1 /*
2 * sortextable.c: Sort the kernel's exception table
3 *
4 * Copyright 2011 - 2012 Cavium, Inc.
5 *
6 * Based on code taken from recortmcount.c which is:
7 *
8 * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
9 * Licensed under the GNU General Public License, version 2 (GPLv2).
10 *
11 * Restructured to fit Linux format, as well as other updates:
12 * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
13 */
14
15 /*
16 * Strategy: alter the vmlinux file in-place.
17 */
18
19 #include <sys/types.h>
20 #include <sys/mman.h>
21 #include <sys/stat.h>
22 #include <getopt.h>
23 #include <elf.h>
24 #include <fcntl.h>
25 #include <setjmp.h>
26 #include <stdio.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <unistd.h>
30
31 #include <tools/be_byteshift.h>
32 #include <tools/le_byteshift.h>
33
34 #ifndef EM_AARCH64
35 #define EM_AARCH64 183
36 #endif
37
38 static int fd_map; /* File descriptor for file being modified. */
39 static int mmap_failed; /* Boolean flag. */
40 static void *ehdr_curr; /* current ElfXX_Ehdr * for resource cleanup */
41 static struct stat sb; /* Remember .st_size, etc. */
42 static jmp_buf jmpenv; /* setjmp/longjmp per-file error escape */
43
44 /* setjmp() return values */
45 enum {
46 SJ_SETJMP = 0, /* hardwired first return */
47 SJ_FAIL,
48 SJ_SUCCEED
49 };
50
51 /* Per-file resource cleanup when multiple files. */
52 static void
cleanup(void)53 cleanup(void)
54 {
55 if (!mmap_failed)
56 munmap(ehdr_curr, sb.st_size);
57 close(fd_map);
58 }
59
60 static void __attribute__((noreturn))
fail_file(void)61 fail_file(void)
62 {
63 cleanup();
64 longjmp(jmpenv, SJ_FAIL);
65 }
66
67 static void __attribute__((noreturn))
succeed_file(void)68 succeed_file(void)
69 {
70 cleanup();
71 longjmp(jmpenv, SJ_SUCCEED);
72 }
73
74
75 /*
76 * Get the whole file as a programming convenience in order to avoid
77 * malloc+lseek+read+free of many pieces. If successful, then mmap
78 * avoids copying unused pieces; else just read the whole file.
79 * Open for both read and write.
80 */
mmap_file(char const * fname)81 static void *mmap_file(char const *fname)
82 {
83 void *addr;
84
85 fd_map = open(fname, O_RDWR);
86 if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
87 perror(fname);
88 fail_file();
89 }
90 if (!S_ISREG(sb.st_mode)) {
91 fprintf(stderr, "not a regular file: %s\n", fname);
92 fail_file();
93 }
94 addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED,
95 fd_map, 0);
96 if (addr == MAP_FAILED) {
97 mmap_failed = 1;
98 fprintf(stderr, "Could not mmap file: %s\n", fname);
99 fail_file();
100 }
101 return addr;
102 }
103
r8be(const uint64_t * x)104 static uint64_t r8be(const uint64_t *x)
105 {
106 return get_unaligned_be64(x);
107 }
rbe(const uint32_t * x)108 static uint32_t rbe(const uint32_t *x)
109 {
110 return get_unaligned_be32(x);
111 }
r2be(const uint16_t * x)112 static uint16_t r2be(const uint16_t *x)
113 {
114 return get_unaligned_be16(x);
115 }
r8le(const uint64_t * x)116 static uint64_t r8le(const uint64_t *x)
117 {
118 return get_unaligned_le64(x);
119 }
rle(const uint32_t * x)120 static uint32_t rle(const uint32_t *x)
121 {
122 return get_unaligned_le32(x);
123 }
r2le(const uint16_t * x)124 static uint16_t r2le(const uint16_t *x)
125 {
126 return get_unaligned_le16(x);
127 }
128
w8be(uint64_t val,uint64_t * x)129 static void w8be(uint64_t val, uint64_t *x)
130 {
131 put_unaligned_be64(val, x);
132 }
wbe(uint32_t val,uint32_t * x)133 static void wbe(uint32_t val, uint32_t *x)
134 {
135 put_unaligned_be32(val, x);
136 }
w2be(uint16_t val,uint16_t * x)137 static void w2be(uint16_t val, uint16_t *x)
138 {
139 put_unaligned_be16(val, x);
140 }
w8le(uint64_t val,uint64_t * x)141 static void w8le(uint64_t val, uint64_t *x)
142 {
143 put_unaligned_le64(val, x);
144 }
wle(uint32_t val,uint32_t * x)145 static void wle(uint32_t val, uint32_t *x)
146 {
147 put_unaligned_le32(val, x);
148 }
w2le(uint16_t val,uint16_t * x)149 static void w2le(uint16_t val, uint16_t *x)
150 {
151 put_unaligned_le16(val, x);
152 }
153
154 static uint64_t (*r8)(const uint64_t *);
155 static uint32_t (*r)(const uint32_t *);
156 static uint16_t (*r2)(const uint16_t *);
157 static void (*w8)(uint64_t, uint64_t *);
158 static void (*w)(uint32_t, uint32_t *);
159 static void (*w2)(uint16_t, uint16_t *);
160
161 typedef void (*table_sort_t)(char *, int);
162
163 /* 32 bit and 64 bit are very similar */
164 #include "sortextable.h"
165 #define SORTEXTABLE_64
166 #include "sortextable.h"
167
compare_relative_table(const void * a,const void * b)168 static int compare_relative_table(const void *a, const void *b)
169 {
170 int32_t av = (int32_t)r(a);
171 int32_t bv = (int32_t)r(b);
172
173 if (av < bv)
174 return -1;
175 if (av > bv)
176 return 1;
177 return 0;
178 }
179
sort_relative_table(char * extab_image,int image_size)180 static void sort_relative_table(char *extab_image, int image_size)
181 {
182 int i;
183
184 /*
185 * Do the same thing the runtime sort does, first normalize to
186 * being relative to the start of the section.
