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 <stdlib.h>
7 #include "dso.h"
8 #include "map.h"
9 #include "symbol.h"
10 #include <internal/lib.h> // page_size
11 #include "tests.h"
12 #include "debug.h"
13 #include "machine.h"
14 
15 #define UM(x) kallsyms_map->unmap_ip(kallsyms_map, (x))
16 
17 int test__vmlinux_matches_kallsyms(struct test *test __maybe_unused, int subtest __maybe_unused)
18 {
19 	int err = -1;
20 	struct rb_node *nd;
21 	struct symbol *sym;
22 	struct map *kallsyms_map, *vmlinux_map, *map;
23 	struct machine kallsyms, vmlinux;
24 	struct maps *maps = machine__kernel_maps(&vmlinux);
25 	u64 mem_start, mem_end;
26 	bool header_printed;
27 
28 	/*
29 	 * Step 1:
30 	 *
31 	 * Init the machines that will hold kernel, modules obtained from
32 	 * both vmlinux + .ko files and from /proc/kallsyms split by modules.
33 	 */
34 	machine__init(&kallsyms, "", HOST_KERNEL_ID);
35 	machine__init(&vmlinux, "", HOST_KERNEL_ID);
36 
37 	/*
38 	 * Step 2:
39 	 *
40 	 * Create the kernel maps for kallsyms and the DSO where we will then
41 	 * load /proc/kallsyms. Also create the modules maps from /proc/modules
42 	 * and find the .ko files that match them in /lib/modules/`uname -r`/.
43 	 */
44 	if (machine__create_kernel_maps(&kallsyms) < 0) {
45 		pr_debug("machine__create_kernel_maps ");
46 		goto out;
47 	}
48 
49 	/*
50 	 * Step 3:
51 	 *
52 	 * Load and split /proc/kallsyms into multiple maps, one per module.
53 	 * Do not use kcore, as this test was designed before kcore support
54 	 * and has parts that only make sense if using the non-kcore code.
55 	 * XXX: extend it to stress the kcorre code as well, hint: the list
56 	 * of modules extracted from /proc/kcore, in its current form, can't
57 	 * be compacted against the list of modules found in the "vmlinux"
58 	 * code and with the one got from /proc/modules from the "kallsyms" code.
59 	 */
60 	if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms") <= 0) {
61 		pr_debug("dso__load_kallsyms ");
62 		goto out;
63 	}
64 
65 	/*
66 	 * Step 4:
67 	 *
68 	 * kallsyms will be internally on demand sorted by name so that we can
69 	 * find the reference relocation * symbol, i.e. the symbol we will use
70 	 * to see if the running kernel was relocated by checking if it has the
71 	 * same value in the vmlinux file we load.
72 	 */
73 	kallsyms_map = machine__kernel_map(&kallsyms);
74 
75 	/*
76 	 * Step 5:
77 	 *
78 	 * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
79 	 */
80 	if (machine__create_kernel_maps(&vmlinux) < 0) {
81 		pr_debug("machine__create_kernel_maps ");
82 		goto out;
83 	}
84 
85 	vmlinux_map = machine__kernel_map(&vmlinux);
86 
87 	/*
88 	 * Step 6:
89 	 *
90 	 * Locate a vmlinux file in the vmlinux path that has a buildid that
91 	 * matches the one of the running kernel.
92 	 *
93 	 * While doing that look if we find the ref reloc symbol, if we find it
94 	 * we'll have its ref_reloc_symbol.unrelocated_addr and then
95 	 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
96 	 * to fixup the symbols.
97 	 */
98 	if (machine__load_vmlinux_path(&vmlinux) <= 0) {
99 		pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
100 		err = TEST_SKIP;
101 		goto out;
102 	}
103 
104 	err = 0;
105 	/*
106 	 * Step 7:
107 	 *
108 	 * Now look at the symbols in the vmlinux DSO and check if we find all of them
109 	 * in the kallsyms dso. For the ones that are in both, check its names and
110 	 * end addresses too.
