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_ARCOMPACT
35 #define EM_ARCOMPACT 93
36 #endif
37
38 #ifndef EM_XTENSA
39 #define EM_XTENSA 94
40 #endif
41
42 #ifndef EM_AARCH64
43 #define EM_AARCH64 183
44 #endif
45
46 #ifndef EM_MICROBLAZE
47 #define EM_MICROBLAZE 189
48 #endif
49
50 #ifndef EM_ARCV2
51 #define EM_ARCV2 195
52 #endif
53
54 static int fd_map; /* File descriptor for file being modified. */
55 static int mmap_failed; /* Boolean flag. */
56 static void *ehdr_curr; /* current ElfXX_Ehdr * for resource cleanup */
57 static struct stat sb; /* Remember .st_size, etc. */
58 static jmp_buf jmpenv; /* setjmp/longjmp per-file error escape */
59
60 /* setjmp() return values */
61 enum {
62 SJ_SETJMP = 0, /* hardwired first return */
63 SJ_FAIL,
64 SJ_SUCCEED
65 };
66
67 /* Per-file resource cleanup when multiple files. */
68 static void
cleanup(void)69 cleanup(void)
70 {
71 if (!mmap_failed)
72 munmap(ehdr_curr, sb.st_size);
73 close(fd_map);
74 }
75
76 static void __attribute__((noreturn))
fail_file(void)77 fail_file(void)
78 {
79 cleanup();
80 longjmp(jmpenv, SJ_FAIL);
81 }
82
83 /*
84 * Get the whole file as a programming convenience in order to avoid
85 * malloc+lseek+read+free of many pieces. If successful, then mmap
86 * avoids copying unused pieces; else just read the whole file.
87 * Open for both read and write.
88 */
mmap_file(char const * fname)89 static void *mmap_file(char const *fname)
90 {
91 void *addr;
92
93 fd_map = open(fname, O_RDWR);
94 if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
95 perror(fname);
96 fail_file();
97 }
98 if (!S_ISREG(sb.st_mode)) {
99 fprintf(stderr, "not a regular file: %s\n", fname);
100 fail_file();
101 }
102 addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED,
103 fd_map, 0);
104 if (addr == MAP_FAILED) {
105 mmap_failed = 1;
106 fprintf(stderr, "Could not mmap file: %s\n", fname);
107 fail_file();
108 }
109 return addr;
110 }
111
r8be(const uint64_t * x)112 static uint64_t r8be(const uint64_t *x)
113 {
114 return get_unaligned_be64(x);
115 }
rbe(const uint32_t * x)116 static uint32_t rbe(const uint32_t *x)
117 {
118 return get_unaligned_be32(x);
119 }
r2be(const uint16_t * x)120 static uint16_t r2be(const uint16_t *x)
121 {
122 return get_unaligned_be16(x);
123 }
r8le(const uint64_t * x)124 static uint64_t r8le(const uint64_t *x)
125 {
126 return get_unaligned_le64(x);
127 }
rle(const uint32_t * x)128 static uint32_t rle(const uint32_t *x)
129 {
130 return get_unaligned_le32(x);
131 }
r2le(const uint16_t * x)132 static uint16_t r2le(const uint16_t *x)
133 {
134 return get_unaligned_le16(x);
135 }
136
w8be(uint64_t val,uint64_t * x)137 static void w8be(uint64_t val, uint64_t *x)
138 {
139 put_unaligned_be64(val, x);
140 }
wbe(uint32_t val,uint32_t * x)141 static void wbe(uint32_t val, uint32_t *x)
142 {
143 put_unaligned_be32(val, x);
144 }
w2be(uint16_t val,uint16_t * x)145 static void w2be(uint16_t val, uint16_t *x)
146 {
147 put_unaligned_be16(val, x);
148 }
w8le(uint64_t val,uint64_t * x)149 static void w8le(uint64_t val, uint64_t *x)
150 {
151 put_unaligned_le64(val, x);
152 }
wle(uint32_t val,uint32_t * x)153 static void wle(uint32_t val, uint32_t *x)
154 {
155 put_unaligned_le32(val, x);
156 }
w2le(uint16_t val,uint16_t * x)157 static void w2le(uint16_t val, uint16_t *x)
158 {
159 put_unaligned_le16(val, x);
160 }
161
162 static uint64_t (*r8)(const uint64_t *);
163 static uint32_t (*r)(const uint32_t *);
164 static uint16_t (*r2)(const uint16_t *);
165 static void (*w8)(uint64_t, uint64_t *);
166 static void (*w)(uint32_t, uint32_t *);
167 static void (*w2)(uint16_t, uint16_t *);
168
169 typedef void (*table_sort_t)(char *, int);
170
171 /*
172 * Move reserved section indices SHN_LORESERVE..SHN_HIRESERVE out of
173 * the way to -256..-1, to avoid conflicting with real section
174 * indices.
