ARC: [arcompact] entry.S: Elide extra check/branch in exception ret path
This is done by improving the laddering logic !
Before:
if Exception
goto excep_or_pure_k_ret
if !Interrupt(L2)
goto l1_chk
else
INTERRUPT_EPILOGUE 2
l1_chk:
if !Interrupt(L1) (i.e. pure kernel mode)
goto excep_or_pure_k_ret
else
INTERRUPT_EPILOGUE 1
excep_or_pure_k_ret:
EXCEPTION_EPILOGUE
Now:
if !Interrupt(L1 or L2) (i.e. exception or pure kernel mode)
goto excep_or_pure_k_ret
; guaranteed to be an interrupt
if !Interrupt(L2)
goto l1_ret
else
INTERRUPT_EPILOGUE 2
; by virtue of above, no need to chk for L1 active
l1_ret:
INTERRUPT_EPILOGUE 1
excep_or_pure_k_ret:
EXCEPTION_EPILOGUE
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/kernel/entry-compact.S b/arch/arc/kernel/entry-compact.S
index d9087a1..5221f194 100644
--- a/arch/arc/kernel/entry-compact.S
+++ b/arch/arc/kernel/entry-compact.S
@@ -333,11 +333,10 @@
; Note that we use realtime STATUS32 (not pt_regs->status32) to
; decide that.
- ; if Returning from Exception
- btst r10, STATUS_AE_BIT
- bnz .Lexcep_ret
+ and.f 0, r10, (STATUS_A1_MASK|STATUS_A2_MASK)
+ bz .Lexcep_or_pure_K_ret
- ; Not Exception so maybe Interrupts (Level 1 or 2)
+ ; Returning from Interrupts (Level 1 or 2)
#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
@@ -378,8 +377,7 @@
st r9, [r10, THREAD_INFO_PREEMPT_COUNT]
149:
- ;return from level 2
- INTERRUPT_EPILOGUE 2
+ INTERRUPT_EPILOGUE 2 ; return from level 2 interrupt
debug_marker_l2:
rtie
@@ -387,15 +385,11 @@
#endif
- bbit0 r10, STATUS_A1_BIT, .Lpure_k_mode_ret
-
- ;return from level 1
- INTERRUPT_EPILOGUE 1
+ INTERRUPT_EPILOGUE 1 ; return from level 1 interrupt
debug_marker_l1:
rtie
-.Lexcep_ret:
-.Lpure_k_mode_ret:
+.Lexcep_or_pure_K_ret:
;this case is for syscalls or Exceptions or pure kernel mode