Make __cerror() use the per-thread errno location if r2 isn't zero. This way

libpthread no longer has to override it which means that we can use a local
call and can avoid setting up r30 as a _GLOBAL_OFFSET_TABLE_ pointer, which
is hard the way the powerpc ABI works.

For now we continue to provide __cerror as a weak symbol, but ___cerror is
now protected and internal calls within libc now use ___cerror instead of
__cerror.

discussed with guenther@

4 files changed, 25 insertions, 17 deletions

diff --git a/lib/libc/arch/powerpc/SYS.h b/lib/libc/arch/powerpc/SYS.h
index fdd4e8913e3..6303d68f7b6 100644
--- a/lib/libc/arch/powerpc/SYS.h
+++ b/lib/libc/arch/powerpc/SYS.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: SYS.h,v 1.16 2015/04/07 01:27:06 guenther Exp $	*/
+/*	$OpenBSD: SYS.h,v 1.17 2015/08/23 15:51:28 kettenis Exp $	*/
 /*-
  * Copyright (c) 1994
  *	Andrew Cagney.  All rights reserved.
@@ -45,13 +45,13 @@
 #include "machine/asm.h"
 
 #define _CONCAT(x,y)	x##y
-#define PSEUDO_PREFIX(p,x,y)	.extern _ASM_LABEL(__cerror) ; \
+#define PSEUDO_PREFIX(p,x,y)	.extern _ASM_LABEL(___cerror) ; \
 			ENTRY(p##x) \
 				li 0, SYS_##y ; \
 				/* sc */
 #define PSEUDO_SUFFIX		cmpwi 0, 0 ; \
 				beqlr+ ; \
-				b PIC_PLT(_ASM_LABEL(__cerror))
+				b _ASM_LABEL(___cerror)
 
 #define PSEUDO_NOERROR_SUFFIX	blr
 
diff --git a/lib/libc/arch/powerpc/sys/cerror.S b/lib/libc/arch/powerpc/sys/cerror.S
index d2cbc5e17c6..db7ba4a84a6 100644
--- a/lib/libc/arch/powerpc/sys/cerror.S
+++ b/lib/libc/arch/powerpc/sys/cerror.S
@@ -1,4 +1,4 @@
-/* $OpenBSD: cerror.S,v 1.9 2012/08/22 22:26:16 deraadt Exp $ */
+/* $OpenBSD: cerror.S,v 1.10 2015/08/23 15:51:28 kettenis Exp $ */
 
 /*
  * Copyright (c) 1996 Dale Rahn
@@ -28,28 +28,36 @@
 #include "SYS.h"
 #include <machine/asm.h>
 
+#define ERRNOPTR_OFFSET	16
+
 WEAK_ALIAS(__cerror, ___cerror)
 
 	.text
+	.protected _ASM_LABEL(___cerror)
 ASENTRY(___cerror)
+	cmpwi	2, 0
+	bne-	.L_threaded
+
 #if defined (__PIC__)
-	stwu	1, -16(1) 		/* follow the SVR4 ABI */
 	mflr	3			/* error value is in r0, use r3 */
-	stw	3, 20(1)
-	bl	_GLOBAL_OFFSET_TABLE_@local-4
-	mflr	4
+	bcl	20, 31, 1f
+1:	mflr	4
+	addis	4, 4, _GLOBAL_OFFSET_TABLE_-1b@ha
+	addi	4, 4, _GLOBAL_OFFSET_TABLE_-1b@l
 	lwz	5,_C_LABEL(errno)@got(4)
+	mtlr	3
 #else
 	addis 5, 0, errno@H
 	ori 5, 5, errno@L
 #endif
+	b	.L_do_store
+
+.L_threaded:
+	lwz  5, 4(2)
+	lwz  5, ERRNOPTR_OFFSET(5)
 
+.L_do_store:
 	stw 0, 0(5)
 	addi 3, 0, -1
 	addi 4, 0, -1
-#if defined (__PIC__)
-	lwz	0, 20(1)
-	mtlr	0
-	addi	1, 1, 16	/* follow the SVR4 ABI */
-#endif
 	blr
diff --git a/lib/libc/arch/powerpc/sys/sigprocmask.S b/lib/libc/arch/powerpc/sys/sigprocmask.S
index 64bc0222a66..4bdb7c7b755 100644
--- a/lib/libc/arch/powerpc/sys/sigprocmask.S
+++ b/lib/libc/arch/powerpc/sys/sigprocmask.S
@@ -1,4 +1,4 @@
-/* $OpenBSD: sigprocmask.S,v 1.7 2002/10/07 04:47:12 drahn Exp $ */
+/* $OpenBSD: sigprocmask.S,v 1.8 2015/08/23 15:51:28 kettenis Exp $ */
 
 /*
  * Copyright (c) 1996 Dale Rahn
@@ -49,7 +49,7 @@ PREFIX(sigprocmask)
 	/* didnt work? */
 	cmpwi	0, 0
 	beq+	.L_sigprocmask_ok
-	b	PIC_PLT(_ASM_LABEL(__cerror))
+	b	_ASM_LABEL(___cerror)
 
 .L_sigprocmask_ok:
 	lwz	5, 12(1)
diff --git a/lib/libc/arch/powerpc/sys/tfork_thread.S b/lib/libc/arch/powerpc/sys/tfork_thread.S
index aa5f59c966d..4d93fda6e6c 100644
--- a/lib/libc/arch/powerpc/sys/tfork_thread.S
+++ b/lib/libc/arch/powerpc/sys/tfork_thread.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tfork_thread.S,v 1.2 2012/06/21 00:56:59 guenther Exp $	*/
+/*	$OpenBSD: tfork_thread.S,v 1.3 2015/08/23 15:51:28 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2005 Tim Wiess <tim@nop.cx>
@@ -46,4 +46,4 @@ ENTRY(__tfork_thread)
 1:
 	li	%r3, -1
 2:
-	b PIC_PLT(_C_LABEL(__cerror))
+	b	_C_LABEL(___cerror)