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Re: ARM mapping symbols and --strip-unneeded
- From: Nick Clifton <nickc at redhat dot com>
- To: "Richard Earnshaw (lists)" <Richard dot Earnshaw at arm dot com>, Michael Weiser <michael at weiser dot dinsnail dot net>
- Cc: binutils at sourceware dot org
- Date: Tue, 28 Jun 2016 13:22:38 +0100
- Subject: Re: ARM mapping symbols and --strip-unneeded
- Authentication-results: sourceware.org; auth=none
- References: <20160626221336 dot GB1916 at weiser dot dinsnail dot net> <e7fff803-6244-4782-2768-6b301387aed8 at redhat dot com> <577132D2 dot 9090903 at arm dot com>
Hi Guys,
On 27/06/16 15:06, Richard Earnshaw (lists) wrote:
> And potentially for little-endian binaries as well. For example, they
> might sometimes be needed to insert correct interworking veneers.
Agreed - so this is what I have checked in. It makes sure that "strip
--strip-unneeded" will not remove mapping symbols from any ARM object
file (little endian or big endian), whilst still allowing them to be
removed from executables and shared libraries.
Cheers
Nick
bfd/ChangeLog
2016-06-28 Nick Clifton <nickc@redhat.com>
* elf32-arm.c (elf32_arm_backend_symbol_processing): New
function. Marks mapping symbols in object files as precious, so
that strip will not remove them.
(elf_backend_symbol_processing): Define.
diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index a7964c1..04e776c 100644
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -18266,6 +18266,24 @@ elf32_arm_copy_special_section_fields (const bfd *ibfd ATTRIBUTE_UNUSED,
return FALSE;
}
+/* Make sure that mapping symbols in object files are not removed via the
+ "strip --strip-unneeded" tool. These symbols are needed in order to
+ correctly generate interworking veneers, and for byte swapping code
+ regions. Once an object file has been linked, it is safe to remove the
+ symbols as they will no longer be needed. */
+
+static void
+elf32_arm_backend_symbol_processing (bfd *abfd, asymbol *sym)
+{
+ if (((abfd->flags & (EXEC_P | DYNAMIC)) == 0)
+ && sym->name != NULL
+ && sym->section != bfd_abs_section_ptr
+ && (strcmp (sym->name, "$a") == 0
+ || strcmp (sym->name, "$t") == 0
+ || strcmp (sym->name, "$d") == 0))
+ sym->flags |= BSF_KEEP;
+}
+
#undef elf_backend_copy_special_section_fields
#define elf_backend_copy_special_section_fields elf32_arm_copy_special_section_fields
@@ -18324,6 +18342,7 @@ elf32_arm_copy_special_section_fields (const bfd *ibfd ATTRIBUTE_UNUSED,
#define elf_backend_begin_write_processing elf32_arm_begin_write_processing
#define elf_backend_add_symbol_hook elf32_arm_add_symbol_hook
#define elf_backend_count_additional_relocs elf32_arm_count_additional_relocs
+#define elf_backend_symbol_processing elf32_arm_backend_symbol_processing
#define elf_backend_can_refcount 1
#define elf_backend_can_gc_sections 1