summaryrefslogtreecommitdiffstats
path: root/tools/perf/tests/vmlinux-kallsyms.c
blob: 3d9088003a5b6d16da0038d0abbfa1fc427ed65b (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
#include <linux/compiler.h>
#include <linux/rbtree.h>
#include <string.h>
#include "map.h"
#include "symbol.h"
#include "util.h"
#include "tests.h"
#include "debug.h"
#include "machine.h"

static int vmlinux_matches_kallsyms_filter(struct map *map __maybe_unused,
					   struct symbol *sym)
{
	bool *visited = symbol__priv(sym);
	*visited = true;
	return 0;
}

#define UM(x) kallsyms_map->unmap_ip(kallsyms_map, (x))

int test__vmlinux_matches_kallsyms(void)
{
	int err = -1;
	struct rb_node *nd;
	struct symbol *sym;
	struct map *kallsyms_map, *vmlinux_map;
	struct machine kallsyms, vmlinux;
	enum map_type type = MAP__FUNCTION;
	u64 mem_start, mem_end;

	/*
	 * Step 1:
	 *
	 * Init the machines that will hold kernel, modules obtained from
	 * both vmlinux + .ko files and from /proc/kallsyms split by modules.
	 */
	machine__init(&kallsyms, "", HOST_KERNEL_ID);
	machine__init(&vmlinux, "", HOST_KERNEL_ID);

	/*
	 * Step 2:
	 *
	 * Create the kernel maps for kallsyms and the DSO where we will then
	 * load /proc/kallsyms. Also create the modules maps from /proc/modules
	 * and find the .ko files that match them in /lib/modules/`uname -r`/.
	 */
	if (machine__create_kernel_maps(&kallsyms) < 0) {
		pr_debug("machine__create_kernel_maps ");
		goto out;
	}

	/*
	 * Step 3:
	 *
	 * Load and split /proc/kallsyms into multiple maps, one per module.
	 */
	if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms", type, NULL) <= 0) {
		pr_debug("dso__load_kallsyms ");
		goto out;
	}

	/*
	 * Step 4:
	 *
	 * kallsyms will be internally on demand sorted by name so that we can
	 * find the reference relocation * symbol, i.e. the symbol we will use
	 * to see if the running kernel was relocated by checking if it has the
	 * same value in the vmlinux file we load.
	 */
	kallsyms_map = machine__kernel_map(&kallsyms, type);

	/*
	 * Step 5:
	 *
	 * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
	 */
	if (machine__create_kernel_maps(&vmlinux) < 0) {
		pr_debug("machine__create_kernel_maps ");
		goto out;
	}

	vmlinux_map = machine__kernel_map(&vmlinux, type);

	/*
	 * Step 6:
	 *
	 * Locate a vmlinux file in the vmlinux path that has a buildid that
	 * matches the one of the running kernel.
	 *
	 * While doing that look if we find the ref reloc symbol, if we find it
	 * we'll have its ref_reloc_symbol.unrelocated_addr and then
	 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
	 * to fixup the symbols.
	 */
	if (machine__load_vmlinux_path(&vmlinux, type,
				       vmlinux_matches_kallsyms_filter) <= 0) {
		pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
		err = TEST_SKIP;
		goto out;
	}

	err = 0;
	/*
	 * Step 7:
	 *
	 * Now look at the symbols in the vmlinux DSO and check if we find all of them
	 * in the kallsyms dso. For the ones that are in both, check its names and
	 * end addresses too.
	 */
	for (nd = rb_first(&vmlinux_map->dso->symbols[type]); nd; nd = rb_next(nd)) {
		struct symbol *pair, *first_pair;
		bool backwards = true;

		sym  = rb_entry(nd, struct symbol, rb_node);

		if (sym->start == sym->end)
			continue;

		mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
		mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);

		first_pair = machine__find_kernel_symbol(&kallsyms, type,
							 mem_start, NULL, NULL);
		pair = first_pair;

		if (pair && UM(pair->start) == mem_start) {
next_pair:
			if (strcmp(sym->name, pair->name) == 0) {
				/*
				 * kallsyms don't have the symbol end, so we
				 * set that by using the next symbol start - 1,
				 * in some cases we get this up to a page
				 * wrong, trace_kmalloc when I was developing
				 * this code was one such example, 2106 bytes
				 * off the real size. More than that and we
				 * _really_ have a problem.
				 */
				s64 skew = mem_end - UM(pair->end);
				if (llabs(skew) >= page_size)
					pr_debug("%#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
						 mem_start, sym->name, mem_end,
						 UM(pair->end));

				/*
				 * Do not count this as a failure, because we
				 * could really find a case where it's not
				 * possible to get proper function end from
				 * kallsyms.
				 */
				continue;

			} else {
				struct rb_node *nnd;
detour:
				nnd = backwards ? rb_prev(&pair->rb_node) :
						  rb_next(&pair->rb_node);
				if (nnd) {
					struct symbol *next = rb_entry(nnd, struct symbol, rb_node);

					if (UM(next->start) == mem_start) {
						pair = next;
						goto next_pair;
					}
				}

				if (backwards) {
					backwards = false;
					pair = first_pair;
					goto detour;
				}

				pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
					 mem_start, sym->name, pair->name);
			}
		} else
			pr_debug("%#" PRIx64 ": %s not on kallsyms\n",
				 mem_start, sym->name);

		err = -1;
	}

	if (!verbose)
		goto out;

	pr_info("Maps only in vmlinux:\n");

	for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
		struct map *pos = rb_entry(nd, struct map, rb_node), *pair;
		/*
		 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
		 * the kernel will have the path for the vmlinux file being used,
		 * so use the short name, less descriptive but the same ("[kernel]" in
		 * both cases.
		 */
		pair = map_groups__find_by_name(&kallsyms.kmaps, type,
						(pos->dso->kernel ?
							pos->dso->short_name :
							pos->dso->name));
		if (pair)
			pair->priv = 1;
		else
			map__fprintf(pos, stderr);
	}

	pr_info("Maps in vmlinux with a different name in kallsyms:\n");

	for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
		struct map *pos = rb_entry(nd, struct map, rb_node), *pair;

		mem_start = vmlinux_map->unmap_ip(vmlinux_map, pos->start);
		mem_end = vmlinux_map->unmap_ip(vmlinux_map, pos->end);

		pair = map_groups__find(&kallsyms.kmaps, type, mem_start);
		if (pair == NULL || pair->priv)
			continue;

		if (pair->start == mem_start) {
			pair->priv = 1;
			pr_info(" %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
				pos->start, pos->end, pos->pgoff, pos->dso->name);
			if (mem_end != pair->end)
				pr_info(":\n*%" PRIx64 "-%" PRIx64 " %" PRIx64,
					pair->start, pair->end, pair->pgoff);
			pr_info(" %s\n", pair->dso->name);
			pair->priv = 1;
		}
	}

	pr_info("Maps only in kallsyms:\n");

	for (nd = rb_first(&kallsyms.kmaps.maps[type]);
	     nd; nd = rb_next(nd)) {
		struct map *pos = rb_entry(nd, struct map, rb_node);

		if (!pos->priv)
			map__fprintf(pos, stderr);
	}
out:
	machine__exit(&kallsyms);
	machine__exit(&vmlinux);
	return err;
}