/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARCompact ISA
*
* Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com)
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
* vineetg: May 2011
* -Userspace unaligned access emulation
*
* vineetg: Feb 2011 (ptrace low level code fixes)
* -traced syscall return code (r0) was not saved into pt_regs for restoring
* into user reg-file when traded task rets to user space.
* -syscalls needing arch-wrappers (mainly for passing sp as pt_regs)
* were not invoking post-syscall trace hook (jumping directly into
* ret_from_system_call)
*
* vineetg: Nov 2010:
* -Vector table jumps (@8 bytes) converted into branches (@4 bytes)
* -To maintain the slot size of 8 bytes/vector, added nop, which is
* not executed at runtime.
*
* vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK)
* -do_signal()invoked upon TIF_RESTORE_SIGMASK as well
* -Wrappers for sys_{,rt_}sigsuspend() no longer needed as they don't
* need ptregs anymore
*
* Vineetg: Oct 2009
* -In a rare scenario, Process gets a Priv-V exception and gets scheduled
* out. Since we don't do FAKE RTIE for Priv-V, CPU exception state remains
* active (AE bit enabled). This causes a double fault for a subseq valid
* exception. Thus FAKE RTIE needed in low level Priv-Violation handler.
* Instr Error could also cause similar scenario, so same there as well.
*
* Vineetg: March 2009 (Supporting 2 levels of Interrupts)
*
* Vineetg: Aug 28th 2008: Bug #94984
* -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap
* Normally CPU does this automatically, however when doing FAKE rtie,
* we need to explicitly do this. The problem in macros
* FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit
* was being "CLEARED" rather then "SET". Since it is Loop INHIBIT Bit,
* setting it and not clearing it clears ZOL context
*
* Vineetg: May 16th, 2008
* - r25 now contains the Current Task when in kernel
*
* Vineetg: Dec 22, 2007
* Minor Surgery of Low Level ISR to make it SMP safe
* - MMU_SCRATCH0 Reg used for freeing up r9 in Level 1 ISR
* - _current_task is made an array of NR_CPUS
* - Access of _current_task wrapped inside a macro so that if hardware
* team agrees for a dedicated reg, no other code is touched
*
* Amit Bhor, Rahul Trivedi, Kanika Nema, Sameer Dhavale : Codito Tech 2004
*/
#include <linux/errno.h>
#include <linux/linkage.h> /* {ENTRY,EXIT} */
#include <asm/entry.h>
#include <asm/irqflags.h>
.cpu A7
;############################ Vector Table #################################
.macro VECTOR lbl
#if 1 /* Just in case, build breaks */
j \lbl
#else
b \lbl
nop
#endif
.endm
.section .vector, "ax",@progbits
.align 4
/* Each entry in the vector table must occupy 2 words. Since it is a jump
* across sections (.vector to .text) we are guaranteed that 'j somewhere'
* will use the 'j limm' form of the instruction as long as somewhere is in
* a section other than .vector.
*/
; ********* Critical System Events **********************
VECTOR res_service ; 0x0, Reset Vector (0x0)
VECTOR mem_service ; 0x8, Mem exception (0x1)
VECTOR instr_service ; 0x10, Instrn Error (0x2)
; ******************** Device ISRs **********************
#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
VECTOR handle_interrupt_level2
#else
VECTOR handle_interrupt_level1
#endif
.rept 28
VECTOR handle_interrupt_level1 ; Other devices
.endr
/* FOR ARC600: timer = 0x3, uart = 0x8, emac = 0x10 */
; ******************** Exceptions **********************
VECTOR EV_MachineCheck ; 0x100, Fatal Machine check (0x20)
VECTOR EV_TLBMissI ; 0x108, Instruction TLB miss (0x21)
VECTOR EV_TLBMissD ; 0x110, Data TLB miss (0x22)
VECTOR EV_TLBProtV ; 0x118, Protection Violation (0x23)
; or Misaligned Access
VECTOR EV_PrivilegeV ; 0x120, Privilege Violation (0x24)
VECTOR EV_Trap ; 0x128, Trap exception (0x25)
VECTOR EV_Extension ; 0x130, Extn Instruction Excp (0x26)
.rept 24
VECTOR reserved ; Reserved Exceptions
.endr
;##################### Scratch Mem for IRQ stack switching #############
ARCFP_DATA int1_saved_reg
.align 32
.type int1_saved_reg, @object
.size int1_saved_reg, 4
int1_saved_reg:
.zero 4
/* Each Interrupt level needs its own scratch */
ARCFP_DATA int2_saved_reg
.type int2_saved_reg, @object
.size int2_saved_reg, 4
int2_saved_reg:
.zero 4
; ---------------------------------------------
.section .text, "ax",@progbits
reserved:
flag 1 ; Unexpected event, halt
;##################### Interrupt Handling ##############################
#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
; ---------------------------------------------
; Level 2 ISR: Can interrupt a Level 1 ISR
; ---------------------------------------------
ENTRY(handle_interrupt_level2)
INTERRUPT_PROLOGUE 2
;------------------------------------------------------
; if L2 IRQ interrupted a L1 ISR, disable preemption
;
; This is to avoid a potential L1-L2-L1 scenario
; -L1 IRQ taken
; -L2 interrupts L1 (before L1 ISR could run)
; -preemption off IRQ, user task in syscall picked to run
