PR ld/20828: Reorder the symbol sweep stage of section GC

Complement commit 81ff47b3a5 ("PR ld/20828: Fix linker script symbols
wrongly forced local with section GC") and move the symbol sweep stage
of section GC from `elf_gc_sweep' to `bfd_elf_size_dynamic_sections',
avoiding the need to clear the `forced_local' marker, problematic for
targets that have special processing in their `elf_backend_hide_symbol'
handler.  Set `mark' instead in `bfd_elf_record_link_assignment' and,
matching changes from commit 3bd43ebcb6 ("ld --gc-sections fail with
__tls_get_addr_opt"), also in PowerPC `__tls_get_addr_opt' handling
code, removing a:

FAIL: PR ld/20828 dynamic symbols with section GC (version script)

test suite failure with the `score-elf' target.

The rationale is it is enough if symbols are swept at the beginning of
`bfd_elf_size_dynamic_sections' as it is only in this function that the
size of the GOT, the dynamic symbol table and other dynamic sections is
determined, which will depend on the number of symbols making it to the
dynamic symbol table.  It is also appropriate to do the sweep at this
point as it is already after any changes have been made to symbols with
`bfd_elf_record_link_assignment', and not possible any earlier as calls
to that function are only made just beforehand -- barring audit entry
processing -- via `gld${EMULATION_NAME}_find_statement_assignment'
invoked from `gld${EMULATION_NAME}_before_allocation' which is the ELF
handler for `ldemul_before_allocation'.

	bfd/
	PR ld/20828
	* elflink.c (bfd_elf_record_link_assignment): Revert last
	change and don't ever clear `forced_local'.  Set `mark'
	unconditionally.
	(elf_gc_sweep_symbol_info, elf_gc_sweep_symbol): Reorder within
	file.
	(elf_gc_sweep): Move the call to `elf_gc_sweep_symbol'...
	(bfd_elf_size_dynamic_sections): ... here.
	* elf32-ppc.c (ppc_elf_tls_setup): Don't clear `forced_local'
	and set `mark' instead in `__tls_get_addr_opt' processing.
	* elf64-ppc.c (ppc64_elf_tls_setup): Likewise.
This commit is contained in:
Maciej W. Rozycki 2017-01-23 11:38:20 +00:00
parent 1a792e1c00
commit b531344c34
4 changed files with 71 additions and 54 deletions

View File

@ -1,3 +1,17 @@
2017-01-24 Maciej W. Rozycki <macro@imgtec.com>
PR ld/20828
* elflink.c (bfd_elf_record_link_assignment): Revert last
change and don't ever clear `forced_local'. Set `mark'
unconditionally.
(elf_gc_sweep_symbol_info, elf_gc_sweep_symbol): Reorder within
file.
(elf_gc_sweep): Move the call to `elf_gc_sweep_symbol'...
(bfd_elf_size_dynamic_sections): ... here.
* elf32-ppc.c (ppc_elf_tls_setup): Don't clear `forced_local'
and set `mark' instead in `__tls_get_addr_opt' processing.
* elf64-ppc.c (ppc64_elf_tls_setup): Likewise.
2017-01-24 Alan Modra <amodra@gmail.com>
* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol): Merge two cases

View File

@ -5287,7 +5287,7 @@ ppc_elf_tls_setup (bfd *obfd, struct bfd_link_info *info)
tga->root.type = bfd_link_hash_indirect;
tga->root.u.i.link = &opt->root;
ppc_elf_copy_indirect_symbol (info, opt, tga);
opt->forced_local = 0;
opt->mark = 1;
if (opt->dynindx != -1)
{
/* Use __tls_get_addr_opt in dynamic relocations. */

View File

@ -8324,7 +8324,7 @@ ppc64_elf_tls_setup (struct bfd_link_info *info)
tga_fd->root.type = bfd_link_hash_indirect;
tga_fd->root.u.i.link = &opt_fd->root;
ppc64_elf_copy_indirect_symbol (info, opt_fd, tga_fd);
opt_fd->forced_local = 0;
opt_fd->mark = 1;
if (opt_fd->dynindx != -1)
{
/* Use __tls_get_addr_opt in dynamic relocations. */
@ -8341,7 +8341,7 @@ ppc64_elf_tls_setup (struct bfd_link_info *info)
tga->root.type = bfd_link_hash_indirect;
tga->root.u.i.link = &opt->root;
ppc64_elf_copy_indirect_symbol (info, opt, tga);
opt->forced_local = 0;
opt->mark = 1;
_bfd_elf_link_hash_hide_symbol (info, opt,
tga->forced_local);
htab->tls_get_addr = (struct ppc_link_hash_entry *) opt;

