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 "map.h"
7 #include "symbol.h"
8 #include "util.h"
9 #include "tests.h"
10 #include "debug.h"
11 #include "machine.h"
12 
13 #define UM(x) kallsyms_map->unmap_ip(kallsyms_map, (x))
14 
15 int test__vmlinux_matches_kallsyms(struct test *test __maybe_unused, int subtest __maybe_unused)
16 {
17 	int err = -1;
18 	struct rb_node *nd;
19 	struct symbol *sym;
20 	struct map *kallsyms_map, *vmlinux_map, *map;
21 	struct machine kallsyms, vmlinux;
22 	struct maps *maps = machine__kernel_maps(&vmlinux);
23 	u64 mem_start, mem_end;
24 	bool header_printed;
25 
26 	/*
27 	 * Step 1:
28 	 *
29 	 * Init the machines that will hold kernel, modules obtained from
30 	 * both vmlinux + .ko files and from /proc/kallsyms split by modules.
31 	 */
32 	machine__init(&kallsyms, "", HOST_KERNEL_ID);
33 	machine__init(&vmlinux, "", HOST_KERNEL_ID);
34 
35 	/*
36 	 * Step 2:
37 	 *
38 	 * Create the kernel maps for kallsyms and the DSO where we will then
39 	 * load /proc/kallsyms. Also create the modules maps from /proc/modules
40 	 * and find the .ko files that match them in /lib/modules/`uname -r`/.
41 	 */
42 	if (machine__create_kernel_maps(&kallsyms) < 0) {
43 		pr_debug("machine__create_kernel_maps ");
44 		goto out;
45 	}
46 
47 	/*
48 	 * Step 3:
49 	 *
50 	 * Load and split /proc/kallsyms into multiple maps, one per module.
51 	 * Do not use kcore, as this test was designed before kcore support
52 	 * and has parts that only make sense if using the non-kcore code.
53 	 * XXX: extend it to stress the kcorre code as well, hint: the list
54 	 * of modules extracted from /proc/kcore, in its current form, can't
55 	 * be compacted against the list of modules found in the "vmlinux"
56 	 * code and with the one got from /proc/modules from the "kallsyms" code.
57 	 */
58 	if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms") <= 0) {
59 		pr_debug("dso__load_kallsyms ");
60 		goto out;
61 	}
62 
63 	/*
64 	 * Step 4:
65 	 *
66 	 * kallsyms will be internally on demand sorted by name so that we can
67 	 * find the reference relocation * symbol, i.e. the symbol we will use
68 	 * to see if the running kernel was relocated by checking if it has the
69 	 * same value in the vmlinux file we load.
70 	 */
71 	kallsyms_map = machine__kernel_map(&kallsyms);
72 
73 	/*
74 	 * Step 5:
75 	 *
76 	 * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
77 	 */
78 	if (machine__create_kernel_maps(&vmlinux) < 0) {
79 		pr_debug("machine__create_kernel_maps ");
80 		goto out;
81 	}
82 
83 	vmlinux_map = machine__kernel_map(&vmlinux);
84 
85 	/*
86 	 * Step 6:
87 	 *
88 	 * Locate a vmlinux file in the vmlinux path that has a buildid that
89 	 * matches the one of the running kernel.
90 	 *
91 	 * While doing that look if we find the ref reloc symbol, if we find it
92 	 * we'll have its ref_reloc_symbol.unrelocated_addr and then
93 	 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
94 	 * to fixup the symbols.
95 	 */
96 	if (machine__load_vmlinux_path(&vmlinux) <= 0) {
97 		pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
98 		err = TEST_SKIP;
99 		goto out;
100 	}
101 
102 	err = 0;
103 	/*
104 	 * Step 7:
105 	 *
106 	 * Now look at the symbols in the vmlinux DSO and check if we find all of them
107 	 * in the kallsyms dso. For the ones that are in both, check its names and
108 	 * end addresses too.
