Dwarf_Word *)&stack->data[offset]; |
217 | pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n" , |
218 | addr, (unsigned long)*result, offset); |
219 | return true; |
220 | } |
221 | |
222 | static const Dwfl_Thread_Callbacks callbacks = { |
223 | .next_thread = next_thread, |
224 | .memory_read = memory_read, |
225 | .set_initial_registers = libdw__arch_set_initial_registers, |
226 | }; |
227 | |
228 | static int |
229 | frame_callback(Dwfl_Frame *state, void *arg) |
230 | { |
231 | struct unwind_info *ui = arg; |
232 | Dwarf_Addr pc; |
233 | bool isactivation; |
234 | |
235 | if (!dwfl_frame_pc(state, &pc, NULL)) { |
236 | if (!ui->best_effort) |
237 | pr_err("%s" , dwfl_errmsg(-1)); |
238 | return DWARF_CB_ABORT; |
239 | } |
240 | |
241 | // report the module before we query for isactivation |
242 | report_module(pc, ui); |
243 | |
244 | if (!dwfl_frame_pc(state, &pc, &isactivation)) { |
245 | if (!ui->best_effort) |
246 | pr_err("%s" , dwfl_errmsg(-1)); |
247 | return DWARF_CB_ABORT; |
248 | } |
249 | |
250 | if (!isactivation) |
251 | --pc; |
252 | |
253 | return entry(pc, ui) || !(--ui->max_stack) ? |
254 | DWARF_CB_ABORT : DWARF_CB_OK; |
255 | } |
256 | |
257 | int unwind__get_entries(unwind_entry_cb_t cb, void *arg, |
258 | struct thread *thread, |
259 | struct perf_sample *data, |
260 | int max_stack, |
261 | bool best_effort) |
262 | { |
263 | struct unwind_info *ui, ui_buf = { |
264 | .sample = data, |
265 | .thread = thread, |
266 | .machine = maps__machine(maps: (thread__maps(thread))), |
267 | .cb = cb, |
268 | .arg = arg, |
269 | .max_stack = max_stack, |
270 | .best_effort = best_effort |
271 | }; |
272 | const char *arch = perf_env__arch(ui_buf.machine->env); |
273 | Dwarf_Word ip; |
274 | int err = -EINVAL, i; |
275 | |
276 | if (!data->user_regs.regs) |
277 | return -EINVAL; |
278 | |
279 | ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack); |
280 | if (!ui) |
281 | return -ENOMEM; |
282 | |
283 | *ui = ui_buf; |
284 | |
285 | ui->dwfl = dwfl_begin(&offline_callbacks); |
286 | if (!ui->dwfl) |
287 | goto out; |
288 | |
289 | err = perf_reg_value(&ip, &data->user_regs, perf_arch_reg_ip(arch)); |
290 | if (err) |
291 | goto out; |
292 | |
293 | err = report_module(ip, ui); |
294 | if (err) |
295 | goto out; |
296 | |
297 | err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread__tid(thread), &callbacks, ui); |
298 | if (err) |
299 | goto out; |
300 | |
301 | err = dwfl_getthread_frames(ui->dwfl, thread__tid(thread), frame_callback, ui); |
302 | |
303 | if (err && ui->max_stack != max_stack) |
304 | err = 0; |
305 | |
306 | /* |
307 | * Display what we got based on the order setup. |
308 | */ |
309 | for (i = 0; i < ui->idx && !err; i++) { |
310 | int j = i; |
311 | |
312 | if (callchain_param.order == ORDER_CALLER) |
313 | j = ui->idx - i - 1; |
314 | |
315 | err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0; |
316 | } |
317 | |
318 | out: |
319 | if (err) |
320 | pr_debug("unwind: failed with '%s'\n" , dwfl_errmsg(-1)); |
321 | |
322 | dwfl_end(ui->dwfl); |
323 | free(ui); |
324 | return 0; |
325 | } |
326 | |