1 /* .sframe section processing.
2 Copyright (C) 2022-2023 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
->flags
& SEC_HAS_CONTENTS
) == 0
197 || sec
->sec_info_type
!= SEC_INFO_TYPE_NONE
)
199 /* This file does not contain .sframe information. */
203 if (bfd_is_abs_section (sec
->output_section
))
205 /* At least one of the sections is being discarded from the
206 link, so we should just ignore them. */
210 /* Read the SFrame stack trace information from abfd. */
211 if (!bfd_malloc_and_get_section (abfd
, sec
, &sfbuf
))
214 /* Decode the buffer and keep decoded contents for later use.
215 Relocations are performed later, but are such that the section's
216 size is unaffected. */
217 sfd_info
= bfd_malloc (sizeof (struct sframe_dec_info
));
220 sfd_info
->sfd_ctx
= sframe_decode ((const char*)sfbuf
, sf_size
, &decerr
);
221 sfd_ctx
= sfd_info
->sfd_ctx
;
223 /* Free'ing up any memory held by decoder context is done by
224 sframe_decode in case of error. */
227 if (!sframe_decoder_init_func_bfdinfo (sec
, sfd_info
, cookie
))
229 sframe_decoder_free (&sfd_ctx
);
233 elf_section_data (sec
)->sec_info
= sfd_info
;
234 sec
->sec_info_type
= SEC_INFO_TYPE_SFRAME
;
240 (_("error in %pB(%pA); no .sframe will be created"),
248 /* This function is called for each input file before the .sframe section
249 is relocated. It marks the SFrame FDE for the discarded functions for
252 The function returns TRUE iff any entries have been deleted. */
255 _bfd_elf_discard_section_sframe
257 bool (*reloc_symbol_deleted_p
) (bfd_vma
, void *),
258 struct elf_reloc_cookie
*cookie
)
263 unsigned int func_desc_offset
;
264 unsigned int num_fidx
;
265 struct sframe_dec_info
*sfd_info
;
268 /* FIXME - if relocatable link and changed = true, how does the final
269 .rela.sframe get updated ?. */
272 sfd_info
= (struct sframe_dec_info
*) elf_section_data (sec
)->sec_info
;
274 /* Skip checking for the linker created .sframe sections
275 (for PLT sections). */
276 if ((sec
->flags
& SEC_LINKER_CREATED
) == 0 || cookie
->rels
!= NULL
)
278 num_fidx
= sframe_decoder_get_num_fidx (sfd_info
->sfd_ctx
);
279 for (i
= 0; i
< num_fidx
; i
++)
281 func_desc_offset
= sframe_decoder_get_func_r_offset (sfd_info
, i
);
283 cookie
->rel
= cookie
->rels
284 + sframe_decoder_get_func_reloc_index (sfd_info
, i
);
285 keep
= !(*reloc_symbol_deleted_p
) (func_desc_offset
, cookie
);
289 sframe_decoder_mark_func_deleted (sfd_info
, i
);
297 /* Update the reference to the output .sframe section in the output ELF
298 BFD ABFD. Returns true if no error. */
301 _bfd_elf_set_section_sframe (bfd
*abfd
,
302 struct bfd_link_info
*info
)
306 cfsec
= bfd_get_section_by_name (info
->output_bfd
, ".sframe");
310 elf_sframe (abfd
) = cfsec
;
315 /* Merge .sframe section SEC. This is called with the relocated
319 _bfd_elf_merge_section_sframe (bfd
*abfd
,
320 struct bfd_link_info
*info
,
324 struct sframe_dec_info
*sfd_info
;
325 struct sframe_enc_info
*sfe_info
;
326 sframe_decoder_ctx
*sfd_ctx
;
327 sframe_encoder_ctx
*sfe_ctx
;
328 unsigned char sfd_ctx_abi_arch
;
329 int8_t sfd_ctx_fixed_fp_offset
;
330 int8_t sfd_ctx_fixed_ra_offset
;
333 struct elf_link_hash_table
*htab
;
336 /* Sanity check - handle SFrame sections only. */
337 if (sec
->sec_info_type
!= SEC_INFO_TYPE_SFRAME
)
340 sfd_info
= (struct sframe_dec_info
*) elf_section_data (sec
)->sec_info
;
341 sfd_ctx
= sfd_info
->sfd_ctx
;
343 htab
= elf_hash_table (info
);
344 sfe_info
= &(htab
->sfe_info
);
345 sfe_ctx
= sfe_info
->sfe_ctx
;
347 /* All input bfds are expected to have a valid SFrame section. Even if
348 the SFrame section is empty with only a header, there must be a valid
349 SFrame decoder context by now. The SFrame encoder context, however,
350 will get set later here, if this is the first call to the function. */
351 if (sfd_ctx
== NULL
|| sfe_info
== NULL
)
354 if (htab
->sfe_info
.sfe_ctx
== NULL
)
356 sfd_ctx_abi_arch
= sframe_decoder_get_abi_arch (sfd_ctx
);
357 sfd_ctx_fixed_fp_offset
= sframe_decoder_get_fixed_fp_offset (sfd_ctx
);
358 sfd_ctx_fixed_ra_offset
= sframe_decoder_get_fixed_ra_offset (sfd_ctx
);
360 /* Valid values are non-zero. */
361 if (!sfd_ctx_abi_arch
)
364 htab
->sfe_info
.sfe_ctx
= sframe_encode (SFRAME_VERSION_1
,
365 0, /* SFrame flags. */
367 sfd_ctx_fixed_fp_offset
,
368 sfd_ctx_fixed_ra_offset
,
370 /* Handle errors from sframe_encode. */
371 if (htab
->sfe_info
.sfe_ctx
== NULL
)
374 sfe_ctx
= sfe_info
->sfe_ctx
;
376 if (sfe_info
->sframe_section
== NULL
)
378 /* Make sure things are set for an eventual write.
