-
Notifications
You must be signed in to change notification settings - Fork 0
/
arm-link.c
444 lines (408 loc) · 14.4 KB
/
arm-link.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
#ifdef TARGET_DEFS_ONLY
#define EM_TCC_TARGET EM_ARM
/* relocation type for 32 bit data relocation */
#define R_DATA_32 R_ARM_ABS32
#define R_DATA_PTR R_ARM_ABS32
#define R_JMP_SLOT R_ARM_JUMP_SLOT
#define R_GLOB_DAT R_ARM_GLOB_DAT
#define R_COPY R_ARM_COPY
#define R_RELATIVE R_ARM_RELATIVE
#define R_NUM R_ARM_NUM
#define ELF_START_ADDR 0x00010000
#define ELF_PAGE_SIZE 0x10000
#define PCRELATIVE_DLLPLT 1
#define RELOCATE_DLLPLT 1
enum float_abi {
ARM_SOFTFP_FLOAT,
ARM_HARD_FLOAT,
};
#else /* !TARGET_DEFS_ONLY */
#include "tcc.h"
#ifdef NEED_RELOC_TYPE
/* Returns 1 for a code relocation, 0 for a data relocation. For unknown
relocations, returns -1. */
int code_reloc (int reloc_type)
{
switch (reloc_type) {
case R_ARM_MOVT_ABS:
case R_ARM_MOVW_ABS_NC:
case R_ARM_THM_MOVT_ABS:
case R_ARM_THM_MOVW_ABS_NC:
case R_ARM_ABS32:
case R_ARM_REL32:
case R_ARM_GOTPC:
case R_ARM_GOTOFF:
case R_ARM_GOT32:
case R_ARM_GOT_PREL:
case R_ARM_COPY:
case R_ARM_GLOB_DAT:
case R_ARM_NONE:
case R_ARM_TARGET1:
case R_ARM_MOVT_PREL:
case R_ARM_MOVW_PREL_NC:
return 0;
case R_ARM_PC24:
case R_ARM_CALL:
case R_ARM_JUMP24:
case R_ARM_PLT32:
case R_ARM_THM_PC22:
case R_ARM_THM_JUMP24:
case R_ARM_PREL31:
case R_ARM_V4BX:
case R_ARM_JUMP_SLOT:
return 1;
}
return -1;
}
/* Returns an enumerator to describe whether and when the relocation needs a
GOT and/or PLT entry to be created. See tcc.h for a description of the
different values. */
int gotplt_entry_type (int reloc_type)
{
switch (reloc_type) {
case R_ARM_NONE:
case R_ARM_COPY:
case R_ARM_GLOB_DAT:
case R_ARM_JUMP_SLOT:
return NO_GOTPLT_ENTRY;
case R_ARM_PC24:
case R_ARM_CALL:
case R_ARM_JUMP24:
case R_ARM_PLT32:
case R_ARM_THM_PC22:
case R_ARM_THM_JUMP24:
case R_ARM_MOVT_ABS:
case R_ARM_MOVW_ABS_NC:
case R_ARM_THM_MOVT_ABS:
case R_ARM_THM_MOVW_ABS_NC:
case R_ARM_PREL31:
case R_ARM_ABS32:
case R_ARM_REL32:
case R_ARM_V4BX:
case R_ARM_TARGET1:
case R_ARM_MOVT_PREL:
case R_ARM_MOVW_PREL_NC:
return AUTO_GOTPLT_ENTRY;
case R_ARM_GOTPC:
case R_ARM_GOTOFF:
return BUILD_GOT_ONLY;
case R_ARM_GOT32:
case R_ARM_GOT_PREL:
return ALWAYS_GOTPLT_ENTRY;
}
return -1;
}
#ifdef NEED_BUILD_GOT
ST_FUNC unsigned create_plt_entry(TCCState *s1, unsigned got_offset, struct sym_attr *attr)
{
Section *plt = s1->plt;
uint8_t *p;
unsigned plt_offset;
/* when building a DLL, GOT entry accesses must be done relative to
start of GOT (see x86_64 example above) */
/* empty PLT: create PLT0 entry that push address of call site and
jump to ld.so resolution routine (GOT + 8) */
