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fd0de36e | 1 | /* Linux bpf specific support for 64-bit ELF |
fd67aa11 | 2 | Copyright (C) 2019-2024 Free Software Foundation, Inc. |
fd0de36e JM |
3 | Contributed by Oracle Inc. |
4 | ||
5 | This file is part of BFD, the Binary File Descriptor library. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 3 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with this program; if not, write to the Free Software | |
19 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, | |
20 | MA 02110-1301, USA. */ | |
21 | ||
22 | #include "sysdep.h" | |
23 | #include "bfd.h" | |
24 | #include "libbfd.h" | |
25 | #include "elf-bfd.h" | |
26 | #include "elf/bpf.h" | |
27 | #include "libiberty.h" | |
28 | ||
29 | /* In case we're on a 32-bit machine, construct a 64-bit "-1" value. */ | |
30 | #define MINUS_ONE (~ (bfd_vma) 0) | |
31 | ||
32 | #define BASEADDR(SEC) ((SEC)->output_section->vma + (SEC)->output_offset) | |
33 | ||
3ee9565c DF |
34 | static bfd_reloc_status_type bpf_elf_generic_reloc |
35 | (bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **); | |
36 | ||
5e4c7a83 CM |
37 | #undef BPF_HOWTO |
38 | #define BPF_HOWTO(type, right, size, bits, pcrel, left, ovf, func, name, \ | |
39 | inplace, src_mask, dst_mask, pcrel_off) \ | |
40 | type##_IDX, | |
41 | enum bpf_reloc_index { | |
42 | R_BPF_INVALID_IDX = -1, | |
43 | #include "bpf-reloc.def" | |
44 | R_BPF_SIZE | |
45 | }; | |
46 | #undef BPF_HOWTO | |
47 | ||
fd0de36e | 48 | /* Relocation tables. */ |
5e4c7a83 | 49 | #define BPF_HOWTO(...) HOWTO(__VA_ARGS__), |
fd0de36e JM |
50 | static reloc_howto_type bpf_elf_howto_table [] = |
51 | { | |
5e4c7a83 | 52 | #include "bpf-reloc.def" |
fd0de36e JM |
53 | }; |
54 | #undef AHOW | |
5e4c7a83 CM |
55 | #undef BPF_HOWTO |
56 | ||
57 | #define BPF_HOWTO(type, right, size, bits, pcrel, left, ovf, func, name, \ | |
58 | inplace, src_mask, dst_mask, pcrel_off) \ | |
59 | case type: { return type##_IDX; } | |
60 | static enum bpf_reloc_index | |
61 | bpf_index_for_rtype(unsigned int r_type) | |
62 | { | |
63 | switch(r_type) { | |
64 | #include "bpf-reloc.def" | |
65 | default: | |
66 | /* Unreachable code. */ | |
67 | BFD_ASSERT(0); | |
68 | return -1; | |
69 | }; | |
70 | } | |
fd0de36e JM |
71 | |
72 | /* Map BFD reloc types to bpf ELF reloc types. */ | |
73 | ||
74 | static reloc_howto_type * | |
75 | bpf_reloc_type_lookup (bfd * abfd ATTRIBUTE_UNUSED, | |
76 | bfd_reloc_code_real_type code) | |
77 | { | |
fd0de36e JM |
78 | switch (code) |
79 | { | |
80 | case BFD_RELOC_NONE: | |
5e4c7a83 CM |
81 | return &bpf_elf_howto_table[ (int) R_BPF_NONE_IDX]; |
82 | ||
fd0de36e | 83 | case BFD_RELOC_32: |
5e4c7a83 | 84 | return &bpf_elf_howto_table[ (int) R_BPF_64_ABS32_IDX]; |
fd0de36e | 85 | case BFD_RELOC_64: |
5e4c7a83 | 86 | return &bpf_elf_howto_table[ (int) R_BPF_64_ABS64_IDX]; |
fd0de36e JM |
87 | |
88 | case BFD_RELOC_BPF_64: | |
5e4c7a83 | 89 | return &bpf_elf_howto_table[ (int) R_BPF_64_64_IDX]; |
fd0de36e | 90 | case BFD_RELOC_BPF_DISP32: |
