From 7106a5ab89c50c6b5aadea0850b40323804a922d Mon Sep 17 00:00:00 2001 From: Benjamin LaHaise Date: Sat, 10 Jan 2009 23:00:22 -0500 Subject: x86-64: remove locked instruction from switch_to() Impact: micro-optimization The patch below removes an unnecessary locked instruction from switch_to(). TIF_FORK is only ever set in copy_thread() on initial process creation, and gets cleared during the first scheduling of the process. As such, it is safe to use an unlocked test for the flag within switch_to(). Signed-off-by: Benjamin LaHaise Signed-off-by: Ingo Molnar --- arch/x86/kernel/entry_64.S | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86/kernel/entry_64.S') diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index e28c7a987793..38dd37458e44 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -408,6 +408,8 @@ END(save_paranoid) ENTRY(ret_from_fork) DEFAULT_FRAME + LOCK ; btr $TIF_FORK,TI_flags(%r8) + push kernel_eflags(%rip) CFI_ADJUST_CFA_OFFSET 8 popf # reset kernel eflags -- cgit v1.2.1 From b8aa287f77be943e37a84fa4657e27df95269bfb Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 28 Jan 2009 14:35:03 -0800 Subject: x86: fix paravirt clobber in entry_64.S Impact: Fix latent bug The clobber is trying to say that anything except RDI is available for clobbering, but actually clobbers everything. This hasn't mattered because the clobbers were basically ignored, but subsequent patches will rely on them. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: H. Peter Anvin --- arch/x86/kernel/entry_64.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kernel/entry_64.S') diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index a52703864a16..e4c9710cae52 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -1140,7 +1140,7 @@ ENTRY(native_load_gs_index) CFI_STARTPROC pushf CFI_ADJUST_CFA_OFFSET 8 - DISABLE_INTERRUPTS(CLBR_ANY | ~(CLBR_RDI)) + DISABLE_INTERRUPTS(CLBR_ANY & ~CLBR_RDI) SWAPGS gs_change: movl %edi,%gs -- cgit v1.2.1