4.18-stable review patch. If anyone has any objections, please let me know.
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From: Samuel Neves sneves@dei.uc.pt
commit e78e5a91456fcecaa2efbb3706572fe043766f4d upstream.
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: a582c540ac1b ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/include/asm/vgtod.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- 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));