x86/vdso: Fix lsl operand order

sneves · KAGA-KOKO · commit e78e5a91456f · 2018-09-01T23:01:56.000+02:00
In the __getcpu function, lsl is using the wrong target and destination registers. Luckily, the compiler tends to choose %eax for both variables, so it has been working so far. Fixes: a582c54 ("x86/vdso: Use RDPID in preference to LSL when available") Signed-off-by: Samuel Neves <sneves@dei.uc.pt> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180901201452.27828-1-sneves@dei.uc.pt
diff --git 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));

Original file line number	Diff line number	Diff line change
`@@ -93,7 +93,7 @@ static inline unsigned int __getcpu(void)`
`93`	`93`	`*`
`94`	`94`	`* If RDPID is available, use it.`
`95`	`95`	`*/`
`96`		`- alternative_io ("lsl %[p],%[seg]",`
	`96`	`+ alternative_io ("lsl %[seg],%[p]",`
`97`	`97`	`".byte 0xf3,0x0f,0xc7,0xf8", /* RDPID %eax/rax */`
`98`	`98`	`X86_FEATURE_RDPID,`
`99`	`99`	`[p] "=a" (p), [seg] "r" (__PER_CPU_SEG));`