1 /* .sframe section processing.
2 Copyright (C) 2022 Free Software Foundation, Inc.
4 This file is part of BFD, the Binary File Descriptor library.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
19 MA 02110-1301, USA. */
25 #include "sframe-api.h"
27 /* Return TRUE if the function has been marked for deletion during the linking
31 sframe_decoder_func_deleted_p (struct sframe_dec_info
*sfd_info
,
32 unsigned int func_idx
)
34 if (func_idx
< sfd_info
->sfd_fde_count
)
35 return sfd_info
->sfd_func_bfdinfo
[func_idx
].func_deleted_p
;
40 /* Mark the function in the decoder info for deletion. */
43 sframe_decoder_mark_func_deleted (struct sframe_dec_info
*sfd_info
,
44 unsigned int func_idx
)
46 if (func_idx
< sfd_info
->sfd_fde_count
)
47 sfd_info
->sfd_func_bfdinfo
[func_idx
].func_deleted_p
= true;
50 /* Get the relocation offset from the decoder info for the given function. */
53 sframe_decoder_get_func_r_offset (struct sframe_dec_info
*sfd_info
,
54 unsigned int func_idx
)
56 BFD_ASSERT (func_idx
< sfd_info
->sfd_fde_count
);
57 unsigned int func_r_offset
58 = sfd_info
->sfd_func_bfdinfo
[func_idx
].func_r_offset
;
59 /* There must have been a reloc. */
60 BFD_ASSERT (func_r_offset
);
64 /* Bookkeep the function relocation offset in the decoder info. */
67 sframe_decoder_set_func_r_offset (struct sframe_dec_info
*sfd_info
,
68 unsigned int func_idx
,
69 unsigned int r_offset
)
71 if (func_idx
< sfd_info
->sfd_fde_count
)
72 sfd_info
->sfd_func_bfdinfo
[func_idx
].func_r_offset
= r_offset
;
75 /* Get the relocation index in the elf_reloc_cookie for the function. */
78 sframe_decoder_get_func_reloc_index (struct sframe_dec_info
*sfd_info
,
79 unsigned int func_idx
)
81 BFD_ASSERT (func_idx
< sfd_info
->sfd_fde_count
);
82 return sfd_info
->sfd_func_bfdinfo
[func_idx
].func_reloc_index
;
85 /* Bookkeep the relocation index in the elf_reloc_cookie for the function. */
88 sframe_decoder_set_func_reloc_index (struct sframe_dec_info
*sfd_info
,
89 unsigned int func_idx
,
90 unsigned int reloc_index
)
92 if (func_idx
< sfd_info
->sfd_fde_count
)
93 sfd_info
->sfd_func_bfdinfo
[func_idx
].func_reloc_index
= reloc_index
;
96 /* Initialize the set of additional information in CFD_INFO,
97 needed for linking SEC. Returns TRUE if setup is done successfully. */
100 sframe_decoder_init_func_bfdinfo (asection
*sec
,
101 struct sframe_dec_info
*sfd_info
,
102 struct elf_reloc_cookie
*cookie
)
104 unsigned int fde_count
;
105 unsigned int func_bfdinfo_size
, i
;
107 fde_count
= sframe_decoder_get_num_fidx (sfd_info
->sfd_ctx
);
108 sfd_info
->sfd_fde_count
= fde_count
;
110 /* Allocate and clear the memory. */
111 func_bfdinfo_size
= (sizeof (struct sframe_func_bfdinfo
)) * fde_count
;
112 sfd_info
->sfd_func_bfdinfo
113 = (struct sframe_func_bfdinfo
*) bfd_malloc (func_bfdinfo_size
);
114 if (sfd_info
->sfd_func_bfdinfo
== NULL
)
116 memset (sfd_info
->sfd_func_bfdinfo
, 0, func_bfdinfo_size
);
118 /* For linker generated .sframe sections, we have no relocs. Skip. */
119 if ((sec
->flags
& SEC_LINKER_CREATED
) && cookie
->rels
== NULL
)
122 for (i
= 0; i
< fde_count
; i
++)
124 cookie
->rel
= cookie
->rels
+ i
;
125 BFD_ASSERT (cookie
->rel
< cookie
->relend
);
