Loading...
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
18static char *debuginfo_path;
19
20static 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
26static 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 thread__find_addr_location(ui->thread,
33 PERF_RECORD_MISC_USER,
34 MAP__FUNCTION, ip, al);
35
36 if (al->map)
37 dso = al->map->dso;
38
39 if (!dso)
40 return 0;
41
42 mod = dwfl_addrmodule(ui->dwfl, ip);
43 if (mod) {
44 Dwarf_Addr s;
45
46 dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL);
47 if (s != al->map->start)
48 mod = 0;
49 }
50
51 if (!mod)
52 mod = dwfl_report_elf(ui->dwfl, dso->short_name,
53 (dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start,
54 false);
55
56 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
57}
58
59static int report_module(u64 ip, struct unwind_info *ui)
60{
61 struct addr_location al;
62
63 return __report_module(&al, ip, ui);
64}
65
66/*
67 * Store all entries within entries array,
68 * we will process it after we finish unwind.
69 */
70static int entry(u64 ip, struct unwind_info *ui)
71
72{
73 struct unwind_entry *e = &ui->entries[ui->idx++];
74 struct addr_location al;
75
76 if (__report_module(&al, ip, ui))
77 return -1;
78
79 e->ip = al.addr;
80 e->map = al.map;
81 e->sym = al.sym;
82
83 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
84 al.sym ? al.sym->name : "''",
85 ip,
86 al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
87 return 0;
88}
89
90static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
91{
92 /* We want only single thread to be processed. */
93 if (*thread_argp != NULL)
94 return 0;
95
96 *thread_argp = arg;
97 return dwfl_pid(dwfl);
98}
99
100static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
101 Dwarf_Word *data)
102{
103 struct addr_location al;
104 ssize_t size;
105
106 thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
107 MAP__FUNCTION, addr, &al);
108 if (!al.map) {
109 /*
110 * We've seen cases (softice) where DWARF unwinder went
111 * through non executable mmaps, which we need to lookup
112 * in MAP__VARIABLE tree.
113 */
114 thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
115 MAP__VARIABLE, addr, &al);
116 }
117
118 if (!al.map) {
119 pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
120 return -1;
121 }
122
123 if (!al.map->dso)
124 return -1;
125
126 size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
127 addr, (u8 *) data, sizeof(*data));
128
129 return !(size == sizeof(*data));
130}
131
132static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
133 void *arg)
134{
135 struct unwind_info *ui = arg;
136 struct stack_dump *stack = &ui->sample->user_stack;
137 u64 start, end;
138 int offset;
139 int ret;
140
141 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
142 if (ret)
143 return false;
144
145 end = start + stack->size;
146
147 /* Check overflow. */
148 if (addr + sizeof(Dwarf_Word) < addr)
149 return false;
150
151 if (addr < start || addr + sizeof(Dwarf_Word) > end) {
152 ret = access_dso_mem(ui, addr, result);
153 if (ret) {
154 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
155 " 0x%" PRIx64 "-0x%" PRIx64 "\n",
156 addr, start, end);
157 return false;
158 }
159 return true;
160 }
161
162 offset = addr - start;
163 *result = *(Dwarf_Word *)&stack->data[offset];
164 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
165 addr, (unsigned long)*result, offset);
166 return true;
167}
168
169static const Dwfl_Thread_Callbacks callbacks = {
170 .next_thread = next_thread,
171 .memory_read = memory_read,
172 .set_initial_registers = libdw__arch_set_initial_registers,
173};
174
175static int
176frame_callback(Dwfl_Frame *state, void *arg)
177{
178 struct unwind_info *ui = arg;
179 Dwarf_Addr pc;
180 bool isactivation;
181
182 if (!dwfl_frame_pc(state, &pc, NULL)) {
183 pr_err("%s", dwfl_errmsg(-1));
184 return DWARF_CB_ABORT;
185 }
186
187 // report the module before we query for isactivation
188 report_module(pc, ui);
189
190 if (!dwfl_frame_pc(state, &pc, &isactivation)) {
191 pr_err("%s", dwfl_errmsg(-1));
192 return DWARF_CB_ABORT;
193 }
194
195 if (!isactivation)
196 --pc;
197
198 return entry(pc, ui) || !(--ui->max_stack) ?