109 	 */
110 	map__for_each_symbol(vmlinux_map, sym, nd) {
111 		struct symbol *pair, *first_pair;
112 
113 		sym  = rb_entry(nd, struct symbol, rb_node);
114 
115 		if (sym->start == sym->end)
116 			continue;
117 
118 		mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
119 		mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
120 
121 		first_pair = machine__find_kernel_symbol(&kallsyms, mem_start, NULL);
122 		pair = first_pair;
123 
124 		if (pair && UM(pair->start) == mem_start) {
125 next_pair:
126 			if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
127 				/*
128 				 * kallsyms don't have the symbol end, so we
129 				 * set that by using the next symbol start - 1,
130 				 * in some cases we get this up to a page
131 				 * wrong, trace_kmalloc when I was developing
132 				 * this code was one such example, 2106 bytes
133 				 * off the real size. More than that and we
134 				 * _really_ have a problem.
135 				 */
136 				s64 skew = mem_end - UM(pair->end);
137 				if (llabs(skew) >= page_size)
138 					pr_debug("WARN: %#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
139 						 mem_start, sym->name, mem_end,
140 						 UM(pair->end));
141 
142 				/*
143 				 * Do not count this as a failure, because we
144 				 * could really find a case where it's not
145 				 * possible to get proper function end from
146 				 * kallsyms.
147 				 */
148 				continue;
149 			} else {
150 				pair = machine__find_kernel_symbol_by_name(&kallsyms, sym->name, NULL);
151 				if (pair) {
152 					if (UM(pair->start) == mem_start)
153 						goto next_pair;
154 
155 					pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
156 						 mem_start, sym->name, pair->name);
157 				} else {
158 					pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
159 						 mem_start, sym->name, first_pair->name);
160 				}
161 
162 				continue;
163 			}
164 		} else if (mem_start == kallsyms.vmlinux_map->end) {
165 			/*
166 			 * Ignore aliases to _etext, i.e. to the end of the kernel text area,
167 			 * such as __indirect_thunk_end.
168 			 */
169 			continue;
170 		} else {
171 			pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
172 				 mem_start, sym->name);
173 		}
174 
175 		err = -1;
176 	}
177 
178 	if (verbose <= 0)
179 		goto out;
180 
181 	header_printed = false;
182 
183 	for (map = maps__first(maps); map; map = map__next(map)) {
184 		struct map *
185 		/*
186 		 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
187 		 * the kernel will have the path for the vmlinux file being used,
188 		 * so use the short name, less descriptive but the same ("[kernel]" in
189 		 * both cases.
190 		 */
191 		pair = map_groups__find_by_name(&kallsyms.kmaps,
192 						(map->dso->kernel ?
193 							map->dso->short_name :
194 							map->dso->name));
195 		if (pair) {
196 			pair->priv = 1;
197 		} else {
198 			if (!header_printed) {
199 				pr_info("WARN: Maps only in vmlinux:\n");
200 				header_printed = true;
201 			}
202 			map__fprintf(map, stderr);
203 		}
204 	}
205 
206 	header_printed = false;
207 
208 	for (map = maps__first(maps); map; map = map__next(map)) {
209 		struct map *pair;
210 
211 		mem_start = vmlinux_map->unmap_ip(vmlinux_map, map->start);
212 		mem_end = vmlinux_map->unmap_ip(vmlinux_map, map->end);
213 
214 		pair = map_groups__find(&kallsyms.kmaps, mem_start);
215 		if (pair == NULL || pair->priv)
216 			continue;
217 
218 		if (pair->start == mem_start) {
219 			if (!header_printed) {
220 				pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
221 				header_printed = true;
222 			}
223 
224 			pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
225 				map->start, map->end, map->pgoff, map->dso->name);
226 			if (mem_end != pair->end)
227 				pr_info(":\nWARN: *%" PRIx64 "-%" PRIx64 " %" PRIx64,
228 					pair->start, pair->end, pair->pgoff);
229 			pr_info(" %s\n", pair->dso->name);
230 			pair->priv = 1;
231 		}
232 	}
233 
234 	header_printed = false;
235 
236 	maps = machine__kernel_maps(&kallsyms);
237 
238 	for (map = maps__first(maps); map; map = map__next(map)) {
239 		if (!map->priv) {
240 			if (!header_printed) {
241 				pr_info("WARN: Maps only in kallsyms:\n");
242 				header_printed = true;
243 			}
244 			map__fprintf(map, stderr);
245 		}
246 	}
247 out:
248 	machine__exit(&kallsyms);
249 	machine__exit(&vmlinux);
250 	return err;
251 }
252