111 	 */
112 	map__for_each_symbol(vmlinux_map, sym, nd) {
113 		struct symbol *pair, *first_pair;
114 
115 		sym  = rb_entry(nd, struct symbol, rb_node);
116 
117 		if (sym->start == sym->end)
118 			continue;
119 
120 		mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
121 		mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
122 
123 		first_pair = machine__find_kernel_symbol(&kallsyms, mem_start, NULL);
124 		pair = first_pair;
125 
126 		if (pair && UM(pair->start) == mem_start) {
127 next_pair:
128 			if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
129 				/*
130 				 * kallsyms don't have the symbol end, so we
131 				 * set that by using the next symbol start - 1,
132 				 * in some cases we get this up to a page
133 				 * wrong, trace_kmalloc when I was developing
134 				 * this code was one such example, 2106 bytes
135 				 * off the real size. More than that and we
136 				 * _really_ have a problem.
137 				 */
138 				s64 skew = mem_end - UM(pair->end);
139 				if (llabs(skew) >= page_size)
140 					pr_debug("WARN: %#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
141 						 mem_start, sym->name, mem_end,
142 						 UM(pair->end));
143 
144 				/*
145 				 * Do not count this as a failure, because we
146 				 * could really find a case where it's not
147 				 * possible to get proper function end from
148 				 * kallsyms.
149 				 */
150 				continue;
151 			} else {
152 				pair = machine__find_kernel_symbol_by_name(&kallsyms, sym->name, NULL);
153 				if (pair) {
154 					if (UM(pair->start) == mem_start)
155 						goto next_pair;
156 
157 					pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
158 						 mem_start, sym->name, pair->name);
159 				} else {
160 					pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
161 						 mem_start, sym->name, first_pair->name);
162 				}
163 
164 				continue;
165 			}
166 		} else if (mem_start == kallsyms.vmlinux_map->end) {
167 			/*
168 			 * Ignore aliases to _etext, i.e. to the end of the kernel text area,
169 			 * such as __indirect_thunk_end.
170 			 */
171 			continue;
172 		} else {
173 			pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
174 				 mem_start, sym->name);
175 		}
176 
177 		err = -1;
178 	}
179 
180 	if (verbose <= 0)
181 		goto out;
182 
183 	header_printed = false;
184 
185 	for (map = maps__first(maps); map; map = map__next(map)) {
186 		struct map *
187 		/*
188 		 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
189 		 * the kernel will have the path for the vmlinux file being used,
190 		 * so use the short name, less descriptive but the same ("[kernel]" in
191 		 * both cases.
192 		 */
193 		pair = map_groups__find_by_name(&kallsyms.kmaps,
194 						(map->dso->kernel ?
195 							map->dso->short_name :
196 							map->dso->name));
197 		if (pair) {
198 			pair->priv = 1;
199 		} else {
200 			if (!header_printed) {
201 				pr_info("WARN: Maps only in vmlinux:\n");
202 				header_printed = true;
203 			}
204 			map__fprintf(map, stderr);
205 		}
206 	}
207 
208 	header_printed = false;
209 
210 	for (map = maps__first(maps); map; map = map__next(map)) {
211 		struct map *pair;
212 
213 		mem_start = vmlinux_map->unmap_ip(vmlinux_map, map->start);
214 		mem_end = vmlinux_map->unmap_ip(vmlinux_map, map->end);
215 
216 		pair = map_groups__find(&kallsyms.kmaps, mem_start);
217 		if (pair == NULL || pair->priv)
218 			continue;
219 
220 		if (pair->start == mem_start) {
221 			if (!header_printed) {
222 				pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
223 				header_printed = true;
224 			}
225 
226 			pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
227 				map->start, map->end, map->pgoff, map->dso->name);
228 			if (mem_end != pair->end)
229 				pr_info(":\nWARN: *%" PRIx64 "-%" PRIx64 " %" PRIx64,
230 					pair->start, pair->end, pair->pgoff);
231 			pr_info(" %s\n", pair->dso->name);
232 			pair->priv = 1;
233 		}
234 	}
235 
236 	header_printed = false;
237 
238 	maps = machine__kernel_maps(&kallsyms);
239 
240 	for (map = maps__first(maps); map; map = map__next(map)) {
241 		if (!map->priv) {
242 			if (!header_printed) {
243 				pr_info("WARN: Maps only in kallsyms:\n");
244 				header_printed = true;
245 			}
246 			map__fprintf(map, stderr);
247 		}
248 	}
249 out:
250 	machine__exit(&kallsyms);
251 	machine__exit(&vmlinux);
252 	return err;
253 }
254