if (plt->data_offset == 0) {
p = section_ptr_add(plt, 20);
write32le(p, 0xe52de004); /* push {lr} */
write32le(p+4, 0xe59fe004); /* ldr lr, [pc, #4] */
write32le(p+8, 0xe08fe00e); /* add lr, pc, lr */
write32le(p+12, 0xe5bef008); /* ldr pc, [lr, #8]! */
/* p+16 is set in relocate_plt */
}
plt_offset = plt->data_offset;
if (attr->plt_thumb_stub) {
p = section_ptr_add(plt, 4);
write32le(p, 0x4778); /* bx pc */
write32le(p+2, 0x46c0); /* nop */
}
p = section_ptr_add(plt, 16);
/* save GOT offset for relocate_plt */
write32le(p + 4, got_offset);
return plt_offset;
}
/* relocate the PLT: compute addresses and offsets in the PLT now that final
address for PLT and GOT are known (see fill_program_header) */
ST_FUNC void relocate_plt(TCCState *s1)
{
uint8_t *p, *p_end;
if (!s1->plt)
return;
p = s1->plt->data;
p_end = p + s1->plt->data_offset;
if (p < p_end) {
int x = s1->got->sh_addr - s1->plt->sh_addr - 12;
write32le(s1->plt->data + 16, x - 4);
p += 20;
while (p < p_end) {
unsigned off = x + read32le(p + 4) + (s1->plt->data - p) + 4;
if (read32le(p) == 0x46c04778) /* PLT Thumb stub present */
p += 4;
write32le(p, 0xe28fc200 | ((off >> 28) & 0xf)); // add ip, pc, #0xN0000000
write32le(p + 4, 0xe28cc600 | ((off >> 20) & 0xff)); // add ip, pc, #0xNN00000
write32le(p + 8, 0xe28cca00 | ((off >> 12) & 0xff)); // add ip, ip, #0xNN000
write32le(p + 12, 0xe5bcf000 | (off & 0xfff)); // ldr pc, [ip, #0xNNN]!
p += 16;
}
}
if (s1->plt->reloc) {
ElfW_Rel *rel;
p = s1->got->data;
for_each_elem(s1->plt->reloc, 0, rel, ElfW_Rel) {
write32le(p + rel->r_offset, s1->plt->sh_addr);
}
}
}
#endif
#endif
void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr, addr_t addr, addr_t val)
{
ElfW(Sym) *sym;
int sym_index, esym_index;
sym_index = ELFW(R_SYM)(rel->r_info);
sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
switch(type) {
case R_ARM_PC24:
case R_ARM_CALL:
case R_ARM_JUMP24:
case R_ARM_PLT32:
{
int x, is_thumb, is_call, h, blx_avail, is_bl, th_ko;
x = (*(int *) ptr) & 0xffffff;
#ifdef DEBUG_RELOC
printf ("reloc %d: x=0x%x val=0x%x ", type, x, val);
#endif
(*(int *)ptr) &= 0xff000000;
if (x & 0x800000)
x -= 0x1000000;
x <<= 2;
blx_avail = (TCC_CPU_VERSION >= 5);
is_thumb = val & 1;
is_bl = (*(unsigned *) ptr) >> 24 == 0xeb;
is_call = (type == R_ARM_CALL || (type == R_ARM_PC24 && is_bl));
x += val - addr;
#ifdef DEBUG_RELOC
printf (" newx=0x%x name=%s\n", x,
(char *) symtab_section->link->data + sym->st_name);
#endif
h = x & 2;
th_ko = (x & 3) && (!blx_avail || !is_call);
if (th_ko || x >= 0x2000000 || x < -0x2000000)
tcc_error_noabort("can't relocate value at %x,%d",addr, type);
x >>= 2;
x &= 0xffffff;
/* Only reached if blx is avail and it is a call */
