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	struct ref_reloc_sym ref_reloc_sym = { .name = "_stext", };
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, type);
72
73	sym = map__find_symbol_by_name(kallsyms_map, ref_reloc_sym.name, NULL);
74	if (sym == NULL) {
75		pr_debug("dso__find_symbol_by_name ");
76		goto out;
77	}
78
79	ref_reloc_sym.addr = UM(sym->start);
80
81	/*
82	 * Step 5:
83	 *
84	 * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
85	 */
86	if (machine__create_kernel_maps(&vmlinux) < 0) {
87		pr_debug("machine__create_kernel_maps ");
88		goto out;
89	}
90
91	vmlinux_map = machine__kernel_map(&vmlinux, type);
92	map__kmap(vmlinux_map)->ref_reloc_sym = &ref_reloc_sym;
93
94	/*
95	 * Step 6:
96	 *
97	 * Locate a vmlinux file in the vmlinux path that has a buildid that
98	 * matches the one of the running kernel.
99	 *
100	 * While doing that look if we find the ref reloc symbol, if we find it
101	 * we'll have its ref_reloc_symbol.unrelocated_addr and then
102	 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
103	 * to fixup the symbols.
104	 */
105	if (machine__load_vmlinux_path(&vmlinux, type,
106				       vmlinux_matches_kallsyms_filter) <= 0) {
107		pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
108		err = TEST_SKIP;
109		goto out;
110	}
111
112	err = 0;
113	/*
114	 * Step 7:
115	 *
116	 * Now look at the symbols in the vmlinux DSO and check if we find all of them
117	 * in the kallsyms dso. For the ones that are in both, check its names and
118	 * end addresses too.
119	 */
120	for (nd = rb_first(&vmlinux_map->dso->symbols[type]); nd; nd = rb_next(nd)) {
121		struct symbol *pair, *first_pair;
122		bool backwards = true;
123
124		sym  = rb_entry(nd, struct symbol, rb_node);
125
126		if (sym->start == sym->end)
127			continue;
128
129		mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
130		mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
131
132		first_pair = machine__find_kernel_symbol(&kallsyms, type,
133							 mem_start, NULL, NULL);
134		pair = first_pair;
135
136		if (pair && UM(pair->start) == mem_start) {
137next_pair:
138			if (strcmp(sym->name, pair->name) == 0) {
139				/*
140				 * kallsyms don't have the symbol end, so we
141				 * set that by using the next symbol start - 1,
142				 * in some cases we get this up to a page
143				 * wrong, trace_kmalloc when I was developing
144				 * this code was one such example, 2106 bytes
145				 * off the real size. More than that and we
146				 * _really_ have a problem.
147				 */
148				s64 skew = mem_end - UM(pair->end);
149				if (llabs(skew) >= page_size)
150					pr_debug("%#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
151						 mem_start, sym->name, mem_end,
152						 UM(pair->end));
153
154				/*
155				 * Do not count this as a failure, because we
156				 * could really find a case where it's not
157				 * possible to get proper function end from
158				 * kallsyms.
159				 */
160				continue;
161
162			} else {
163				struct rb_node *nnd;
164detour:
165				nnd = backwards ? rb_prev(&pair->rb_node) :
166						  rb_next(&pair->rb_node);
167				if (nnd) {
168					struct symbol *next = rb_entry(nnd, struct symbol, rb_node);
169
170					if (UM(next->start) == mem_start) {
171						pair = next;
172						goto next_pair;
173					}
174				}
175
176				if (backwards) {
177					backwards = false;
178					pair = first_pair;
179					goto detour;
180				}
181
182				pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
183					 mem_start, sym->name, pair->name);
184			}
185		} else
186			pr_debug("%#" PRIx64 ": %s not on kallsyms\n",
187				 mem_start, sym->name);
188
189		err = -1;
190	}
191
192	if (!verbose)
193		goto out;
194
195	pr_info("Maps only in vmlinux:\n");
196
197	for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
198		struct map *pos = rb_entry(nd, struct map, rb_node), *pair;
199		/*
200		 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
201		 * the kernel will have the path for the vmlinux file being used,
202		 * so use the short name, less descriptive but the same ("[kernel]" in
203		 * both cases.
204		 */
205		pair = map_groups__find_by_name(&kallsyms.kmaps, type,
206						(pos->dso->kernel ?
207							pos->dso->short_name :
208							pos->dso->name));
209		if (pair)
210			pair->priv = 1;
211		else
212			map__fprintf(pos, stderr);
213	}
214
215	pr_info("Maps in vmlinux with a different name in kallsyms:\n");
216
217	for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
218		struct map *pos = rb_entry(nd, struct map, rb_node), *pair;
219
220		mem_start = vmlinux_map->unmap_ip(vmlinux_map, pos->start);
221		mem_end = vmlinux_map->unmap_ip(vmlinux_map, pos->end);
222
223		pair = map_groups__find(&kallsyms.kmaps, type, mem_start);
224		if (pair == NULL || pair->priv)
225			continue;
226
227		if (pair->start == mem_start) {
228			pair->priv = 1;
229			pr_info(" %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
230				pos->start, pos->end, pos->pgoff, pos->dso->name);
231			if (mem_end != pair->end)
232				pr_info(":\n*%" PRIx64 "-%" PRIx64 " %" PRIx64,
233					pair->start, pair->end, pair->pgoff);
234			pr_info(" %s\n", pair->dso->name);
235			pair->priv = 1;
236		}
237	}
238
239	pr_info("Maps only in kallsyms:\n");
240
241	for (nd = rb_first(&kallsyms.kmaps.maps[type]);
242	     nd; nd = rb_next(nd)) {
243		struct map *pos = rb_entry(nd, struct map, rb_node);
244
245		if (!pos->priv)
246			map__fprintf(pos, stderr);
247	}
248out:
249	machine__exit(&kallsyms);
250	machine__exit(&vmlinux);
251	return err;
252}
253