379 Size of the output section is not known until
380 _bfd_elf_write_section_sframe is ready with the buffer
382 cfsec
= bfd_get_section_by_name (info
->output_bfd
, ".sframe");
385 sfe_info
->sframe_section
= cfsec
;
386 // elf_sframe (abfd) = cfsec;
392 /* Check that all .sframe sections being linked have the same
394 if (sframe_decoder_get_abi_arch (sfd_ctx
)
395 != sframe_encoder_get_abi_arch (sfe_ctx
))
398 (_("input SFrame sections with different abi prevent .sframe"
403 /* Iterate over the function descriptor entries and the FREs of the
404 function from the decoder context. Add each of them to the encoder
405 context, if suitable. */
406 unsigned int i
= 0, j
= 0, cur_fidx
= 0;
408 unsigned int num_fidx
= sframe_decoder_get_num_fidx (sfd_ctx
);
409 unsigned int num_enc_fidx
= sframe_encoder_get_num_fidx (sfe_ctx
);
411 for (i
= 0; i
< num_fidx
; i
++)
413 unsigned int num_fres
= 0;
414 int32_t func_start_address
;
416 uint32_t func_size
= 0;
417 unsigned char func_info
= 0;
418 unsigned int r_offset
= 0;
419 bool pltn_reloc_by_hand
= false;
420 unsigned int pltn_r_offset
= 0;
422 if (!sframe_decoder_get_funcdesc (sfd_ctx
, i
, &num_fres
, &func_size
,
423 &func_start_address
, &func_info
))
425 /* If function belongs to a deleted section, skip editing the
426 function descriptor entry. */
427 if (sframe_decoder_func_deleted_p(sfd_info
, i
))
430 /* Don't edit function descriptor entries for relocatable link. */
431 if (!bfd_link_relocatable (info
))
433 if (!(sec
->flags
& SEC_LINKER_CREATED
))
435 /* Get relocated contents by reading the value of the
436 relocated function start address at the beginning of the
437 function descriptor entry. */
438 r_offset
= sframe_decoder_get_func_r_offset (sfd_info
, i
);
442 /* Expected to land here when SFrame stack trace info is
443 created dynamically for the .plt* sections. These
444 sections are expected to have upto two SFrame FDE entries.
445 Although the code should work for > 2, leaving this
446 assert here for safety. */
447 BFD_ASSERT (num_fidx
<= 2);
448 /* For the first entry, we know the offset of the SFrame FDE's
449 sfde_func_start_address. Side note: see how the value
450 of PLT_SFRAME_FDE_START_OFFSET is also set to the
452 r_offset
= sframe_decoder_get_hdr_size (sfd_ctx
);
453 /* For any further SFrame FDEs, the generator has already put
454 in an offset in place of sfde_func_start_address of the
455 corresponding FDE. We will use it by hand to relocate. */
459 = r_offset
+ (i
* sizeof (sframe_func_desc_entry
));
460 pltn_reloc_by_hand
= true;
464 /* Get the SFrame FDE function start address after relocation. */
465 address
= sframe_read_value (abfd
, contents
, r_offset
, 4);
466 if (pltn_reloc_by_hand
)
467 address
+= sframe_read_value (abfd
, contents
,
469 address
+= (sec
->output_offset
+ r_offset
);
471 /* FIXME For testing only. Cleanup later. */
472 // address += (sec->output_section->vma);
474 func_start_address
= address
;
477 /* Update the encoder context with updated content. */
478 int err
= sframe_encoder_add_funcdesc (sfe_ctx
, func_start_address
,
479 func_size
, func_info
,
485 for (j
= 0; j
< num_fres
; j
++)
487 sframe_frame_row_entry fre
;
488 if (!sframe_decoder_get_fre (sfd_ctx
, i
, j
, &fre
))
490 int err
= sframe_encoder_add_fre (sfe_ctx
,
491 cur_fidx
-1+num_enc_fidx
,
497 /* Free the SFrame decoder context. */
498 sframe_decoder_free (&sfd_ctx
);
503 /* Write out the .sframe section. This must be called after
504 _bfd_elf_merge_section_sframe has been called on all input
508 _bfd_elf_write_section_sframe (bfd
*abfd
, struct bfd_link_info
*info
)
512 struct elf_link_hash_table
*htab
;
513 struct sframe_enc_info
*sfe_info
;
514 sframe_encoder_ctx
*sfe_ctx
;
520 htab
= elf_hash_table (info
);
521 sfe_info
= &htab
->sfe_info
;
522 sec
= sfe_info
->sframe_section
;
523 sfe_ctx
= sfe_info
->sfe_ctx
;
528 contents
= sframe_encoder_write (sfe_ctx
, &sec_size
, &err
);
529 sec
->size
= (bfd_size_type
) sec_size
;
531 if (!bfd_set_section_contents (abfd
, sec
->output_section
, contents
,
532 (file_ptr
) sec
->output_offset
,
535 else if (!bfd_link_relocatable (info
))
537 Elf_Internal_Shdr
*hdr
= &elf_section_data (sec
)->this_hdr
;
538 hdr
->sh_size
= sec
->size
;
540 /* For relocatable links, do not update the section size as the section
541 contents have not been relocated. */
543 sframe_encoder_free (&sfe_ctx
);