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Re: PATCH: Support ps common sections
On Fri, Jun 17, 2005 at 02:05:52PM -0700, H. J. Lu wrote:
> On Fri, Jun 17, 2005 at 03:09:49PM +0200, Jan Hubicka wrote:
> > > On Fri, Jun 17, 2005 at 11:08:52AM +0200, Jan Hubicka wrote:
> > > >
> > > > 1) I am unsure how to get page alignment only when .lrosegment is
> > > > non-zero. I tried to play around with SIZEOF operator but I am not sure
> > > > if I can apply SIZEOF to the alignment before .lrodata that might (in
> > > > theory) change size of .lrodata due to alignments.
> > > >
> > >
> > > I have implemented the similar thing for another project. I will take a
> > > look after I fix the SHN issue.
> > >
> > > > 2) I am completely such with the SHN issue. I've dicussed this with
> > >
> > > I am working on it now. I will add a few functions to ELF backend to
> > > deal with it. I hope to have something very soon.
> >
> > Thanks a lot! (I will try to cleanup the GCC part of changes in meantime.)
>
> Here is the infrastructure patch for SHN_XXX_COMMON.
>
Here is the updated patch. elf_fake_sections shouldn't clear sh_flags
since assembler may set additional bits.
H.J.
---
2005-06-17 H.J. Lu <hongjiu.lu@intel.com>
* elf-bfd.h (elf_backend_data): Add special_section,
common_definition, common_section_index, common_section,
and merge_symbol.
(_bfd_elf_common_definition): New.
(_bfd_elf_common_section_index): New.
(_bfd_elf_common_section): New.
* elf.c (elf_fake_sections): Don't clear sh_flags.
* elflink.c (_bfd_elf_merge_symbol): Call backend merge_symbol
if it is available.
(is_global_data_symbol_definition): Call backend
common_definition instead of checking SHN_COMMON.
(elf_link_add_object_symbols): Likewise.
(elf_link_output_extsym): Call backend common_section_index
for common section index.
(elf_link_input_bfd): Call backend special_section for unknown
special section indices.
(_bfd_elf_common_definition): New.
(_bfd_elf_common_section_index): New.
(_bfd_elf_common_section): New.
* elfxx-target.h (elf_backend_common_definition): New.
(elf_backend_common_section_index): New.
(elf_backend_common_section): New.
(elf_backend_special_section): New.
(elf_backend_merge_symbol): New.
(elfNN_bed): Initialize special_section, common_definition,
common_section_index, common_section, and merge_symbol.
* section.c (BFD_FAKE_SECTION): New.
(STD_SECTION): Use it.
* bfd-in2.h: Regenerated.
--- bfd/elf-bfd.h.common 2005-06-17 18:10:04.000000000 -0700
+++ bfd/elf-bfd.h 2005-06-17 18:10:04.000000000 -0700
@@ -970,6 +970,22 @@ struct elf_backend_data
see elf.c. */
bfd_vma (*plt_sym_val) (bfd_vma, const asection *, const arelent *);
+ /* Return the special section where symbol is defined. */
+ asection *(*special_section) (Elf_Internal_Sym *);
+
+ /* Is symbol defined in common section? */
+ bfd_boolean (*common_definition) (Elf_Internal_Sym *);
+
+ /* Return a common section index for section. */
+ unsigned int (*common_section_index) (asection *);
+
+ /* Return a common section for section. */
+ asection *(*common_section) (asection *);
+
+ /* Return TRUE if we can merge 2 definitions. */
+ bfd_boolean (*merge_symbol) (struct elf_link_hash_entry *,
+ bfd *, asection *, bfd *, asection *);
+
/* Used to handle bad SHF_LINK_ORDER input. */
bfd_error_handler_type link_order_error_handler;
@@ -1741,6 +1757,15 @@ extern int bfd_elf_link_record_local_dyn
extern bfd_boolean _bfd_elf_close_and_cleanup
(bfd *);
+extern bfd_boolean _bfd_elf_common_definition
+ (Elf_Internal_Sym *);
+
+extern unsigned int _bfd_elf_common_section_index
+ (asection *);
+
+extern asection *_bfd_elf_common_section
+ (asection *);
+
extern void _bfd_dwarf2_cleanup_debug_info
(bfd *);
--- bfd/elf.c.common 2005-06-17 15:26:44.000000000 -0700
+++ bfd/elf.c 2005-06-17 18:10:04.000000000 -0700
@@ -2626,7 +2626,7 @@ elf_fake_sections (bfd *abfd, asection *
return;
}
- this_hdr->sh_flags = 0;
+ /* Don't clear sh_flags. Assembler may set additional bits. */
if ((asect->flags & SEC_ALLOC) != 0
|| asect->user_set_vma)
--- bfd/elflink.c.common 2005-06-17 18:10:04.000000000 -0700
+++ bfd/elflink.c 2005-06-17 18:10:04.000000000 -0700
@@ -783,6 +783,7 @@ _bfd_elf_merge_symbol (bfd *abfd,
bfd *oldbfd;
bfd_boolean newdyn, olddyn, olddef, newdef, newdyncommon, olddyncommon;
bfd_boolean newweak, oldweak;
+ const struct elf_backend_data *bed;
*skip = FALSE;
*override = FALSE;
@@ -960,6 +961,11 @@ _bfd_elf_merge_symbol (bfd *abfd,
return FALSE;
}
+ bed = get_elf_backend_data (abfd);
