[klibc] Bug#334917: [PATCH] Re: klibc barfs on m68k syscall interface

[Thorsten Glaser]

maximilian attems dixit:

>please use format-patch.

Here, with ifdef comment addressed. (On a side note, mksh behaves the
same as on i386 so #516294 is not specific to i386.)

bye,
//mirabilos
-- 
FWIW, I'm quite impressed with mksh interactively. I thought it was much
*much* more bare bones. But it turns out it beats the living hell out of
ksh93 in that respect. I'd even consider it for my daily use if I hadn't
wasted half my life on my zsh setup. :-) -- Frank Terbeck in #!/bin/mksh
-------------- next part --------------
From 9dcefd83262364ecf00b51663f5a1c16a1f2540a Mon Sep 17 00:00:00 2001
From: Thorsten Glaser <tg at mirbsd.de>
Date: Sat, 29 Jan 2011 17:19:10 +0000
Subject: [PATCH] Fix m68k syscall API and support 6-argument syscalls.

Debian: (Closes: #334917)

Signed-off-by: Thorsten Glaser <tg at mirbsd.de>
---
 usr/klibc/arch/m68k/syscall.S |   42 +++++++++++++++++++++++++++++++++-------
 usr/klibc/arch/m68k/vfork.S   |   13 +++--------
 2 files changed, 38 insertions(+), 17 deletions(-)

diff --git a/usr/klibc/arch/m68k/syscall.S b/usr/klibc/arch/m68k/syscall.S
index 966c92d..f468678 100644
--- a/usr/klibc/arch/m68k/syscall.S
+++ b/usr/klibc/arch/m68k/syscall.S
@@ -11,17 +11,43 @@
 	.globl	__syscall_common
 	.type	__syscall_common, @function
 __syscall_common:
-	movem.l %d2-%d6, -(%sp)	/* 5 registers saved */
-	movem.l	24(%sp), %d1-%d6
+	/*
+	 * According to eglibc, separate moves are faster than movem;
+	 * speed is important and this code is not duplicated anyway,
+	 * so we do the same here. We use %a1 as scratch register for
+	 * saving; syscall arguments are to be in %d1 to %d5 and %a0.
+	 */
+	move.l	24(%sp), %a0		/* orig.sp+24: arg 6 */
+	move.l	%d5, -(%sp)		/* push d5 (callee saved) */
+	move.l	24(%sp), %d5		/* orig.sp+20: arg 5 */
+	move.l	%d4, -(%sp)		/* push d4 (callee saved) */
+	move.l	24(%sp), %d4		/* orig.sp+16: arg 4 */
+	move.l	%d3, -(%sp)		/* push d3 (callee saved) */
+	move.l	24(%sp), %d3		/* orig.sp+12: arg 3 */
+	move.l	%d2, %a1		/* save d2 (callee saved) in a1 */
+	move.l	20(%sp), %d2		/* orig.sp+8:  arg 2 */
+	move.l	16(%sp), %d1		/* orig.sp+4:  arg 1 */
 	trap	#0
-	cmpi.l	#-4095, %d0
-	blt.l	1f
+	move.l	%a1, %d2		/* restore d2 from a1 (scratch) */
+	move.l	(%sp)+, %d3		/* pop d3..d5, see above */
+	move.l	(%sp)+, %d4
+	move.l	(%sp)+, %d5
+
+	/* syscall is done, result in %d0, registers are restored */
+	.globl	__syscall_checkandout
+__syscall_checkandout:
+	/* now check for error */
+	cmp.l	#-4095, %d0
+	bcs.l	1f			/* jmp short if _not_ error */
+
+	/* prepare for error return */
 	neg.l	%d0
 	move.l	%d0, (errno)
-	moveq	#-1, %d0
-1:
-	movea.l	%d0, %a0	/* Redundant return */
-	movem.l (%sp)+, %d2-%d6 /* Restore registers */
+	move.l	#-1, %d0
+	/* fallthrough to common return path */
+
+1:	/* copy return value to %a0 for syscalls returning pointers */
+	move.l	%d0, %a0
 	rts
 
 	.size	__syscall_common,.-__syscall_common
diff --git a/usr/klibc/arch/m68k/vfork.S b/usr/klibc/arch/m68k/vfork.S
index a3a7e44..ec8baeb 100644
--- a/usr/klibc/arch/m68k/vfork.S
+++ b/usr/klibc/arch/m68k/vfork.S
@@ -15,14 +15,9 @@ vfork:
 	move.l	(%sp)+, %d1		/* Return address */
 	move.l	# __NR_vfork, %d0
 	trap	#0
-	move.l	%d1, -(%sp)
-	cmpi.l	#-4095, %d0
-	blt.l	1f
-	neg.l	%d0
-	move.l	%d0, (errno)
-	moveq	#-1, %d0
-1:
-	movea.l	%d0, %a0
-	rts
+	move.l	%d1, -(%sp)		/* restore stack */
+
+	/* common code from syscall.S */
+	bra	__syscall_checkandout
 
 	.size	vfork, .-vfork
-- 
1.7.2.3