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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 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
29static 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
63static 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 */
74static 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
94static 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
104static 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
124static 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
161static 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
167static int
168frame_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
194int 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}