arm64: scs: Store absolute SCS stack pointer value in thread_info
Storing the SCS information in thread_info as a {base,offset} pair
introduces an additional load instruction on the ret-to-user path,
since the SCS stack pointer in x18 has to be converted back to an offset
by subtracting the base.
Replace the offset with the absolute SCS stack pointer value instead
and avoid the redundant load.
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
diff --git a/kernel/scs.c b/kernel/scs.c
index 9389c28..5ff8663 100644
--- a/kernel/scs.c
+++ b/kernel/scs.c
@@ -60,8 +60,7 @@ int scs_prepare(struct task_struct *tsk, int node)
if (!s)
return -ENOMEM;
- task_scs(tsk) = s;
- task_scs_offset(tsk) = 0;
+ task_scs(tsk) = task_scs_sp(tsk) = s;
scs_account(tsk, 1);
return 0;
}
