1// SPDX-License-Identifier: GPL-2.0
2#include <linux/compiler.h>
3#include <linux/rbtree.h>
4#include <inttypes.h>
5#include <string.h>
6#include <ctype.h>
7#include <stdlib.h>
8#include "dso.h"
9#include "map.h"
10#include "symbol.h"
11#include <internal/lib.h> // page_size
12#include "tests.h"
13#include "debug.h"
14#include "machine.h"
15
16#define UM(x) map__unmap_ip(kallsyms_map, (x))
17
18static bool is_ignored_symbol(const char *name, char type)
19{
20	/* Symbol names that exactly match to the following are ignored.*/
21	static const char * const ignored_symbols[] = {
22		/*
23		 * Symbols which vary between passes. Passes 1 and 2 must have
24		 * identical symbol lists. The kallsyms_* symbols below are
25		 * only added after pass 1, they would be included in pass 2
26		 * when --all-symbols is specified so exclude them to get a
27		 * stable symbol list.
28		 */
29		"kallsyms_addresses",
30		"kallsyms_offsets",
31		"kallsyms_relative_base",
32		"kallsyms_num_syms",
33		"kallsyms_names",
34		"kallsyms_markers",
35		"kallsyms_token_table",
36		"kallsyms_token_index",
37		/* Exclude linker generated symbols which vary between passes */
38		"_SDA_BASE_",		/* ppc */
39		"_SDA2_BASE_",		/* ppc */
40		NULL
41	};
42
43	/* Symbol names that begin with the following are ignored.*/
44	static const char * const ignored_prefixes[] = {
45		"$",			/* local symbols for ARM, MIPS, etc. */
46		".L",			/* local labels, .LBB,.Ltmpxxx,.L__unnamed_xx,.LASANPC, etc. */
47		"__crc_",		/* modversions */
48		"__efistub_",		/* arm64 EFI stub namespace */
49		"__kvm_nvhe_$",		/* arm64 local symbols in non-VHE KVM namespace */
50		"__kvm_nvhe_.L",	/* arm64 local symbols in non-VHE KVM namespace */
51		"__AArch64ADRPThunk_",	/* arm64 lld */
52		"__ARMV5PILongThunk_",	/* arm lld */
53		"__ARMV7PILongThunk_",
54		"__ThumbV7PILongThunk_",
55		"__LA25Thunk_",		/* mips lld */
56		"__microLA25Thunk_",
57		NULL
58	};
59
60	/* Symbol names that end with the following are ignored.*/
61	static const char * const ignored_suffixes[] = {
62		"_from_arm",		/* arm */
63		"_from_thumb",		/* arm */
64		"_veneer",		/* arm */
65		NULL
66	};
67
68	/* Symbol names that contain the following are ignored.*/
69	static const char * const ignored_matches[] = {
70		".long_branch.",	/* ppc stub */
71		".plt_branch.",		/* ppc stub */
72		NULL
73	};
74
75	const char * const *p;
76
77	for (p = ignored_symbols; *p; p++)
78		if (!strcmp(name, *p))
79			return true;
80
81	for (p = ignored_prefixes; *p; p++)
82		if (!strncmp(name, *p, strlen(*p)))
83			return true;
84
85	for (p = ignored_suffixes; *p; p++) {
86		int l = strlen(name) - strlen(*p);
87
88		if (l >= 0 && !strcmp(name + l, *p))
89			return true;
90	}
91
92	for (p = ignored_matches; *p; p++) {
93		if (strstr(name, *p))
94			return true;
95	}
96
97	if (type == 'U' || type == 'u')
98		return true;
99	/* exclude debugging symbols */
100	if (type == 'N' || type == 'n')
101		return true;
102
103	if (toupper(type) == 'A') {
104		/* Keep these useful absolute symbols */
105		if (strcmp(name, "__kernel_syscall_via_break") &&
106		    strcmp(name, "__kernel_syscall_via_epc") &&
107		    strcmp(name, "__kernel_sigtramp") &&
108		    strcmp(name, "__gp"))
109			return true;
110	}
111
112	return false;
113}
114
115static int test__vmlinux_matches_kallsyms(struct test_suite *test __maybe_unused,
116					int subtest __maybe_unused)
117{
118	int err = TEST_FAIL;
119	struct rb_node *nd;
120	struct symbol *sym;
121	struct map *kallsyms_map, *vmlinux_map;
122	struct map_rb_node *rb_node;
123	struct machine kallsyms, vmlinux;
124	struct maps *maps;
125	u64 mem_start, mem_end;
126	bool header_printed;
127
128	/*
129	 * Step 1:
130	 *
131	 * Init the machines that will hold kernel, modules obtained from
132	 * both vmlinux + .ko files and from /proc/kallsyms split by modules.
