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ARC: entry.S: micro-optimize Trap handler

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Elide the need to re-read ECR in Trap handler by ensuring that
EXCEPTION_PROLOGUE does that at the very end just before returning
to Trap handler

ARCv2 EXCEPTION_PROLOGUE already did that, so same for ARcompact and the
common trap handler adjusted to use cached ECR

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2015-03-13 11:50:23 +05:30
parent c7e6d79204
commit 62fb64034d
2 changed files with 5 additions and 4 deletions
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5
arch/arc/include/asm/entry-compact.h
View File

@ -181,8 +181,6 @@
/* ARC700 doesn't provide auto-stack switching */
SWITCH_TO_KERNEL_STK
lr r9, [ecr]
st r9, [sp, 8] /* ECR */
st r0, [sp, 4] /* orig_r0, needed only for sys calls */
/* Restore r9 used to code the early prologue */
@ -198,6 +196,9 @@
PUSHAX lp_end
PUSHAX lp_start
PUSHAX erbta
lr r9, [ecr]
st r9, [sp, PT_event] /* EV_Trap expects r9 to have ECR */
.endm
/*--------------------------------------------------------------

4
arch/arc/kernel/entry.S
View File

@ -258,8 +258,8 @@ ENTRY(EV_Trap)
EXCEPTION_PROLOGUE
;============ TRAP 1 :breakpoints
lr r10, [ecr]
bmsk.f 0, r10, 7
; Check ECR for trap with arg (PROLOGUE ensures r9 has ECR)
bmsk.f 0, r9, 7
bnz trap_with_param
;============ TRAP (no param): syscall top level