[PATCH v5 06/17] x86,ftrace: Shrink ftrace_regs_caller() by one byte

[Peter Zijlstra]

'Optimize' ftrace_regs_caller. Instead of comparing against an
immediate, the more natural way to test for zero on x86 is: 'test
%r,%r'.

  48 83 f8 00             cmp    $0x0,%rax
  74 49                   je     226 <ftrace_regs_call+0xa3>

  48 85 c0                test   %rax,%rax
  74 49                   je     225 <ftrace_regs_call+0xa2>

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
 arch/x86/kernel/ftrace_64.S |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -240,8 +240,8 @@ SYM_INNER_LABEL(ftrace_regs_call, SYM_L_
 	 * See arch_ftrace_set_direct_caller().
 	 */
 	movq ORIG_RAX(%rsp), %rax
-	cmpq	$0, %rax
-	je	1f
+	testq	%rax, %rax
+	jz	1f
 
 	/* Swap the flags with orig_rax */
 	movq MCOUNT_REG_SIZE(%rsp), %rdi