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Re: Consistency check for merge sections
- From: Alan Modra <amodra at gmail dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: binutils at sourceware dot org
- Date: Thu, 1 Oct 2015 07:43:55 +0930
- Subject: Re: Consistency check for merge sections
- Authentication-results: sourceware.org; auth=none
- References: <20150930064101 dot GC32709 at bubble dot grove dot modra dot org> <20150930124035 dot GA28547 at gmail dot com>
On Wed, Sep 30, 2015 at 05:40:35AM -0700, H.J. Lu wrote:
> On Wed, Sep 30, 2015 at 04:11:01PM +0930, Alan Modra wrote:
> > We can't allow sections to be merged and sized by the ELF linker
> > backend and then later be output by the generic linker backend. The
> > generic linker backend doesn't understand merge sections.
> >
> > PR ld/19013
> > * elflink.c (_bfd_elf_merge_sections): Only merge input bfds that
> > will be handled by elf_link_input_bfd. Rename abfd param to obfd.
> >
>
> This isn't sufficient. When we check consistency for merge ELF sections,
> we should not only check EI_CLASS, but also compatible e_machine. I
> checked in this to check e_machine.
>
> H.J.
> ---
> bfd/
>
> PR ld/19013
> * elflink.c (_bfd_elf_merge_sections): Only merge input bfds
> that have the compatible ELF machine code with the output bfd.
The whole point of my patch was as I said, to merge sections only when
the output will be done by the ELF linker backend. ie. the condition
under which we merge sections needs to match this code in
bfd_elf_final_link:
if (p->type == bfd_indirect_link_order
&& (bfd_get_flavour ((sub = p->u.indirect.section->owner))
== bfd_target_elf_flavour)
&& elf_elfheader (sub)->e_ident[EI_CLASS] == bed->s->elfclass)
{
if (! sub->output_has_begun)
{
if (! elf_link_input_bfd (&flinfo, sub))
goto error_return;
sub->output_has_begun = TRUE;
}
You added an extra check for no good reason as far as I can see. I am
reverting your elflink.c patch until you can explain why it is needed.
commit 017e6bceee1a96d4b57175687560b4d625fdb150
Author: Alan Modra <amodra@gmail.com>
Date: Thu Oct 1 07:38:07 2015 +0930
Revert "Also check e_machine when merging sections"
Commit 9865bd0d added a bogus check in _bfd_elf_merge_sections.
bfd/
PR ld/19013
* elflink.c (_bfd_elf_merge_sections): Revert last change.
ld/testsuite/
* ld-x86-64/pr19013-x32.d: Update.
diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 3610948..76c8a5c 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,8 @@
+2015-10-01 Alan Modra <amodra@gmail.com>
+
+ PR ld/19013
+ * elflink.c (_bfd_elf_merge_sections): Revert last change.
+
2015-09-30 H.J. Lu <hongjiu.lu@intel.com>
PR ld/19031
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 70c231b..90af6cf 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -6818,23 +6818,15 @@ _bfd_elf_merge_sections (bfd *obfd, struct bfd_link_info *info)
{
bfd *ibfd;
asection *sec;
- const struct elf_backend_data *bed;
if (!is_elf_hash_table (info->hash))
return FALSE;
- bed = get_elf_backend_data (obfd);
for (ibfd = info->input_bfds; ibfd != NULL; ibfd = ibfd->link.next)
if ((ibfd->flags & DYNAMIC) == 0
&& bfd_get_flavour (ibfd) == bfd_target_elf_flavour
- && (elf_elfheader (ibfd)->e_ident[EI_CLASS] == bed->s->elfclass)
- && (bed->elf_machine_code == elf_elfheader (ibfd)->e_machine
- || (bed->elf_machine_alt1 != 0
- && (bed->elf_machine_alt1
- == elf_elfheader (ibfd)->e_machine))
- || (bed->elf_machine_alt2 != 0
- && (bed->elf_machine_alt2
- == elf_elfheader (ibfd)->e_machine))))
+ && (elf_elfheader (ibfd)->e_ident[EI_CLASS]
+ == get_elf_backend_data (obfd)->s->elfclass))
for (sec = ibfd->sections; sec != NULL; sec = sec->next)
if ((sec->flags & SEC_MERGE) != 0
&& !bfd_is_abs_section (sec->output_section))
diff --git a/ld/testsuite/ChangeLog b/ld/testsuite/ChangeLog
index e73d09f..b8724af 100644
--- a/ld/testsuite/ChangeLog
+++ b/ld/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2015-10-01 Alan Modra <amodra@gmail.com>
+
+ * ld-x86-64/pr19013-x32.d: Update.
+
2015-09-30 H.J. Lu <hongjiu.lu@intel.com>
* ld-x86-64/pr19013.d (ld): Add -m elf_x86_64.
diff --git a/ld/testsuite/ld-x86-64/pr19013-x32.d b/ld/testsuite/ld-x86-64/pr19013-x32.d
index fb70966..97fb841 100644
--- a/ld/testsuite/ld-x86-64/pr19013-x32.d
+++ b/ld/testsuite/ld-x86-64/pr19013-x32.d
@@ -5,5 +5,5 @@
#notarget: x86_64-*-nacl*
#...
- [0-9a-f]+ 00000203 00414243 4400 +.....ABCD. +
+ [0-9a-f]+ 02030041 42434400 +...ABCD. +
#pass
--
Alan Modra
Australia Development Lab, IBM