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5ea84154 JO |
1 | #include <linux/compiler.h> |
2 | #include <elfutils/libdw.h> | |
3 | #include <elfutils/libdwfl.h> | |
4 | #include <inttypes.h> | |
5 | #include <errno.h> | |
84f5d36f | 6 | #include "debug.h" |
5ea84154 JO |
7 | #include "unwind.h" |
8 | #include "unwind-libdw.h" | |
9 | #include "machine.h" | |
10 | #include "thread.h" | |
d944c4ee | 11 | #include <linux/types.h> |
5ea84154 JO |
12 | #include "event.h" |
13 | #include "perf_regs.h" | |
14 | ||
15 | static char *debuginfo_path; | |
16 | ||
17 | static const Dwfl_Callbacks offline_callbacks = { | |
18 | .find_debuginfo = dwfl_standard_find_debuginfo, | |
19 | .debuginfo_path = &debuginfo_path, | |
20 | .section_address = dwfl_offline_section_address, | |
21 | }; | |
22 | ||
23 | static int __report_module(struct addr_location *al, u64 ip, | |
24 | struct unwind_info *ui) | |
25 | { | |
26 | Dwfl_Module *mod; | |
27 | struct dso *dso = NULL; | |
28 | ||
29 | thread__find_addr_location(ui->thread, ui->machine, | |
30 | PERF_RECORD_MISC_USER, | |
31 | MAP__FUNCTION, ip, al); | |
32 | ||
33 | if (al->map) | |
34 | dso = al->map->dso; | |
35 | ||
36 | if (!dso) | |
37 | return 0; | |
38 | ||
39 | mod = dwfl_addrmodule(ui->dwfl, ip); | |
40 | if (!mod) | |
41 | mod = dwfl_report_elf(ui->dwfl, dso->short_name, | |
42 | dso->long_name, -1, al->map->start, | |
43 | false); | |
44 | ||
45 | return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; | |
46 | } | |
47 | ||
48 | static int report_module(u64 ip, struct unwind_info *ui) | |
49 | { | |
50 | struct addr_location al; | |
51 | ||
52 | return __report_module(&al, ip, ui); | |
53 | } | |
54 | ||
55 | static int entry(u64 ip, struct unwind_info *ui) | |
56 | ||
57 | { | |
58 | struct unwind_entry e; | |
59 | struct addr_location al; | |
60 | ||
61 | if (__report_module(&al, ip, ui)) | |
62 | return -1; | |
63 | ||
64 | e.ip = ip; | |
65 | e.map = al.map; | |
66 | e.sym = al.sym; | |
67 | ||
68 | pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n", | |
69 | al.sym ? al.sym->name : "''", | |
70 | ip, | |
71 | al.map ? al.map->map_ip(al.map, ip) : (u64) 0); | |
72 | ||
73 | return ui->cb(&e, ui->arg); | |
74 | } | |
75 | ||
76 | static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp) | |
77 | { | |
78 | /* We want only single thread to be processed. */ | |
79 | if (*thread_argp != NULL) | |
80 | return 0; | |
81 | ||
82 | *thread_argp = arg; | |
83 | return dwfl_pid(dwfl); | |
84 | } | |
85 | ||
86 | static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr, | |
87 | Dwarf_Word *data) | |
88 | { | |
89 | struct addr_location al; | |
90 | ssize_t size; | |
91 | ||
92 | thread__find_addr_map(ui->thread, ui->machine, PERF_RECORD_MISC_USER, | |
93 | MAP__FUNCTION, addr, &al); | |
94 | if (!al.map) { | |
95 | pr_debug("unwind: no map for %lx\n", (unsigned long)addr); | |
96 | return -1; | |
97 | } | |
98 | ||
99 | if (!al.map->dso) | |
100 | return -1; | |
101 | ||
102 | size = dso__data_read_addr(al.map->dso, al.map, ui->machine, | |
103 | addr, (u8 *) data, sizeof(*data)); | |
104 | ||
105 | return !(size == sizeof(*data)); | |