187 */
188 i = 0;
189 while (i < image_size) {
190 uint32_t *loc = (uint32_t *)(extab_image + i);
191 w(r(loc) + i, loc);
192 i += 4;
193 }
194
195 qsort(extab_image, image_size / 8, 8, compare_relative_table);
196
197 /* Now denormalize. */
198 i = 0;
199 while (i < image_size) {
200 uint32_t *loc = (uint32_t *)(extab_image + i);
201 w(r(loc) - i, loc);
202 i += 4;
203 }
204 }
205
206 static void
do_file(char const * const fname)207 do_file(char const *const fname)
208 {
209 table_sort_t custom_sort;
210 Elf32_Ehdr *ehdr = mmap_file(fname);
211
212 ehdr_curr = ehdr;
213 switch (ehdr->e_ident[EI_DATA]) {
214 default:
215 fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
216 ehdr->e_ident[EI_DATA], fname);
217 fail_file();
218 break;
219 case ELFDATA2LSB:
220 r = rle;
221 r2 = r2le;
222 r8 = r8le;
223 w = wle;
224 w2 = w2le;
225 w8 = w8le;
226 break;
227 case ELFDATA2MSB:
228 r = rbe;
229 r2 = r2be;
230 r8 = r8be;
231 w = wbe;
232 w2 = w2be;
233 w8 = w8be;
234 break;
235 } /* end switch */
236 if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
237 || r2(&ehdr->e_type) != ET_EXEC
238 || ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
239 fprintf(stderr, "unrecognized ET_EXEC file %s\n", fname);
240 fail_file();
241 }
242
243 custom_sort = NULL;
244 switch (r2(&ehdr->e_machine)) {
245 default:
246 fprintf(stderr, "unrecognized e_machine %d %s\n",
247 r2(&ehdr->e_machine), fname);
248 fail_file();
249 break;
250 case EM_386:
251 case EM_X86_64:
252 case EM_S390:
253 custom_sort = sort_relative_table;
254 break;
255 case EM_ARM:
256 case EM_AARCH64:
257 case EM_MIPS:
258 break;
259 } /* end switch */
260
261 switch (ehdr->e_ident[EI_CLASS]) {
262 default:
263 fprintf(stderr, "unrecognized ELF class %d %s\n",
264 ehdr->e_ident[EI_CLASS], fname);
265 fail_file();
266 break;
267 case ELFCLASS32:
268 if (r2(&ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
269 || r2(&ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
270 fprintf(stderr,
271 "unrecognized ET_EXEC file: %s\n", fname);
272 fail_file();
273 }
274 do32(ehdr, fname, custom_sort);
275 break;
276 case ELFCLASS64: {
277 Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
278 if (r2(&ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
279 || r2(&ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
280 fprintf(stderr,
281 "unrecognized ET_EXEC file: %s\n", fname);
282 fail_file();
283 }
284 do64(ghdr, fname, custom_sort);
285 break;
286 }
287 } /* end switch */
288
289 cleanup();
290 }
291
292 int
main(int argc,char * argv[])293 main(int argc, char *argv[])
294 {
295 int n_error = 0; /* gcc-4.3.0 false positive complaint */
296 int i;
297
298 if (argc < 2) {
299 fprintf(stderr, "usage: sortextable vmlinux...\n");
300 return 0;
301 }
302
303 /* Process each file in turn, allowing deep failure. */
304 for (i = 1; i < argc; i++) {
305 char *file = argv[i];
306 int const sjval = setjmp(jmpenv);
307
308 switch (sjval) {
309 default:
310 fprintf(stderr, "internal error: %s\n", file);
311 exit(1);
312 break;
313 case SJ_SETJMP: /* normal sequence */
314 /* Avoid problems if early cleanup() */
315 fd_map = -1;
316 ehdr_curr = NULL;
317 mmap_failed = 1;
318 do_file(file);
319 break;
320 case SJ_FAIL: /* error in do_file or below */
321 ++n_error;
322 break;
323 case SJ_SUCCEED: /* premature success */
324 /* do nothing */
325 break;
326 } /* end switch */
327 }
328 return !!n_error;
329 }
330