[PATCH V1 5/6] arm64: exception: handle instruction abort at current EL

Add a handler for instruction aborts at the current EL
(ESR_ELx_EC_IABT_CUR) so they are no longer handled in el1_inv.
This allows firmware first handling for possible SEA
(Synchronous External Abort) caused instruction abort at
current EL.

Signed-off-by: Tyler Baicar <redacted>
Signed-off-by: Naveen Kaje <redacted>
---
 arch/arm64/kernel/entry.S | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 1f7f5a2..6b7fb14 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S

@@ -336,6 +336,8 @@ el1_sync:
 	lsr	x24, x1, #ESR_ELx_EC_SHIFT	// exception class
 	cmp	x24, #ESR_ELx_EC_DABT_CUR	// data abort in EL1
 	b.eq	el1_da
+	cmp	x24, #ESR_ELx_EC_IABT_CUR	// instruction abort in EL1
+	b.eq	el1_ia
 	cmp	x24, #ESR_ELx_EC_SYS64		// configurable trap
 	b.eq	el1_undef
 	cmp	x24, #ESR_ELx_EC_SP_ALIGN	// stack alignment exception

@@ -363,6 +365,23 @@ el1_da:
 	// disable interrupts before pulling preserved data off the stack
 	disable_irq
 	kernel_exit 1
+el1_ia:
+	/*
+	 * Instruction abort handling
+	 */
+	mrs	x0, far_el1
+	enable_dbg
+	// re-enable interrupts if they were enabled in the aborted context
+	tbnz	x23, #7, 1f			// PSR_I_BIT
+	enable_irq
+1:
+	orr	x1, x1, #1 << 24		// use reserved ISS bit for instruction aborts