1 files changed, 249 insertions, 0 deletions
diff --git a/arch/arc/kernel/entry-arcv2.S b/arch/arc/kernel/entry-arcv2.S
new file mode 100644
index 0000000000..2e49c81c80
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+++ b/arch/arc/kernel/entry-arcv2.S
@@ -0,0 +1,249 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * ARCv2 ISA based core Low Level Intr/Traps/Exceptions(non-TLB) Handling
+ *
+ * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
+ */
+
+#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>
+#include <asm/mmu.h>
+
+; A maximum number of supported interrupts in the core interrupt controller.
+; This number is not equal to the maximum interrupt number (256) because
+; first 16 lines are reserved for exceptions and are not configurable.
+#define NR_CPU_IRQS	240
+
+	.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) Inter core Interrupt (IPI)
+VECTOR	handle_interrupt	; (20) perf Interrupt
+VECTOR	handle_interrupt	; (21) Software Triggered Intr (Self IPI)
+VECTOR	handle_interrupt	; unused
+VECTOR	handle_interrupt	; (23) unused
+# End of fixed IRQs
+
+.rept NR_CPU_IRQS - 8
+	VECTOR	handle_interrupt
+.endr
+
+	.section .text, "ax",@progbits
+
+reserved:
+	flag 1		; Unexpected event, halt
+
+;##################### Interrupt Handling ##############################
+
+ENTRY(handle_interrupt)
+
+	INTERRUPT_PROLOGUE
+
+	# irq control APIs local_irq_save/restore/disable/enable fiddle with
+	# global interrupt enable bits in STATUS32 (.IE for 1 prio, .E[] for 2 prio)
+	# However a taken interrupt doesn't clear these bits. Thus irqs_disabled()
+	# query in hard ISR path would return false (since .IE is set) which would
+	# trips genirq interrupt handling asserts.
+	#
+	# So do a "soft" disable of interrutps here.
+	#
+	# Note this disable is only for consistent book-keeping as further interrupts
+	# will be disabled anyways even w/o this. Hardware tracks active interrupts
+	# seperately in AUX_IRQ_ACT.active and will not take new interrupts
+	# unless this one returns (or higher prio becomes pending in 2-prio scheme)
+
+	IRQ_DISABLE
+
+	; icause is banked: one per priority level
+	; so a higher prio interrupt taken here won't clobber prev prio icause
+	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)
+	; TODO: implement this
+	EXCEPTION_PROLOGUE
+	b   ret_from_exception
+END(EV_SWI)
+
+ENTRY(EV_DivZero)
+	; TODO: implement this
+	EXCEPTION_PROLOGUE
+	b   ret_from_exception
+END(EV_DivZero)
+
+ENTRY(EV_DCError)
+	; TODO: implement this
+	EXCEPTION_PROLOGUE
+	b   ret_from_exception
+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
+
+	bl  do_memory_error
+	b   ret_from_exception
+END(mem_service)
+
+ENTRY(EV_Misaligned)
+
+	EXCEPTION_PROLOGUE
+
+	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
+
+	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:
+restore_regs:
+
+	# Interrpts are actually disabled from this point on, but will get
+	# reenabled after we return from interrupt/exception.
+	# But irq tracer needs to be told now...
+	TRACE_ASM_IRQ_ENABLE
+
+	ld	r0, [sp, PT_status32]	; U/K mode at time of entry
+	lr	r10, [AUX_IRQ_ACT]
+
+	bmsk	r11, r10, 15		; extract AUX_IRQ_ACT.active
+	breq	r11, 0, .Lexcept_ret	; No intr active, ret from Exception
+
+;####### Return from Intr #######
+
+.Lisr_ret:
+
+debug_marker_l1:
+	; bbit1.nt r0, STATUS_DE_BIT, .Lintr_ret_to_delay_slot
+	btst	r0, STATUS_DE_BIT		; Z flag set if bit clear
+	bnz	.Lintr_ret_to_delay_slot	; branch if STATUS_DE_BIT set
+
+	; 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
+	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 to drop out of interrupt context into pure kernel mode
+; and return from pure kernel mode which does right things for delay slot
+
+.Lintr_ret_to_delay_slot:
+debug_marker_ds:
+
+	ld	r2, [@intr_to_DE_cnt]
+	add	r2, r2, 1
+	st	r2, [@intr_to_DE_cnt]
+
+	; drop out of interrupt context (clear AUX_IRQ_ACT.active)
+	bmskn	r11, r10, 15
+	sr	r11, [AUX_IRQ_ACT]
+	b	.Lexcept_ret
+
+END(ret_from_exception)