b5c37946 | 91 | case BFD_RELOC_BPF_DISPCALL32: |
5e4c7a83 | 92 | return &bpf_elf_howto_table[ (int) R_BPF_64_32_IDX]; |
b5c37946 SJ |
93 | case BFD_RELOC_BPF_DISP16: |
94 | return &bpf_elf_howto_table[ (int) R_BPF_GNU_64_16_IDX]; | |
fd0de36e JM |
95 | |
96 | default: | |
97 | /* Pacify gcc -Wall. */ | |
98 | return NULL; | |
99 | } | |
100 | return NULL; | |
101 | } | |
102 | ||
103 | /* Map BFD reloc names to bpf ELF reloc names. */ | |
104 | ||
105 | static reloc_howto_type * | |
106 | bpf_reloc_name_lookup (bfd *abfd ATTRIBUTE_UNUSED, const char *r_name) | |
107 | { | |
108 | unsigned int i; | |
109 | ||
5e4c7a83 | 110 | for (i = 0; i < R_BPF_SIZE; i++) |
fd0de36e JM |
111 | if (bpf_elf_howto_table[i].name != NULL |
112 | && strcasecmp (bpf_elf_howto_table[i].name, r_name) == 0) | |
113 | return &bpf_elf_howto_table[i]; | |
114 | ||
115 | return NULL; | |
116 | } | |
117 | ||
118 | /* Set the howto pointer for a bpf reloc. */ | |
119 | ||
0a1b45a2 | 120 | static bool |
fd0de36e JM |
121 | bpf_info_to_howto (bfd *abfd, arelent *bfd_reloc, |
122 | Elf_Internal_Rela *elf_reloc) | |
123 | { | |
124 | unsigned int r_type; | |
5e4c7a83 | 125 | unsigned int i; |
fd0de36e | 126 | r_type = ELF64_R_TYPE (elf_reloc->r_info); |
5e4c7a83 CM |
127 | |
128 | i = bpf_index_for_rtype(r_type); | |
129 | if (i == (unsigned int) -1) | |
fd0de36e JM |
130 | { |
131 | /* xgettext:c-format */ | |
132 | _bfd_error_handler (_("%pB: unsupported relocation type %#x"), | |
133 | abfd, r_type); | |
134 | bfd_set_error (bfd_error_bad_value); | |
0a1b45a2 | 135 | return false; |
fd0de36e JM |
136 | } |
137 | ||
5e4c7a83 | 138 | bfd_reloc->howto = &bpf_elf_howto_table [i]; |
0a1b45a2 | 139 | return true; |
fd0de36e JM |
140 | } |
141 | ||
fc8de8e2 JM |
142 | /* Relocate an eBPF ELF section. |
143 | ||
144 | The RELOCATE_SECTION function is called by the new ELF backend linker | |
145 | to handle the relocations for a section. | |
146 | ||
147 | The relocs are always passed as Rela structures; if the section | |
148 | actually uses Rel structures, the r_addend field will always be | |
149 | zero. | |
150 | ||
151 | This function is responsible for adjusting the section contents as | |
152 | necessary, and (if using Rela relocs and generating a relocatable | |
153 | output file) adjusting the reloc addend as necessary. | |
154 | ||
155 | This function does not have to worry about setting the reloc | |
156 | address or the reloc symbol index. | |
157 | ||
158 | LOCAL_SYMS is a pointer to the swapped in local symbols. | |
159 | ||
160 | LOCAL_SECTIONS is an array giving the section in the input file | |
161 | corresponding to the st_shndx field of each local symbol. | |
162 | ||
163 | The global hash table entry for the global symbols can be found | |
164 | via elf_sym_hashes (input_bfd). | |
165 | ||
166 | When generating relocatable output, this function must handle | |
167 | STB_LOCAL/STT_SECTION symbols specially. The output symbol is | |
168 | going to be the section symbol corresponding to the output | |
