linux-kernel - Re: [tip:x86/asm] x86/asm/msr: Make wrmsrl

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Date:	Fri, 05 Jun 2015 01:57:43 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	linux-tip-commits@...r.kernel.org,
	tip-bot for Andy Lutomirski <tipbot@...or.com>
CC:	peterz@...radead.org, torvalds@...ux-foundation.org,
	luto@...nel.org, linux-kernel@...r.kernel.org, tglx@...utronix.de,
	mingo@...nel.org, akpm@...ux-foundation.org
Subject: Re: [tip:x86/asm] x86/asm/msr: Make wrmsrl_safe() a function

Shouldn't we make it a proper function sine there is going to have to be a function call involved anyway?

On June 5, 2015 1:42:56 AM PDT, tip-bot for Andy Lutomirski <tipbot@...or.com> wrote:
>Commit-ID:  cf991de2f614f454b3cb2a300c06ecdf69f3a70d
>Gitweb:    
>http://git.kernel.org/tip/cf991de2f614f454b3cb2a300c06ecdf69f3a70d
>Author:     Andy Lutomirski <luto@...nel.org>
>AuthorDate: Thu, 4 Jun 2015 17:13:44 -0700
>Committer:  Ingo Molnar <mingo@...nel.org>
>CommitDate: Fri, 5 Jun 2015 09:41:22 +0200
>
>x86/asm/msr: Make wrmsrl_safe() a function
>
>The wrmsrl_safe macro performs invalid shifts if the value
>argument is 32 bits.  This makes it unnecessarily awkward to
>write code that puts an unsigned long into an MSR.
>
>Convert it to a real inline function.
>
>For inspiration, see:
>
> 7c74d5b7b7b6 ("x86/asm/entry/64: Fix MSR_IA32_SYSENTER_CS MSR value").
>
>Signed-off-by: Andy Lutomirski <luto@...nel.org>
>Cc: <linux-kernel@...r.kernel.org>
>Cc: Andrew Morton <akpm@...ux-foundation.org>
>Cc: H. Peter Anvin <hpa@...or.com>
>Cc: Linus Torvalds <torvalds@...ux-foundation.org>
>Cc: Peter Zijlstra <peterz@...radead.org>
>Cc: Thomas Gleixner <tglx@...utronix.de>
>[ Applied small improvements. ]
>Signed-off-by: Ingo Molnar <mingo@...nel.org>
>---
> arch/x86/include/asm/msr.h | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
>diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
>index de36f22..13bf576 100644
>--- a/arch/x86/include/asm/msr.h
>+++ b/arch/x86/include/asm/msr.h
>@@ -205,8 +205,13 @@ do {                                              
>             \
> 
> #endif	/* !CONFIG_PARAVIRT */
> 
>-#define wrmsrl_safe(msr, val) wrmsr_safe((msr), (u32)(val),		\
>-					     (u32)((val) >> 32))
>+/*
>+ * 64-bit version of wrmsr_safe():
>+ */
>+static inline int wrmsrl_safe(u32 msr, u64 val)
>+{
>+	return wrmsr_safe(msr, (u32)val,  (u32)(val >> 32));
>+}
> 
> #define write_tsc(low, high) wrmsr(MSR_IA32_TSC, (low), (high))
> 

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