[PATCH] ld: Always call elf_backend_output_arch_local_syms

[PATCH] ld: Always call elf_backend_output_arch_local_syms

[H.J. Lu]

Always call elf_backend_output_arch_local_syms since only the backend
knows if elf_backend_output_arch_local_syms is needed when all symbols
are striped.  elf_backend_output_arch_local_syms is defined only for
x86, ARM and AARCH64.  On x86, elf_backend_output_arch_local_syms must
be called to handle local IFUNC symbols even if all symbols are striped.
Update ARM and AARCH64 to skip elf_backend_output_arch_local_syms when
symbols aren't needed.

bfd/

	PR ld/29797
	* elf32-arm.c (elf32_arm_output_arch_local_syms): Skip if symbols
	aren't needed.
	* elfnn-aarch64.c (elfNN_aarch64_output_arch_local_syms):
	Likewise.
	* elflink.c (bfd_elf_final_link): Always call
	elf_backend_output_arch_local_syms if available.

ld/

	PR ld/29797
	* testsuite/ld-elf/linux-x86.exp: Run PR ld/29797 test.
	* testsuite/ld-elf/pr29797.c: New file.
---
 bfd/elf32-arm.c                   |  5 +++++
 bfd/elflink.c                     |  3 +--
 bfd/elfnn-aarch64.c               |  5 +++++
 ld/testsuite/ld-elf/linux-x86.exp | 15 +++++++++++++++
 ld/testsuite/ld-elf/pr29797.c     | 21 +++++++++++++++++++++
 5 files changed, 47 insertions(+), 2 deletions(-)
 create mode 100644 ld/testsuite/ld-elf/pr29797.c

diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index ec18a8ab362..c7d73171e62 100644
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -18110,6 +18110,11 @@ elf32_arm_output_arch_local_syms (bfd *output_bfd,
   bfd_size_type size;
   bfd *input_bfd;
 
+  if (info->strip == strip_all
+      && !info->emitrelocations
+      && !bfd_link_relocatable (info))
+    return true;
+
   htab = elf32_arm_hash_table (info);
   if (htab == NULL)
     return false;
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 20cee4c76a4..81b34129463 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -12877,8 +12877,7 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 
   /* If backend needs to output some local symbols not present in the hash
      table, do it now.  */
-  if (bed->elf_backend_output_arch_local_syms
-      && (info->strip != strip_all || emit_relocs))
+  if (bed->elf_backend_output_arch_local_syms)
     {
       if (! ((*bed->elf_backend_output_arch_local_syms)
 	     (abfd, info, &flinfo, elf_link_output_symstrtab)))
diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index 7b93672c0df..a9fefbd44a9 100644
--- a/bfd/elfnn-aarch64.c
+++ b/bfd/elfnn-aarch64.c
@@ -8476,6 +8476,11 @@ elfNN_aarch64_output_arch_local_syms (bfd *output_bfd,
   output_arch_syminfo osi;
   struct elf_aarch64_link_hash_table *htab;
 
+  if (info->strip == strip_all
+      && !info->emitrelocations
+      && !bfd_link_relocatable (info))
+    return true;
+
   htab = elf_aarch64_hash_table (info);
 
   osi.finfo = finfo;
diff --git a/ld/testsuite/ld-elf/linux-x86.exp b/ld/testsuite/ld-elf/linux-x86.exp
index 06379057ff2..7822bd227f0 100644
--- a/ld/testsuite/ld-elf/linux-x86.exp
+++ b/ld/testsuite/ld-elf/linux-x86.exp
@@ -203,6 +203,21 @@ run_ld_link_exec_tests [list \
     ] \
 ]
 
+# Run-time tests which require working ifunc attribute support.
+if { [check_ifunc_attribute_available] } {
+    run_ld_link_exec_tests [list \
+	[list \
+	    "Run pr29797" \
+	    "-s" \
+	    "" \
+	    { pr29797.c } \
+	    "pr29797" \
+	    "pass.out" \
+	    "-O0" \
+	] \
+    ]
+}
+
 # Old gcc silently ignores __attribute__ ((aligned())) with too big alignment.
 proc compiler_honours_aligned { } {
     global CC_FOR_TARGET READELF srcdir subdir
diff --git a/ld/testsuite/ld-elf/pr29797.c b/ld/testsuite/ld-elf/pr29797.c
new file mode 100644
index 00000000000..9e3113fe98d
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr29797.c
@@ -0,0 +1,21 @@
+#include <stdio.h>
+
+static int foo (int x) __attribute__ ((ifunc ("resolve_foo")));
+
+static int foo_impl(int x)
+{
+  return x;
+}
+
+static void *resolve_foo (void)
+{
+  return (void *) foo_impl;
+}
+
+int
+main ()
+{
+  foo (0);
+  puts ("PASS");
+  return 0;
+}
-- 
2.37.3

Re: [PATCH] ld: Always call elf_backend_output_arch_local_syms

[Alan Modra]

On Wed, Nov 16, 2022 at 03:20:39PM -0800, H.J. Lu via Binutils wrote:
> Always call elf_backend_output_arch_local_syms since only the backend
> knows if elf_backend_output_arch_local_syms is needed when all symbols
> are striped.  elf_backend_output_arch_local_syms is defined only for
> x86, ARM and AARCH64.  On x86, elf_backend_output_arch_local_syms must
> be called to handle local IFUNC symbols even if all symbols are striped.
> Update ARM and AARCH64 to skip elf_backend_output_arch_local_syms when
> symbols aren't needed.
> 
> bfd/
> 
> 	PR ld/29797
> 	* elf32-arm.c (elf32_arm_output_arch_local_syms): Skip if symbols
> 	aren't needed.
> 	* elfnn-aarch64.c (elfNN_aarch64_output_arch_local_syms):
> 	Likewise.
> 	* elflink.c (bfd_elf_final_link): Always call
> 	elf_backend_output_arch_local_syms if available.
> 
> ld/
> 
> 	PR ld/29797
> 	* testsuite/ld-elf/linux-x86.exp: Run PR ld/29797 test.
> 	* testsuite/ld-elf/pr29797.c: New file.

OK.

-- 
Alan Modra
Australia Development Lab, IBM