On 8/12/2020 7:00 PM, Will Deacon wrote:
On Tue, Aug 04, 2020 at 07:44:42PM +0530, Gaurav Kohli wrote:
In a system where no cpu's implement SSBS, for
them no need to set pstate. This might help to save
few cpu cycles during context switch.
Signed-off-by: Gaurav Kohli <gkohli@xxxxxxxxxxxxxx>
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 6089638..79f80f1 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -477,6 +477,13 @@ static void ssbs_thread_switch(struct task_struct *next)
struct pt_regs *regs = task_pt_regs(next);
/*
+ * For Targets which don't have SSBS support, they
+ * can return from here.
+ */
+ if (!IS_ENABLED(CONFIG_ARM64_SSBD))
+ return;
Does this actually make a measurable difference?
Will
Hi Will,
While doing code review between older kernel and latest kernel for
context switch case, there i have found this and thought it is good to
have for non-ssbs system to return early(as this might improve).
Please let me know if you want to run some tests.
Regards
Gaurav
