This source file includes following definitions.
- __report_module
- report_module
- entry
- next_thread
- access_dso_mem
- memory_read
- frame_callback
- unwind__get_entries
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
21 static char *debuginfo_path;
22
23 static 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
29 static 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
36
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
63 static 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
72
73
74 static 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
94 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
95 {
96
97 if (*thread_argp != NULL)
98 return 0;
99
100 *thread_argp = arg;
101 return dwfl_pid(dwfl);
102 }
103
104 static 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
124 static 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
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
161 static 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
167 static int
168 frame_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
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
194 int 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
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 }