From b43d7c278ce9b35401a121323bd85088ec5b9443 Mon Sep 17 00:00:00 2001
From: jca <jca@openbsd.org>
Date: Sun, 9 Jun 2024 21:15:29 +0000
Subject: [PATCH] Add a compiler barrier where missing in CPU_BUSY_CYCLE()
 implems

Having differences between architectures is asking for problems. And
adding a barrier here just makes sense in most cases. This is also what
cpu_relax() provides in Linux land.

ok kettenis@ claudio@
---
 sys/arch/alpha/include/cpu.h     | 6 ++++--
 sys/arch/amd64/include/cpu.h     | 4 ++--
 sys/arch/arm/include/cpu.h       | 4 ++--
 sys/arch/hppa/include/cpu.h      | 4 ++--
 sys/arch/i386/include/cpu.h      | 4 ++--
 sys/arch/m88k/include/cpu.h      | 4 ++--
 sys/arch/mips64/include/cpu.h    | 4 ++--
 sys/arch/powerpc64/include/cpu.h | 4 ++--
 sys/arch/sh/include/cpu.h        | 4 ++--
 9 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/sys/arch/alpha/include/cpu.h b/sys/arch/alpha/include/cpu.h
index f91536fe066..04997fd8272 100644
--- a/sys/arch/alpha/include/cpu.h
+++ b/sys/arch/alpha/include/cpu.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: cpu.h,v 1.74 2024/05/21 23:16:06 jsg Exp $ */
+/* $OpenBSD: cpu.h,v 1.75 2024/06/09 21:15:29 jca Exp $ */
 /* $NetBSD: cpu.h,v 1.45 2000/08/21 02:03:12 thorpej Exp $ */
 
 /*-
@@ -264,6 +264,8 @@ do {									\
 	struct cpu_info *__ci = curcpu();				\
 	int __s;							\
 									\
+	__asm volatile ("" ::: "memory");				\
+									\
 	if (__ci->ci_ipis != 0) {					\
 		__s = splipi();						\
 		alpha_ipi_process_with_frame(__ci);			\
@@ -277,7 +279,7 @@ do {									\
 #define	CPU_IS_PRIMARY(ci)		1
 #define	CPU_IS_RUNNING(ci)		1
 #define cpu_unidle(ci)			do { /* nothing */ } while (0)
-#define CPU_BUSY_CYCLE()		do {} while (0)
+#define CPU_BUSY_CYCLE()		__asm volatile ("" ::: "memory")
 
 #endif /* MULTIPROCESSOR */
 
diff --git a/sys/arch/amd64/include/cpu.h b/sys/arch/amd64/include/cpu.h
index 90f5dd9e905..82d3552c43e 100644
--- a/sys/arch/amd64/include/cpu.h
+++ b/sys/arch/amd64/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.172 2024/06/07 16:53:35 kettenis Exp $	*/
+/*	$OpenBSD: cpu.h,v 1.173 2024/06/09 21:15:29 jca Exp $	*/
 /*	$NetBSD: cpu.h,v 1.1 2003/04/26 18:39:39 fvdl Exp $	*/
 
 /*-
@@ -319,7 +319,7 @@ void cpu_unidle(struct cpu_info *);
 #define cpu_kick(ci)
 #define cpu_unidle(ci)
 
-#define CPU_BUSY_CYCLE()	do {} while (0)
+#define CPU_BUSY_CYCLE()	__asm volatile ("" ::: "memory")
 
 #endif
 
diff --git a/sys/arch/arm/include/cpu.h b/sys/arch/arm/include/cpu.h
index 1b973d3f569..a598a46bca1 100644
--- a/sys/arch/arm/include/cpu.h
+++ b/sys/arch/arm/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.66 2024/02/25 19:15:50 cheloha Exp $	*/
+/*	$OpenBSD: cpu.h,v 1.67 2024/06/09 21:15:29 jca Exp $	*/
 /*	$NetBSD: cpu.h,v 1.34 2003/06/23 11:01:08 martin Exp $	*/
 
 /*
@@ -251,7 +251,7 @@ extern struct cpu_info *cpu_info[MAXCPUS];
 void cpu_boot_secondary_processors(void);
 #endif /* !MULTIPROCESSOR */
 
-#define CPU_BUSY_CYCLE()	do {} while (0)
+#define CPU_BUSY_CYCLE()	__asm volatile ("" ::: "memory")
 
 #define curpcb		curcpu()->ci_curpcb
 
diff --git a/sys/arch/hppa/include/cpu.h b/sys/arch/hppa/include/cpu.h
index 47abd9cfd4f..e2ff730c9d4 100644
--- a/sys/arch/hppa/include/cpu.h
+++ b/sys/arch/hppa/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.104 2024/02/25 19:15:50 cheloha Exp $	*/
+/*	$OpenBSD: cpu.h,v 1.105 2024/06/09 21:15:29 jca Exp $	*/
 