133	 */
134	machine__init(&kallsyms, "", HOST_KERNEL_ID);
135	machine__init(&vmlinux, "", HOST_KERNEL_ID);
136
137	maps = machine__kernel_maps(&vmlinux);
138
139	/*
140	 * Step 2:
141	 *
142	 * Create the kernel maps for kallsyms and the DSO where we will then
143	 * load /proc/kallsyms. Also create the modules maps from /proc/modules
144	 * and find the .ko files that match them in /lib/modules/`uname -r`/.
145	 */
146	if (machine__create_kernel_maps(&kallsyms) < 0) {
147		pr_debug("machine__create_kernel_maps failed");
148		err = TEST_SKIP;
149		goto out;
150	}
151
152	/*
153	 * Step 3:
154	 *
155	 * Load and split /proc/kallsyms into multiple maps, one per module.
156	 * Do not use kcore, as this test was designed before kcore support
157	 * and has parts that only make sense if using the non-kcore code.
158	 * XXX: extend it to stress the kcorre code as well, hint: the list
159	 * of modules extracted from /proc/kcore, in its current form, can't
160	 * be compacted against the list of modules found in the "vmlinux"
161	 * code and with the one got from /proc/modules from the "kallsyms" code.
162	 */
163	if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms") <= 0) {
164		pr_debug("machine__load_kallsyms failed");
165		err = TEST_SKIP;
166		goto out;
167	}
168
169	/*
170	 * Step 4:
171	 *
172	 * kallsyms will be internally on demand sorted by name so that we can
173	 * find the reference relocation * symbol, i.e. the symbol we will use
174	 * to see if the running kernel was relocated by checking if it has the
175	 * same value in the vmlinux file we load.
176	 */
177	kallsyms_map = machine__kernel_map(&kallsyms);
178
179	/*
180	 * Step 5:
181	 *
182	 * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
183	 */
184	if (machine__create_kernel_maps(&vmlinux) < 0) {
185		pr_info("machine__create_kernel_maps failed");
186		goto out;
187	}
188
189	vmlinux_map = machine__kernel_map(&vmlinux);
190
191	/*
192	 * Step 6:
193	 *
194	 * Locate a vmlinux file in the vmlinux path that has a buildid that
195	 * matches the one of the running kernel.
196	 *
197	 * While doing that look if we find the ref reloc symbol, if we find it
198	 * we'll have its ref_reloc_symbol.unrelocated_addr and then
199	 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
200	 * to fixup the symbols.
201	 */
202	if (machine__load_vmlinux_path(&vmlinux) <= 0) {
203		pr_info("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
204		err = TEST_SKIP;
205		goto out;
206	}
207
208	err = 0;
209	/*
210	 * Step 7:
211	 *
212	 * Now look at the symbols in the vmlinux DSO and check if we find all of them
213	 * in the kallsyms dso. For the ones that are in both, check its names and
214	 * end addresses too.
215	 */
216	map__for_each_symbol(vmlinux_map, sym, nd) {
217		struct symbol *pair, *first_pair;
218
219		sym  = rb_entry(nd, struct symbol, rb_node);
220
221		if (sym->start == sym->end)
222			continue;
223
224		mem_start = map__unmap_ip(vmlinux_map, sym->start);
225		mem_end = map__unmap_ip(vmlinux_map, sym->end);
226
227		first_pair = machine__find_kernel_symbol(&kallsyms, mem_start, NULL);
228		pair = first_pair;
229
230		if (pair && UM(pair->start) == mem_start) {
231next_pair:
232			if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
233				/*
234				 * kallsyms don't have the symbol end, so we
235				 * set that by using the next symbol start - 1,
236				 * in some cases we get this up to a page
237				 * wrong, trace_kmalloc when I was developing
238				 * this code was one such example, 2106 bytes
239				 * off the real size. More than that and we
240				 * _really_ have a problem.
