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* [PATCH] elf: Discard input .note.gnu.build-id sections
@ 2021-12-01  4:46 H.J. Lu
  2021-12-01  7:23 ` Alan Modra
  0 siblings, 1 reply; 7+ messages in thread
From: H.J. Lu @ 2021-12-01  4:46 UTC (permalink / raw)
  To: binutils

1. Discard input .note.gnu.build-id , excluding the first one.
2. Clear the build ID field before writing.
3. Use the input .note.gnu.build-id section if available.

	PR ld/28639
	* ldelf.c (ldelf_after_open): Discard input .note.gnu.build-id
	sections, excluding the first one.
	(write_build_id): Clear the build ID field before writing.
	(ldelf_setup_build_id): Use the input .note.gnu.build-id section
	if available.
	* testsuite/ld-elf/build-id.exp: New file.
	* testsuite/ld-elf/pr28639a.rd: Likewise.
	* testsuite/ld-elf/pr28639b.rd: Likewise.
---
 ld/ldelf.c                       | 23 +++++++++--
 ld/testsuite/ld-elf/build-id.exp | 67 ++++++++++++++++++++++++++++++++
 ld/testsuite/ld-elf/pr28639a.rd  |  6 +++
 ld/testsuite/ld-elf/pr28639b.rd  |  6 +++
 4 files changed, 99 insertions(+), 3 deletions(-)
 create mode 100644 ld/testsuite/ld-elf/build-id.exp
 create mode 100644 ld/testsuite/ld-elf/pr28639a.rd
 create mode 100644 ld/testsuite/ld-elf/pr28639b.rd

diff --git a/ld/ldelf.c b/ld/ldelf.c
index 0c39eb6024f..f77547b3e82 100644
--- a/ld/ldelf.c
+++ b/ld/ldelf.c
@@ -997,6 +997,7 @@ ldelf_after_open (int use_libpath, int native, int is_linux, int is_freebsd,
   asection *s;
   bfd *abfd;
   bfd **save_input_bfd_tail;
+  bfd *abfd_build_id = NULL;
 
   after_open_default ();
 
@@ -1036,6 +1037,7 @@ ldelf_after_open (int use_libpath, int native, int is_linux, int is_freebsd,
 	  free ((char *) ldelf_emit_note_gnu_build_id);
 	  ldelf_emit_note_gnu_build_id = NULL;
 	}
+      abfd_build_id = abfd;
     }
 
   get_elf_backend_data (link_info.output_bfd)->setup_gnu_properties (&link_info);
@@ -1043,6 +1045,14 @@ ldelf_after_open (int use_libpath, int native, int is_linux, int is_freebsd,
   /* Do not allow executable files to be used as inputs to the link.  */
   for (abfd = link_info.input_bfds; abfd; abfd = abfd->link.next)
     {
+      /* Discard input .note.gnu.build-id sections.  */
+      if (abfd != abfd_build_id)
+	{
+	  s = bfd_get_section_by_name (abfd, ".note.gnu.build-id");
+	  if (s != NULL)
+	    s->flags |= SEC_EXCLUDE;
+	}
+
       if (abfd->xvec->flavour == bfd_target_elf_flavour
 	  && !bfd_input_just_syms (abfd)
 	  && elf_tdata (abfd) != NULL
@@ -1386,6 +1396,9 @@ write_build_id (bfd *abfd)
   id_bits = contents + size;
   size = asec->size - size;
 
+  /* Clear the build ID field.  */
+  memset (id_bits, 0, size);
+
   bfd_h_put_32 (abfd, sizeof "GNU", &e_note->namesz);
   bfd_h_put_32 (abfd, size, &e_note->descsz);
   bfd_h_put_32 (abfd, NT_GNU_BUILD_ID, &e_note->type);
@@ -1415,9 +1428,13 @@ ldelf_setup_build_id (bfd *ibfd)
       return false;
     }
 