 /*
  * Copyright (c) 2000-2004 Michael Shalayeff
@@ -165,7 +165,7 @@ curcpu(void)
 #define CPU_INFO_FOREACH(cii, ci) \
 	for (cii = 0, ci = &cpu_info[0]; cii < ncpus; cii++, ci++)
 
-#define CPU_BUSY_CYCLE()	do {} while (0)
+#define CPU_BUSY_CYCLE()	__asm volatile ("" ::: "memory")
 
 /* types */
 enum hppa_cpu_type {
diff --git a/sys/arch/i386/include/cpu.h b/sys/arch/i386/include/cpu.h
index 565f6159c74..d9b5cb50bc9 100644
--- a/sys/arch/i386/include/cpu.h
+++ b/sys/arch/i386/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.190 2024/06/07 16:53:35 kettenis Exp $	*/
+/*	$OpenBSD: cpu.h,v 1.191 2024/06/09 21:15:29 jca Exp $	*/
 /*	$NetBSD: cpu.h,v 1.35 1996/05/05 19:29:26 christos Exp $	*/
 
 /*-
@@ -262,7 +262,7 @@ void cpu_unidle(struct cpu_info *);
 #define cpu_kick(ci)
 #define cpu_unidle(ci)
 
-#define CPU_BUSY_CYCLE()	do {} while (0)
+#define CPU_BUSY_CYCLE()	__asm volatile ("" ::: "memory")
 
 #endif
 
diff --git a/sys/arch/m88k/include/cpu.h b/sys/arch/m88k/include/cpu.h
index d5ce5dff711..4dbb4d9786d 100644
--- a/sys/arch/m88k/include/cpu.h
+++ b/sys/arch/m88k/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.78 2024/05/28 09:27:54 claudio Exp $ */
+/*	$OpenBSD: cpu.h,v 1.79 2024/06/09 21:15:29 jca Exp $ */
 /*
  * Copyright (c) 1996 Nivas Madhur
  * Copyright (c) 1992, 1993
@@ -221,7 +221,7 @@ void	m88k_broadcast_ipi(int);
 
 #endif	/* MULTIPROCESSOR */
 
-#define CPU_BUSY_CYCLE()	do {} while (0)
+#define CPU_BUSY_CYCLE()	__asm volatile ("" ::: "memory")
 
 struct cpu_info *set_cpu_number(cpuid_t);
 
diff --git a/sys/arch/mips64/include/cpu.h b/sys/arch/mips64/include/cpu.h
index dccd1157ab4..6578a1bad4d 100644
--- a/sys/arch/mips64/include/cpu.h
+++ b/sys/arch/mips64/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.146 2024/02/25 19:15:50 cheloha Exp $	*/
+/*	$OpenBSD: cpu.h,v 1.147 2024/06/09 21:15:29 jca Exp $	*/
 
 /*-
  * Copyright (c) 1992, 1993
@@ -258,7 +258,7 @@ void	smp_rendezvous_cpus(unsigned long, void (*)(void *), void *arg);
 #define get_cpu_info(i)			(&cpu_info_primary)
 #endif
 
-#define CPU_BUSY_CYCLE()	do {} while (0)
+#define CPU_BUSY_CYCLE()	__asm volatile ("" ::: "memory")
 
 extern void (*md_initclock)(void);
 extern void (*md_startclock)(struct cpu_info *);
diff --git a/sys/arch/powerpc64/include/cpu.h b/sys/arch/powerpc64/include/cpu.h
index 13c67b80628..fe0394f457b 100644
--- a/sys/arch/powerpc64/include/cpu.h
+++ b/sys/arch/powerpc64/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.36 2024/02/25 19:15:50 cheloha Exp $	*/
+/*	$OpenBSD: cpu.h,v 1.37 2024/06/09 21:15:29 jca Exp $	*/
 
 /*
  * Copyright (c) 2020 Mark Kettenis <kettenis@openbsd.org>
@@ -170,7 +170,7 @@ void	mp_setperf(int);
 
 void signotify(struct proc *);
 
-#define CPU_BUSY_CYCLE()	do {} while (0)
+#define CPU_BUSY_CYCLE()	__asm volatile ("" ::: "memory")
 
 #define curpcb			curcpu()->ci_curpcb
 
diff --git a/sys/arch/sh/include/cpu.h b/sys/arch/sh/include/cpu.h
index eeae150d812..e1bb2283c64 100644
--- a/sys/arch/sh/include/cpu.h
+++ b/sys/arch/sh/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.38 2024/03/31 07:23:29 miod Exp $	*/
+/*	$OpenBSD: cpu.h,v 1.39 2024/06/09 21:15:29 jca Exp $	*/
 /*	$NetBSD: cpu.h,v 1.41 2006/01/21 04:24:12 uwe Exp $	*/
 
 /*-
@@ -90,7 +90,7 @@ extern struct cpu_info cpu_info_store;
 #define MAXCPUS	1
 #define cpu_unidle(ci)
 
-#define CPU_BUSY_CYCLE()	do {} while (0)
+#define CPU_BUSY_CYCLE()	__asm volatile ("" ::: "memory")
 
 
 /*
-- 
2.20.1