199 DWARF_CB_ABORT : DWARF_CB_OK;
200}
201
202int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
203 struct thread *thread,
204 struct perf_sample *data,
205 int max_stack)
206{
207 struct unwind_info *ui, ui_buf = {
208 .sample = data,
209 .thread = thread,
210 .machine = thread->mg->machine,
211 .cb = cb,
212 .arg = arg,
213 .max_stack = max_stack,
214 };
215 Dwarf_Word ip;
216 int err = -EINVAL, i;
217
218 if (!data->user_regs.regs)
219 return -EINVAL;
220
221 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack);
222 if (!ui)
223 return -ENOMEM;
224
225 *ui = ui_buf;
226
227 ui->dwfl = dwfl_begin(&offline_callbacks);
228 if (!ui->dwfl)
229 goto out;
230
231 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
232 if (err)
233 goto out;
234
235 err = report_module(ip, ui);
236 if (err)
237 goto out;
238
239 err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui);
240 if (err)
241 goto out;
242
243 err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui);
244
245 if (err && ui->max_stack != max_stack)
246 err = 0;
247
248 /*
249 * Display what we got based on the order setup.
250 */
251 for (i = 0; i < ui->idx && !err; i++) {
252 int j = i;
253
254 if (callchain_param.order == ORDER_CALLER)
255 j = ui->idx - i - 1;
256
257 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;
258 }
259
260 out:
261 if (err)
262 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));
263
264 dwfl_end(ui->dwfl);
265 free(ui);
266 return 0;
267}
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
21static char *debuginfo_path;
22
23static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata,
24 const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused,
25 const char *file_name, const char *debuglink_file __maybe_unused,
26 GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name)
27{
28 const struct dso *dso = *userdata;
29
30 assert(dso);
31 if (dso->symsrc_filename && strcmp (file_name, dso->symsrc_filename))
32 *debuginfo_file_name = strdup(dso->symsrc_filename);
33 return -1;
34}
35
36static const Dwfl_Callbacks offline_callbacks = {
37 .find_debuginfo = __find_debuginfo,
38 .debuginfo_path = &debuginfo_path,
39 .section_address = dwfl_offline_section_address,
40 // .find_elf is not set as we use dwfl_report_elf() instead.
41};
42
43static int __report_module(struct addr_location *al, u64 ip,
44 struct unwind_info *ui)
45{
46 Dwfl_Module *mod;
47 struct dso *dso = NULL;
48 /*
49 * Some callers will use al->sym, so we can't just use the
50 * cheaper thread__find_map() here.
51 */
52 thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al);
53
54 if (al->map)
55 dso = al->map->dso;
56
57 if (!dso)
58 return 0;
59
60 mod = dwfl_addrmodule(ui->dwfl, ip);
61 if (mod) {
62 Dwarf_Addr s;
63
64 dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL);
65 if (s != al->map->start - al->map->pgoff)
66 mod = 0;
67 }
68
69 if (!mod)
70 mod = dwfl_report_elf(ui->dwfl, dso->short_name, dso->long_name, -1,
71 al->map->start - al->map->pgoff, false);
72 if (!mod) {
73 char filename[PATH_MAX];
74
75 if (dso__build_id_filename(dso, filename, sizeof(filename), false))
76 mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1,
77 al->map->start - al->map->pgoff, false);
78 }
79
80 if (mod) {
81 void **userdatap;
82
83 dwfl_module_info(mod, &userdatap, NULL, NULL, NULL, NULL, NULL, NULL);
84 *userdatap = dso;
85 }
86
87 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
88}
89
90static int report_module(u64 ip, struct unwind_info *ui)
91{
92 struct addr_location al;
93
94 return __report_module(&al, ip, ui);
95}
96
97/*
98 * Store all entries within entries array,
99 * we will process it after we finish unwind.
