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lto: fix LTO debug sections copying.

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readelf -S prints:

There are 81999 section headers, starting at offset 0x1f488060:

Section Headers:
  [Nr] Name              Type            Address          Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            0000000000000000 000000 01404f 00     81998   0  0
  [ 1] .group            GROUP           0000000000000000 000040 000008 04     81995 105027  4
...
  [81995] .symtab           SYMTAB          0000000000000000 d5d9298 2db310 18     81997 105026  8
  [81996] .symtab_shndx     SYMTAB SECTION INDICES 0000000000000000 d8b45a8 079dd8 04     81995   0  4
  [81997] .strtab           STRTAB          0000000000000000 d92e380 80460c 00      0   0  1
...

Looking at the documentation:
Table 7–15 ELF sh_link and sh_info Interpretation

sh_type - sh_link
SHT_SYMTAB - The section header index of the associated string table.
SHT_SYMTAB_SHNDX - The section header index of the associated symbol table.

As seen, sh_link of a SHT_SYMTAB always points to a .strtab and readelf
confirms that.

So we need to use reverse mapping taken from
  [81996] .symtab_shndx     SYMTAB SECTION INDICES 0000000000000000 d8b45a8 079dd8 04     81995   0  4

where sh_link points to 81995.

libiberty/ChangeLog:

	PR lto/97290
	* simple-object-elf.c (simple_object_elf_copy_lto_debug_sections):
	Use sh_link of a .symtab_shndx section.
This commit is contained in:
Martin Liska 2020-10-05 18:03:08 +02:00
parent a9a88a0a55
commit 190c04ba36
1 changed files with 7 additions and 4 deletions
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11
libiberty/simple-object-elf.c
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@ -1191,7 +1191,7 @@ simple_object_elf_copy_lto_debug_sections (simple_object_read *sobj,
unsigned int sh_link;
sh_link = ELF_FETCH_FIELD (type_functions, ei_class, Shdr,
shdr, sh_link, Elf_Word);
symtab_indices_shndx[sh_link - 1] = i;
symtab_indices_shndx[sh_link - 1] = i - 1;
/* Always discard the extended index sections, after
copying it will not be needed. This way we don't need to
update it and deal with the ordering constraints of
@ -1372,19 +1372,22 @@ simple_object_elf_copy_lto_debug_sections (simple_object_read *sobj,
{
unsigned entsize = ELF_FETCH_FIELD (type_functions, ei_class, Shdr,
shdr, sh_entsize, Elf_Addr);
unsigned strtab = ELF_FETCH_FIELD (type_functions, ei_class, Shdr,
shdr, sh_link, Elf_Word);
size_t prevailing_name_idx = 0;
unsigned char *ent;
unsigned *shndx_table = NULL;
/* Read the section index table if present. */
if (symtab_indices_shndx[i - 1] != 0)
{
unsigned char *sidxhdr = shdrs + (strtab - 1) * shdr_size;
unsigned char *sidxhdr = shdrs + symtab_indices_shndx[i - 1] * shdr_size;
off_t sidxoff = ELF_FETCH_FIELD (type_functions, ei_class, Shdr,
sidxhdr, sh_offset, Elf_Addr);
size_t sidxsz = ELF_FETCH_FIELD (type_functions, ei_class, Shdr,
sidxhdr, sh_size, Elf_Addr);
unsigned int shndx_type
= ELF_FETCH_FIELD (type_functions, ei_class, Shdr,
sidxhdr, sh_type, Elf_Word);
if (shndx_type != SHT_SYMTAB_SHNDX)
return "Wrong section type of a SYMTAB SECTION INDICES section";
shndx_table = (unsigned *)XNEWVEC (char, sidxsz);
simple_object_internal_read (sobj->descriptor,
sobj->offset + sidxoff,