From: miod <miod@openbsd.org>
Date: Wed, 27 Mar 2024 20:03:29 +0000 (+0000)
Subject: When the syscall number has to be loaded from a pc-relative location,
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=fc31befaf105b97a112f7671f6f1ed3695619019;p=openbsd

When the syscall number has to be loaded from a pc-relative location,
abuse END macros to place the number at the end of the syscall wrapper
rather than in the middle of it, so that there is no need to branch
around it; this saves two instructions per syscall number >= 128.

While there, also tweak the error return (SET_ERRNO_AND_RETURN) to only
return a 64-bit value for lseek; this saves another instruction for
all other syscalls.

With input from guenther@; "Anything that makes the machine faster" deraadt@
---

diff --git a/lib/libc/arch/sh/SYS.h b/lib/libc/arch/sh/SYS.h
index cb3fd7ef1e6..684ac52333a 100644
--- a/lib/libc/arch/sh/SYS.h
+++ b/lib/libc/arch/sh/SYS.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: SYS.h,v 1.15 2023/12/11 22:24:16 kettenis Exp $	*/
+/*	$OpenBSD: SYS.h,v 1.16 2024/03/27 20:03:29 miod Exp $	*/
 /*-
  * Copyright (c) 1990 The Regents of the University of California.
  * All rights reserved.
@@ -78,13 +78,6 @@
 #define	SYSENTRY_HIDDEN(x)				\
 	ENTRY(_thread_sys_ ## x)
 
-#define	__END_HIDDEN(x)					\
-	SET_ENTRY_SIZE(_thread_sys_ ## x);		\
-	_HIDDEN_FALIAS(x,_thread_sys_ ## x);		\
-	SET_ENTRY_SIZE(_HIDDEN(x))
-#define	__END(x)					\
-	__END_HIDDEN(x); SET_ENTRY_SIZE(x)
-
 #define PINSYSCALL(sysno, label)					\
 	.pushsection .openbsd.syscalls,"",@progbits;			\
 	.p2align 2;							\
@@ -95,7 +88,8 @@
 #ifdef __ASSEMBLER__
 /*
  * If the system call number fits in a 8-bit signed value (i.e. fits in 7 bits),
- * then we can use the #imm8 addressing mode.
+ * then we can use the #imm8 addressing mode. Otherwise, we'll load the number
+ * from memory at the end of the system call wrapper.
  */
 
 .macro systrap num
@@ -107,13 +101,26 @@
 	mov.l	903f, r0
 97:	trapa	#0x80
 	PINSYSCALL(\num, 97b)
-	bra	904f
-	 nop
+.endif
+.endm
+
+.macro systrap_data num
+.iflt \num - 128
+.else
+	.text
 	.align	2
  903:	.long	\num
- 904:
 .endif
 .endm
+
+.macro syscall_error num
+.ifeq \num - SYS_lseek
+	mov	#-1, r1
+.endif
+	rts
+	 mov	#-1, r0
+.endm
+
 #endif
 
 #define SYSTRAP(x)					\
@@ -126,26 +133,32 @@
 		SYSENTRY_HIDDEN(x);			\
 		SYSTRAP(y)
 
-#define SET_ERRNO_AND_RETURN				\
+#define SET_ERRNO_AND_RETURN(y)				\
 		stc	gbr,r1;				\
 		mov	#TCB_OFFSET_ERRNO_NEG,r2;	\
 		sub	r2,r1;				\
 		mov.l	r0,@r1;				\
-		mov	#-1, r1;	/* for lseek */	\
-		rts;					\
-		 mov	#-1, r0
+		syscall_error SYS_ ## y
 
 #define _SYSCALL(x,y)					\
 		.text;					\
-	911:	SET_ERRNO_AND_RETURN;			\
+	911:	SET_ERRNO_AND_RETURN(y);		\
 		_SYSCALL_NOERROR(x,y);			\
 		bf	911b
 #define _SYSCALL_HIDDEN(x,y)				\
 		.text;					\
-	911:	SET_ERRNO_AND_RETURN;			\
+	911:	SET_ERRNO_AND_RETURN(y);		\
 		_SYSCALL_HIDDEN_NOERROR(x,y);		\
 		bf	911b
 
+#define	__END_HIDDEN(x,y)				\
+		systrap_data SYS_ ## y;			\
+		SET_ENTRY_SIZE(_thread_sys_ ## x);	\
+		_HIDDEN_FALIAS(x,_thread_sys_ ## x);	\
+		SET_ENTRY_SIZE(_HIDDEN(x))
+#define	__END(x,y)					\
+		__END_HIDDEN(x,y); SET_ENTRY_SIZE(x)
+
 #define SYSCALL_NOERROR(x)				\
 		_SYSCALL_NOERROR(x,x)
 
@@ -156,22 +169,22 @@
 		_SYSCALL_NOERROR(x,y);			\
 		rts;					\
 		 nop;					\
-		__END(x)
+		__END(x,y)
 