View File

@ -671,17 +671,15 @@ bfd_elf_record_link_assignment (bfd *output_bfd,
/* If this symbol is not being provided by the linker script, and it is
currently defined by a dynamic object, but not by a regular object,
then undo any forced local marking that may have been set by input
section garbage collection and clear out any version information
because the symbol will not be associated with the dynamic object
any more. */
then clear out any version information because the symbol will not be
associated with the dynamic object any more. */
if (!provide
&& h->def_dynamic
&& !h->def_regular)
{
h->forced_local = 0;
h->verinfo.verdef = NULL;
}
h->verinfo.verdef = NULL;
/* Make sure this symbol is not garbage collected. */
h->mark = 1;
h->def_regular = 1;
@ -5876,6 +5874,38 @@ bfd_elf_stack_segment_size (bfd *output_bfd,
return TRUE;
}
/* Sweep symbols in swept sections. Called via elf_link_hash_traverse. */
struct elf_gc_sweep_symbol_info
{
struct bfd_link_info *info;
void (*hide_symbol) (struct bfd_link_info *, struct elf_link_hash_entry *,
bfd_boolean);
};
static bfd_boolean
elf_gc_sweep_symbol (struct elf_link_hash_entry *h, void *data)
{
if (!h->mark
&& (((h->root.type == bfd_link_hash_defined
|| h->root.type == bfd_link_hash_defweak)
&& !((h->def_regular || ELF_COMMON_DEF_P (h))
&& h->root.u.def.section->gc_mark))
|| h->root.type == bfd_link_hash_undefined
|| h->root.type == bfd_link_hash_undefweak))
{
struct elf_gc_sweep_symbol_info *inf;
inf = (struct elf_gc_sweep_symbol_info *) data;
(*inf->hide_symbol) (inf->info, h, TRUE);
h->def_regular = 0;
h->ref_regular = 0;
h->ref_regular_nonweak = 0;
}
return TRUE;
}
/* Set up the sizes and contents of the ELF dynamic sections. This is
called by the ELF linker emulation before_allocation routine. We
must set the sizes of the sections before the linker sets the
@ -5906,6 +5936,22 @@ bfd_elf_size_dynamic_sections (bfd *output_bfd,
bed = get_elf_backend_data (output_bfd);
if (info->gc_sections && bed->can_gc_sections)
{
struct elf_gc_sweep_symbol_info sweep_info;
unsigned long section_sym_count;
/* Remove the symbols that were in the swept sections from the
dynamic symbol table. GCFIXME: Anyone know how to get them
out of the static symbol table as well? */
sweep_info.info = info;
sweep_info.hide_symbol = bed->elf_backend_hide_symbol;
elf_link_hash_traverse (elf_hash_table (info), elf_gc_sweep_symbol,
&sweep_info);
_bfd_elf_link_renumber_dynsyms (output_bfd, info, &section_sym_count);
}
/* Any syms created from now on start with -1 in
got.refcount/offset and plt.refcount/offset. */
elf_hash_table (info)->init_got_refcount
@ -12853,38 +12899,6 @@ _bfd_elf_gc_mark_extra_sections (struct bfd_link_info *info,
return TRUE;
}
/* Sweep symbols in swept sections. Called via elf_link_hash_traverse. */
struct elf_gc_sweep_symbol_info
{
struct bfd_link_info *info;
void (*hide_symbol) (struct bfd_link_info *, struct elf_link_hash_entry *,
bfd_boolean);
};
static bfd_boolean
elf_gc_sweep_symbol (struct elf_link_hash_entry *h, void *data)
{
if (!h->mark
&& (((h->root.type == bfd_link_hash_defined
|| h->root.type == bfd_link_hash_defweak)
&& !((h->def_regular || ELF_COMMON_DEF_P (h))
&& h->root.u.def.section->gc_mark))
|| h->root.type == bfd_link_hash_undefined
|| h->root.type == bfd_link_hash_undefweak))
{
struct elf_gc_sweep_symbol_info *inf;
inf = (struct elf_gc_sweep_symbol_info *) data;
(*inf->hide_symbol) (inf->info, h, TRUE);
h->def_regular = 0;
h->ref_regular = 0;
h->ref_regular_nonweak = 0;
}
return TRUE;
}
/* The sweep phase of garbage collection. Remove all garbage sections. */
typedef bfd_boolean (*gc_sweep_hook_fn)
@ -12896,8 +12910,6 @@ elf_gc_sweep (bfd *abfd, struct bfd_link_info *info)
bfd *sub;
const struct elf_backend_data *bed = get_elf_backend_data (abfd);
gc_sweep_hook_fn gc_sweep_hook = bed->gc_sweep_hook;
unsigned long section_sym_count;
struct elf_gc_sweep_symbol_info sweep_info;
for (sub = info->input_bfds; sub != NULL; sub = sub->link.next)
{
@ -12963,15 +12975,6 @@ elf_gc_sweep (bfd *abfd, struct bfd_link_info *info)
}
}
/* Remove the symbols that were in the swept sections from the dynamic
symbol table. GCFIXME: Anyone know how to get them out of the
static symbol table as well? */
sweep_info.info = info;
sweep_info.hide_symbol = bed->elf_backend_hide_symbol;
elf_link_hash_traverse (elf_hash_table (info), elf_gc_sweep_symbol,
&sweep_info);
_bfd_elf_link_renumber_dynsyms (abfd, info, &section_sym_count);
return TRUE;
}