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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> | |
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 | ||
14 | static char *debuginfo_path; | |
15 | ||
16 | static 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 | ||
22 | static 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 | ||
47 | static 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 | ||
54 | static 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 | ||
75 | static 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 | ||
85 | static 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 | ||
107 | static 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 | ||
144 | static 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 | ||
150 | static int | |
151 | frame_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 | ||
165 | int 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 | } |