Re: Remove .eh_frame zero terminators

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Thu, Aug 31, 2017 at 3:35 AM, Alan Modra <amodra@gmail.com> wrote:
> The machinery to do this was there, but not enabled if the terminator
> was the only thing in the section.
>
> We should have seen quite a lot of exception handling failures due to
> ld's nasty LTO support.  It has the habit of adding object files
> extracted from archives after crtend.o, the file that has the
> .eh_frame terminator.  The saving grace is that with --eh-frame-hdr
> there doesn't need to be a scan of section contents (which would
> terminate on hitting the terminator) for an FDE covering a given
> address.
>
> bfd/
>         * elf-eh-frame.c (_bfd_elf_parse_eh_frame): Don't exit early
>         for a section containing just a terminator.  Allow multiple
>         terminators at end of section.
>         * elflink.c (bfd_elf_discard_info): Iterate over .eh_frame
>         sections when not adding alignment.  Assert on terminator in
>         the middle of FDEs.
> ld/
>         * testsuite/ld-elf/eh3.d: Update.
>         * testsuite/ld-elf/eh4.d: Update.
>

I am checking in this to add a testcase.

Thanks.

H.J.

From b94704c0f778cd579b4a864cc9c7359b94724a52 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 30 Aug 2017 21:59:17 -0700
Subject: [PATCH] Add a test for PR ld/22048

	PR ld/22048
	* testsuite/ld-x86-64/pr22048.d: New file.
	* testsuite/ld-x86-64/pr22048a.s: Likewise.
	* testsuite/ld-x86-64/pr22048b.s: Likewise.
	* testsuite/ld-x86-64/x86-64.exp: Run pr22048.
---
 ld/testsuite/ld-x86-64/pr22048.d  | 25 +++++++++++++++++++++++++
 ld/testsuite/ld-x86-64/pr22048a.s |  4 ++++
 ld/testsuite/ld-x86-64/pr22048b.s |  8 ++++++++
 ld/testsuite/ld-x86-64/x86-64.exp |  1 +
 4 files changed, 38 insertions(+)
 create mode 100644 ld/testsuite/ld-x86-64/pr22048.d
 create mode 100644 ld/testsuite/ld-x86-64/pr22048a.s
 create mode 100644 ld/testsuite/ld-x86-64/pr22048b.s

diff --git a/ld/testsuite/ld-x86-64/pr22048.d b/ld/testsuite/ld-x86-64/pr22048.d
new file mode 100644
index 0000000000..063d305c4d
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr22048.d
@@ -0,0 +1,25 @@
+#source: pr22048a.s
+#source: pr22048b.s
+#as: --64
+#ld: -melf_x86_64 -Ttext 0x400078
+#readelf: -wf
+
+Contents of the .eh_frame section:
+
+0+0000 0+014 0+0000 CIE
+  Version:               1
+  Augmentation:          "zR"
+  Code alignment factor: 1
+  Data alignment factor: -8
+  Return address column: 16
+  Augmentation data:     1b
+
+  DW_CFA_def_cfa: r7 \(rsp\) ofs 8
+  DW_CFA_offset: r16 \(rip\) at cfa-8
+  DW_CFA_nop
+  DW_CFA_nop
+
+0+0018 0+0010 0+001c FDE cie=0+0000 pc=0+400078\.\.0+40007a
+  DW_CFA_nop
+  DW_CFA_nop
+  DW_CFA_nop
diff --git a/ld/testsuite/ld-x86-64/pr22048a.s b/ld/testsuite/ld-x86-64/pr22048a.s
new file mode 100644
index 0000000000..060bd0171c
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr22048a.s
@@ -0,0 +1,4 @@
+	.section	.eh_frame,"a",@progbits
+	.align 4
+	.zero	4
+	.ident	"GCC"
diff --git a/ld/testsuite/ld-x86-64/pr22048b.s b/ld/testsuite/ld-x86-64/pr22048b.s
new file mode 100644
index 0000000000..eae6752255
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr22048b.s
@@ -0,0 +1,8 @@
+	.text
+	.globl _start
+	.type	_start, @function
+_start:
+	.cfi_startproc
+	rep ret
+	.cfi_endproc
+	.size	_start, .-_start
diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp
index 0e018c5577..bf73534c1b 100644
--- a/ld/testsuite/ld-x86-64/x86-64.exp
+++ b/ld/testsuite/ld-x86-64/x86-64.exp
@@ -570,6 +570,7 @@ run_dump_test "pr20253-4f"
 run_dump_test "pr20253-5a"
 run_dump_test "pr20253-5b"
 run_dump_test "tlsdesc2"
+run_dump_test "pr22048"
 
 proc undefined_weak {cflags ldflags} {
     set testname "Undefined weak symbol"
-- 
2.13.5