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macos: Fix GOT access to local defined symbols

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if a GOT slot is required (due to codegen, indicated by
presence of some relocation types), then it needs to contain
the address of the wanted symbol, also when it's local and defined,
i.e. not overridable.  For simplicity we use a GOT slot for that as
well (other storage would require rewriting relocs and symbols,
as resolving of GOT relocs is hardwired to be based on s1->got).
But that means we need to fill in its indirect symbol mapping slot as
well, for which Mach-O provides a mean to say "not symbol based,
resolved locally".  So this fixes this testcase:

static int loc;
int _start(void)
{
  loc = 42;
  return loc - 42;
}

(where our codegen currently uses a GOT-based access for the write
by accident)
This commit is contained in:
Michael Matz 2020-05-17 04:39:40 +02:00
parent 6ebd463021
commit fab8787b23
1 changed files with 11 additions and 1 deletions
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12
tccmacho.c
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@ -321,7 +321,17 @@ static void check_relocs(TCCState *s1, struct macho *mo)
attr->got_offset = s1->got->data_offset;
attr->plt_offset = 1; /* used as flag */
section_ptr_add(s1->got, PTR_SIZE);
*pi = mo->e2msym[sym_index];
if (ELFW(ST_BIND)(sym->st_info) == STB_LOCAL) {
if (sym->st_shndx == SHN_UNDEF)
tcc_error("undefined local symbol???");
*pi = 0x80000000; /* INDIRECT_SYMBOL_LOCAL */
/* The pointer slot we generated must point to the
symbol, whose address is only known after layout,
so register a simply relocation for that. */
put_elf_reloc (s1->symtab, s1->got, attr->got_offset,
R_DATA_PTR, sym_index);
} else
*pi = mo->e2msym[sym_index];
}
}
}