Messages in this thread Patch in this message | | | Date | Tue, 05 May 2020 15:16:11 +0200 | From | Thomas Gleixner <> | Subject | [patch V4 part 1 09/36] x86/entry/64: Avoid pointless code when CONTEXT_TRACKING=n |
| |
From: Thomas Gleixner <tglx@linutronix.de>
GAS cannot optimize out the test and conditional jump when context tracking is disabled and CALL_enter_from_user_mode is an empty macro.
Wrap it in #ifdeffery. Will go away once all this is moved to C.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Frederic Weisbecker <frederic@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org>
--- arch/x86/entry/entry_64.S | 2 ++ 1 file changed, 2 insertions(+)
--- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -888,12 +888,14 @@ apicinterrupt IRQ_WORK_VECTOR irq_work TRACE_IRQS_OFF .endif +#ifdef CONFIG_CONTEXT_TRACKING .if \paranoid == 0 testb $3, CS(%rsp) jz .Lfrom_kernel_no_context_tracking_\@ CALL_enter_from_user_mode .Lfrom_kernel_no_context_tracking_\@: .endif +#endif movq %rsp, %rdi /* pt_regs pointer */
| |