SH: ____longjmp_chk for GNU/Linux with sigaltstack support

[Thomas Schwinge]

Hi!

On Sat, 23 Jun 2012 11:59:31 +0200, I wrote:
> On Wed, 13 Jun 2012 20:40:48 +0900, Kaz Kojima <kkojima@rr.iij4u.or.jp> wrote:
> > Thomas Schwinge <thomas@codesourcery.com> wrote:
> > > This one is based on Joseph's suggestions as posted in
> > > <http://sourceware.org/ml/libc-ports/2009-08/msg00002.html>; a part of
> > > the following assembler bits are what .,A;gcc -O2 -S.,A+ produced for Joseph's
> > > C code.  No regressions and debug/tst-longjmp_chk2 now passes -- Kaz,
> > > would you please review this patch?
> > 
> > Looks fine to me.
> 
> I pushed the following as commit
> db9b505976a9448911e728c01885e71ad6e9461f:
> 
> 	* sysdeps/unix/sysv/linux/sh/____longjmp_chk.S: New file, based on
> 	sysdeps/sh/____longjmp_chk.S.
> 	* sysdeps/unix/sysv/linux/sh/sigaltstack-offsets.sym: New file, based
> 	on sysdeps/unix/sysv/linux/x86_64/sigaltstack-offsets.sym.
> 	* sysdeps/unix/sysv/linux/sh/Makefile [subdir=misc]
> 	(gen-as-const-headers): Append sigaltstack-offsets.sym.

To optimize assembler code in context of calls to __fortify_fail
(__fortify_fail has »__attribute__ ((__noreturn__))«), I pushed the
following as commit 1518f58b6120289e69aeba9426eca9234cd9a200:

	* sysdeps/sh/____longjmp_chk.S (CALL_FAIL): Don't plan for the call to
	__fortify_fail returning.
	* sysdeps/unix/sysv/linux/sh/____longjmp_chk.S (CALL_FAIL): Likewise.

diff --git a/sysdeps/sh/____longjmp_chk.S b/sysdeps/sh/____longjmp_chk.S
index 5d17f3a..e8d5f68 100644
--- a/sysdeps/sh/____longjmp_chk.S
+++ b/sysdeps/sh/____longjmp_chk.S
@@ -33,31 +33,27 @@ longjmp_msg:
 	add	r0, r12;				\
 	bsrf	r1;					\
 	 add	r12, r4;				\
+	/* Unreachable.	 */				\
 .Lfail0:						\
-	bra	0f;					\
-	 nop;						\
 	.align	2;					\
 .Lgot:							\
 	.long	_GLOBAL_OFFSET_TABLE_;			\
 .Lstr:							\
 	.long	longjmp_msg@GOTOFF;			\
 .Lfail:							\
-	.long	__GI___fortify_fail@PLT-(.Lfail0-.);	\
-0:
+	.long	__GI___fortify_fail@PLT-(.Lfail0-.);
 #else
 # define CALL_FAIL \
 	mov.l	.Lfail, r1;				\
 	mov.l	.Lstr, r4;				\
 	jsr	@r1;					\
 	 nop;						\
-	bra	0f;					\
-	 nop;						\
+	/* Unreachable.	 */				\
 	.align	2;					\
 .Lstr:							\
 	.long	longjmp_msg;				\
 .Lfail:							\
-	.long	__fortify_fail;				\
-0:
+	.long	__fortify_fail;
 #endif
 
 #define CHECK_SP(reg) \
diff --git a/sysdeps/unix/sysv/linux/sh/____longjmp_chk.S b/sysdeps/unix/sysv/linux/sh/____longjmp_chk.S
index d034afc..bcf828b 100644
--- a/sysdeps/unix/sysv/linux/sh/____longjmp_chk.S
+++ b/sysdeps/unix/sysv/linux/sh/____longjmp_chk.S
@@ -38,30 +38,26 @@ longjmp_msg:
 	bsrf	r1;					\
 	 add	r12, r4;				\
 .Lfail0:						\
-	bra	0f;					\
-	 nop;						\
+	/* Unreachable.	 */				\
 	.align	2;					\
 .Lgot:							\
 	.long	_GLOBAL_OFFSET_TABLE_;			\
 .Lstr:							\
 	.long	longjmp_msg@GOTOFF;			\
 .Lfail:							\
-	.long	__GI___fortify_fail@PLT-(.Lfail0-.);	\
-0:
+	.long	__GI___fortify_fail@PLT-(.Lfail0-.);
 #else
 # define CALL_FAIL \
 	mov.l	.Lfail, r1;				\
 	mov.l	.Lstr, r4;				\
 	jsr	@r1;					\
 	 nop;						\
-	bra	0f;					\
-	 nop;						\
+	/* Unreachable.	 */				\
 	.align	2;					\
 .Lstr:							\
 	.long	longjmp_msg;				\
 .Lfail:							\
-	.long	__fortify_fail;				\
-0:
+	.long	__fortify_fail;
 #endif
 
 #define CHECK_SP(reg) \


Grüße,
 Thomas
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