1 // SPDX-License-Identifier: GPL-2.0 1
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 _
25 const char *modnam
26 const char *file_n
27 GElf_Word debuglin
28 {
29 const struct dso *dso = *userdata;
30
31 assert(dso);
32 if (dso__symsrc_filename(dso) && strcm
33 *debuginfo_file_name = strdup(
34 return -1;
35 }
36
37 static const Dwfl_Callbacks offline_callbacks
38 .find_debuginfo = __find_debug
39 .debuginfo_path = &debuginfo_p
40 .section_address = dwfl_offline
41 // .find_elf is not set as we use dwfl
42 };
43
44 static int __report_module(struct addr_locatio
45 struct unwind_info
46 {
47 Dwfl_Module *mod;
48 struct dso *dso = NULL;
49 Dwarf_Addr base;
50 /*
51 * Some callers will use al->sym, so w
52 * cheaper thread__find_map() here.
53 */
54 thread__find_symbol(ui->thread, PERF_R
55
56 if (al->map)
57 dso = map__dso(al->map);
58
59 if (!dso)
60 return 0;
61
62 /*
63 * The generated JIT DSO files only ma
64 * ELF headers. Since JIT codes used
65 * segment, calculating the base addre
66 * a different code in another DSO. S
67 * directly to pick the correct one.
68 */
69 if (!strncmp(dso__long_name(dso), "/tm
70 base = map__start(al->map);
71 else
72 base = map__start(al->map) - m
73
74 mod = dwfl_addrmodule(ui->dwfl, ip);
75 if (mod) {
76 Dwarf_Addr s;
77
78 dwfl_module_info(mod, NULL, &s
79 if (s != base)
80 mod = NULL;
81 }
82
83 if (!mod) {
84 char filename[PATH_MAX];
85
86 __symbol__join_symfs(filename,
87 mod = dwfl_report_elf(ui->dwfl
88 base, fa
89 }
90 if (!mod) {
91 char filename[PATH_MAX];
92
93 if (dso__build_id_filename(dso
94 mod = dwfl_report_elf(
95
96 }
97
98 if (mod) {
99 void **userdatap;
100
101 dwfl_module_info(mod, &userdat
102 *userdatap = dso;
103 }
104
105 return mod && dwfl_addrmodule(ui->dwfl
106 }
107
108 static int report_module(u64 ip, struct unwind
109 {
110 struct addr_location al;
111 int res;
112
113 addr_location__init(&al);
114 res = __report_module(&al, ip, ui);
115 addr_location__exit(&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 *u
124
125 {
126 struct unwind_entry *e = &ui->entries[
127 struct addr_location al;
128
129 addr_location__init(&al);
130 if (__report_module(&al, ip, ui)) {
131 addr_location__exit(&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
141 al.sym ? al.sym->name : "''",
142 ip,
143 al.map ? map__map_ip(al.map,
144 addr_location__exit(&al);
145 return 0;
146 }
147
148 static pid_t next_thread(Dwfl *dwfl, void *arg
149 {
150 /* We want only single thread to be pr
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 *
159 Dwarf_Word *data)
160 {
161 struct addr_location al;
162 ssize_t size;
163 struct dso *dso;
164
165 addr_location__init(&al);
166 if (!thread__find_map(ui->thread, PERF
167 pr_debug("unwind: no map for %
168 goto out_fail;
169 }
170 dso = map__dso(al.map);
171 if (!dso)
172 goto out_fail;
173
174 size = dso__data_read_addr(dso, al.map
175
176 addr_location__exit(&al);
177 return !(size == sizeof(*data));
178 out_fail:
179 addr_location__exit(&al);
180 return -1;
181 }
182
183 static bool memory_read(Dwfl *dwfl __maybe_unu
184 void *arg)
185 {
186 struct unwind_info *ui = arg;
187 const char *arch = perf_env__arch(ui->
188 struct stack_dump *stack = &ui->sample
189 u64 start, end;
190 int offset;
191 int ret;
192
193 ret = perf_reg_value(&start, &ui->samp
194 perf_arch_reg_sp(
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(Dwar
205 ret = access_dso_mem(ui, addr,
206 if (ret) {
207 pr_debug("unwind: acce
208 " 0x%" PRIx64
209 addr, start, e
210 return false;
211 }
212 return true;
213 }
214
215 offset = addr - start;
216 *result = *(Dwarf_Word *)&stack->data[
217 pr_debug("unwind: access_mem addr 0x%"
218 addr, (unsigned long)*result,
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_
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_errm
238 return DWARF_CB_ABORT;
239 }
240
241 // report the module before we query f
242 report_module(pc, ui);
243
244 if (!dwfl_frame_pc(state, &pc, &isacti
245 if (!ui->best_effort)
246 pr_err("%s", dwfl_errm
247 return DWARF_CB_ABORT;
248 }
249
250 if (!isactivation)
251 --pc;
252
253 return entry(pc, ui) || !(--ui->max_st
254 DWARF_CB_ABORT : DWARF_CB_OK;
255 }
256
257 int unwind__get_entries(unwind_entry_cb_t cb,
258 struct thread *thread,
259 struct perf_sample *da
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__machin
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_b
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
280 if (!ui)
281 return -ENOMEM;
282
283 *ui = ui_buf;
284
285 ui->dwfl = dwfl_begin(&offline_callbac
286 if (!ui->dwfl)
287 goto out;
288
289 err = perf_reg_value(&ip, &data->user_
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_
298 if (err)
299 goto out;
300
301 err = dwfl_getthread_frames(ui->dwfl,
302
303 if (err && ui->max_stack != max_stack)
304 err = 0;
305
306 /*
307 * Display what we got based on the or
308 */
309 for (i = 0; i < ui->idx && !err; i++)
310 int j = i;
311
312 if (callchain_param.order == O
313 j = ui->idx - i - 1;
314
315 err = ui->entries[j].ip ? ui->
316 }
317
318 out:
319 if (err)
320 pr_debug("unwind: failed with
321
322 dwfl_end(ui->dwfl);
323 free(ui);
324 return 0;
325 }
326
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