[PATCH] Add missing unwind information to ld.so on powerpc32 (bug 23707)

[Andreas Schwab]

	[BZ #23707]
	* sysdeps/powerpc/powerpc32/dl-start.S: Add unwind information.
	* elf/Makefile (tests): Add tst-unwind-ctor.
	(modules-names): Add tst-unwind-ctor-lib.
	($(objpfx)tst-unwind-ctor): Depend on
	$(objpfx)tst-unwind-ctor-lib.so.
---
 elf/Makefile                         |  7 +++--
 elf/tst-unwind-ctor-lib.c            | 41 ++++++++++++++++++++++++++++
 elf/tst-unwind-ctor.c                | 25 +++++++++++++++++
 sysdeps/powerpc/powerpc32/dl-start.S |  3 ++
 4 files changed, 74 insertions(+), 2 deletions(-)
 create mode 100644 elf/tst-unwind-ctor-lib.c
 create mode 100644 elf/tst-unwind-ctor.c

diff --git a/elf/Makefile b/elf/Makefile
index 037f68165b..455ec730fc 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -186,7 +186,8 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
 	 tst-tlsalign tst-tlsalign-extern tst-nodelete-opened \
 	 tst-nodelete2 tst-audit11 tst-audit12 tst-dlsym-error tst-noload \
 	 tst-latepthread tst-tls-manydynamic tst-nodelete-dlclose \
-	 tst-debug1 tst-main1 tst-absolute-sym tst-absolute-zero tst-big-note
+	 tst-debug1 tst-main1 tst-absolute-sym tst-absolute-zero tst-big-note \
+	 tst-unwind-ctor
 #	 reldep9
 tests-internal += loadtest unload unload2 circleload1 \
 	 neededtest neededtest2 neededtest3 neededtest4 \
@@ -273,7 +274,7 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
 		tst-latepthreadmod $(tst-tls-many-dynamic-modules) \
 		tst-nodelete-dlclose-dso tst-nodelete-dlclose-plugin \
 		tst-main1mod tst-libc_dlvsym-dso tst-absolute-sym-lib \
-		tst-absolute-zero-lib tst-big-note-lib
+		tst-absolute-zero-lib tst-big-note-lib tst-unwind-ctor-lib
 # Most modules build with _ISOMAC defined, but those filtered out
 # depend on internal headers.
 modules-names-tests = $(filter-out ifuncmod% tst-libc_dlvsym-dso tst-tlsmod%,\
@@ -1492,3 +1493,5 @@ tst-libc_dlvsym-static-ENV = \
 $(objpfx)tst-libc_dlvsym-static.out: $(objpfx)tst-libc_dlvsym-dso.so
 
 $(objpfx)tst-big-note: $(objpfx)tst-big-note-lib.so
+
+$(objpfx)tst-unwind-ctor: $(objpfx)tst-unwind-ctor-lib.so
diff --git a/elf/tst-unwind-ctor-lib.c b/elf/tst-unwind-ctor-lib.c
new file mode 100644
index 0000000000..f517e43ec4
--- /dev/null
+++ b/elf/tst-unwind-ctor-lib.c
@@ -0,0 +1,41 @@
+/* Unit test for _Unwind_Backtrace in a shared object constructor.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <unwind.h>
+#include <unistd.h>
+
+static _Unwind_Reason_Code
+callback (struct _Unwind_Context *ctx, void *arg)
+{
+  return _URC_NO_REASON;
+}
+
+static void
+__attribute__ ((constructor))
+do_unwind (void)
+{
+  /* Arrange for this test to be killed if _Unwind_Backtrace runs into an
+     endless loop.  */
+  alarm (20);
+  _Unwind_Backtrace (callback, 0);
+}
+
+void
+dummy (void)
+{
+}
diff --git a/elf/tst-unwind-ctor.c b/elf/tst-unwind-ctor.c
new file mode 100644
index 0000000000..96100527b2
--- /dev/null
+++ b/elf/tst-unwind-ctor.c
@@ -0,0 +1,25 @@
+/* Unit test for _Unwind_Backtrace in a shared object constructor.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+extern void dummy (void);
+
+int
+main (void)
+{
+  dummy ();
+}
diff --git a/sysdeps/powerpc/powerpc32/dl-start.S b/sysdeps/powerpc/powerpc32/dl-start.S
index 244d87fb6d..243fb8352b 100644
--- a/sysdeps/powerpc/powerpc32/dl-start.S
+++ b/sysdeps/powerpc/powerpc32/dl-start.S
@@ -34,6 +34,9 @@ ENTRY(_start)
    _dl_start to save the link register).  */
 	li	r4,0
 	addi	r1,r1,-16
+	cfi_adjust_cfa_offset (16)
+/* Mark lr as undefined to stop unwinding.  */
+	cfi_undefined (lr)
 	stw	r4,0(r1)
 	bl	_dl_start@local
 
-- 
2.19.0


-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."