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Diffstat (limited to 'arch/arc/kernel/entry-arcv2.S')
| -rw-r--r-- | arch/arc/kernel/entry-arcv2.S | 263 |
1 files changed, 263 insertions, 0 deletions
diff --git a/arch/arc/kernel/entry-arcv2.S b/arch/arc/kernel/entry-arcv2.S new file mode 100644 index 000000000..12d5f12d1 --- /dev/null +++ b/arch/arc/kernel/entry-arcv2.S @@ -0,0 +1,263 @@ +/* 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> + +; 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 + + 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: +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) |