linux-kernel - [PATCH 2/5] arm: LLVMLinux: use current_stack

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Date:	Fri,  6 Sep 2013 17:28:08 -0400
From:	behanw@...verseincode.com
To:	linux@....linux.org.uk, Tejun Heo <tj@...nel.org>,
	Christoph Lameter <cl@...ux-foundation.org>
Cc:	behanw@...verseincode.com, Mark Charlebois <charlebm@...il.com>,
	linux-arm-kernel@...ts.infradead.org (moderated list:ARM PORT),
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 2/5] arm: LLVMLinux: use current_stack_pointer for percpu

From: Behan Webster <behanw@...verseincode.com>

The existing code uses named registers to get the value of the stack pointer.
The new current_stack_pointer macro is more readable and allows for a central
portable implementation of how to get the stack pointer with ASM.  This change
supports being able to compile the kernel with both gcc and Clang.

Signed-off-by: Mark Charlebois <charlebm@...il.com>
Signed-off-by: Behan Webster <behanw@...verseincode.com>
Reviewed-by: Jan-Simon Möller <dl9pf@....de>
---
 arch/arm/include/asm/percpu.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/percpu.h b/arch/arm/include/asm/percpu.h
index 209e650..629a975 100644
--- a/arch/arm/include/asm/percpu.h
+++ b/arch/arm/include/asm/percpu.h
@@ -30,14 +30,14 @@ static inline void set_my_cpu_offset(unsigned long off)
 static inline unsigned long __my_cpu_offset(void)
 {
 	unsigned long off;
-	register unsigned long *sp asm ("sp");
+	unsigned long sp = current_stack_pointer;
 
 	/*
 	 * Read TPIDRPRW.
 	 * We want to allow caching the value, so avoid using volatile and
 	 * instead use a fake stack read to hazard against barrier().
 	 */
-	asm("mrc p15, 0, %0, c13, c0, 4" : "=r" (off) : "Q" (*sp));
+	asm("mrc p15, 0, %0, c13, c0, 4" : "=r" (off) : "Q" (sp));
 
 	return off;
 }
-- 
1.8.1.2

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