if (is_thumb) {
x |= h << 24;
(*(int *)ptr) = 0xfa << 24; /* bl -> blx */
}
(*(int *) ptr) |= x;
}
return;
/* Since these relocations only concern Thumb-2 and blx instruction was
introduced before Thumb-2, we can assume blx is available and not
guard its use */
case R_ARM_THM_PC22:
case R_ARM_THM_JUMP24:
{
int x, hi, lo, s, j1, j2, i1, i2, imm10, imm11;
int to_thumb, is_call, to_plt, blx_bit = 1 << 12;
Section *plt;
/* weak reference */
if (sym->st_shndx == SHN_UNDEF &&
ELFW(ST_BIND)(sym->st_info) == STB_WEAK)
return;
/* Get initial offset */
hi = (*(uint16_t *)ptr);
lo = (*(uint16_t *)(ptr+2));
s = (hi >> 10) & 1;
j1 = (lo >> 13) & 1;
j2 = (lo >> 11) & 1;
i1 = (j1 ^ s) ^ 1;
i2 = (j2 ^ s) ^ 1;
imm10 = hi & 0x3ff;
imm11 = lo & 0x7ff;
x = (s << 24) | (i1 << 23) | (i2 << 22) |
(imm10 << 12) | (imm11 << 1);
if (x & 0x01000000)
x -= 0x02000000;
/* Relocation infos */
to_thumb = val & 1;
plt = s1->plt;
to_plt = (val >= plt->sh_addr) &&
(val < plt->sh_addr + plt->data_offset);
is_call = (type == R_ARM_THM_PC22);
if (!to_thumb && !to_plt && !is_call) {
int index;
uint8_t *p;
char *name, buf[1024];
Section *text;
name = (char *) symtab_section->link->data + sym->st_name;
text = s1->sections[sym->st_shndx];
/* Modify reloc to target a thumb stub to switch to ARM */
snprintf(buf, sizeof(buf), "%s_from_thumb", name);
index = put_elf_sym(symtab_section,
text->data_offset + 1,
sym->st_size, sym->st_info, 0,
sym->st_shndx, buf);
to_thumb = 1;
val = text->data_offset + 1;
rel->r_info = ELFW(R_INFO)(index, type);
/* Create a thumb stub function to switch to ARM mode */
put_elf_reloc(symtab_section, text,
text->data_offset + 4, R_ARM_JUMP24,
sym_index);
p = section_ptr_add(text, 8);
write32le(p, 0x4778); /* bx pc */
write32le(p+2, 0x46c0); /* nop */
write32le(p+4, 0xeafffffe); /* b $sym */
}
/* Compute final offset */
x += val - addr;
if (!to_thumb && is_call) {
blx_bit = 0; /* bl -> blx */
x = (x + 3) & -4; /* Compute offset from aligned PC */
}
/* Check that relocation is possible
* offset must not be out of range
* if target is to be entered in arm mode:
- bit 1 must not set
- instruction must be a call (bl) or a jump to PLT */
if (!to_thumb || x >= 0x1000000 || x < -0x1000000)
if (to_thumb || (val & 2) || (!is_call && !to_plt))
tcc_error_noabort("can't relocate value at %x,%d",addr, type);
/* Compute and store final offset */
s = (x >> 24) & 1;
i1 = (x >> 23) & 1;
i2 = (x >> 22) & 1;
j1 = s ^ (i1 ^ 1);
j2 = s ^ (i2 ^ 1);
imm10 = (x >> 12) & 0x3ff;
imm11 = (x >> 1) & 0x7ff;
(*(uint16_t *)ptr) = (uint16_t) ((hi & 0xf800) |
(s << 10) | imm10);
(*(uint16_t *)(ptr+2)) = (uint16_t) ((lo & 0xc000) |
(j1 << 13) | blx_bit | (j2 << 11) |
imm11);
}
return;
