* [binutils-gdb] ignore some symbols in elf.c:swap_out_syms
@ 2024-04-23 12:38 Alan Modra
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From: Alan Modra @ 2024-04-23 12:38 UTC (permalink / raw)
To: binutils-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ef1c830f003acaf149bb9ee230be0d0067e1855c
commit ef1c830f003acaf149bb9ee230be0d0067e1855c
Author: Alan Modra <amodra@gmail.com>
Date: Mon Apr 22 09:29:28 2024 +0930
ignore some symbols in elf.c:swap_out_syms
The reason behind this patch was noticing that generic ELF targets
fail to remove "bar" in the recently committed ld-elf/undefweak-1
test. (Despite that, those targets pass the test due to it being too
strict when matching symbols. "bar" gets turned into a local weak
defined absolute symbol.)
swap_out_syms currently drops local section syms that are defined in
discarded sections. Extend that to also drop other symbols in
discarded sections too, even global symbols. The linker goes to quite
a lot of effort to ensure globals in discarded section take a
definition from the kept linkonce or comdat group section. So the
global sym change should only affect cases where something is quite
wrong about the set of linkonce or comdat group sections. However
that change to elf_map_symbols meant we dropped _DYNAMIC_LINK /
_DYNAMIC_LINKING for mips, a global absolute symbol given STT_SECTION
type for some reason. That problem is fixed by reverting the pr14493
change which is no longer needed due to a) BSF_SECTION_SYM_USED on
x86, and b) fixing objcopy to use copy_private_symbol_data.
bfd/
PR 14493
* elf.c (ignore_sym): Rename from ignore_section_sym. Return
true for any symbol without a section or in a discarded section.
Revert pr14493 change.
(elf_map_symbols): Tidy. Use ignore_sym on all symbols.
(swap_out_syms): Tidy.
ld/
* testsuite/ld-elf/undefweak-1.rd: Match any "bar".
Diff:
---
bfd/elf.c | 103 +++++++++++++++++--------------------
ld/testsuite/ld-elf/undefweak-1.rd | 2 +-
2 files changed, 49 insertions(+), 56 deletions(-)
diff --git a/bfd/elf.c b/bfd/elf.c
index 41ec649ebab..0f4907adc32 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -4573,36 +4573,32 @@ _bfd_elf_filter_global_symbols (bfd *abfd, struct bfd_link_info *info,
return dst_count;
}
-/* Don't output section symbols for sections that are not going to be
- output, that are duplicates or there is no BFD section. */
+/* Don't output symbols for sections that are not going to be output,
+ that are duplicates or there is no BFD section. */
static bool
-ignore_section_sym (bfd *abfd, asymbol *sym)
+ignore_sym (asymbol *sym)
{
- elf_symbol_type *type_ptr;
-
if (sym == NULL)
return false;
- if ((sym->flags & BSF_SECTION_SYM) == 0)
- return false;
-
- /* Ignore the section symbol if it isn't used. */
- if ((sym->flags & BSF_SECTION_SYM_USED) == 0)
- return true;
-
if (sym->section == NULL)
return true;
- type_ptr = elf_symbol_from (sym);
- return ((type_ptr != NULL
- && type_ptr->internal_elf_sym.st_shndx != 0
- && bfd_is_abs_section (sym->section))
- || !(sym->section->owner == abfd
- || (sym->section->output_section != NULL
- && sym->section->output_section->owner == abfd
- && sym->section->output_offset == 0)
- || bfd_is_abs_section (sym->section)));
+ if ((sym->flags & BSF_SECTION_SYM) != 0)
+ {
+ if ((sym->flags & BSF_SECTION_SYM_USED) == 0)
+ return true;
+ /* With ld -r on generic elf targets it is possible to have
+ multiple section symbols in the output for a given section.
+ We'd like to get rid of all but the first one. This drops
+ them if the first input section is non-zero size, but fails
+ to do so if the first input section is zero sized. */
+ if (sym->section->output_offset != 0)
+ return true;
+ }
+
+ return discarded_section (sym->section);
}
/* Map symbol from it's internal number to the external number, moving
@@ -4616,8 +4612,6 @@ elf_map_symbols (bfd *abfd, unsigned int *pnum_locals)
asymbol **sect_syms;
unsigned int num_locals = 0;
unsigned int num_globals = 0;
- unsigned int num_locals2 = 0;
- unsigned int num_globals2 = 0;
unsigned int max_index = 0;
unsigned int idx;
asection *asect;
@@ -4651,7 +4645,7 @@ elf_map_symbols (bfd *abfd, unsigned int *pnum_locals)
if ((sym->flags & BSF_SECTION_SYM) != 0
&& sym->value == 0
- && !ignore_section_sym (abfd, sym)
+ && !ignore_sym (sym)
&& !bfd_is_abs_section (sym->section))
{
asection *sec = sym->section;
@@ -4666,9 +4660,11 @@ elf_map_symbols (bfd *abfd, unsigned int *pnum_locals)
/* Classify all of the symbols. */
for (idx = 0; idx < symcount; idx++)
{
+ if (ignore_sym (syms[idx]))