 #define PSEUDO(x,y)					\
 		_SYSCALL(x,y);				\
 		rts;					\
 		 nop;					\
-		__END(x)
+		__END(x,y)
 
 #define PSEUDO_HIDDEN(x,y)				\
 		_SYSCALL_HIDDEN(x,y);			\
 		rts;					\
 		 nop;					\
-		__END_HIDDEN(x)
+		__END_HIDDEN(x,y)
 
 #define RSYSCALL_NOERROR(x)		PSEUDO_NOERROR(x,x)
 #define RSYSCALL(x)			PSEUDO(x,x)
 #define RSYSCALL_HIDDEN(x)		PSEUDO_HIDDEN(x,x)
-#define SYSCALL_END(x)			__END(x)
-#define SYSCALL_END_HIDDEN(x)		__END_HIDDEN(x)
+#define SYSCALL_END(x)			__END(x,x)
+#define SYSCALL_END_HIDDEN(x)		__END_HIDDEN(x,x)
diff --git a/lib/libc/arch/sh/sys/brk.S b/lib/libc/arch/sh/sys/brk.S
index 5a98da3597d..5701f48fcb4 100644
--- a/lib/libc/arch/sh/sys/brk.S
+++ b/lib/libc/arch/sh/sys/brk.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: brk.S,v 1.9 2023/12/10 16:45:52 deraadt Exp $	*/
+/*	$OpenBSD: brk.S,v 1.10 2024/03/27 20:03:29 miod Exp $	*/
 /*	$NetBSD: brk.S,v 1.10 2006/01/06 03:58:31 uwe Exp $	*/
 
 /*-
@@ -64,13 +64,7 @@ ENTRY(brk)
 	bf	1f
 	mov	r0, r4
 1:
-#if SYS_break >= 128
-	mov.l	LSYS_break, r0
-#else
-	mov	#SYS_break, r0
-#endif
-99:	trapa	#0x80
-	PINSYSCALL(SYS_break, 99b)
+	systrap SYS_break
 	bf	2f
 #ifdef __PIC__
 	mov.l	Lcurbrk, r0
@@ -83,12 +77,10 @@ ENTRY(brk)
 	rts
 	 mov.l	r4, @r1
 2:
-	SET_ERRNO_AND_RETURN
+	SET_ERRNO_AND_RETURN(break)
 
 	.align	2
-#if SYS_break >= 128
-LSYS_break:	.long	SYS_break
-#endif
+	systrap_data SYS_break
 #ifdef __PIC__
 L_GOT:		.long	_GLOBAL_OFFSET_TABLE_
 Lminbrk:	.long	__minbrk@GOT
diff --git a/lib/libc/arch/sh/sys/sbrk.S b/lib/libc/arch/sh/sys/sbrk.S
index b86d0eb7573..a250c8d844e 100644
--- a/lib/libc/arch/sh/sys/sbrk.S
+++ b/lib/libc/arch/sh/sys/sbrk.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sbrk.S,v 1.9 2023/12/10 16:45:52 deraadt Exp $	*/
+/*	$OpenBSD: sbrk.S,v 1.10 2024/03/27 20:03:29 miod Exp $	*/
 /*	$NetBSD: sbrk.S,v 1.9 2006/01/06 03:58:31 uwe Exp $	*/
 
 /*-
@@ -64,13 +64,7 @@ ENTRY(sbrk)
 #endif
 	mov.l	@r0, r0
 	add	r0, r4
-#if SYS_break >= 128
-	mov.l	LSYS_break, r0
-#else
-	mov	#SYS_break, r0
-#endif
-99:	trapa	#0x80
-	PINSYSCALL(SYS_break, 99b)
+	systrap SYS_break
 	bf	1f
 #ifdef __PIC__
 	mov.l	Lcurbrk, r0
@@ -83,12 +77,10 @@ ENTRY(sbrk)
 	rts
 	 mov.l	r2, @r1
 1:
-	SET_ERRNO_AND_RETURN
+	SET_ERRNO_AND_RETURN(break)
 
 	.align	2
-#if SYS_break >= 128
-LSYS_break:	.long	SYS_break
-#endif
+	systrap_data SYS_break
 #ifdef __PIC__
 L_GOT:		.long	_GLOBAL_OFFSET_TABLE_
 Lcurbrk:	.long	__curbrk@GOT
diff --git a/lib/libc/arch/sh/sys/sigprocmask.S b/lib/libc/arch/sh/sys/sigprocmask.S
index 28841e6003d..34421e4dbbc 100644
--- a/lib/libc/arch/sh/sys/sigprocmask.S
+++ b/lib/libc/arch/sh/sys/sigprocmask.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sigprocmask.S,v 1.7 2023/12/10 16:45:52 deraadt Exp $	*/
+/*	$OpenBSD: sigprocmask.S,v 1.8 2024/03/27 20:03:29 miod Exp $	*/
 /*	$NetBSD: sigprocmask.S,v 1.6 2003/08/07 16:42:21 agc Exp $	*/
 