169 | section, which means that the addend must be adjusted | |
170 | accordingly. */ | |
171 | ||
172 | #define sec_addr(sec) ((sec)->output_section->vma + (sec)->output_offset) | |
173 | ||
0f684201 | 174 | static int |
fc8de8e2 JM |
175 | bpf_elf_relocate_section (bfd *output_bfd ATTRIBUTE_UNUSED, |
176 | struct bfd_link_info *info, | |
177 | bfd *input_bfd, | |
178 | asection *input_section, | |
179 | bfd_byte *contents, | |
180 | Elf_Internal_Rela *relocs, | |
181 | Elf_Internal_Sym *local_syms, | |
182 | asection **local_sections) | |
183 | { | |
184 | Elf_Internal_Shdr *symtab_hdr; | |
185 | struct elf_link_hash_entry **sym_hashes; | |
186 | Elf_Internal_Rela *rel; | |
187 | Elf_Internal_Rela *relend; | |
188 | ||
189 | symtab_hdr = & elf_tdata (input_bfd)->symtab_hdr; | |
190 | sym_hashes = elf_sym_hashes (input_bfd); | |
191 | relend = relocs + input_section->reloc_count; | |
192 | ||
193 | for (rel = relocs; rel < relend; rel ++) | |
194 | { | |
195 | reloc_howto_type * howto; | |
551fde0a | 196 | unsigned int howto_index; |
fc8de8e2 JM |
197 | unsigned long r_symndx; |
198 | Elf_Internal_Sym * sym; | |
199 | asection * sec; | |
200 | struct elf_link_hash_entry * h; | |
201 | bfd_vma relocation; | |
202 | bfd_reloc_status_type r; | |
203 | const char * name = NULL; | |
204 | int r_type ATTRIBUTE_UNUSED; | |
3ee9565c DF |
205 | bfd_signed_vma addend; |
206 | bfd_byte * where; | |
fc8de8e2 JM |
207 | |
208 | r_type = ELF64_R_TYPE (rel->r_info); | |
209 | r_symndx = ELF64_R_SYM (rel->r_info); | |
551fde0a CM |
210 | |
211 | howto_index = bpf_index_for_rtype (ELF64_R_TYPE (rel->r_info)); | |
212 | howto = &bpf_elf_howto_table[howto_index]; | |
fc8de8e2 JM |
213 | h = NULL; |
214 | sym = NULL; | |
215 | sec = NULL; | |
3ee9565c | 216 | where = contents + rel->r_offset; |
fc8de8e2 JM |
217 | |
218 | if (r_symndx < symtab_hdr->sh_info) | |
219 | { | |
220 | sym = local_syms + r_symndx; | |
221 | sec = local_sections [r_symndx]; | |
222 | relocation = BASEADDR (sec) + sym->st_value; | |
223 | ||
224 | name = bfd_elf_string_from_elf_section | |
225 | (input_bfd, symtab_hdr->sh_link, sym->st_name); | |
fd361982 | 226 | name = name == NULL ? bfd_section_name (sec) : name; |
fc8de8e2 JM |
227 | } |
228 | else | |
229 | { | |
0a1b45a2 AM |
230 | bool warned ATTRIBUTE_UNUSED; |
231 | bool unresolved_reloc ATTRIBUTE_UNUSED; | |
232 | bool ignored ATTRIBUTE_UNUSED; | |
fc8de8e2 JM |
233 | |
234 | RELOC_FOR_GLOBAL_SYMBOL (info, input_bfd, input_section, rel, | |
235 | r_symndx, symtab_hdr, sym_hashes, | |
236 | h, sec, relocation, | |
237 | unresolved_reloc, warned, ignored); | |
238 | ||
239 | name = h->root.root.string; | |
240 | } | |
241 | ||
242 | if (sec != NULL && discarded_section (sec)) | |
243 | RELOC_AGAINST_DISCARDED_SECTION (info, input_bfd, input_section, | |
244 | rel, 1, relend, howto, 0, contents); | |
245 | ||
246 | if (bfd_link_relocatable (info)) | |
247 | continue; | |
248 | ||
249 | switch (howto->type) | |
250 | { | |
5e4c7a83 | 251 | case R_BPF_64_32: |
fc8de8e2 | 252 | { |
