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 "unwind.h"
9#include "unwind-libdw.h"
10#include "machine.h"
11#include "map.h"
12#include "symbol.h"
13#include "thread.h"
14#include <linux/types.h>
15#include "event.h"
16#include "perf_regs.h"
17#include "callchain.h"
18#include "util.h"
19
20static char *debuginfo_path;
21
22static const Dwfl_Callbacks offline_callbacks = {
23 .find_debuginfo = dwfl_standard_find_debuginfo,
24 .debuginfo_path = &debuginfo_path,
25 .section_address = dwfl_offline_section_address,
26};
27
28static int __report_module(struct addr_location *al, u64 ip,
29 struct unwind_info *ui)
30{
31 Dwfl_Module *mod;
32 struct dso *dso = NULL;
33
34
35
36
37 thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al);
38
39 if (al->map)
40 dso = al->map->dso;
41
42 if (!dso)
43 return 0;
44
45 mod = dwfl_addrmodule(ui->dwfl, ip);
46 if (mod) {
47 Dwarf_Addr s;
48
49 dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL);
50 if (s != al->map->start - al->map->pgoff)
51 mod = 0;
52 }
53
54 if (!mod)
55 mod = dwfl_report_elf(ui->dwfl, dso->short_name,
56 (dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start - al->map->pgoff,
57 false);
58
59 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
60}
61
62static int report_module(u64 ip, struct unwind_info *ui)
63{
64 struct addr_location al;
65
66 return __report_module(&al, ip, ui);
67}
68
69
70
71
72
73static int entry(u64 ip, struct unwind_info *ui)
74
75{
76 struct unwind_entry *e = &ui->entries[ui->idx++];
77 struct addr_location al;
78
79 if (__report_module(&al, ip, ui))
80 return -1;
81
82 e->ip = ip;
83 e->map = al.map;
84 e->sym = al.sym;
85
86 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
87 al.sym ? al.sym->name : "''",
88 ip,
89 al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
90 return 0;
91}
92
93static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
94{
95
96 if (*thread_argp != NULL)
97 return 0;
98
99 *thread_argp = arg;
100 return dwfl_pid(dwfl);
101}
102
103static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
104 Dwarf_Word *data)
105{
106 struct addr_location al;
107 ssize_t size;
108
109 if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) {
110 pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
111 return -1;
112 }
113
114 if (!al.map->dso)
115 return -1;
116
117 size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
118 addr, (u8 *) data, sizeof(*data));
119
120 return !(size == sizeof(*data));
121}
122
123static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
124 void *arg)
125{
126 struct unwind_info *ui = arg;
127 struct stack_dump *stack = &ui->sample->user_stack;
128 u64 start, end;
129 int offset;
130 int ret;
131
132 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
133 if (ret)
134 return false;
135
136 end = start + stack->size;
137
138
139 if (addr + sizeof(Dwarf_Word) < addr)
140 return false;
141
142 if (addr < start || addr + sizeof(Dwarf_Word) > end) {
143 ret = access_dso_mem(ui, addr, result);
144 if (ret) {
145 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
146 " 0x%" PRIx64 "-0x%" PRIx64 "\n",
147 addr, start, end);
148 return false;
149 }
150 return true;
151 }
152
153 offset = addr - start;
154 *result = *(Dwarf_Word *)&stack->data[offset];
155 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
156 addr, (unsigned long)*result, offset);
157 return true;
158}
159
160static const Dwfl_Thread_Callbacks callbacks = {
161 .next_thread = next_thread,
162 .memory_read = memory_read,
163 .set_initial_registers = libdw__arch_set_initial_registers,
164};
165
166static int
167frame_callback(Dwfl_Frame *state, void *arg)
168{
169 struct unwind_info *ui = arg;
170 Dwarf_Addr pc;
171 bool isactivation;
172
173 if (!dwfl_frame_pc(state, &pc, NULL)) {
174 pr_err("%s", dwfl_errmsg(-1));
175 return DWARF_CB_ABORT;
176 }
177
178
179 report_module(pc, ui);
180
181 if (!dwfl_frame_pc(state, &pc, &isactivation)) {
182 pr_err("%s", dwfl_errmsg(-1));
183 return DWARF_CB_ABORT;
184 }
185
186 if (!isactivation)
187 --pc;
188
189 return entry(pc, ui) || !(--ui->max_stack) ?
190 DWARF_CB_ABORT : DWARF_CB_OK;
191}
192
193int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
194 struct thread *thread,
195 struct perf_sample *data,
196 int max_stack)
197{
198 struct unwind_info *ui, ui_buf = {
199 .sample = data,
200 .thread = thread,
201 .machine = thread->mg->machine,
202 .cb = cb,
203 .arg = arg,
204 .max_stack = max_stack,
205 };
206 Dwarf_Word ip;
207 int err = -EINVAL, i;
208
209 if (!data->user_regs.regs)
210 return -EINVAL;
211
212 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack);
213 if (!ui)
214 return -ENOMEM;
215
216 *ui = ui_buf;
217
218 ui->dwfl = dwfl_begin(&offline_callbacks);
219 if (!ui->dwfl)
220 goto out;
221
222 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
223 if (err)
224 goto out;
225
226 err = report_module(ip, ui);
227 if (err)
228 goto out;
229
230 err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui);
231 if (err)
232 goto out;
233
234 err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui);
235
236 if (err && ui->max_stack != max_stack)
237 err = 0;
238
239
240
241
242 for (i = 0; i < ui->idx && !err; i++) {
243 int j = i;
244
245 if (callchain_param.order == ORDER_CALLER)
246 j = ui->idx - i - 1;
247
248 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;
249 }
250
251 out:
252 if (err)
253 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));
254
255 dwfl_end(ui->dwfl);
256 free(ui);
257 return 0;
258}
259