 /*-
@@ -47,13 +47,7 @@ SYSENTRY_HIDDEN(sigprocmask)
 1:	mov.l	@r2, r2			/* fetch indirect ... */
 	mov	r2, r5			/* to new mask arg */
 2:	
-#if SYS_sigprocmask >= 128
-	mov.l	LSYS_sigprocmask, r0
-#else
-	mov	#SYS_sigprocmask, r0
-#endif
-99:	trapa	#0x80
-	PINSYSCALL(SYS_sigprocmask, 99b)
+	systrap SYS_sigprocmask
 	bf	4f
 	mov	r6, r2			/* fetch old mask requested */
 	tst	r2, r2			/* test if old mask requested */
@@ -64,11 +58,6 @@ SYSENTRY_HIDDEN(sigprocmask)
 	rts
 	 nop
 4:
-	SET_ERRNO_AND_RETURN
-
-	.align	2
-#if SYS_sigprocmask >= 128
-LSYS_sigprocmask:
-	.long	SYS_sigprocmask
-#endif
+	SET_ERRNO_AND_RETURN(sigprocmask)
+	systrap_data(SYS_sigprocmask)
 SYSCALL_END_HIDDEN(sigprocmask)
diff --git a/lib/libc/arch/sh/sys/sigsuspend.S b/lib/libc/arch/sh/sys/sigsuspend.S
index b2e2b25fca1..6e2f6ad511b 100644
--- a/lib/libc/arch/sh/sys/sigsuspend.S
+++ b/lib/libc/arch/sh/sys/sigsuspend.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sigsuspend.S,v 1.6 2023/12/10 16:45:52 deraadt Exp $	*/
+/*	$OpenBSD: sigsuspend.S,v 1.7 2024/03/27 20:03:29 miod Exp $	*/
 /*	$NetBSD: sigsuspend.S,v 1.5 2003/08/07 16:42:21 agc Exp $	*/
 
 /*-
@@ -41,18 +41,7 @@ SYSENTRY_HIDDEN(sigsuspend)
 	mov	r4, r0		/* fetch mask arg */
 	mov.l	@r0, r0		/* indirect to mask arg */
 	mov	r0, r4
-#if SYS_sigsuspend >= 128
-	mov.l	LSYS_sigsuspend, r0
-#else
-	mov	#SYS_sigsuspend, r0
-#endif
-99:	trapa	#0x80
-	PINSYSCALL(SYS_sigsuspend, 99b)
-	SET_ERRNO_AND_RETURN
-
-	.align	2
-#if SYS_sigsuspend >= 128
-LSYS_sigsuspend:
-	.long	SYS_sigsuspend
-#endif
+	systrap SYS_sigsuspend
+	SET_ERRNO_AND_RETURN(sigsuspend)
+	systrap_data SYS_sigsuspend
 SYSCALL_END_HIDDEN(sigsuspend)
diff --git a/lib/libc/arch/sh/sys/tfork_thread.S b/lib/libc/arch/sh/sys/tfork_thread.S
index b17f2cffc8a..fb2d9e49d6d 100644
--- a/lib/libc/arch/sh/sys/tfork_thread.S
+++ b/lib/libc/arch/sh/sys/tfork_thread.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tfork_thread.S,v 1.5 2023/12/10 16:45:52 deraadt Exp $	*/
+/*	$OpenBSD: tfork_thread.S,v 1.6 2024/03/27 20:03:29 miod Exp $	*/
 
 /*
  * Copyright (c) 2007 Miodrag Vallat.
@@ -24,13 +24,7 @@
  *			r4			r5		   r6		r7
  */
 ENTRY(__tfork_thread)
-#if SYS___tfork >= 128
-	mov.l	.LSYS___tfork, r0
-#else
-	mov	#SYS___tfork, r0
-#endif
-99:	trapa	#0x80
-	PINSYSCALL(SYS___tfork, 99b)
+	systrap SYS___tfork
 	bf	9f
 
 	tst	r0, r0
@@ -42,6 +36,8 @@ ENTRY(__tfork_thread)
 	rts
 	 nop
 
+	systrap_data SYS___tfork
+
 1:
 	/*
 	 * In child process: invoke function, then exit.
@@ -49,26 +45,13 @@ ENTRY(__tfork_thread)
 	jsr	@r6
 	 mov	r7, r4
 
-#if SYS___threxit >= 128
-	mov.l	.LSYS___threxit, r0
-#else
-	mov	#SYS___threxit, r0
-#endif
-98:	trapa	#0x80
-	PINSYSCALL(SYS___threxit, 98b)
+	systrap SYS___threxit
+	systrap_data SYS___threxit
 
 9:
 	/*
 	 * System call failure.
 	 */
-	SET_ERRNO_AND_RETURN
-
-	.align 2
-#if SYS___tfork >= 128
-.LSYS___tfork:	.long SYS___tfork
-#endif
-#if SYS___threxit >= 128
-.LSYS___threxit:	.long SYS___threxit
-#endif
+	SET_ERRNO_AND_RETURN(__tfork)
 
 	SET_ENTRY_SIZE(__tfork_thread)