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authorVineet Gupta <vgupta@synopsys.com>2013-07-09 17:06:40 +0530
committerVineet Gupta <vgupta@synopsys.com>2013-08-26 09:40:25 +0530
commitfce16bc35ae4a45634f3dc348d8d297a25c277cf (patch)
treead8bd83bf1ec3210208bad9a566a7585583ee876 /arch/arc/kernel
parent37f3ac498c988536f0d42b4659fb5d2c050b2f96 (diff)
ARC: Entry Handler tweaks: Optimize away redundant IRQ_DISABLE_SAVE
In the exception return path, for both U/K cases, intr are already disabled (for various existing reasons). So when we drop down to @restore_regs, we need not redo that. There was subtle issue - when intr were NOT being disabled for ret-to-kernel-but-no-preemption case - now fixed by moving the IRQ_DISABLE further up in @resume_kernel_mode. So what do we gain: * Shaves off a few insn in return path. * Eliminates the need for IRQ_DISABLE_SAVE assembler macro for ARCv2 hence allows for entry code sharing. Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to 'arch/arc/kernel')
-rw-r--r--arch/arc/kernel/entry.S10
1 files changed, 5 insertions, 5 deletions
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index 059ca94e3df8..b908dde8a331 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -612,6 +612,9 @@ resume_kernel_mode:
#ifdef CONFIG_PREEMPT
+ ; This is a must for preempt_schedule_irq()
+ IRQ_DISABLE r9
+
; Can't preempt if preemption disabled
GET_CURR_THR_INFO_FROM_SP r10
ld r8, [r10, THREAD_INFO_PREEMPT_COUNT]
@@ -621,8 +624,6 @@ resume_kernel_mode:
ld r9, [r10, THREAD_INFO_FLAGS]
bbit0 r9, TIF_NEED_RESCHED, restore_regs
- IRQ_DISABLE r9
-
; Invoke PREEMPTION
bl preempt_schedule_irq
@@ -635,12 +636,11 @@ resume_kernel_mode:
;
; Restore the saved sys context (common exit-path for EXCPN/IRQ/Trap)
; IRQ shd definitely not happen between now and rtie
+; All 2 entry points to here already disable interrupts
restore_regs :
- ; Disable Interrupts while restoring reg-file back
- ; XXX can this be optimised out
- IRQ_DISABLE_SAVE r9, r10 ;@r10 has prisitine (pre-disable) copy
+ lr r10, [status32]
; Restore REG File. In case multiple Events outstanding,
; use the same priorty as rtie: EXCPN, L2 IRQ, L1 IRQ, None