fc8de8e2 | 253 | /* Make the relocation PC-relative, and change its unit to |
d844f10a DF |
254 | 64-bit words. Note we need *signed* arithmetic |
255 | here. */ | |
256 | relocation = ((bfd_signed_vma) relocation | |
257 | - (sec_addr (input_section) + rel->r_offset)); | |
258 | relocation = (bfd_signed_vma) relocation / 8; | |
fc8de8e2 JM |
259 | |
260 | /* Get the addend from the instruction and apply it. */ | |
261 | addend = bfd_get (howto->bitsize, input_bfd, | |
262 | contents + rel->r_offset | |
263 | + (howto->bitsize == 16 ? 2 : 4)); | |
264 | ||
265 | if ((addend & (((~howto->src_mask) >> 1) & howto->src_mask)) != 0) | |
266 | addend -= (((~howto->src_mask) >> 1) & howto->src_mask) << 1; | |
267 | relocation += addend; | |
268 | ||
269 | /* Write out the relocated value. */ | |
270 | bfd_put (howto->bitsize, input_bfd, relocation, | |
271 | contents + rel->r_offset | |
272 | + (howto->bitsize == 16 ? 2 : 4)); | |
273 | ||
274 | r = bfd_reloc_ok; | |
275 | break; | |
276 | } | |
5e4c7a83 CM |
277 | case R_BPF_64_ABS64: |
278 | case R_BPF_64_ABS32: | |
ad4e57ab | 279 | case R_BPF_64_NODYLD32: |
3ee9565c DF |
280 | { |
281 | addend = bfd_get (howto->bitsize, input_bfd, where); | |
282 | relocation += addend; | |
283 | bfd_put (howto->bitsize, input_bfd, relocation, where); | |
284 | ||
285 | r = bfd_reloc_ok; | |
286 | break; | |
287 | } | |
5e4c7a83 | 288 | case R_BPF_64_64: |
12adf805 DF |
289 | { |
290 | /* | |
291 | LDDW instructions are 128 bits long, with a 64-bit immediate. | |
292 | The lower 32 bits of the immediate are in the same position | |
293 | as the imm32 field of other instructions. | |
294 | The upper 32 bits of the immediate are stored at the end of | |
295 | the instruction. | |
296 | */ | |
3ee9565c DF |
297 | |
298 | ||
299 | /* Get the addend. The upper and lower 32 bits are split. | |
300 | 'where' is the beginning of the 16-byte instruction. */ | |
301 | addend = bfd_get_32 (input_bfd, where + 4); | |
302 | addend |= (bfd_get_32 (input_bfd, where + 12) << 32); | |
303 | ||
304 | relocation += addend; | |
305 | ||
306 | bfd_put_32 (input_bfd, (relocation & 0xFFFFFFFF), where + 4); | |
307 | bfd_put_32 (input_bfd, (relocation >> 32), where + 12); | |
12adf805 DF |
308 | r = bfd_reloc_ok; |
309 | break; | |
310 | } | |
fc8de8e2 | 311 | default: |
3ee9565c | 312 | r = bfd_reloc_notsupported; |
fc8de8e2 JM |
313 | } |
314 | ||
3ee9565c DF |
315 | if (r == bfd_reloc_ok) |
316 | r = bfd_check_overflow (howto->complain_on_overflow, | |
317 | howto->bitsize, | |
318 | howto->rightshift, | |
319 | 64, relocation); | |
320 | ||
fc8de8e2 JM |
321 | if (r != bfd_reloc_ok) |
322 | { | |
323 | const char * msg = NULL; | |
324 | ||
325 | switch (r) | |
326 | { | |
327 | case bfd_reloc_overflow: | |
328 | (*info->callbacks->reloc_overflow) | |
329 | (info, (h ? &h->root : NULL), name, howto->name, | |
330 | (bfd_vma) 0, input_bfd, input_section, rel->r_offset); | |
331 | break; | |
332 | ||
333 | case bfd_reloc_undefined: | |
334 | (*info->callbacks->undefined_symbol) | |
