1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * sortextable.c: Sort the kernel's exception table
4 *
5 * Copyright 2011 - 2012 Cavium, Inc.
6 *
7 * Based on code taken from recortmcount.c which is:
8 *
9 * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
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
x86_sort_relative_table(char * extab_image,int image_size)212 static void x86_sort_relative_table(char *extab_image, int image_size)
213 {
214 int i;
215
216 i = 0;
217 while (i < image_size) {
218 uint32_t *loc = (uint32_t *)(extab_image + i);
219
220 w(r(loc) + i, loc);
221 w(r(loc + 1) + i + 4, loc + 1);
222 w(r(loc + 2) + i + 8, loc + 2);
223
224 i += sizeof(uint32_t) * 3;
225 }
226
227 qsort(extab_image, image_size / 12, 12, compare_relative_table);
228
229 i = 0;
230 while (i < image_size) {
231 uint32_t *loc = (uint32_t *)(extab_image + i);
232
233 w(r(loc) - i, loc);
234 w(r(loc + 1) - (i + 4), loc + 1);
235 w(r(loc + 2) - (i + 8), loc + 2);
236
237 i += sizeof(uint32_t) * 3;
238 }
239 }
240
sort_relative_table(char * extab_image,int image_size)241 static void sort_relative_table(char *extab_image, int image_size)
242 {
243 int i;
244
245 /*
246 * Do the same thing the runtime sort does, first normalize to
247 * being relative to the start of the section.
248 */
249 i = 0;
250 while (i < image_size) {
251 uint32_t *loc = (uint32_t *)(extab_image + i);
252 w(r(loc) + i, loc);
253 i += 4;
254 }
255
256 qsort(extab_image, image_size / 8, 8, compare_relative_table);
257
258 /* Now denormalize. */
259 i = 0;
260 while (i < image_size) {
261 uint32_t *loc = (uint32_t *)(extab_image + i);
262 w(r(loc) - i, loc);
263 i += 4;
264 }
265 }
266
267 static void
do_file(char const * const fname)268 do_file(char const *const fname)
269 {
270 table_sort_t custom_sort;
271 Elf32_Ehdr *ehdr = mmap_file(fname);
272
273 ehdr_curr = ehdr;
274 switch (ehdr->e_ident[EI_DATA]) {
275 default:
276 fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
277 ehdr->e_ident[EI_DATA], fname);
278 fail_file();
279 break;
280 case ELFDATA2LSB:
281 r = rle;
282 r2 = r2le;
283 r8 = r8le;
284 w = wle;
285 w2 = w2le;
286 w8 = w8le;
287 break;
288 case ELFDATA2MSB:
289 r = rbe;
290 r2 = r2be;
291 r8 = r8be;
292 w = wbe;
293 w2 = w2be;
294 w8 = w8be;
295 break;
296 } /* end switch */
297 if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
298 || (r2(&ehdr->e_type) != ET_EXEC && r2(&ehdr->e_type) != ET_DYN)
299 || ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
300 fprintf(stderr, "unrecognized ET_EXEC/ET_DYN file %s\n", fname);
301 fail_file();
302 }
303
304 custom_sort = NULL;
305 switch (r2(&ehdr->e_machine)) {
306 default:
307 fprintf(stderr, "unrecognized e_machine %d %s\n",
308 r2(&ehdr->e_machine), fname);
309 fail_file();
310 break;
311 case EM_386:
312 case EM_X86_64:
313 custom_sort = x86_sort_relative_table;
314 break;
315
316 case EM_S390:
317 case EM_AARCH64:
318 case EM_PARISC:
319 case EM_PPC:
320 case EM_PPC64:
321 custom_sort = sort_relative_table;
322 break;
323 case EM_ARCOMPACT:
324 case EM_ARCV2:
325 case EM_ARM:
326 case EM_MICROBLAZE:
327 case EM_MIPS:
328 case EM_XTENSA:
329 break;
330 } /* end switch */
331
332 switch (ehdr->e_ident[EI_CLASS]) {
333 default:
334 fprintf(stderr, "unrecognized ELF class %d %s\n",
335 ehdr->e_ident[EI_CLASS], fname);
336 fail_file();
337 break;
338 case ELFCLASS32:
339 if (r2(&ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
340 || r2(&ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
341 fprintf(stderr,
342 "unrecognized ET_EXEC/ET_DYN file: %s\n", fname);
343 fail_file();
344 }
345 do32(ehdr, fname, custom_sort);
346 break;
347 case ELFCLASS64: {
348 Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
349 if (r2(&ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
350 || r2(&ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
351 fprintf(stderr,
352 "unrecognized ET_EXEC/ET_DYN file: %s\n", fname);
353 fail_file();
354 }
355 do64(ghdr, fname, custom_sort);
356 break;
357 }
358 } /* end switch */
359
360 cleanup();
361 }
362
363 int
main(int argc,char * argv[])364 main(int argc, char *argv[])
365 {
366 int n_error = 0; /* gcc-4.3.0 false positive complaint */
367 int i;
368
369 if (argc < 2) {
370 fprintf(stderr, "usage: sortextable vmlinux...\n");
371 return 0;
372 }
373
374 /* Process each file in turn, allowing deep failure. */
375 for (i = 1; i < argc; i++) {
376 char *file = argv[i];
377 int const sjval = setjmp(jmpenv);
378
379 switch (sjval) {
380 default:
381 fprintf(stderr, "internal error: %s\n", file);
382 exit(1);
383 break;
384 case SJ_SETJMP: /* normal sequence */
385 /* Avoid problems if early cleanup() */
386 fd_map = -1;
387 ehdr_curr = NULL;
388 mmap_failed = 1;
389 do_file(file);
390 break;
391 case SJ_FAIL: /* error in do_file or below */
392 ++n_error;
393 break;
394 case SJ_SUCCEED: /* premature success */
395 /* do nothing */
396 break;
397 } /* end switch */
398 }
399 return !!n_error;
400 }
401