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authorWill Deacon <will@kernel.org>2020-05-15 14:11:05 +0100
committerWill Deacon <will@kernel.org>2020-05-18 17:47:22 +0100
commit51189c7a7ed1b4ed4493e27275d466ff60406d3a (patch)
treec06448db0ce33c2d4a5ae1494806a3b81082aa96 /kernel
parentcc49c71d2abe99c1c2c9bedf0693ad2d3ee4a067 (diff)
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/scs.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/scs.c b/kernel/scs.c
index 9389c28f0853..5ff8663e4a67 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;
}