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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
5ea84154 JO |
2 | #include <linux/compiler.h> |
3 | #include <elfutils/libdw.h> | |
4 | #include <elfutils/libdwfl.h> | |
5 | #include <inttypes.h> | |
6 | #include <errno.h> | |
84f5d36f | 7 | #include "debug.h" |
5ea84154 JO |
8 | #include "unwind.h" |
9 | #include "unwind-libdw.h" | |
10 | #include "machine.h" | |
11 | #include "thread.h" | |
d944c4ee | 12 | #include <linux/types.h> |
5ea84154 JO |
13 | #include "event.h" |
14 | #include "perf_regs.h" | |
8bd508b0 | 15 | #include "callchain.h" |
9a3993d4 | 16 | #include "util.h" |
5ea84154 JO |
17 | |
18 | static char *debuginfo_path; | |
19 | ||
20 | static 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 | ||
26 | static 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 | ||
bb871a9c | 32 | thread__find_addr_location(ui->thread, |
5ea84154 JO |
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); | |
2538b9e2 MW |
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 | ||
5ea84154 JO |
51 | if (!mod) |
52 | mod = dwfl_report_elf(ui->dwfl, dso->short_name, | |
53 | dso->long_name, -1, al->map->start, | |
54 | false); | |
55 | ||
56 | return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; | |
57 | } | |
58 | ||
59 | static 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 | ||
8bd508b0 JO |
66 | /* |
67 | * Store all entries within entries array, | |
68 | * we will process it after we finish unwind. | |
69 | */ | |
5ea84154 JO |
70 | static int entry(u64 ip, struct unwind_info *ui) |
71 | ||
72 | { | |
8bd508b0 | 73 | struct unwind_entry *e = &ui->entries[ui->idx++]; |
5ea84154 JO |
74 | struct addr_location al; |
75 | ||
76 | if (__report_module(&al, ip, ui)) | |
77 | return -1; | |
78 | ||
67540759 | 79 | e->ip = al.addr; |
8bd508b0 JO |
80 | e->map = al.map; |
81 | e->sym = al.sym; | |
5ea84154 JO |
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); | |
8bd508b0 | 87 | return 0; |
5ea84154 JO |
88 | } |
89 | ||
90 | static 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 | ||
100 | static 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 | ||
bb871a9c | 106 | thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER, |
5ea84154 | 107 | MAP__FUNCTION, addr, &al); |
0ba98149 JO |
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 | ||
5ea84154 JO |
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 | ||
132 | static 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 | ||
169 | static 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 | ||
175 | static int | |
176 | frame_callback(Dwfl_Frame *state, void *arg) | |
177 | { | |
178 | struct unwind_info *ui = arg; | |
179 | Dwarf_Addr pc; | |
1982ad48 | 180 | bool isactivation; |
5ea84154 | 181 | |
9126cbba MW |
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 | ||
1982ad48 | 190 | if (!dwfl_frame_pc(state, &pc, &isactivation)) { |
5ea84154 JO |
191 | pr_err("%s", dwfl_errmsg(-1)); |
192 | return DWARF_CB_ABORT; | |
193 | } | |
194 | ||
1982ad48 MW |
195 | if (!isactivation) |
196 | --pc; | |
197 | ||
5ea84154 JO |
198 | return entry(pc, ui) || !(--ui->max_stack) ? |
199 | DWARF_CB_ABORT : DWARF_CB_OK; | |
200 | } | |
201 | ||
202 | int unwind__get_entries(unwind_entry_cb_t cb, void *arg, | |
dd8c17a5 | 203 | struct thread *thread, |
5ea84154 JO |
204 | struct perf_sample *data, |
205 | int max_stack) | |
206 | { | |
8bd508b0 | 207 | struct unwind_info *ui, ui_buf = { |
5ea84154 JO |
208 | .sample = data, |
209 | .thread = thread, | |
dd8c17a5 | 210 | .machine = thread->mg->machine, |
5ea84154 JO |
211 | .cb = cb, |
212 | .arg = arg, | |
213 | .max_stack = max_stack, | |
214 | }; | |
215 | Dwarf_Word ip; | |
8bd508b0 | 216 | int err = -EINVAL, i; |
5ea84154 JO |
217 | |
218 | if (!data->user_regs.regs) | |
219 | return -EINVAL; | |
220 | ||
8bd508b0 JO |
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) | |
5ea84154 JO |
229 | goto out; |
230 | ||
231 | err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP); | |
232 | if (err) | |
233 | goto out; | |
234 | ||
8bd508b0 | 235 | err = report_module(ip, ui); |
5ea84154 JO |
236 | if (err) |
237 | goto out; | |
238 | ||
8bd508b0 | 239 | if (!dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui)) |
5ea84154 JO |
240 | goto out; |
241 | ||
8bd508b0 | 242 | err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui); |
5ea84154 | 243 | |
5ea0416f | 244 | if (err && ui->max_stack != max_stack) |
5ea84154 JO |
245 | err = 0; |
246 | ||
8bd508b0 JO |
247 | /* |
248 | * Display what we got based on the order setup. | |
249 | */ | |
250 | for (i = 0; i < ui->idx && !err; i++) { | |
251 | int j = i; | |
252 | ||
253 | if (callchain_param.order == ORDER_CALLER) | |
254 | j = ui->idx - i - 1; | |
255 | ||
256 | err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0; | |
257 | } | |
258 | ||
5ea84154 JO |
259 | out: |
260 | if (err) | |
261 | pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1)); | |
262 | ||
8bd508b0 JO |
263 | dwfl_end(ui->dwfl); |
264 | free(ui); | |
5ea84154 JO |
265 | return 0; |
266 | } |