241				 */
242				s64 skew = mem_end - UM(pair->end);
243				if (llabs(skew) >= page_size)
244					pr_debug("WARN: %#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
245						 mem_start, sym->name, mem_end,
246						 UM(pair->end));
247
248				/*
249				 * Do not count this as a failure, because we
250				 * could really find a case where it's not
251				 * possible to get proper function end from
252				 * kallsyms.
253				 */
254				continue;
255			} else {
256				pair = machine__find_kernel_symbol_by_name(&kallsyms, sym->name, NULL);
257				if (pair) {
258					if (UM(pair->start) == mem_start)
259						goto next_pair;
260
261					pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
262						 mem_start, sym->name, pair->name);
263				} else {
264					pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
265						 mem_start, sym->name, first_pair->name);
266				}
267
268				continue;
269			}
270		} else if (mem_start == map__end(kallsyms.vmlinux_map)) {
271			/*
272			 * Ignore aliases to _etext, i.e. to the end of the kernel text area,
273			 * such as __indirect_thunk_end.
274			 */
275			continue;
276		} else if (is_ignored_symbol(sym->name, sym->type)) {
277			/*
278			 * Ignore hidden symbols, see scripts/kallsyms.c for the details
279			 */
280			continue;
281		} else {
282			pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
283				 mem_start, sym->name);
284		}
285
286		err = -1;
287	}
288
289	if (verbose <= 0)
290		goto out;
291
292	header_printed = false;
293
294	maps__for_each_entry(maps, rb_node) {
295		struct map *map = rb_node->map;
296		struct dso *dso = map__dso(map);
297		/*
298		 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
299		 * the kernel will have the path for the vmlinux file being used,
300		 * so use the short name, less descriptive but the same ("[kernel]" in
301		 * both cases.
302		 */
303		struct map *pair = maps__find_by_name(kallsyms.kmaps, (dso->kernel ?
304								dso->short_name :
305								dso->name));
306		if (pair) {
307			map__set_priv(pair, 1);
308		} else {
309			if (!header_printed) {
310				pr_info("WARN: Maps only in vmlinux:\n");
311				header_printed = true;
312			}
313			map__fprintf(map, stderr);
314		}
315	}
316
317	header_printed = false;
318
319	maps__for_each_entry(maps, rb_node) {
320		struct map *pair, *map = rb_node->map;
321
322		mem_start = map__unmap_ip(vmlinux_map, map__start(map));
323		mem_end = map__unmap_ip(vmlinux_map, map__end(map));
324
325		pair = maps__find(kallsyms.kmaps, mem_start);
326		if (pair == NULL || map__priv(pair))
327			continue;
328
329		if (map__start(pair) == mem_start) {
330			struct dso *dso = map__dso(map);
331
332			if (!header_printed) {
333				pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
334				header_printed = true;
335			}
336
337			pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
338				map__start(map), map__end(map), map__pgoff(map), dso->name);
339			if (mem_end != map__end(pair))
340				pr_info(":\nWARN: *%" PRIx64 "-%" PRIx64 " %" PRIx64,
341					map__start(pair), map__end(pair), map__pgoff(pair));
342			pr_info(" %s\n", dso->name);
343			map__set_priv(pair, 1);
344		}
345	}
346
347	header_printed = false;
348
349	maps = machine__kernel_maps(&kallsyms);
350
351	maps__for_each_entry(maps, rb_node) {
352		struct map *map = rb_node->map;
353
354		if (!map__priv(map)) {
355			if (!header_printed) {
356				pr_info("WARN: Maps only in kallsyms:\n");
357				header_printed = true;
358			}
359			map__fprintf(map, stderr);
360		}
361	}
362out:
363	machine__exit(&kallsyms);
364	machine__exit(&vmlinux);
365	return err;
366}
367
368DEFINE_SUITE("vmlinux symtab matches kallsyms", vmlinux_matches_kallsyms);
369