1 #include <linux/compiler.h>
2 #include <linux/rbtree.h>
3 #include <string.h>
4 #include "map.h"
5 #include "symbol.h"
6 #include "util.h"
7 #include "tests.h"
8 #include "debug.h"
9 #include "machine.h"
10 
11 static int vmlinux_matches_kallsyms_filter(struct map *map __maybe_unused,
12 					   struct symbol *sym)
13 {
14 	bool *visited = symbol__priv(sym);
15 	*visited = true;
16 	return 0;
17 }
18 
19 #define UM(x) kallsyms_map->unmap_ip(kallsyms_map, (x))
20 
21 int test__vmlinux_matches_kallsyms(void)
22 {
23 	int err = -1;
24 	struct rb_node *nd;
25 	struct symbol *sym;
26 	struct map *kallsyms_map, *vmlinux_map, *map;
27 	struct machine kallsyms, vmlinux;
28 	enum map_type type = MAP__FUNCTION;
29 	struct maps *maps = &vmlinux.kmaps.maps[type];
30 	u64 mem_start, mem_end;
31 
32 	/*
33 	 * Step 1:
34 	 *
35 	 * Init the machines that will hold kernel, modules obtained from
36 	 * both vmlinux + .ko files and from /proc/kallsyms split by modules.
37 	 */
38 	machine__init(&kallsyms, "", HOST_KERNEL_ID);
39 	machine__init(&vmlinux, "", HOST_KERNEL_ID);
40 
41 	/*
42 	 * Step 2:
43 	 *
44 	 * Create the kernel maps for kallsyms and the DSO where we will then
45 	 * load /proc/kallsyms. Also create the modules maps from /proc/modules
46 	 * and find the .ko files that match them in /lib/modules/`uname -r`/.
47 	 */
48 	if (machine__create_kernel_maps(&kallsyms) < 0) {
49 		pr_debug("machine__create_kernel_maps ");
50 		goto out;
51 	}
52 
53 	/*
54 	 * Step 3:
55 	 *
56 	 * Load and split /proc/kallsyms into multiple maps, one per module.
57 	 */
58 	if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms", type, NULL) <= 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, type,
97 				       vmlinux_matches_kallsyms_filter) <= 0) {
98 		pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
99 		err = TEST_SKIP;
100 		goto out;
101 	}
102 
103 	err = 0;
104 	/*
105 	 * Step 7:
106 	 *
107 	 * Now look at the symbols in the vmlinux DSO and check if we find all of them
108 	 * in the kallsyms dso. For the ones that are in both, check its names and
109 	 * end addresses too.
110 	 */
111 	for (nd = rb_first(&vmlinux_map->dso->symbols[type]); nd; nd = rb_next(nd)) {
112 		struct symbol *pair, *first_pair;
113 		bool backwards = true;
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, type,
124 							 mem_start, NULL, NULL);
125 		pair = first_pair;
126 
127 		if (pair && UM(pair->start) == mem_start) {
128 next_pair:
129 			if (strcmp(sym->name, pair->name) == 0) {
130 				/*
131 				 * kallsyms don't have the symbol end, so we
132 				 * set that by using the next symbol start - 1,
133 				 * in some cases we get this up to a page
134 				 * wrong, trace_kmalloc when I was developing
135 				 * this code was one such example, 2106 bytes
136 				 * off the real size. More than that and we
137 				 * _really_ have a problem.
138 				 */
139 				s64 skew = mem_end - UM(pair->end);
140 				if (llabs(skew) >= page_size)
141 					pr_debug("%#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
142 						 mem_start, sym->name, mem_end,
143 						 UM(pair->end));
144 
145 				/*
146 				 * Do not count this as a failure, because we
147 				 * could really find a case where it's not
148 				 * possible to get proper function end from
149 				 * kallsyms.
150 				 */
151 				continue;
152 
153 			} else {
154 				struct rb_node *nnd;
155 detour:
156 				nnd = backwards ? rb_prev(&pair->rb_node) :
157 						  rb_next(&pair->rb_node);
158 				if (nnd) {
159 					struct symbol *next = rb_entry(nnd, struct symbol, rb_node);
160 
161 					if (UM(next->start) == mem_start) {
162 						pair = next;
163 						goto next_pair;
164 					}
165 				}
166 
167 				if (backwards) {
168 					backwards = false;
169 					pair = first_pair;
170 					goto detour;
171 				}
172 
173 				pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
174 					 mem_start, sym->name, pair->name);
175 			}
176 		} else
177 			pr_debug("%#" PRIx64 ": %s not on kallsyms\n",
178 				 mem_start, sym->name);
179 
180 		err = -1;
181 	}
182 
183 	if (!verbose)
184 		goto out;
185 
186 	pr_info("Maps only in vmlinux:\n");
187 
188 	for (map = maps__first(maps); map; map = map__next(map)) {
189 		struct map *
190 		/*
191 		 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
192 		 * the kernel will have the path for the vmlinux file being used,
193 		 * so use the short name, less descriptive but the same ("[kernel]" in
194 		 * both cases.
195 		 */
196 		pair = map_groups__find_by_name(&kallsyms.kmaps, type,
197 						(map->dso->kernel ?
198 							map->dso->short_name :
199 							map->dso->name));
200 		if (pair)
201 			pair->priv = 1;
202 		else
203 			map__fprintf(map, stderr);
204 	}
205 
206 	pr_info("Maps in vmlinux with a different name in kallsyms:\n");
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, type, mem_start);
215 		if (pair == NULL || pair->priv)
216 			continue;
217 
218 		if (pair->start == mem_start) {
219 			pair->priv = 1;
220 			pr_info(" %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
221 				map->start, map->end, map->pgoff, map->dso->name);
222 			if (mem_end != pair->end)
223 				pr_info(":\n*%" PRIx64 "-%" PRIx64 " %" PRIx64,
224 					pair->start, pair->end, pair->pgoff);
225 			pr_info(" %s\n", pair->dso->name);
226 			pair->priv = 1;
227 		}
228 	}
229 
230 	pr_info("Maps only in kallsyms:\n");
231 
232 	maps = &kallsyms.kmaps.maps[type];
233 
234 	for (map = maps__first(maps); map; map = map__next(map)) {
235 		if (!map->priv)
236 			map__fprintf(map, stderr);
237 	}
238 out:
239 	machine__exit(&kallsyms);
240 	machine__exit(&vmlinux);
241 	return err;
242 }
243