-  flags = (SEC_ALLOC | SEC_LOAD | SEC_IN_MEMORY
-	   | SEC_LINKER_CREATED | SEC_READONLY | SEC_DATA);
-  s = bfd_make_section_with_flags (ibfd, ".note.gnu.build-id", flags);
+  s = bfd_get_section_by_name (ibfd, ".note.gnu.build-id");
+  if (s == NULL)
+    {
+      flags = (SEC_ALLOC | SEC_LOAD | SEC_IN_MEMORY
+	       | SEC_LINKER_CREATED | SEC_READONLY | SEC_DATA);
+      s = bfd_make_section_with_flags (ibfd, ".note.gnu.build-id", flags);
+    }
   if (s != NULL && bfd_set_section_alignment (s, 2))
     {
       struct elf_obj_tdata *t = elf_tdata (link_info.output_bfd);
diff --git a/ld/testsuite/ld-elf/build-id.exp b/ld/testsuite/ld-elf/build-id.exp
new file mode 100644
index 00000000000..2658d36863a
--- /dev/null
+++ b/ld/testsuite/ld-elf/build-id.exp
@@ -0,0 +1,67 @@
+# Expect script for --build-id tests.
+#   Copyright (C) 2021 Free Software Foundation, Inc.
+#
+# This file is part of the GNU Binutils.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+# MA 02110-1301, USA.
+#
+
+# Exclude non-ELF targets.
+
+if ![is_elf_format] {
+    return
+}
+
+if { [istarget frv-*-*] || [istarget lm32-*-*] } {
+    return
+}
+
+if { !([istarget *-*-linux*]
+       || [istarget arm*-*-uclinuxfdpiceabi]
+       || [istarget *-*-nacl*]
+       || [istarget *-*-gnu*]) } then {
+    return
+}
+
+run_ld_link_tests [list \
+    [list \
+	"pr28639a.o" \
+	"-r --build-id=md5" \
+	"" \
+	"" \
+	{start.s} \
+	{{readelf {--notes} pr28639a.rd}} \
+	"pr28639a.o" \
+    ] \
+    [list \
+	"pr28639a.o" \
+	"-r --build-id" \
+	"" \
+	"" \
+	{dummy.s} \
+	{{readelf {--notes} pr28639b.rd}} \
+	"pr28639b.o" \
+    ] \
+    [list \
+	"pr28639" \
+	"--build-id tmpdir/pr28639a.o tmpdir/pr28639b.o" \
+	"" \
+	"" \
+	{dummy.s} \
+	{{readelf {--notes} pr28639b.rd}} \
+	"pr28639b.o" \
+    ] \
+]
diff --git a/ld/testsuite/ld-elf/pr28639a.rd b/ld/testsuite/ld-elf/pr28639a.rd
new file mode 100644
index 00000000000..e85087064d0
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr28639a.rd
@@ -0,0 +1,6 @@
+#...
+Displaying notes found in: \.note\.gnu\.build-id
+  Owner                Data size 	Description
+  GNU                  0x00000010	NT_GNU_BUILD_ID \(unique build ID bitstring\)
+    Build ID: [0-9a-f]+
+#pass
diff --git a/ld/testsuite/ld-elf/pr28639b.rd b/ld/testsuite/ld-elf/pr28639b.rd
new file mode 100644
index 00000000000..04dcb04bec2
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr28639b.rd
@@ -0,0 +1,6 @@
+#...
+Displaying notes found in: \.note\.gnu\.build-id
+  Owner                Data size 	Description
+  GNU                  0x00000014	NT_GNU_BUILD_ID \(unique build ID bitstring\)
+    Build ID: [0-9a-f]+
+#pass
-- 
2.33.1


^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2021-12-02  0:02 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-12-01  4:46 [PATCH] elf: Discard input .note.gnu.build-id sections H.J. Lu
2021-12-01  7:23 ` Alan Modra
2021-12-01  7:56   ` Fangrui Song
2021-12-01 11:55     ` Alan Modra
2021-12-01 11:58       ` [PATCH v2] " H.J. Lu
2021-12-01 12:17         ` [PATCH v3] " H.J. Lu
2021-12-02  0:02           ` Alan Modra

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