126 /* Bookkeep the relocation offset and relocation index of each function
128 sframe_decoder_set_func_r_offset (sfd_info
, i
, cookie
->rel
->r_offset
);
129 sframe_decoder_set_func_reloc_index (sfd_info
, i
,
130 (cookie
->rel
- cookie
->rels
));
134 BFD_ASSERT (cookie
->rel
== cookie
->relend
);
139 /* Read the value from CONTENTS at the specified OFFSET for the given ABFD. */
142 sframe_read_value (bfd
*abfd
, bfd_byte
*contents
, unsigned int offset
,
145 BFD_ASSERT (contents
&& offset
);
146 /* Supporting the usecase of reading only the 4-byte relocated
147 value (signed offset for func start addr) for now. */
148 BFD_ASSERT (width
== 4);
149 /* FIXME endianness ?? */
150 unsigned char *buf
= contents
+ offset
;
151 bfd_vma value
= bfd_get_signed_32 (abfd
, buf
);
155 /* Return true if there is at least one non-empty .sframe section in
156 input files. Can only be called after ld has mapped input to
157 output sections, and before sections are stripped. */
160 _bfd_elf_sframe_present (struct bfd_link_info
*info
)
162 asection
*sframe
= bfd_get_section_by_name (info
->output_bfd
, ".sframe");
167 /* Count only sections which have at least a single FDE. */
168 for (sframe
= sframe
->map_head
.s
; sframe
!= NULL
; sframe
= sframe
->map_head
.s
)
169 /* Note that this may become an approximate check in the future when
170 some ABI/arch begin to use the sfh_auxhdr_len. When sfh_auxhdr_len has
171 non-zero value, it will need to be accounted for in the calculation of
172 the SFrame header size. */
173 if (sframe
->size
> sizeof (sframe_header
))
178 /* Try to parse .sframe section SEC, which belongs to ABFD. Store the
179 information in the section's sec_info field on success. COOKIE
180 describes the relocations in SEC.
182 Returns TRUE if success, FALSE if any error or failure. */
185 _bfd_elf_parse_sframe (bfd
*abfd
,
186 struct bfd_link_info
*info ATTRIBUTE_UNUSED
,
187 asection
*sec
, struct elf_reloc_cookie
*cookie
)
189 bfd_byte
*sfbuf
= NULL
;
190 struct sframe_dec_info
*sfd_info
;
191 sframe_decoder_ctx
*sfd_ctx
;
192 bfd_size_type sf_size
;
196 || sec
->sec_info_type
!= SEC_INFO_TYPE_NONE
)
198 /* This file does not contain .sframe information. */
202 if (bfd_is_abs_section (sec
->output_section
))
204 /* At least one of the sections is being discarded from the
205 link, so we should just ignore them. */
209 /* Read the SFrame unwind information from abfd. */
210 if (!bfd_malloc_and_get_section (abfd
, sec
, &sfbuf
))
213 /* Decode the buffer and keep decoded contents for later use.
214 Relocations are performed later, but are such that the section's
215 size is unaffected. */
216 sfd_info
= bfd_malloc (sizeof (struct sframe_dec_info
));
219 sfd_info
->sfd_ctx
= sframe_decode ((const char*)sfbuf
, sf_size
, &decerr
);
220 sfd_ctx
= sfd_info
->sfd_ctx
;
222 /* Free'ing up any memory held by decoder context is done by
223 sframe_decode in case of error. */
226 if (!sframe_decoder_init_func_bfdinfo (sec
, sfd_info
, cookie
))
228 sframe_decoder_free (&sfd_ctx
);
232 elf_section_data (sec
)->sec_info
= sfd_info
;
233 sec
->sec_info_type
= SEC_INFO_TYPE_SFRAME
;
239 (_("error in %pB(%pA); no .sframe will be created"),
247 /* This function is called for each input file before the .sframe section