0a1b45a2 | 335 | (info, name, input_bfd, input_section, rel->r_offset, true); |
fc8de8e2 JM |
336 | break; |
337 | ||
338 | case bfd_reloc_outofrange: | |
339 | msg = _("internal error: out of range error"); | |
340 | break; | |
341 | ||
342 | case bfd_reloc_notsupported: | |
343 | if (sym != NULL) /* Only if it's not an unresolved symbol. */ | |
344 | msg = _("internal error: relocation not supported"); | |
345 | break; | |
346 | ||
347 | case bfd_reloc_dangerous: | |
348 | msg = _("internal error: dangerous relocation"); | |
349 | break; | |
350 | ||
351 | default: | |
352 | msg = _("internal error: unknown error"); | |
353 | break; | |
354 | } | |
355 | ||
356 | if (msg) | |
357 | (*info->callbacks->warning) (info, msg, name, input_bfd, | |
358 | input_section, rel->r_offset); | |
359 | } | |
360 | } | |
361 | ||
0a1b45a2 | 362 | return true; |
fc8de8e2 JM |
363 | } |
364 | ||
fd0de36e JM |
365 | /* Merge backend specific data from an object file to the output |
366 | object file when linking. */ | |
367 | ||
0a1b45a2 | 368 | static bool |
fd0de36e JM |
369 | elf64_bpf_merge_private_bfd_data (bfd *ibfd, struct bfd_link_info *info) |
370 | { | |
371 | /* Check if we have the same endianness. */ | |
372 | if (! _bfd_generic_verify_endian_match (ibfd, info)) | |
0a1b45a2 | 373 | return false; |
fd0de36e | 374 | |
0a1b45a2 | 375 | return true; |
fd0de36e JM |
376 | } |
377 | ||
3ee9565c | 378 | /* A generic howto special function for installing BPF relocations. |
b4c4b8aa AM |
379 | This function will be called by the assembler (via bfd_install_relocation), |
380 | and by various get_relocated_section_contents functions. | |
3ee9565c DF |
381 | At link time, bpf_elf_relocate_section will resolve the final relocations. |
382 | ||
383 | BPF instructions are always big endian, and this approach avoids problems in | |
384 | bfd_install_relocation. */ | |
385 | ||
386 | static bfd_reloc_status_type | |
b4c4b8aa | 387 | bpf_elf_generic_reloc (bfd *abfd, arelent *reloc_entry, asymbol *symbol, |
3ee9565c | 388 | void *data, asection *input_section, |
07b2745f | 389 | bfd *output_bfd ATTRIBUTE_UNUSED, |
3ee9565c DF |
390 | char **error_message ATTRIBUTE_UNUSED) |
391 | { | |
392 | ||
393 | bfd_signed_vma relocation; | |
394 | bfd_reloc_status_type status; | |
395 | bfd_byte *where; | |
396 | ||
397 | /* Sanity check that the address is in range. */ | |
9b54b561 AM |
398 | bfd_size_type end = bfd_get_section_limit_octets (abfd, input_section); |
399 | bfd_size_type reloc_size; | |
5e4c7a83 | 400 | if (reloc_entry->howto->type == R_BPF_64_64) |
9b54b561 AM |
401 | reloc_size = 16; |
402 | else | |
403 | reloc_size = (reloc_entry->howto->bitsize | |
404 | + reloc_entry->howto->bitpos) / 8; | |
405 | ||
406 | if (reloc_entry->address > end | |
407 | || end - reloc_entry->address < reloc_size) | |
3ee9565c DF |
408 | return bfd_reloc_outofrange; |
409 | ||
410 | /* Get the symbol value. */ | |
411 | if (bfd_is_com_section (symbol->section)) | |
412 | relocation = 0; | |
413 | else | |
414 | relocation = symbol->value; | |
