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ARC: [arcompact] entry.S: Improve early return from exception

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The requirement is to
 - Reenable Exceptions (AE cleared)
 - Reenable Interrupts (E1/E2 set)

We need to do wiggle these bits into ERSTATUS and call RTIE.

Prev version used the pre-exception STATUS32 as starting point for what
goes into ERSTATUS. This required explicit fixups of U/DE/L bits.

Instead, use the current (in-exception) STATUS32 as starting point.
Being in exception handler U/DE/L can be safely assumed to be correct.
Only AE/E1/E2 need to be fixed.

So the new implementation is slightly better
 -Avoids read form memory
 -Is 4 bytes smaller for the typical 1 level of intr configuration
 -Depicts the semantics more clearly

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta
2015-09-05 23:08:31 +05:30
parent 9dbd3d9bfd
commit 55a2ae775a
2 changed files with 8 additions and 7 deletions
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2
arch/arc/include/asm/irqflags-compact.h
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@@ -23,11 +23,13 @@
#define STATUS_E2_BIT 2 /* Int 2 enable */
#define STATUS_A1_BIT 3 /* Int 1 active */
#define STATUS_A2_BIT 4 /* Int 2 active */
#define STATUS_AE_BIT 5 /* Exception active */
#define STATUS_E1_MASK (1<<STATUS_E1_BIT)
#define STATUS_E2_MASK (1<<STATUS_E2_BIT)
#define STATUS_A1_MASK (1<<STATUS_A1_BIT)
#define STATUS_A2_MASK (1<<STATUS_A2_BIT)
#define STATUS_AE_MASK (1<<STATUS_AE_BIT)
#define STATUS_IE_MASK (STATUS_E1_MASK | STATUS_E2_MASK)
/* Other Interrupt Handling related Aux regs */