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
11static 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
21int 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;
27	struct machine kallsyms, vmlinux;
28	enum map_type type = MAP__FUNCTION;
29	u64 mem_start, mem_end;
30
31	/*
32	 * Step 1:
33	 *
34	 * Init the machines that will hold kernel, modules obtained from
35	 * both vmlinux + .ko files and from /proc/kallsyms split by modules.
36	 */
37	machine__init(&kallsyms, "", HOST_KERNEL_ID);
38	machine__init(&vmlinux, "", HOST_KERNEL_ID);
39
40	/*
41	 * Step 2:
42	 *
43	 * Create the kernel maps for kallsyms and the DSO where we will then
44	 * load /proc/kallsyms. Also create the modules maps from /proc/modules
45	 * and find the .ko files that match them in /lib/modules/`uname -r`/.
46	 */
47	if (machine__create_kernel_maps(&kallsyms) < 0) {
48		pr_debug("machine__create_kernel_maps ");
49		goto out;
50	}
51
52	/*
53	 * Step 3:
54	 *
55	 * Load and split /proc/kallsyms into multiple maps, one per module.
56	 */
57	if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms", type, NULL) <= 0) {
58		pr_debug("dso__load_kallsyms ");
59		goto out;
60	}
61
62	/*
63	 * Step 4:
64	 *
65	 * kallsyms will be internally on demand sorted by name so that we can
66	 * find the reference relocation * symbol, i.e. the symbol we will use
67	 * to see if the running kernel was relocated by checking if it has the
68	 * same value in the vmlinux file we load.
69	 */
70	kallsyms_map = machine__kernel_map(&kallsyms, type);
71
72	/*
73	 * Step 5:
74	 *
75	 * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
76	 */
77	if (machine__create_kernel_maps(&vmlinux) < 0) {
78		pr_debug("machine__create_kernel_maps ");
79		goto out;
80	}
81
82	vmlinux_map = machine__kernel_map(&vmlinux, type);
83
84	/*
85	 * Step 6:
86	 *
87	 * Locate a vmlinux file in the vmlinux path that has a buildid that
88	 * matches the one of the running kernel.
89	 *
90	 * While doing that look if we find the ref reloc symbol, if we find it
91	 * we'll have its ref_reloc_symbol.unrelocated_addr and then
92	 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
93	 * to fixup the symbols.
94	 */
95	if (machine__load_vmlinux_path(&vmlinux, type,
96				       vmlinux_matches_kallsyms_filter) <= 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	for (nd = rb_first(&vmlinux_map->dso->symbols[type]); nd; nd = rb_next(nd)) {
111		struct symbol *pair, *first_pair;
112		bool backwards = true;
113
114		sym  = rb_entry(nd, struct symbol, rb_node);
115
116		if (sym->start == sym->end)
117			continue;
118
119		mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
120		mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
121
122		first_pair = machine__find_kernel_symbol(&kallsyms, type,
123							 mem_start, NULL, NULL);
124		pair = first_pair;
125
126		if (pair && UM(pair->start) == mem_start) {
127next_pair:
128			if (strcmp(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("%#" 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
152			} else {
153				struct rb_node *nnd;
154detour:
155				nnd = backwards ? rb_prev(&pair->rb_node) :
156						  rb_next(&pair->rb_node);
157				if (nnd) {
158					struct symbol *next = rb_entry(nnd, struct symbol, rb_node);
159
160					if (UM(next->start) == mem_start) {
161						pair = next;
162						goto next_pair;
163					}
164				}
165
166				if (backwards) {
167					backwards = false;
168					pair = first_pair;
169					goto detour;
170				}
171
172				pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
173					 mem_start, sym->name, pair->name);
174			}
175		} else
176			pr_debug("%#" PRIx64 ": %s not on kallsyms\n",
177				 mem_start, sym->name);
178
179		err = -1;
180	}
181
182	if (!verbose)
183		goto out;
184
185	pr_info("Maps only in vmlinux:\n");
186
187	for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
188		struct map *pos = rb_entry(nd, struct map, rb_node), *pair;
189		/*
190		 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
191		 * the kernel will have the path for the vmlinux file being used,
192		 * so use the short name, less descriptive but the same ("[kernel]" in
193		 * both cases.
194		 */
195		pair = map_groups__find_by_name(&kallsyms.kmaps, type,
196						(pos->dso->kernel ?
197							pos->dso->short_name :
198							pos->dso->name));
199		if (pair)
200			pair->priv = 1;
201		else
202			map__fprintf(pos, stderr);
203	}
204
205	pr_info("Maps in vmlinux with a different name in kallsyms:\n");
206
207	for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
208		struct map *pos = rb_entry(nd, struct map, rb_node), *pair;
209
210		mem_start = vmlinux_map->unmap_ip(vmlinux_map, pos->start);
211		mem_end = vmlinux_map->unmap_ip(vmlinux_map, pos->end);
212
213		pair = map_groups__find(&kallsyms.kmaps, type, mem_start);
214		if (pair == NULL || pair->priv)
215			continue;
216
217		if (pair->start == mem_start) {
218			pair->priv = 1;
219			pr_info(" %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
220				pos->start, pos->end, pos->pgoff, pos->dso->name);
221			if (mem_end != pair->end)
222				pr_info(":\n*%" PRIx64 "-%" PRIx64 " %" PRIx64,
223					pair->start, pair->end, pair->pgoff);
224			pr_info(" %s\n", pair->dso->name);
225			pair->priv = 1;
226		}
227	}
228
229	pr_info("Maps only in kallsyms:\n");
230
231	for (nd = rb_first(&kallsyms.kmaps.maps[type]);
232	     nd; nd = rb_next(nd)) {
233		struct map *pos = rb_entry(nd, struct map, rb_node);
234
235		if (!pos->priv)
236			map__fprintf(pos, stderr);
237	}
238out:
239	machine__exit(&kallsyms);
240	machine__exit(&vmlinux);
241	return err;
242}
243