415 | ||
416 | if (symbol->flags & BSF_SECTION_SYM) | |
417 | /* Relocation against a section symbol: add in the section base address. */ | |
418 | relocation += BASEADDR (symbol->section); | |
419 | ||
420 | relocation += reloc_entry->addend; | |
421 | ||
422 | where = (bfd_byte *) data + reloc_entry->address; | |
423 | ||
424 | status = bfd_check_overflow (reloc_entry->howto->complain_on_overflow, | |
425 | reloc_entry->howto->bitsize, | |
426 | reloc_entry->howto->rightshift, 64, relocation); | |
427 | ||
428 | if (status != bfd_reloc_ok) | |
429 | return status; | |
430 | ||
431 | /* Now finally install the relocation. */ | |
5e4c7a83 | 432 | if (reloc_entry->howto->type == R_BPF_64_64) |
3ee9565c DF |
433 | { |
434 | /* lddw is a 128-bit (!) instruction that allows loading a 64-bit | |
435 | immediate into a register. the immediate is split in half, with the | |
436 | lower 32 bits in the same position as the imm32 field of other | |
437 | instructions, and the upper 32 bits placed at the very end of the | |
438 | instruction. that is, there are 32 unused bits between them. */ | |
439 | ||
b4c4b8aa AM |
440 | bfd_put_32 (abfd, (relocation & 0xFFFFFFFF), where + 4); |
441 | bfd_put_32 (abfd, (relocation >> 32), where + 12); | |
3ee9565c DF |
442 | } |
443 | else | |
444 | { | |
445 | /* For other kinds of relocations, the relocated value simply goes | |
446 | BITPOS bits from the start of the entry. This is always a multiple | |
447 | of 8, i.e. whole bytes. */ | |
b4c4b8aa | 448 | bfd_put (reloc_entry->howto->bitsize, abfd, relocation, |
3ee9565c DF |
449 | where + reloc_entry->howto->bitpos / 8); |
450 | } | |
451 | ||
452 | reloc_entry->addend = relocation; | |
453 | reloc_entry->address += input_section->output_offset; | |
454 | ||
455 | return bfd_reloc_ok; | |
456 | } | |
457 | ||
458 | ||
fd0de36e JM |
459 | /* The macros below configure the architecture. */ |
460 | ||
461 | #define TARGET_LITTLE_SYM bpf_elf64_le_vec | |
462 | #define TARGET_LITTLE_NAME "elf64-bpfle" | |
463 | ||
464 | #define TARGET_BIG_SYM bpf_elf64_be_vec | |
465 | #define TARGET_BIG_NAME "elf64-bpfbe" | |
466 | ||
467 | #define ELF_ARCH bfd_arch_bpf | |
468 | #define ELF_MACHINE_CODE EM_BPF | |
469 | ||
470 | #define ELF_MAXPAGESIZE 0x100000 | |
471 | ||
472 | #define elf_info_to_howto_rel bpf_info_to_howto | |
473 | #define elf_info_to_howto bpf_info_to_howto | |
474 | ||
475 | #define elf_backend_may_use_rel_p 1 | |
476 | #define elf_backend_may_use_rela_p 0 | |
477 | #define elf_backend_default_use_rela_p 0 | |
fc8de8e2 | 478 | #define elf_backend_relocate_section bpf_elf_relocate_section |
fd0de36e JM |
479 | |
480 | #define elf_backend_can_gc_sections 0 | |
481 | ||
482 | #define elf_symbol_leading_char '_' | |
483 | #define bfd_elf64_bfd_reloc_type_lookup bpf_reloc_type_lookup | |
484 | #define bfd_elf64_bfd_reloc_name_lookup bpf_reloc_name_lookup | |
485 | ||
486 | #define bfd_elf64_bfd_merge_private_bfd_data elf64_bpf_merge_private_bfd_data | |
487 | ||
488 | #include "elf64-target.h" |