248 is relocated. It marks the SFrame FDE for the discarded functions for
251 The function returns TRUE iff any entries have been deleted. */
254 _bfd_elf_discard_section_sframe
256 bool (*reloc_symbol_deleted_p
) (bfd_vma
, void *),
257 struct elf_reloc_cookie
*cookie
)
262 unsigned int func_desc_offset
;
263 unsigned int num_fidx
;
264 struct sframe_dec_info
*sfd_info
;
267 /* FIXME - if relocatable link and changed = true, how does the final
268 .rela.sframe get updated ?. */
271 sfd_info
= (struct sframe_dec_info
*) elf_section_data (sec
)->sec_info
;
273 /* Skip checking for the linker created .sframe sections
274 (for PLT sections). */
275 if ((sec
->flags
& SEC_LINKER_CREATED
) == 0 || cookie
->rels
!= NULL
)
277 num_fidx
= sframe_decoder_get_num_fidx (sfd_info
->sfd_ctx
);
278 for (i
= 0; i
< num_fidx
; i
++)
280 func_desc_offset
= sframe_decoder_get_func_r_offset (sfd_info
, i
);
282 cookie
->rel
= cookie
->rels
283 + sframe_decoder_get_func_reloc_index (sfd_info
, i
);
284 keep
= !(*reloc_symbol_deleted_p
) (func_desc_offset
, cookie
);
288 sframe_decoder_mark_func_deleted (sfd_info
, i
);
296 /* Update the reference to the output .sframe section in the output ELF
297 BFD ABFD. Returns true if no error. */
300 _bfd_elf_set_section_sframe (bfd
*abfd
,
301 struct bfd_link_info
*info
)
305 cfsec
= bfd_get_section_by_name (info
->output_bfd
, ".sframe");
309 elf_sframe (abfd
) = cfsec
;
314 /* Merge .sframe section SEC. This is called with the relocated
318 _bfd_elf_merge_section_sframe (bfd
*abfd
,
319 struct bfd_link_info
*info
,
323 struct sframe_dec_info
*sfd_info
;
324 struct sframe_enc_info
*sfe_info
;
325 sframe_decoder_ctx
*sfd_ctx
;
326 sframe_encoder_ctx
*sfe_ctx
;
327 unsigned char sfd_ctx_abi_arch
;
328 int8_t sfd_ctx_fixed_fp_offset
;
329 int8_t sfd_ctx_fixed_ra_offset
;
332 struct elf_link_hash_table
*htab
;
335 /* Sanity check - handle SFrame sections only. */
336 if (sec
->sec_info_type
!= SEC_INFO_TYPE_SFRAME
)
339 sfd_info
= (struct sframe_dec_info
*) elf_section_data (sec
)->sec_info
;
340 sfd_ctx
= sfd_info
->sfd_ctx
;
342 htab
= elf_hash_table (info
);
343 sfe_info
= &(htab
->sfe_info
);
344 sfe_ctx
= sfe_info
->sfe_ctx
;
346 /* All input bfds are expected to have a valid SFrame section. Even if
347 the SFrame section is empty with only a header, there must be a valid
348 SFrame decoder context by now. The SFrame encoder context, however,
349 will get set later here, if this is the first call to the function. */
350 if (sfd_ctx
== NULL
|| sfe_info
== NULL
)
353 if (htab
->sfe_info
.sfe_ctx
== NULL
)
355 sfd_ctx_abi_arch
= sframe_decoder_get_abi_arch (sfd_ctx
);
356 sfd_ctx_fixed_fp_offset
= sframe_decoder_get_fixed_fp_offset (sfd_ctx
);
357 sfd_ctx_fixed_ra_offset
= sframe_decoder_get_fixed_ra_offset (sfd_ctx
);
359 /* Valid values are non-zero. */
360 if (!sfd_ctx_abi_arch
)
363 htab
->sfe_info
.sfe_ctx
= sframe_encode (SFRAME_VERSION_1
,
364 0, /* SFrame flags. */
366 sfd_ctx_fixed_fp_offset
,
367 sfd_ctx_fixed_ra_offset
,
369 /* Handle errors from sframe_encode. */
370 if (htab
->sfe_info
.sfe_ctx
== NULL
)
373 sfe_ctx
= sfe_info
->sfe_ctx
;
375 if (sfe_info
->sframe_section
== NULL
)
377 /* Make sure things are set for an eventual write.
