[linux-2.6-block.git] / arch / arc / kernel / 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	res_service		; Reset Vector
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

reserved:
	flag 1		; Unexpected event, halt

;##################### 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)

; ---------------------------------------------
; Memory Error Exception Handler
;   - Unlike ARCompact, handles Bus errors for both User/Kernel mode,
;     Instruction fetch or Data access, under a single Exception Vector
; ---------------------------------------------

ENTRY(mem_service)

	EXCEPTION_PROLOGUE

	lr  r0, [efa]
	mov r1, sp

	FAKE_RET_FROM_EXCPN

	bl  do_memory_error
	b   ret_from_exception
END(mem_service)

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:
	bbit1.nt r0, STATUS_DE_BIT, .Lintr_ret_to_delay_slot

.Lisr_ret_fast_path:
	; 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

;####### Return from Intr to insn in delay slot #######

; Handle special case #2: (Entry via Exception in Delay Slot, Return via IRQ)
;
; Intr returning to a Delay Slot (DS) insn
; (since IRQ NOT allowed in DS in ARCv2, this can only happen if orig
; entry was via Exception in DS which got preempted in kernel).
;
; IRQ RTIE won't reliably restore DE bit and/or BTA, needs workaround
;
; Solution is return from Intr w/o any delay slot quirks into a kernel trampoline
; and from pure kernel mode return to delay slot which handles DS bit/BTA correctly

.Lintr_ret_to_delay_slot:
debug_marker_ds:

	ld	r2, [@intr_to_DE_cnt]
	add	r2, r2, 1
	st	r2, [@intr_to_DE_cnt]

	ld	r2, [sp, PT_ret]
	ld	r3, [sp, PT_status32]

	; STAT32 for Int return created from scratch
	; (No delay dlot, disable Further intr in trampoline)

	bic  	r0, r3, STATUS_U_MASK|STATUS_DE_MASK|STATUS_IE_MASK|STATUS_L_MASK
	st	r0, [sp, PT_status32]

	mov	r1, .Lintr_ret_to_delay_slot_2
	st	r1, [sp, PT_ret]

	; Orig exception PC/STAT32 safekept @orig_r0 and @event stack slots
	st	r2, [sp, 0]
	st	r3, [sp, 4]

	b	.Lisr_ret_fast_path

.Lintr_ret_to_delay_slot_2:
	; Trampoline to restore orig exception PC/STAT32/BTA/AUX_USER_SP
	sub	sp, sp, SZ_PT_REGS
	st	r9, [sp, -4]

	ld	r9, [sp, 0]
	sr	r9, [eret]

	ld	r9, [sp, 4]
	sr	r9, [erstatus]

	; restore AUX_USER_SP if returning to U mode
	bbit0	r9, STATUS_U_BIT, 1f
	ld	r9, [sp, PT_sp]
	sr	r9, [AUX_USER_SP]

1:
	ld	r9, [sp, 8]
	sr	r9, [erbta]

