aboutsummaryrefslogtreecommitdiffstats
path: root/tools/perf/util/unwind-libdw.c
blob: b4c20124d2ee1a693e2125a5efe8ecb7473c7703 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
#include <linux/compiler.h>
#include <elfutils/libdw.h>
#include <elfutils/libdwfl.h>
#include <inttypes.h>
#include <errno.h>
#include "debug.h"
#include "unwind.h"
#include "unwind-libdw.h"
#include "machine.h"
#include "thread.h"
#include <linux/types.h>
#include "event.h"
#include "perf_regs.h"
#include "callchain.h"
#include "util.h"

static char *debuginfo_path;

static const Dwfl_Callbacks offline_callbacks = {
	.find_debuginfo		= dwfl_standard_find_debuginfo,
	.debuginfo_path		= &debuginfo_path,
	.section_address	= dwfl_offline_section_address,
};

static int __report_module(struct addr_location *al, u64 ip,
			    struct unwind_info *ui)
{
	Dwfl_Module *mod;
	struct dso *dso = NULL;

	thread__find_addr_location(ui->thread,
				   PERF_RECORD_MISC_USER,
				   MAP__FUNCTION, ip, al);

	if (al->map)
		dso = al->map->dso;

	if (!dso)
		return 0;

	mod = dwfl_addrmodule(ui->dwfl, ip);
	if (!mod)
		mod = dwfl_report_elf(ui->dwfl, dso->short_name,
				      dso->long_name, -1, al->map->start,
				      false);

	return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
}

static int report_module(u64 ip, struct unwind_info *ui)
{
	struct addr_location al;

	return __report_module(&al, ip, ui);
}

/*
 * Store all entries within entries array,
 * we will process it after we finish unwind.
 */
static int entry(u64 ip, struct unwind_info *ui)

{
	struct unwind_entry *e = &ui->entries[ui->idx++];
	struct addr_location al;

	if (__report_module(&al, ip, ui))
		return -1;

	e->ip  = al.addr;
	e->map = al.map;
	e->sym = al.sym;

	pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
		 al.sym ? al.sym->name : "''",
		 ip,
		 al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
	return 0;
}

static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
{
	/* We want only single thread to be processed. */
	if (*thread_argp != NULL)
		return 0;

	*thread_argp = arg;
	return dwfl_pid(dwfl);
}

static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
			  Dwarf_Word *data)
{
	struct addr_location al;
	ssize_t size;

	thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
			      MAP__FUNCTION, addr, &al);
	if (!al.map) {
		/*
		 * We've seen cases (softice) where DWARF unwinder went
		 * through non executable mmaps, which we need to lookup
		 * in MAP__VARIABLE tree.
		 */
		thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
				      MAP__VARIABLE, addr, &al);
	}

	if (!al.map) {
		pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
		return -1;
	}

	if (!al.map->dso)
		return -1;

	size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
				   addr, (u8 *) data, sizeof(*data));

	return !(size == sizeof(*data));
}

static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
			void *arg)
{
	struct unwind_info *ui = arg;
	struct stack_dump *stack = &ui->sample->user_stack;
	u64 start, end;
	int offset;
	int ret;

	ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
	if (ret)
		return false;

	end = start + stack->size;

	/* Check overflow. */
	if (addr + sizeof(Dwarf_Word) < addr)
		return false;

	if (addr < start || addr + sizeof(Dwarf_Word) > end) {
		ret = access_dso_mem(ui, addr, result);
		if (ret) {
			pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
				 " 0x%" PRIx64 "-0x%" PRIx64 "\n",
				addr, start, end);
			return false;
		}
		return true;
	}

	offset  = addr - start;
	*result = *(Dwarf_Word *)&stack->data[offset];
	pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
		 addr, (unsigned long)*result, offset);
	return true;
}

static const Dwfl_Thread_Callbacks callbacks = {
	.next_thread		= next_thread,
	.memory_read		= memory_read,
	.set_initial_registers	= libdw__arch_set_initial_registers,
};

static int
frame_callback(Dwfl_Frame *state, void *arg)
{
	struct unwind_info *ui = arg;
	Dwarf_Addr pc;
	bool isactivation;

	if (!dwfl_frame_pc(state, &pc, &isactivation)) {
		pr_err("%s", dwfl_errmsg(-1));
		return DWARF_CB_ABORT;
	}

	if (!isactivation)
		--pc;

	return entry(pc, ui) || !(--ui->max_stack) ?
	       DWARF_CB_ABORT : DWARF_CB_OK;
}

int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
			struct thread *thread,
			struct perf_sample *data,
			int max_stack)
{
	struct unwind_info *ui, ui_buf = {
		.sample		= data,
		.thread		= thread,
		.machine	= thread->mg->machine,
		.cb		= cb,
		.arg		= arg,
		.max_stack	= max_stack,
	};
	Dwarf_Word ip;
	int err = -EINVAL, i;

	if (!data->user_regs.regs)
		return -EINVAL;

	ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack);
	if (!ui)
		return -ENOMEM;

	*ui = ui_buf;

	ui->dwfl = dwfl_begin(&offline_callbacks);
	if (!ui->dwfl)
		goto out;

	err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
	if (err)
		goto out;

	err = report_module(ip, ui);
	if (err)
		goto out;

	if (!dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui))
		goto out;

	err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui);

	if (err && ui->max_stack != max_stack)
		err = 0;

	/*
	 * Display what we got based on the order setup.
	 */
	for (i = 0; i < ui->idx && !err; i++) {
		int j = i;

		if (callchain_param.order == ORDER_CALLER)
			j = ui->idx - i - 1;

		err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;
	}

 out:
	if (err)
		pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));

	dwfl_end(ui->dwfl);
	free(ui);
	return 0;
}

Privacy Policy