+ continue;
if (sym_is_global (abfd, syms[idx]))
num_globals++;
- else if (!ignore_section_sym (abfd, syms[idx]))
+ else
num_locals++;
}
@@ -4680,13 +4676,13 @@ elf_map_symbols (bfd *abfd, unsigned int *pnum_locals)
{
asymbol *sym = asect->symbol;
/* Don't include ignored section symbols. */
- if (!ignore_section_sym (abfd, sym)
+ if (!ignore_sym (sym)
&& sect_syms[asect->index] == NULL)
{
- if (!sym_is_global (abfd, asect->symbol))
- num_locals++;
- else
+ if (sym_is_global (abfd, asect->symbol))
num_globals++;
+ else
+ num_locals++;
}
}
@@ -4696,34 +4692,36 @@ elf_map_symbols (bfd *abfd, unsigned int *pnum_locals)
if (new_syms == NULL)
return false;
+ unsigned int num_globals2 = 0;
+ unsigned int num_locals2 = 0;
for (idx = 0; idx < symcount; idx++)
{
asymbol *sym = syms[idx];
unsigned int i;
+ if (ignore_sym (sym))
+ continue;
+
if (sym_is_global (abfd, sym))
i = num_locals + num_globals2++;
- /* Don't include ignored section symbols. */
- else if (!ignore_section_sym (abfd, sym))
- i = num_locals2++;
else
- continue;
+ i = num_locals2++;
new_syms[i] = sym;
sym->udata.i = i + 1;
}
for (asect = abfd->sections; asect; asect = asect->next)
{
asymbol *sym = asect->symbol;
- if (!ignore_section_sym (abfd, sym)
+ if (!ignore_sym (sym)
&& sect_syms[asect->index] == NULL)
{
unsigned int i;
sect_syms[asect->index] = sym;
- if (!sym_is_global (abfd, sym))
- i = num_locals2++;
- else
+ if (sym_is_global (abfd, sym))
i = num_locals + num_globals2++;
+ else
+ i = num_locals2++;
new_syms[i] = sym;
sym->udata.i = i + 1;
}
@@ -8897,8 +8895,8 @@ swap_out_syms (bfd *abfd,
sym.st_other = 0;
sym.st_shndx = SHN_UNDEF;
sym.st_target_internal = 0;
- symstrtab[0].sym = sym;
- symstrtab[0].dest_index = outbound_syms_index;
+ symstrtab[outbound_syms_index].sym = sym;
+ symstrtab[outbound_syms_index].dest_index = outbound_syms_index;
outbound_syms_index++;
}
@@ -8907,14 +8905,11 @@ swap_out_syms (bfd *abfd,
&& bed->elf_backend_name_local_section_symbols (abfd));
syms = bfd_get_outsymbols (abfd);
- for (idx = 0; idx < symcount;)
+ for (idx = 0; idx < symcount; idx++)
{
Elf_Internal_Sym sym;
- bfd_vma value = syms[idx]->value;
- elf_symbol_type *type_ptr;
- flagword flags = syms[idx]->flags;
- int type;
+ flagword flags = syms[idx]->flags;
if (!name_local_sections
&& (flags & (BSF_SECTION_SYM | BSF_GLOBAL)) == BSF_SECTION_SYM)
{
@@ -8932,10 +8927,11 @@ swap_out_syms (bfd *abfd,
goto error_return;
}
- type_ptr = elf_symbol_from (syms[idx]);
+ bfd_vma value = syms[idx]->value;
+ elf_symbol_type *type_ptr = elf_symbol_from (syms[idx]);
+ asection *sec = syms[idx]->section;
- if ((flags & BSF_SECTION_SYM) == 0
- && bfd_is_com_section (syms[idx]->section))
+ if ((flags & BSF_SECTION_SYM) == 0 && bfd_is_com_section (sec))
{
/* ELF common symbols put the alignment into the `value' field,
and the size into the `size' field. This is backwards from
@@ -8946,12 +8942,10 @@ swap_out_syms (bfd *abfd,
sym.st_value = value >= 16 ? 16 : (1 << bfd_log2 (value));
else
sym.st_value = type_ptr->internal_elf_sym.st_value;
- sym.st_shndx = _bfd_elf_section_from_bfd_section
- (abfd, syms[idx]->section);
+ sym.st_shndx = _bfd_elf_section_from_bfd_section (abfd, sec);
}
else
{
- asection *sec = syms[idx]->section;
unsigned int shndx;
if (sec->output_section)
@@ -9049,6 +9043,7 @@ Unable to handle section index %x in ELF symbol. Using ABS instead."),
sym.st_shndx = shndx;
}
+ int type;
if ((flags & BSF_THREAD_LOCAL) != 0)
type = STT_TLS;
else if ((flags & BSF_GNU_INDIRECT_FUNCTION) != 0)
@@ -9128,10 +9123,8 @@ Unable to handle section index %x in ELF symbol. Using ABS instead."),
sym.st_target_internal = 0;
}
- idx++;
- symstrtab[idx].sym = sym;
- symstrtab[idx].dest_index = outbound_syms_index;
-
+ symstrtab[outbound_syms_index].sym = sym;
+ symstrtab[outbound_syms_index].dest_index = outbound_syms_index;
outbound_syms_index++;
}
@@ -9139,7 +9132,7 @@ Unable to handle section index %x in ELF symbol. Using ABS instead."),
_bfd_elf_strtab_finalize (stt);
/* Swap out the .strtab section. */
- for (idx = 0; idx <= symcount; idx++)
+ for (idx = 0; idx < outbound_syms_index; idx++)
{
struct elf_sym_strtab *elfsym = &symstrtab[idx];
if (elfsym->sym.st_name == (unsigned long) -1)
diff --git a/ld/testsuite/ld-elf/undefweak-1.rd b/ld/testsuite/ld-elf/undefweak-1.rd
index 5b48c13c892..6bf3da0ce60 100644
--- a/ld/testsuite/ld-elf/undefweak-1.rd
+++ b/ld/testsuite/ld-elf/undefweak-1.rd
@@ -6,5 +6,5 @@
#failif
#...
-.*: 0+ +0 +FUNC +WEAK +DEFAULT +UND +bar
+.* bar
#pass
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