linux-kernel - [PATCH] x86/vdso: fix lsl operand order

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Message-Id: <20180901201452.27828-1-sneves@dei.uc.pt>
Date:   Sat,  1 Sep 2018 21:14:52 +0100
From:   Samuel Neves <sneves@....uc.pt>
To:     Andy Lutomirski <luto@...nel.org>, linux-kernel@...r.kernel.org
Cc:     Samuel Neves <sneves@....uc.pt>, x86@...nel.org,
        stable@...r.kernel.org
Subject: [PATCH] x86/vdso: fix lsl operand order

In the __getcpu function, lsl was using the wrong target
and destination registers. Luckily, the compiler tends to
choose %eax for both variables, so it has been working
so far.

Cc: x86@...nel.org
Cc: stable@...r.kernel.org
Signed-off-by: Samuel Neves <sneves@....uc.pt>
---
 arch/x86/include/asm/vgtod.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h
index fb856c9f0449..53748541c487 100644
--- a/arch/x86/include/asm/vgtod.h
+++ b/arch/x86/include/asm/vgtod.h
@@ -93,7 +93,7 @@ static inline unsigned int __getcpu(void)
 	 *
 	 * If RDPID is available, use it.
 	 */
-	alternative_io ("lsl %[p],%[seg]",
+	alternative_io ("lsl %[seg],%[p]",
 			".byte 0xf3,0x0f,0xc7,0xf8", /* RDPID %eax/rax */
 			X86_FEATURE_RDPID,
 			[p] "=a" (p), [seg] "r" (__PER_CPU_SEG));
-- 
2.17.1