entry-arcv2.S

/*
 * ARCv2 ISA based core Low Level Intr/Traps/Exceptions(non-TLB) Handling
 *
 * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/linkage.h>   /* ARC_{EXTRY,EXIT} */
#include <asm/entry.h>       /* SAVE_ALL_{INT1,INT2,TRAP...} */
#include <asm/errno.h>
#include <asm/arcregs.h>
#include <asm/irqflags.h>

	.cpu HS

#define VECTOR	.word

;############################ Vector Table #################################

	.section .vector,"a",@progbits
	.align 4

# Initial 16 slots are Exception Vectors
VECTOR	stext			; Restart Vector (jump to entry point)
VECTOR	mem_service		; Mem exception
VECTOR	instr_service		; Instrn Error
VECTOR	EV_MachineCheck		; Fatal Machine check
VECTOR	EV_TLBMissI		; Intruction TLB miss
VECTOR	EV_TLBMissD		; Data TLB miss
VECTOR	EV_TLBProtV		; Protection Violation
VECTOR	EV_PrivilegeV		; Privilege Violation
VECTOR	EV_SWI			; Software Breakpoint
VECTOR	EV_Trap			; Trap exception
VECTOR	EV_Extension		; Extn Instruction Exception
VECTOR	EV_DivZero		; Divide by Zero
VECTOR	EV_DCError		; Data Cache Error
VECTOR	EV_Misaligned		; Misaligned Data Access
VECTOR	reserved		; Reserved slots
VECTOR	reserved		; Reserved slots

# Begin Interrupt Vectors
VECTOR	handle_interrupt	; (16) Timer0
VECTOR	handle_interrupt	; unused (Timer1)
VECTOR	handle_interrupt	; unused (WDT)
VECTOR	handle_interrupt	; (19) ICI (inter core interrupt)
VECTOR	handle_interrupt
VECTOR	handle_interrupt
VECTOR	handle_interrupt
VECTOR	handle_interrupt	; (23) End of fixed IRQs

.rept CONFIG_ARC_NUMBER_OF_INTERRUPTS - 8
	VECTOR	handle_interrupt
.endr

	.section .text, "ax",@progbits

res_service:		; processor restart
	flag    0x1     ; not implemented
	nop
	nop

reserved:		; processor restart
	rtie            ; jump to processor initializations

;##################### Interrupt Handling ##############################

ENTRY(handle_interrupt)

	INTERRUPT_PROLOGUE  irq

	clri		; To make status32.IE agree with CPU internal state

	lr  r0, [ICAUSE]

	mov   blink, ret_from_exception

	b.d  arch_do_IRQ
	mov r1, sp

END(handle_interrupt)

;################### Non TLB Exception Handling #############################

ENTRY(EV_SWI)
	flag 1
END(EV_SWI)

ENTRY(EV_DivZero)
	flag 1
END(EV_DivZero)

ENTRY(EV_DCError)
	flag 1
END(EV_DCError)

ENTRY(EV_Misaligned)

	EXCEPTION_PROLOGUE

	lr  r0, [efa]	; Faulting Data address
	mov r1, sp

	FAKE_RET_FROM_EXCPN

	SAVE_CALLEE_SAVED_USER
	mov r2, sp              ; callee_regs

	bl  do_misaligned_access

	; TBD: optimize - do this only if a callee reg was involved
	; either a dst of emulated LD/ST or src with address-writeback
	RESTORE_CALLEE_SAVED_USER

	b   ret_from_exception
END(EV_Misaligned)

; ---------------------------------------------
; Protection Violation Exception Handler
; ---------------------------------------------

ENTRY(EV_TLBProtV)

	EXCEPTION_PROLOGUE

	lr  r0, [efa]	; Faulting Data address
	mov r1, sp	; pt_regs

	FAKE_RET_FROM_EXCPN

	mov blink, ret_from_exception
	b   do_page_fault

END(EV_TLBProtV)

; From Linux standpoint Slow Path I/D TLB Miss is same a ProtV as they
; need to call do_page_fault().
; ECR in pt_regs provides whether access was R/W/X

.global        call_do_page_fault
.set call_do_page_fault, EV_TLBProtV

;############# Common Handlers for ARCompact and ARCv2 ##############

#include "entry.S"

;############# Return from Intr/Excp/Trap (ARCv2 ISA Specifics) ##############
;
; 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

.Lrestore_regs:

	ld	r0, [sp, PT_status32]	; U/K mode at time of entry
	lr	r10, [AUX_IRQ_ACT]

	bmsk	r11, r10, 15	; AUX_IRQ_ACT.ACTIVE
	breq	r11, 0, .Lexcept_ret	; No intr active, ret from Exception

;####### Return from Intr #######

debug_marker_l1:
	; Handle special case #1: (Entry via Exception, Return via IRQ)
	;
	; Exception in U mode, preempted in kernel, Intr taken (K mode), orig
	; task now returning to U mode (riding the Intr)
	; AUX_IRQ_ACTIVE won't have U bit set (since intr in K mode), hence SP
	; won't be switched to correct U mode value (from AUX_SP)
	; So force AUX_IRQ_ACT.U for such a case

	btst	r0, STATUS_U_BIT		; Z flag set if K (Z clear for U)
	bset.nz	r11, r11, AUX_IRQ_ACT_BIT_U	; NZ means U
	sr	r11, [AUX_IRQ_ACT]

	INTERRUPT_EPILOGUE  irq
	rtie

;####### Return from Exception / pure kernel mode #######

.Lexcept_ret:	; Expects r0 has PT_status32

debug_marker_syscall:
	EXCEPTION_EPILOGUE
	rtie

END(ret_from_exception)