[PATCH 17/20] ARC: entry: replace 8 byte OR with 4 byte BSET

Vineet Gupta
2023-08-15T00:49:28Z

FAKE_RET_FROM_EXCEPTION drops down to pure kernel mode. It currently has
an 8 byte instruction which can be replaced with 4 byte BSET

This is applicable to both ARCv2 and ARCv3 entr code.

ARCv2 current
------------
00000804 <EV_Trap>:
...
874: 216a 1280 lr r9,[status32]
878: 2146 1809 bic r9,r9,0x20
87c: 2105 1f89 8000 0000 or r9,r9,0x80000000
^^^^^^^^^
884: 2029 8240 kflag r9

ARCv2 after
----------
000007e0 <EV_Trap>:
...
850: 216a 1280 lr r9,[status32]
854: 2150 1149 bclr r9,r9,0x5
858: 214f 17c9 bset r9,r9,0x1f
85c: 2029 8240 kflag r9

Signed-off-by: Vineet Gupta <vgupta@kernel.org>
---
arch/arc/include/asm/entry-arcv2.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index 11b48ab39154..f7c9b3915d10 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -274,8 +274,8 @@

.macro FAKE_RET_FROM_EXCPN
lr r9, [status32]
- bic r9, r9, STATUS_AE_MASK
- or r9, r9, STATUS_IE_MASK
+ bclr r9, r9, STATUS_AE_BIT
+ bset r9, r9, STATUS_IE_BIT
kflag r9
.endm

--
2.34.1