	ld	r9, [sp, -4]
	add	sp, sp, SZ_PT_REGS

	; return from pure kernel mode to delay slot
	rtie

END(ret_from_exception)
Commit	Line	Data
1f6ccfff VG	1	/*
	2	* ARCv2 ISA based core Low Level Intr/Traps/Exceptions(non-TLB) Handling
	3	*
	4	* Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*/
	10
	11	#include <linux/linkage.h> /* ARC_{EXTRY,EXIT} */
	12	#include <asm/entry.h> /* SAVE_ALL_{INT1,INT2,TRAP...} */
	13	#include <asm/errno.h>
	14	#include <asm/arcregs.h>
	15	#include <asm/irqflags.h>
	16
	17	.cpu HS
	18
	19	#define VECTOR .word
	20
	21	;############################ Vector Table #################################
	22
	23	.section .vector,"a",@progbits
	24	.align 4
	25
	26	# Initial 16 slots are Exception Vectors
3971cdc2	27	VECTOR res_service ; Reset Vector
1f6ccfff VG	28	VECTOR mem_service ; Mem exception
	29	VECTOR instr_service ; Instrn Error
	30	VECTOR EV_MachineCheck ; Fatal Machine check
	31	VECTOR EV_TLBMissI ; Intruction TLB miss
	32	VECTOR EV_TLBMissD ; Data TLB miss
	33	VECTOR EV_TLBProtV ; Protection Violation
	34	VECTOR EV_PrivilegeV ; Privilege Violation
	35	VECTOR EV_SWI ; Software Breakpoint
	36	VECTOR EV_Trap ; Trap exception
	37	VECTOR EV_Extension ; Extn Instruction Exception
	38	VECTOR EV_DivZero ; Divide by Zero
	39	VECTOR EV_DCError ; Data Cache Error
	40	VECTOR EV_Misaligned ; Misaligned Data Access
	41	VECTOR reserved ; Reserved slots
	42	VECTOR reserved ; Reserved slots
	43
	44	# Begin Interrupt Vectors
	45	VECTOR handle_interrupt ; (16) Timer0
	46	VECTOR handle_interrupt ; unused (Timer1)
	47	VECTOR handle_interrupt ; unused (WDT)
	48	VECTOR handle_interrupt ; (19) ICI (inter core interrupt)
	49	VECTOR handle_interrupt
	50	VECTOR handle_interrupt
	51	VECTOR handle_interrupt
	52	VECTOR handle_interrupt ; (23) End of fixed IRQs
	53
	54	.rept CONFIG_ARC_NUMBER_OF_INTERRUPTS - 8
	55	VECTOR handle_interrupt
	56	.endr
	57
	58	.section .text, "ax",@progbits
	59
3d592659 VG	60	reserved:
3d592659 VG	61	flag 1 ; Unexpected event, halt
1f6ccfff VG	62
	63	;##################### Interrupt Handling ##############################
	64
	65	ENTRY(handle_interrupt)
	66
	67	INTERRUPT_PROLOGUE irq
	68
	69	clri ; To make status32.IE agree with CPU internal state
	70
	71	lr r0, [ICAUSE]
	72
	73	mov blink, ret_from_exception
	74
	75	b.d arch_do_IRQ
	76	mov r1, sp
	77
	78	END(handle_interrupt)
	79
	80	;################### Non TLB Exception Handling #############################
	81
	82	ENTRY(EV_SWI)
	83	flag 1
	84	END(EV_SWI)
	85
	86	ENTRY(EV_DivZero)
	87	flag 1
	88	END(EV_DivZero)
	89
	90	ENTRY(EV_DCError)
	91	flag 1
	92	END(EV_DCError)
	93
541366da VG	94	; ---------------------------------------------
	95	; Memory Error Exception Handler
	96	; - Unlike ARCompact, handles Bus errors for both User/Kernel mode,
	97	; Instruction fetch or Data access, under a single Exception Vector
	98	; ---------------------------------------------
	99
	100	ENTRY(mem_service)
	101
	102	EXCEPTION_PROLOGUE
	103
	104	lr r0, [efa]
	105	mov r1, sp
	106
	107	FAKE_RET_FROM_EXCPN
	108
	109	bl do_memory_error
	110	b ret_from_exception
	111	END(mem_service)
	112
1f6ccfff VG	113	ENTRY(EV_Misaligned)
	114
	115	EXCEPTION_PROLOGUE
	116
	117	lr r0, [efa] ; Faulting Data address
	118	mov r1, sp
	119
	120	FAKE_RET_FROM_EXCPN
	121
	122	SAVE_CALLEE_SAVED_USER
	123	mov r2, sp ; callee_regs
	124
	125	bl do_misaligned_access
	126
	127	; TBD: optimize - do this only if a callee reg was involved
	128	; either a dst of emulated LD/ST or src with address-writeback
	129	RESTORE_CALLEE_SAVED_USER
	130
	131	b ret_from_exception
	132	END(EV_Misaligned)
	133
	134	; ---------------------------------------------
	135	; Protection Violation Exception Handler
	136	; ---------------------------------------------
	137
	138	ENTRY(EV_TLBProtV)
	139
	140	EXCEPTION_PROLOGUE
	141
	142	lr r0, [efa] ; Faulting Data address
	143	mov r1, sp ; pt_regs
	144
	145	FAKE_RET_FROM_EXCPN
	146
