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