blob: 67db73ec3dabb4600034cd2280f268636316e3eb [file] [log] [blame]
Jiri Olsa5ea84152014-02-19 16:52:57 +01001#include <linux/compiler.h>
2#include <elfutils/libdw.h>
3#include <elfutils/libdwfl.h>
4#include <inttypes.h>
5#include <errno.h>
6#include "unwind.h"
7#include "unwind-libdw.h"
8#include "machine.h"
9#include "thread.h"
10#include "types.h"
11#include "event.h"
12#include "perf_regs.h"
13
14static char *debuginfo_path;
15
16static const Dwfl_Callbacks offline_callbacks = {
17 .find_debuginfo = dwfl_standard_find_debuginfo,
18 .debuginfo_path = &debuginfo_path,
19 .section_address = dwfl_offline_section_address,
20};
21
22static int __report_module(struct addr_location *al, u64 ip,
23 struct unwind_info *ui)
24{
25 Dwfl_Module *mod;
26 struct dso *dso = NULL;
27
28 thread__find_addr_location(ui->thread, ui->machine,
29 PERF_RECORD_MISC_USER,
30 MAP__FUNCTION, ip, al);
31
32 if (al->map)
33 dso = al->map->dso;
34
35 if (!dso)
36 return 0;
37
38 mod = dwfl_addrmodule(ui->dwfl, ip);
39 if (!mod)
40 mod = dwfl_report_elf(ui->dwfl, dso->short_name,
41 dso->long_name, -1, al->map->start,
42 false);
43
44 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
45}
46
47static int report_module(u64 ip, struct unwind_info *ui)
48{
49 struct addr_location al;
50
51 return __report_module(&al, ip, ui);
52}
53
54static int entry(u64 ip, struct unwind_info *ui)
55
56{
57 struct unwind_entry e;
58 struct addr_location al;
59
60 if (__report_module(&al, ip, ui))
61 return -1;
62
63 e.ip = ip;
64 e.map = al.map;
65 e.sym = al.sym;
66
67 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
68 al.sym ? al.sym->name : "''",
69 ip,
70 al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
71
72 return ui->cb(&e, ui->arg);
73}
74
75static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
76{
77 /* We want only single thread to be processed. */
78 if (*thread_argp != NULL)
79 return 0;
80
81 *thread_argp = arg;
82 return dwfl_pid(dwfl);
83}
84
85static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
86 Dwarf_Word *data)
87{
88 struct addr_location al;
89 ssize_t size;
90
91 thread__find_addr_map(ui->thread, ui->machine, PERF_RECORD_MISC_USER,
92 MAP__FUNCTION, addr, &al);
93 if (!al.map) {
94 pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
95 return -1;
96 }
97
98 if (!al.map->dso)
99 return -1;
100
101 size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
102 addr, (u8 *) data, sizeof(*data));
103
104 return !(size == sizeof(*data));
105}
106
107static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
108 void *arg)
109{
110 struct unwind_info *ui = arg;
111 struct stack_dump *stack = &ui->sample->user_stack;
112 u64 start, end;
113 int offset;
114 int ret;
115
116 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
117 if (ret)
118 return false;
119
120 end = start + stack->size;
121
122 /* Check overflow. */
123 if (addr + sizeof(Dwarf_Word) < addr)
124 return false;
125
126 if (addr < start || addr + sizeof(Dwarf_Word) > end) {
127 ret = access_dso_mem(ui, addr, result);
128 if (ret) {
129 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
130 " 0x%" PRIx64 "-0x%" PRIx64 "\n",
131 addr, start, end);
132 return false;
133 }
134 return true;
135 }
136
137 offset = addr - start;
138 *result = *(Dwarf_Word *)&stack->data[offset];
139 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
140 addr, (unsigned long)*result, offset);
141 return true;
142}
143
144static const Dwfl_Thread_Callbacks callbacks = {
145 .next_thread = next_thread,
146 .memory_read = memory_read,
147 .set_initial_registers = libdw__arch_set_initial_registers,
148};
149
150static int
151frame_callback(Dwfl_Frame *state, void *arg)
152{
153 struct unwind_info *ui = arg;
154 Dwarf_Addr pc;
155
156 if (!dwfl_frame_pc(state, &pc, NULL)) {
157 pr_err("%s", dwfl_errmsg(-1));
158 return DWARF_CB_ABORT;
159 }
160
161 return entry(pc, ui) || !(--ui->max_stack) ?
162 DWARF_CB_ABORT : DWARF_CB_OK;
163}
164
165int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
166 struct machine *machine, struct thread *thread,
167 struct perf_sample *data,
168 int max_stack)
169{
170 struct unwind_info ui = {
171 .sample = data,
172 .thread = thread,
173 .machine = machine,
174 .cb = cb,
175 .arg = arg,
176 .max_stack = max_stack,
177 };
178 Dwarf_Word ip;
179 int err = -EINVAL;
180
181 if (!data->user_regs.regs)
182 return -EINVAL;
183
184 ui.dwfl = dwfl_begin(&offline_callbacks);
185 if (!ui.dwfl)
186 goto out;
187
188 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
189 if (err)
190 goto out;
191
192 err = report_module(ip, &ui);
193 if (err)
194 goto out;
195
196 if (!dwfl_attach_state(ui.dwfl, EM_NONE, thread->tid, &callbacks, &ui))
197 goto out;
198
199 err = dwfl_getthread_frames(ui.dwfl, thread->tid, frame_callback, &ui);
200
201 if (err && !ui.max_stack)
202 err = 0;
203
204 out:
205 if (err)
206 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));
207
208 dwfl_end(ui.dwfl);
209 return 0;
210}