	147	mov blink, ret_from_exception
	148	b do_page_fault
	149
	150	END(EV_TLBProtV)
	151
	152	; From Linux standpoint Slow Path I/D TLB Miss is same a ProtV as they
	153	; need to call do_page_fault().
	154	; ECR in pt_regs provides whether access was R/W/X
	155
	156	.global call_do_page_fault
	157	.set call_do_page_fault, EV_TLBProtV
	158
	159	;############# Common Handlers for ARCompact and ARCv2 ##############
	160
	161	#include "entry.S"
	162
	163	;############# Return from Intr/Excp/Trap (ARCv2 ISA Specifics) ##############
	164	;
	165	; Restore the saved sys context (common exit-path for EXCPN/IRQ/Trap)
	166	; IRQ shd definitely not happen between now and rtie
	167	; All 2 entry points to here already disable interrupts
	168
	169	.Lrestore_regs:
	170
	171	ld r0, [sp, PT_status32] ; U/K mode at time of entry
	172	lr r10, [AUX_IRQ_ACT]
	173
	174	bmsk r11, r10, 15 ; AUX_IRQ_ACT.ACTIVE
	175	breq r11, 0, .Lexcept_ret ; No intr active, ret from Exception
	176
177	;####### Return from Intr #######
178
179	debug_marker_l1:
4255b07f VG	180	bbit1.nt r0, STATUS_DE_BIT, .Lintr_ret_to_delay_slot
	181
	182	.Lisr_ret_fast_path:
1f6ccfff VG	183	; Handle special case #1: (Entry via Exception, Return via IRQ)
	184	;
	185	; Exception in U mode, preempted in kernel, Intr taken (K mode), orig
	186	; task now returning to U mode (riding the Intr)
	187	; AUX_IRQ_ACTIVE won't have U bit set (since intr in K mode), hence SP
	188	; won't be switched to correct U mode value (from AUX_SP)
	189	; So force AUX_IRQ_ACT.U for such a case
	190
	191	btst r0, STATUS_U_BIT ; Z flag set if K (Z clear for U)
	192	bset.nz r11, r11, AUX_IRQ_ACT_BIT_U ; NZ means U
	193	sr r11, [AUX_IRQ_ACT]
	194
	195	INTERRUPT_EPILOGUE irq
	196	rtie
	197
	198	;####### Return from Exception / pure kernel mode #######
	199
	200	.Lexcept_ret: ; Expects r0 has PT_status32
	201
	202	debug_marker_syscall:
	203	EXCEPTION_EPILOGUE
	204	rtie
	205
4255b07f VG	206	;####### Return from Intr to insn in delay slot #######
	207
	208	; Handle special case #2: (Entry via Exception in Delay Slot, Return via IRQ)
	209	;
	210	; Intr returning to a Delay Slot (DS) insn
	211	; (since IRQ NOT allowed in DS in ARCv2, this can only happen if orig
	212	; entry was via Exception in DS which got preempted in kernel).
	213	;
cbfe74a7 VG	214	; IRQ RTIE won't reliably restore DE bit and/or BTA, needs workaround
	215	;
	216	; Solution is return from Intr w/o any delay slot quirks into a kernel trampoline
	217	; and from pure kernel mode return to delay slot which handles DS bit/BTA correctly
	218
4255b07f VG	219	.Lintr_ret_to_delay_slot:
	220	debug_marker_ds:
	221
	222	ld r2, [@intr_to_DE_cnt]
	223	add r2, r2, 1
	224	st r2, [@intr_to_DE_cnt]
	225
	226	ld r2, [sp, PT_ret]
	227	ld r3, [sp, PT_status32]
	228
cbfe74a7 VG	229	; STAT32 for Int return created from scratch
	230	; (No delay dlot, disable Further intr in trampoline)
	231
4255b07f VG	232	bic r0, r3, STATUS_U_MASK\|STATUS_DE_MASK\|STATUS_IE_MASK\|STATUS_L_MASK
	233	st r0, [sp, PT_status32]
	234
	235	mov r1, .Lintr_ret_to_delay_slot_2
	236	st r1, [sp, PT_ret]
	237
cbfe74a7	238	; Orig exception PC/STAT32 safekept @orig_r0 and @event stack slots
4255b07f VG	239	st r2, [sp, 0]
	240	st r3, [sp, 4]
	241
	242	b .Lisr_ret_fast_path
	243
	244	.Lintr_ret_to_delay_slot_2:
cbfe74a7	245	; Trampoline to restore orig exception PC/STAT32/BTA/AUX_USER_SP
4255b07f VG	246	sub sp, sp, SZ_PT_REGS
	247	st r9, [sp, -4]
	248
	249	ld r9, [sp, 0]
	250	sr r9, [eret]
	251
	252	ld r9, [sp, 4]
	253	sr r9, [erstatus]
	254
cbfe74a7 VG	255	; restore AUX_USER_SP if returning to U mode
	256	bbit0 r9, STATUS_U_BIT, 1f
	257	ld r9, [sp, PT_sp]
	258	sr r9, [AUX_USER_SP]
	259
	260	1:
4255b07f VG	261	ld r9, [sp, 8]
	262	sr r9, [erbta]
	263
	264	ld r9, [sp, -4]
	265	add sp, sp, SZ_PT_REGS
cbfe74a7 VG	266
cbfe74a7 VG	267	; return from pure kernel mode to delay slot
4255b07f VG	268	rtie
4255b07f VG	269
1f6ccfff	270	END(ret_from_exception)