summaryrefslogtreecommitdiff
path: root/tools/perf/tests/vmlinux-kallsyms.c
blob: 8ab035b55875c7152c70f3a23864c1f3adeb2bfd (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
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
// SPDX-License-Identifier: GPL-2.0
#include <linux/compiler.h>
#include <linux/rbtree.h>
#include <inttypes.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#include "dso.h"
#include "map.h"
#include "symbol.h"
#include <internal/lib.h> // page_size
#include "tests.h"
#include "debug.h"
#include "machine.h"

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

static bool is_ignored_symbol(const char *name, char type)
{
	/* Symbol names that exactly match to the following are ignored.*/
	static const char * const ignored_symbols[] = {
		/*
		 * Symbols which vary between passes. Passes 1 and 2 must have
		 * identical symbol lists. The kallsyms_* symbols below are
		 * only added after pass 1, they would be included in pass 2
		 * when --all-symbols is specified so exclude them to get a
		 * stable symbol list.
		 */
		"kallsyms_addresses",
		"kallsyms_offsets",
		"kallsyms_relative_base",
		"kallsyms_num_syms",
		"kallsyms_names",
		"kallsyms_markers",
		"kallsyms_token_table",
		"kallsyms_token_index",
		/* Exclude linker generated symbols which vary between passes */
		"_SDA_BASE_",		/* ppc */
		"_SDA2_BASE_",		/* ppc */
		NULL
	};

	/* Symbol names that begin with the following are ignored.*/
	static const char * const ignored_prefixes[] = {
		"$",			/* local symbols for ARM, MIPS, etc. */
		".L",			/* local labels, .LBB,.Ltmpxxx,.L__unnamed_xx,.LASANPC, etc. */
		"__crc_",		/* modversions */
		"__efistub_",		/* arm64 EFI stub namespace */
		"__kvm_nvhe_$",		/* arm64 local symbols in non-VHE KVM namespace */
		"__kvm_nvhe_.L",	/* arm64 local symbols in non-VHE KVM namespace */
		"__AArch64ADRPThunk_",	/* arm64 lld */
		"__ARMV5PILongThunk_",	/* arm lld */
		"__ARMV7PILongThunk_",
		"__ThumbV7PILongThunk_",
		"__LA25Thunk_",		/* mips lld */
		"__microLA25Thunk_",
		NULL
	};

	/* Symbol names that end with the following are ignored.*/
	static const char * const ignored_suffixes[] = {
		"_from_arm",		/* arm */
		"_from_thumb",		/* arm */
		"_veneer",		/* arm */
		NULL
	};

	/* Symbol names that contain the following are ignored.*/
	static const char * const ignored_matches[] = {
		".long_branch.",	/* ppc stub */
		".plt_branch.",		/* ppc stub */
		NULL
	};

	const char * const *p;

	for (p = ignored_symbols; *p; p++)
		if (!strcmp(name, *p))
			return true;

	for (p = ignored_prefixes; *p; p++)
		if (!strncmp(name, *p, strlen(*p)))
			return true;

	for (p = ignored_suffixes; *p; p++) {
		int l = strlen(name) - strlen(*p);

		if (l >= 0 && !strcmp(name + l, *p))
			return true;
	}

	for (p = ignored_matches; *p; p++) {
		if (strstr(name, *p))
			return true;
	}

	if (type == 'U' || type == 'u')
		return true;
	/* exclude debugging symbols */
	if (type == 'N' || type == 'n')
		return true;

	if (toupper(type) == 'A') {
		/* Keep these useful absolute symbols */
		if (strcmp(name, "__kernel_syscall_via_break") &&
		    strcmp(name, "__kernel_syscall_via_epc") &&
		    strcmp(name, "__kernel_sigtramp") &&
		    strcmp(name, "__gp"))
			return true;
	}

	return false;
}

static int test__vmlinux_matches_kallsyms(struct test_suite *test __maybe_unused,
					int subtest __maybe_unused)
{
	int err = TEST_FAIL;
	struct rb_node *nd;
	struct symbol *sym;
	struct map *kallsyms_map, *vmlinux_map, *map;
	struct machine kallsyms, vmlinux;
	struct maps *maps;
	u64 mem_start, mem_end;
	bool header_printed;

	/*
	 * 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);

	maps = machine__kernel_maps(&vmlinux);

	/*
	 * 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 failed");
		err = TEST_SKIP;
		goto out;
	}

	/*
	 * Step 3:
	 *
	 * Load and split /proc/kallsyms into multiple maps, one per module.
	 * Do not use kcore, as this test was designed before kcore support
	 * and has parts that only make sense if using the non-kcore code.
	 * XXX: extend it to stress the kcorre code as well, hint: the list
	 * of modules extracted from /proc/kcore, in its current form, can't
	 * be compacted against the list of modules found in the "vmlinux"
	 * code and with the one got from /proc/modules from the "kallsyms" code.
	 */
	if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms") <= 0) {
		pr_debug("machine__load_kallsyms failed");
		err = TEST_SKIP;
		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);

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

	vmlinux_map = machine__kernel_map(&vmlinux);

	/*
	 * 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) <= 0) {
		pr_info("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.
	 */
	map__for_each_symbol(vmlinux_map, sym, nd) {
		struct symbol *pair, *first_pair;

		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, mem_start, NULL);
		pair = first_pair;

		if (pair && UM(pair->start) == mem_start) {
next_pair:
			if (arch__compare_symbol_names(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("WARN: %#" 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 {
				pair = machine__find_kernel_symbol_by_name(&kallsyms, sym->name, NULL);
				if (pair) {
					if (UM(pair->start) == mem_start)
						goto next_pair;

					pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
						 mem_start, sym->name, pair->name);
				} else {
					pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
						 mem_start, sym->name, first_pair->name);
				}

				continue;
			}
		} else if (mem_start == kallsyms.vmlinux_map->end) {
			/*
			 * Ignore aliases to _etext, i.e. to the end of the kernel text area,
			 * such as __indirect_thunk_end.
			 */
			continue;
		} else if (is_ignored_symbol(sym->name, sym->type)) {
			/*
			 * Ignore hidden symbols, see scripts/kallsyms.c for the details
			 */
			continue;
		} else {
			pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
				 mem_start, sym->name);
		}

		err = -1;
	}

	if (verbose <= 0)
		goto out;

	header_printed = false;

	maps__for_each_entry(maps, map) {
		struct map *
		/*
		 * 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 = maps__find_by_name(kallsyms.kmaps, (map->dso->kernel ?
								map->dso->short_name :
								map->dso->name));
		if (pair) {
			pair->priv = 1;
		} else {
			if (!header_printed) {
				pr_info("WARN: Maps only in vmlinux:\n");
				header_printed = true;
			}
			map__fprintf(map, stderr);
		}
	}

	header_printed = false;

	maps__for_each_entry(maps, map) {
		struct map *pair;

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

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

		if (pair->start == mem_start) {
			if (!header_printed) {
				pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
				header_printed = true;
			}

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

	header_printed = false;

	maps = machine__kernel_maps(&kallsyms);

	maps__for_each_entry(maps, map) {
		if (!map->priv) {
			if (!header_printed) {
				pr_info("WARN: Maps only in kallsyms:\n");
				header_printed = true;
			}
			map__fprintf(map, stderr);
		}
	}
out:
	machine__exit(&kallsyms);
	machine__exit(&vmlinux);
	return err;
}

DEFINE_SUITE("vmlinux symtab matches kallsyms", vmlinux_matches_kallsyms);