106 | } | |
107 | ||
108 | static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result, | |
109 | void *arg) | |
110 | { | |
111 | struct unwind_info *ui = arg; | |
112 | struct stack_dump *stack = &ui->sample->user_stack; | |
113 | u64 start, end; | |
114 | int offset; | |
115 | int ret; | |
116 | ||
117 | ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP); | |
118 | if (ret) | |
119 | return false; | |
120 | ||
121 | end = start + stack->size; | |
122 | ||
123 | /* Check overflow. */ | |
124 | if (addr + sizeof(Dwarf_Word) < addr) | |
125 | return false; | |
126 | ||
127 | if (addr < start || addr + sizeof(Dwarf_Word) > end) { | |
128 | ret = access_dso_mem(ui, addr, result); | |
129 | if (ret) { | |
130 | pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range" | |
131 | " 0x%" PRIx64 "-0x%" PRIx64 "\n", | |
132 | addr, start, end); | |
133 | return false; | |
134 | } | |
135 | return true; | |
136 | } | |
137 | ||
138 | offset = addr - start; | |
139 | *result = *(Dwarf_Word *)&stack->data[offset]; | |
140 | pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n", | |
141 | addr, (unsigned long)*result, offset); | |
142 | return true; | |
143 | } | |
144 | ||
145 | static const Dwfl_Thread_Callbacks callbacks = { | |
146 | .next_thread = next_thread, | |
147 | .memory_read = memory_read, | |
148 | .set_initial_registers = libdw__arch_set_initial_registers, | |
149 | }; | |
150 | ||
151 | static int | |
152 | frame_callback(Dwfl_Frame *state, void *arg) | |
153 | { | |
154 | struct unwind_info *ui = arg; | |
155 | Dwarf_Addr pc; | |
156 | ||
157 | if (!dwfl_frame_pc(state, &pc, NULL)) { | |
158 | pr_err("%s", dwfl_errmsg(-1)); | |
159 | return DWARF_CB_ABORT; | |
160 | } | |
161 | ||
162 | return entry(pc, ui) || !(--ui->max_stack) ? | |
163 | DWARF_CB_ABORT : DWARF_CB_OK; | |
164 | } | |
165 | ||
166 | int unwind__get_entries(unwind_entry_cb_t cb, void *arg, | |
167 | struct machine *machine, struct thread *thread, | |
168 | struct perf_sample *data, | |
169 | int max_stack) | |
170 | { | |
171 | struct unwind_info ui = { | |
172 | .sample = data, | |
173 | .thread = thread, | |
174 | .machine = machine, | |
175 | .cb = cb, | |
176 | .arg = arg, | |
177 | .max_stack = max_stack, | |
178 | }; | |
179 | Dwarf_Word ip; | |
180 | int err = -EINVAL; | |
181 | ||
182 | if (!data->user_regs.regs) | |
183 | return -EINVAL; | |
184 | ||
185 | ui.dwfl = dwfl_begin(&offline_callbacks); | |
186 | if (!ui.dwfl) | |
187 | goto out; | |
188 | ||
189 | err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP); | |
190 | if (err) | |
191 | goto out; | |
192 | ||
193 | err = report_module(ip, &ui); | |
194 | if (err) | |
195 | goto out; | |
196 | ||
197 | if (!dwfl_attach_state(ui.dwfl, EM_NONE, thread->tid, &callbacks, &ui)) | |
198 | goto out; | |
199 | ||
200 | err = dwfl_getthread_frames(ui.dwfl, thread->tid, frame_callback, &ui); | |
201 | ||
202 | if (err && !ui.max_stack) | |
203 | err = 0; | |
204 | ||
205 | out: | |
206 | if (err) | |
207 | pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1)); | |
208 | ||
209 | dwfl_end(ui.dwfl); | |
210 | return 0; | |
211 | } |