+ if (bed->merge_symbol
+ && !bed->merge_symbol (h, abfd, sec, oldbfd, oldsec))
+ return FALSE;
+
/* We need to remember if a symbol has a definition in a dynamic
object or is weak in all dynamic objects. Internal and hidden
visibility will make it unavailable to dynamic objects. */
@@ -1200,7 +1206,7 @@ _bfd_elf_merge_symbol (bfd *abfd,
newdef = FALSE;
newdyncommon = FALSE;
*pvalue = sym->st_size;
- *psec = sec = bfd_com_section_ptr;
+ *psec = sec = bed->common_section (sec);
*size_change_ok = TRUE;
}
@@ -2664,6 +2670,8 @@ static bfd_boolean
is_global_data_symbol_definition (bfd *abfd ATTRIBUTE_UNUSED,
Elf_Internal_Sym *sym)
{
+ const struct elf_backend_data *bed;
+
/* Local symbols do not count, but target specific ones might. */
if (ELF_ST_BIND (sym->st_info) != STB_GLOBAL
&& ELF_ST_BIND (sym->st_info) < STB_LOOS)
@@ -2679,7 +2687,8 @@ is_global_data_symbol_definition (bfd *a
/* If the symbol is defined in the common section, then
it is a common definition and so does not count. */
- if (sym->st_shndx == SHN_COMMON)
+ bed = get_elf_backend_data (abfd);
+ if (bed->common_definition (sym))
return FALSE;
/* If the symbol is in a target specific section then we
@@ -3593,7 +3602,7 @@ elf_link_add_object_symbols (bfd *abfd,
else if (bind == STB_GLOBAL)
{
if (isym->st_shndx != SHN_UNDEF
- && isym->st_shndx != SHN_COMMON)
+ && !bed->common_definition (isym))
flags = BSF_GLOBAL;
}
else if (bind == STB_WEAK)
@@ -3883,7 +3892,7 @@ elf_link_add_object_symbols (bfd *abfd,
}
/* Set the alignment of a common symbol. */
- if ((isym->st_shndx == SHN_COMMON
+ if ((bed->common_definition (isym)
|| bfd_is_com_section (sec))
&& h->root.type == bfd_link_hash_common)
{
@@ -3915,7 +3924,8 @@ elf_link_add_object_symbols (bfd *abfd,
definition or a common symbol is ignored due to the old
normal definition. We need to make sure the maximum
alignment is maintained. */
- if ((old_alignment || isym->st_shndx == SHN_COMMON)
+ if ((old_alignment
+ || bed->common_definition (isym))
&& h->root.type != bfd_link_hash_common)
{
unsigned int common_align;
@@ -6528,7 +6538,7 @@ elf_link_output_extsym (struct elf_link_
case bfd_link_hash_common:
input_sec = h->root.u.c.p->section;
- sym.st_shndx = SHN_COMMON;
+ sym.st_shndx = bed->common_section_index (input_sec);
sym.st_value = 1 << h->root.u.c.p->alignment_power;
break;
@@ -6882,6 +6892,8 @@ elf_link_input_bfd (struct elf_final_lin
isec = bfd_abs_section_ptr;
else if (isym->st_shndx == SHN_COMMON)
isec = bfd_com_section_ptr;
+ else if (bed->special_section)
+ isec = bed->special_section (isym);
else
{
/* Who knows? */
@@ -9906,3 +9918,21 @@ _bfd_elf_provide_section_bound_symbols (
if (do_end)
bfd_elf_set_symbol (he, end_val);
}
+
+bfd_boolean
+_bfd_elf_common_definition (Elf_Internal_Sym *sym)
+{
+ return sym->st_shndx == SHN_COMMON;
+}
+
+unsigned int
+_bfd_elf_common_section_index (asection *sec ATTRIBUTE_UNUSED)
+{
+ return SHN_COMMON;
+}
+
+asection *
+_bfd_elf_common_section (asection *sec ATTRIBUTE_UNUSED)
+{
+ return bfd_com_section_ptr;
+}
--- bfd/elfxx-target.h.common 2005-05-25 06:51:27.000000000 -0700
+++ bfd/elfxx-target.h 2005-06-17 18:10:04.000000000 -0700
@@ -518,6 +518,26 @@
#define elf_backend_link_order_error_handler _bfd_default_error_handler
#endif
+#ifndef elf_backend_common_definition
+#define elf_backend_common_definition _bfd_elf_common_definition
+#endif
+
+#ifndef elf_backend_common_section_index
+#define elf_backend_common_section_index _bfd_elf_common_section_index
+#endif
+
+#ifndef elf_backend_common_section
+#define elf_backend_common_section _bfd_elf_common_section
+#endif
+
+#ifndef elf_backend_special_section
+#define elf_backend_special_section NULL
+#endif
+
+#ifndef elf_backend_merge_symbol
+#define elf_backend_merge_symbol NULL
+#endif
+
extern const struct elf_size_info _bfd_elfNN_size_info;
#ifndef INCLUDED_TARGET_FILE
@@ -586,6 +606,11 @@ static const struct elf_backend_data elf
elf_backend_ecoff_debug_swap,
elf_backend_bfd_from_remote_memory,
elf_backend_plt_sym_val,
+ elf_backend_special_section,
+ elf_backend_common_definition,
+ elf_backend_common_section_index,
+ elf_backend_common_section,
+ elf_backend_merge_symbol,
elf_backend_link_order_error_handler,
elf_backend_relplt_name,
ELF_MACHINE_ALT1,
--- bfd/section.c.common 2005-05-18 10:37:28.000000000 -0700
+++ bfd/section.c 2005-06-17 18:10:04.000000000 -0700
@@ -634,6 +634,47 @@ CODE_FRAGMENT
.#define bfd_section_removed_from_list(ABFD, S) \
. ((S)->next == NULL ? (ABFD)->section_last != (S) : (S)->next->prev != (S))
.