378 Size of the output section is not known until
379 _bfd_elf_write_section_sframe is ready with the buffer
381 cfsec
= bfd_get_section_by_name (info
->output_bfd
, ".sframe");
384 sfe_info
->sframe_section
= cfsec
;
385 // elf_sframe (abfd) = cfsec;
391 /* Check that all .sframe sections being linked have the same
393 if (sframe_decoder_get_abi_arch (sfd_ctx
)
394 != sframe_encoder_get_abi_arch (sfe_ctx
))
397 (_("input SFrame sections with different abi prevent .sframe"
402 /* Iterate over the function descriptor entries and the FREs of the
403 function from the decoder context. Add each of them to the encoder
404 context, if suitable. */
405 unsigned int i
= 0, j
= 0, cur_fidx
= 0;
407 unsigned int num_fidx
= sframe_decoder_get_num_fidx (sfd_ctx
);
408 unsigned int num_enc_fidx
= sframe_encoder_get_num_fidx (sfe_ctx
);
410 for (i
= 0; i
< num_fidx
; i
++)
412 unsigned int num_fres
= 0;
413 int32_t func_start_address
;
415 uint32_t func_size
= 0;
416 unsigned char func_info
= 0;
417 unsigned int r_offset
= 0;
418 bool pltn_reloc_by_hand
= false;
419 unsigned int pltn_r_offset
= 0;
421 if (!sframe_decoder_get_funcdesc (sfd_ctx
, i
, &num_fres
, &func_size
,
422 &func_start_address
, &func_info
))
424 /* If function belongs to a deleted section, skip editing the
425 function descriptor entry. */
426 if (sframe_decoder_func_deleted_p(sfd_info
, i
))
429 /* Don't edit function descriptor entries for relocatable link. */
430 if (!bfd_link_relocatable (info
))
432 if (!(sec
->flags
& SEC_LINKER_CREATED
))
434 /* Get relocated contents by reading the value of the
435 relocated function start address at the beginning of the
436 function descriptor entry. */
437 r_offset
= sframe_decoder_get_func_r_offset (sfd_info
, i
);
441 /* Expected to land here for SFrame unwind info as created
442 for the .plt* sections. These sections can have upto two
443 FDE entries. Although the code should work for > 2,
444 leaving this assert here for safety. */
445 BFD_ASSERT (num_fidx
<= 2);
446 /* For the first entry, we know the offset of the SFrame FDE's
447 sfde_func_start_address. Side note: see how the value
448 of PLT_SFRAME_FDE_START_OFFSET is also set to the
450 r_offset
= sframe_decoder_get_hdr_size (sfd_ctx
);
451 /* For any further SFrame FDEs, the generator has already put
452 in an offset in place of sfde_func_start_address of the
453 corresponding FDE. We will use it by hand to relocate. */
457 = r_offset
+ (i
* sizeof (sframe_func_desc_entry
));
458 pltn_reloc_by_hand
= true;
462 /* Get the SFrame FDE function start address after relocation. */
463 address
= sframe_read_value (abfd
, contents
, r_offset
, 4);
464 if (pltn_reloc_by_hand
)
465 address
+= sframe_read_value (abfd
, contents
,
467 address
+= (sec
->output_offset
+ r_offset
);
469 /* FIXME For testing only. Cleanup later. */
470 // address += (sec->output_section->vma);
472 func_start_address
= address
;
475 /* Update the encoder context with updated content. */
476 int err
= sframe_encoder_add_funcdesc (sfe_ctx
, func_start_address
,
477 func_size
, func_info
,
483 for (j
= 0; j
< num_fres
; j
++)
485 sframe_frame_row_entry fre
;
486 if (!sframe_decoder_get_fre (sfd_ctx
, i
, j
, &fre
))
488 int err
= sframe_encoder_add_fre (sfe_ctx
,
489 cur_fidx
-1+num_enc_fidx
,
495 /* Free the SFrame decoder context. */
496 sframe_decoder_free (&sfd_ctx
);
501 /* Write out the .sframe section. This must be called after
502 _bfd_elf_merge_section_sframe has been called on all input
506 _bfd_elf_write_section_sframe (bfd
*abfd
, struct bfd_link_info
*info
)
510 struct elf_link_hash_table
*htab
;
511 struct sframe_enc_info
*sfe_info
;
512 sframe_encoder_ctx
*sfe_ctx
;
518 htab
= elf_hash_table (info
);
519 sfe_info
= &htab
->sfe_info
;
520 sec
= sfe_info
->sframe_section
;
521 sfe_ctx
= sfe_info
->sfe_ctx
;
526 contents
= sframe_encoder_write (sfe_ctx
, &sec_size
, &err
);
527 sec
->size
= (bfd_size_type
) sec_size
;
529 if (!bfd_set_section_contents (abfd
, sec
->output_section
, contents
,
530 (file_ptr
) sec
->output_offset
,
533 else if (!bfd_link_relocatable (info
))
535 Elf_Internal_Shdr
*hdr
= &elf_section_data (sec
)->this_hdr
;
536 hdr
->sh_size
= sec
->size
;
538 /* For relocatable links, do not update the section size as the section
539 contents have not been relocated. */
541 sframe_encoder_free (&sfe_ctx
);