175 */
176 #define SPECIAL(i) ((i) - (SHN_HIRESERVE + 1))
177
is_shndx_special(unsigned int i)178 static inline int is_shndx_special(unsigned int i)
179 {
180 return i != SHN_XINDEX && i >= SHN_LORESERVE && i <= SHN_HIRESERVE;
181 }
182
183 /* Accessor for sym->st_shndx, hides ugliness of "64k sections" */
get_secindex(unsigned int shndx,unsigned int sym_offs,const Elf32_Word * symtab_shndx_start)184 static inline unsigned int get_secindex(unsigned int shndx,
185 unsigned int sym_offs,
186 const Elf32_Word *symtab_shndx_start)
187 {
188 if (is_shndx_special(shndx))
189 return SPECIAL(shndx);
190 if (shndx != SHN_XINDEX)
191 return shndx;
192 return r(&symtab_shndx_start[sym_offs]);
193 }
194
195 /* 32 bit and 64 bit are very similar */
196 #include "sortextable.h"
197 #define SORTEXTABLE_64
198 #include "sortextable.h"
199
compare_relative_table(const void * a,const void * b)200 static int compare_relative_table(const void *a, const void *b)
201 {
202 int32_t av = (int32_t)r(a);
203 int32_t bv = (int32_t)r(b);
204
205 if (av < bv)
206 return -1;
207 if (av > bv)
208 return 1;
209 return 0;
210 }
211
sort_relative_table(char * extab_image,int image_size)212 static void sort_relative_table(char *extab_image, int image_size)
213 {
214 int i;
215
216 /*
217 * Do the same thing the runtime sort does, first normalize to
218 * being relative to the start of the section.
219 */
220 i = 0;
221 while (i < image_size) {
222 uint32_t *loc = (uint32_t *)(extab_image + i);
223 w(r(loc) + i, loc);
224 i += 4;
225 }
226
227 qsort(extab_image, image_size / 8, 8, compare_relative_table);
228
229 /* Now denormalize. */
230 i = 0;
231 while (i < image_size) {
232 uint32_t *loc = (uint32_t *)(extab_image + i);
233 w(r(loc) - i, loc);
234 i += 4;
235 }
236 }
237
238 static void
do_file(char const * const fname)239 do_file(char const *const fname)
240 {
241 table_sort_t custom_sort;
242 Elf32_Ehdr *ehdr = mmap_file(fname);
243
244 ehdr_curr = ehdr;
245 switch (ehdr->e_ident[EI_DATA]) {
246 default:
247 fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
248 ehdr->e_ident[EI_DATA], fname);
249 fail_file();
250 break;
251 case ELFDATA2LSB:
252 r = rle;
253 r2 = r2le;
254 r8 = r8le;
255 w = wle;
256 w2 = w2le;
257 w8 = w8le;
258 break;
259 case ELFDATA2MSB:
260 r = rbe;
261 r2 = r2be;
262 r8 = r8be;
263 w = wbe;
264 w2 = w2be;
265 w8 = w8be;
266 break;
267 } /* end switch */
268 if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
269 || (r2(&ehdr->e_type) != ET_EXEC && r2(&ehdr->e_type) != ET_DYN)
270 || ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
271 fprintf(stderr, "unrecognized ET_EXEC/ET_DYN file %s\n", fname);
272 fail_file();
273 }
274
275 custom_sort = NULL;
276 switch (r2(&ehdr->e_machine)) {
277 default:
278 fprintf(stderr, "unrecognized e_machine %d %s\n",
279 r2(&ehdr->e_machine), fname);
280 fail_file();
281 break;
282 case EM_386:
283 case EM_X86_64:
284 case EM_S390:
285 case EM_AARCH64:
286 custom_sort = sort_relative_table;
287 break;
288 case EM_ARCOMPACT:
289 case EM_ARCV2:
290 case EM_ARM:
291 case EM_MICROBLAZE:
292 case EM_MIPS:
293 case EM_XTENSA:
294 break;
295 } /* end switch */
296
297 switch (ehdr->e_ident[EI_CLASS]) {
298 default:
299 fprintf(stderr, "unrecognized ELF class %d %s\n",
300 ehdr->e_ident[EI_CLASS], fname);
301 fail_file();
302 break;
303 case ELFCLASS32:
304 if (r2(&ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
305 || r2(&ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
306 fprintf(stderr,
307 "unrecognized ET_EXEC/ET_DYN file: %s\n", fname);
308 fail_file();
309 }
310 do32(ehdr, fname, custom_sort);
311 break;
312 case ELFCLASS64: {
313 Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
314 if (r2(&ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
315 || r2(&ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
316 fprintf(stderr,
317 "unrecognized ET_EXEC/ET_DYN file: %s\n", fname);
318 fail_file();
319 }
320 do64(ghdr, fname, custom_sort);
321 break;
322 }
323 } /* end switch */
324
325 cleanup();
326 }
327
328 int
main(int argc,char * argv[])329 main(int argc, char *argv[])
330 {
331 int n_error = 0; /* gcc-4.3.0 false positive complaint */
332 int i;
333
334 if (argc < 2) {
335 fprintf(stderr, "usage: sortextable vmlinux...\n");
336 return 0;
337 }
338
339 /* Process each file in turn, allowing deep failure. */
340 for (i = 1; i < argc; i++) {
341 char *file = argv[i];
342 int const sjval = setjmp(jmpenv);
343
344 switch (sjval) {
345 default:
346 fprintf(stderr, "internal error: %s\n", file);
347 exit(1);
348 break;
349 case SJ_SETJMP: /* normal sequence */
350 /* Avoid problems if early cleanup() */
351 fd_map = -1;
352 ehdr_curr = NULL;
353 mmap_failed = 1;
354 do_file(file);
355 break;
356 case SJ_FAIL: /* error in do_file or below */
357 ++n_error;
358 break;
359 case SJ_SUCCEED: /* premature success */
360 /* do nothing */
361 break;
362 } /* end switch */
363 }
364 return !!n_error;
365 }
366