+.#define BFD_FAKE_SECTION(SEC, FLAGS, SYM, SYM_PTR, NAME, IDX) \
+. {* name, id, index, next, prev, flags, user_set_vma, *} \
+. { NAME, IDX, 0, NULL, NULL, FLAGS, 0, \
+. \
+. {* linker_mark, linker_has_input, gc_mark, segment_mark, *} \
+. 0, 0, 1, 0, \
+. \
+. {* sec_info_type, use_rela_p, has_tls_reloc, has_gp_reloc, *} \
+. 0, 0, 0, 0, \
+. \
+. {* need_finalize_relax, reloc_done, *} \
+. 0, 0, \
+. \
+. {* vma, lma, size, rawsize *} \
+. 0, 0, 0, 0, \
+. \
+. {* output_offset, output_section, alignment_power, *} \
+. 0, (struct bfd_section *) &SEC, 0, \
+. \
+. {* relocation, orelocation, reloc_count, filepos, rel_filepos, *} \
+. NULL, NULL, 0, 0, 0, \
+. \
+. {* line_filepos, userdata, contents, lineno, lineno_count, *} \
+. 0, NULL, NULL, NULL, 0, \
+. \
+. {* entsize, kept_section, moving_line_filepos, *} \
+. 0, NULL, 0, \
+. \
+. {* target_index, used_by_bfd, constructor_chain, owner, *} \
+. 0, NULL, NULL, NULL, \
+. \
+. {* symbol, *} \
+. (struct bfd_symbol *) SYM, \
+. \
+. {* symbol_ptr_ptr, *} \
+. (struct bfd_symbol **) SYM_PTR, \
+. \
+. {* map_head, map_tail *} \
+. { NULL }, { NULL } \
+. }
+.
*/
/* We use a macro to initialize the static asymbol structures because
@@ -661,46 +702,8 @@ static const asymbol global_syms[] =
#define STD_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
const asymbol * const SYM = (asymbol *) &global_syms[IDX]; \
- asection SEC = \
- /* name, id, index, next, prev, flags, user_set_vma, */ \
- { NAME, IDX, 0, NULL, NULL, FLAGS, 0, \
- \
- /* linker_mark, linker_has_input, gc_mark, segment_mark, */ \
- 0, 0, 1, 0, \
- \
- /* sec_info_type, use_rela_p, has_tls_reloc, has_gp_reloc, */ \
- 0, 0, 0, 0, \
- \
- /* need_finalize_relax, reloc_done, */ \
- 0, 0, \
- \
- /* vma, lma, size, rawsize */ \
- 0, 0, 0, 0, \
- \
- /* output_offset, output_section, alignment_power, */ \
- 0, (struct bfd_section *) &SEC, 0, \
- \
- /* relocation, orelocation, reloc_count, filepos, rel_filepos, */ \
- NULL, NULL, 0, 0, 0, \
- \
- /* line_filepos, userdata, contents, lineno, lineno_count, */ \
- 0, NULL, NULL, NULL, 0, \
- \
- /* entsize, kept_section, moving_line_filepos, */ \
- 0, NULL, 0, \
- \
- /* target_index, used_by_bfd, constructor_chain, owner, */ \
- 0, NULL, NULL, NULL, \
- \
- /* symbol, */ \
- (struct bfd_symbol *) &global_syms[IDX], \
- \
- /* symbol_ptr_ptr, */ \
- (struct bfd_symbol **) &SYM, \
- \
- /* map_head, map_tail */ \
- { NULL }, { NULL } \
- }
+ asection SEC = BFD_FAKE_SECTION(SEC, FLAGS, &global_syms[IDX], &SYM, \
+ NAME, IDX)
STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol,
BFD_COM_SECTION_NAME, 0);