100 */
101static int entry(u64 ip, struct unwind_info *ui)
102
103{
104 struct unwind_entry *e = &ui->entries[ui->idx++];
105 struct addr_location al;
106
107 if (__report_module(&al, ip, ui))
108 return -1;
109
110 e->ip = ip;
111 e->ms.maps = al.maps;
112 e->ms.map = al.map;
113 e->ms.sym = al.sym;
114
115 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
116 al.sym ? al.sym->name : "''",
117 ip,
118 al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
119 return 0;
120}
121
122static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
123{
124 /* We want only single thread to be processed. */
125 if (*thread_argp != NULL)
126 return 0;
127
128 *thread_argp = arg;
129 return dwfl_pid(dwfl);
130}
131
132static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
133 Dwarf_Word *data)
134{
135 struct addr_location al;
136 ssize_t size;
137
138 if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) {
139 pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
140 return -1;
141 }
142
143 if (!al.map->dso)
144 return -1;
145
146 size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
147 addr, (u8 *) data, sizeof(*data));
148
149 return !(size == sizeof(*data));
150}
151
152static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
153 void *arg)
154{
155 struct unwind_info *ui = arg;
156 struct stack_dump *stack = &ui->sample->user_stack;
157 u64 start, end;
158 int offset;
159 int ret;
160
161 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
162 if (ret)
163 return false;
164
165 end = start + stack->size;
166
167 /* Check overflow. */
168 if (addr + sizeof(Dwarf_Word) < addr)
169 return false;
170
171 if (addr < start || addr + sizeof(Dwarf_Word) > end) {
172 ret = access_dso_mem(ui, addr, result);
173 if (ret) {
174 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
175 " 0x%" PRIx64 "-0x%" PRIx64 "\n",
176 addr, start, end);
177 return false;
178 }
179 return true;
180 }
181
182 offset = addr - start;
183 *result = *(Dwarf_Word *)&stack->data[offset];
184 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
185 addr, (unsigned long)*result, offset);
186 return true;
187}
188
189static const Dwfl_Thread_Callbacks callbacks = {
190 .next_thread = next_thread,
191 .memory_read = memory_read,
192 .set_initial_registers = libdw__arch_set_initial_registers,
193};
194
195static int
196frame_callback(Dwfl_Frame *state, void *arg)
197{
198 struct unwind_info *ui = arg;
199 Dwarf_Addr pc;
200 bool isactivation;
201
202 if (!dwfl_frame_pc(state, &pc, NULL)) {
203 if (!ui->best_effort)
204 pr_err("%s", dwfl_errmsg(-1));
205 return DWARF_CB_ABORT;
206 }
207
208 // report the module before we query for isactivation
209 report_module(pc, ui);
210
211 if (!dwfl_frame_pc(state, &pc, &isactivation)) {
212 if (!ui->best_effort)
213 pr_err("%s", dwfl_errmsg(-1));
214 return DWARF_CB_ABORT;
215 }
216
217 if (!isactivation)
218 --pc;
219
220 return entry(pc, ui) || !(--ui->max_stack) ?
221 DWARF_CB_ABORT : DWARF_CB_OK;
222}
223
224int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
225 struct thread *thread,
226 struct perf_sample *data,
227 int max_stack,
228 bool best_effort)
229{
230 struct unwind_info *ui, ui_buf = {
231 .sample = data,
232 .thread = thread,
233 .machine = thread->maps->machine,
234 .cb = cb,
235 .arg = arg,
236 .max_stack = max_stack,
237 .best_effort = best_effort
238 };
239 Dwarf_Word ip;
240 int err = -EINVAL, i;
241
242 if (!data->user_regs.regs)
243 return -EINVAL;
244
245 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack);
246 if (!ui)
247 return -ENOMEM;
248
249 *ui = ui_buf;
250
251 ui->dwfl = dwfl_begin(&offline_callbacks);
252 if (!ui->dwfl)
253 goto out;
254
255 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
256 if (err)
257 goto out;
258
259 err = report_module(ip, ui);
260 if (err)
261 goto out;
262
263 err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui);
264 if (err)
265 goto out;
266
267 err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui);
268
269 if (err && ui->max_stack != max_stack)
270 err = 0;
271
272 /*
273 * Display what we got based on the order setup.
274 */
275 for (i = 0; i < ui->idx && !err; i++) {
276 int j = i;
277
278 if (callchain_param.order == ORDER_CALLER)
279 j = ui->idx - i - 1;
280
281 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;
282 }
283
284 out:
285 if (err)
286 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));
287
288 dwfl_end(ui->dwfl);
289 free(ui);
290 return 0;
291}