case R_ARM_MOVT_ABS:
case R_ARM_MOVW_ABS_NC:
{
int x, imm4, imm12;
if (type == R_ARM_MOVT_ABS)
val >>= 16;
imm12 = val & 0xfff;
imm4 = (val >> 12) & 0xf;
x = (imm4 << 16) | imm12;
if (type == R_ARM_THM_MOVT_ABS)
*(int *)ptr |= x;
else
*(int *)ptr += x;
}
return;
case R_ARM_MOVT_PREL:
case R_ARM_MOVW_PREL_NC:
{
int insn = *(int *)ptr;
int addend = ((insn >> 4) & 0xf000) | (insn & 0xfff);
addend = (addend ^ 0x8000) - 0x8000;
val += addend - addr;
if (type == R_ARM_MOVT_PREL)
val >>= 16;
*(int *)ptr = (insn & 0xfff0f000) |
((val & 0xf000) << 4) | (val & 0xfff);
}
return;
case R_ARM_THM_MOVT_ABS:
case R_ARM_THM_MOVW_ABS_NC:
{
int x, i, imm4, imm3, imm8;
if (type == R_ARM_THM_MOVT_ABS)
val >>= 16;
imm8 = val & 0xff;
imm3 = (val >> 8) & 0x7;
i = (val >> 11) & 1;
imm4 = (val >> 12) & 0xf;
x = (imm3 << 28) | (imm8 << 16) | (i << 10) | imm4;
if (type == R_ARM_THM_MOVT_ABS)
*(int *)ptr |= x;
else
*(int *)ptr += x;
}
return;
case R_ARM_PREL31:
{
int x;
x = (*(int *)ptr) & 0x7fffffff;
(*(int *)ptr) &= 0x80000000;
x = (x * 2) / 2;
x += val - addr;
if((x^(x>>1))&0x40000000)
tcc_error_noabort("can't relocate value at %x,%d",addr, type);
(*(int *)ptr) |= x & 0x7fffffff;
}
return;
case R_ARM_ABS32:
case R_ARM_TARGET1:
if (s1->output_type & TCC_OUTPUT_DYN) {
esym_index = get_sym_attr(s1, sym_index, 0)->dyn_index;
qrel->r_offset = rel->r_offset;
if (esym_index) {
qrel->r_info = ELFW(R_INFO)(esym_index, R_ARM_ABS32);
qrel++;
return;
} else {
qrel->r_info = ELFW(R_INFO)(0, R_ARM_RELATIVE);
qrel++;
}
}
*(int *)ptr += val;
return;
case R_ARM_REL32:
*(int *)ptr += val - addr;
return;
case R_ARM_GOTPC:
*(int *)ptr += s1->got->sh_addr - addr;
return;
case R_ARM_GOTOFF:
*(int *)ptr += val - s1->got->sh_addr;
return;
case R_ARM_GOT32:
/* we load the got offset */
*(int *)ptr += get_sym_attr(s1, sym_index, 0)->got_offset;
return;
case R_ARM_GOT_PREL:
/* we load the pc relative got offset */
*(int *)ptr += s1->got->sh_addr +
get_sym_attr(s1, sym_index, 0)->got_offset -
addr;
return;
case R_ARM_COPY:
return;
case R_ARM_V4BX:
/* trade Thumb support for ARMv4 support */
if ((0x0ffffff0 & *(int*)ptr) == 0x012FFF10)
*(int*)ptr ^= 0xE12FFF10 ^ 0xE1A0F000; /* BX Rm -> MOV PC, Rm */
return;
case R_ARM_GLOB_DAT:
case R_ARM_JUMP_SLOT:
*(addr_t *)ptr = val;
return;
case R_ARM_NONE:
/* Nothing to do. Normally used to indicate a dependency
on a certain symbol (like for exception handling under EABI). */
return;
case R_ARM_RELATIVE:
#ifdef TCC_TARGET_PE
add32le(ptr, val - s1->pe_imagebase);
#endif
/* do nothing */
return;
default:
fprintf(stderr,"FIXME: handle reloc type %d at %x [%p] to %x\n",
type, (unsigned)addr, ptr, (unsigned)val);
return;
}
}
#endif /* !TARGET_DEFS_ONLY */