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ARC: entry: replace 8 byte OR with 4 byte BSET

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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>
This commit is contained in:
Vineet Gupta 2020-06-17 16:23:38 -07:00
parent 13347c1039
commit dfb12071dd
1 changed files with 2 additions and 2 deletions
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4
arch/arc/include/asm/entry-arcv2.h
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@ -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