; -RTIE to userspace
; Returns from L2 context fine
; But both L1 and L2 re-enabled, so another L1 can be taken
; while prev L1 is still unserviced
;
;------------------------------------------------------
; L2 interrupting L1 implies both L2 and L1 active
; However both A2 and A1 are NOT set in STATUS32, thus
; need to check STATUS32_L2 to determine if L1 was active
ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs)
bbit0 r9, STATUS_A1_BIT, 1f ; L1 not active when L2 IRQ, so normal
; bump thread_info->preempt_count (Disable preemption)
GET_CURR_THR_INFO_FROM_SP r10
ld r9, [r10, THREAD_INFO_PREEMPT_COUNT]
add r9, r9, 1
st r9, [r10, THREAD_INFO_PREEMPT_COUNT]
1:
;------------------------------------------------------
; setup params for Linux common ISR and invoke it
;------------------------------------------------------
lr r0, [icause2]
and r0, r0, 0x1f
bl.d @arch_do_IRQ
mov r1, sp
mov r8,0x2
sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg
b ret_from_exception
END(handle_interrupt_level2)
#endif
; ---------------------------------------------
; User Mode Memory Bus Error Interrupt Handler
; (Kernel mode memory errors handled via separate exception vectors)
; ---------------------------------------------
ENTRY(mem_service)
INTERRUPT_PROLOGUE 2
mov r0, ilink2
mov r1, sp
; User process needs to be killed with SIGBUS, but first need to get
; out of the L2 interrupt context (drop to pure kernel mode) and jump
; off to "C" code where SIGBUS in enqueued
lr r3, [status32]
bclr r3, r3, STATUS_A2_BIT
or r3, r3, (STATUS_E1_MASK|STATUS_E2_MASK)
sr r3, [status32_l2]
mov ilink2, 1f
rtie
1:
bl do_memory_error
b ret_from_exception
END(mem_service)
; ---------------------------------------------
; Level 1 ISR
; ---------------------------------------------
ENTRY(handle_interrupt_level1)
INTERRUPT_PROLOGUE 1
lr r0, [icause1]
and r0, r0, 0x1f
#ifdef CONFIG_TRACE_IRQFLAGS
; icause1 needs to be read early, before calling tracing, which
; can clobber scratch regs, hence use of stack to stash it
push r0
TRACE_ASM_IRQ_DISABLE
pop r0
#endif
bl.d @arch_do_IRQ
mov r1, sp
mov r8,0x1
sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg
b ret_from_exception
END(handle_interrupt_level1)
;################### Non TLB Exception Handling #############################
; ---------------------------------------------
; Protection Violation Exception Handler
; ---------------------------------------------
ENTRY(EV_TLBProtV)
EXCEPTION_PROLOGUE ; ECR returned in r10
;------ (5) Type of Protection Violation? ----------
;
; ProtV Hardware Exception is triggered for Access Faults of 2 types
; -Access Violation : 00_23_(00|01|02|03)_00
; x r w r+w
; -Unaligned Access : 00_23_04_00
bbit1 r10, ECR_C_BIT_PROTV_MISALIG_DATA, 4f
;========= (6a) Access Violation Processing ========
bl do_page_fault
b ret_from_exception
;========== (6b) Non aligned access ============
4:
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_TLBProtV)
; Wrapper for Linux page fault handler called from EV_TLBMiss*
; Very similar to ProtV handler case (6a) above, but avoids the extra checks
; for Misaligned access
;
ENTRY(call_do_page_fault)
EXCEPTION_PROLOGUE
mov blink, ret_from_exception
b do_page_fault
END(call_do_page_fault)
;############# Common Handlers for ARCompact and ARCv2 ##############
#include "entry.S"
;############# Return from Intr/Excp/Trap (ARC 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:
# Interrupts 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
lr r10, [status32]
; Restore REG File. In case multiple Events outstanding,
; use the same priority as rtie: EXCPN, L2 IRQ, L1 IRQ, None
; Note that we use realtime STATUS32 (not pt_regs->status32) to
; decide that.
and.f 0, r10, (STATUS_A1_MASK|STATUS_A2_MASK)
bz .Lexcep_or_pure_K_ret
; Returning from Interrupts (Level 1 or 2)
#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
; Level 2 interrupt return Path - from hardware standpoint
bbit0 r10, STATUS_A2_BIT, not_level2_interrupt
;------------------------------------------------------------------
; However the context returning might not have taken L2 intr itself
; e.g. Task'A' user-code -> L2 intr -> schedule -> 'B' user-code ret
; Special considerations needed for the context which took L2 intr
ld r9, [sp, PT_event] ; Ensure this is L2 intr context
brne r9, event_IRQ2, 149f
;------------------------------------------------------------------
; if L2 IRQ interrupted an L1 ISR, we'd disabled preemption earlier
; so that sched doesn't move to new task, causing L1 to be delayed
; undeterministically. Now that we've achieved that, let's reset
; things to what they were, before returning from L2 context
;----------------------------------------------------------------
ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs)
bbit0 r9, STATUS_A1_BIT, 149f ; L1 not active when L2 IRQ, so normal
; decrement thread_info->preempt_count (re-enable preemption)
GET_CURR_THR_INFO_FROM_SP r10
ld r9, [r10, THREAD_INFO_PREEMPT_COUNT]
; paranoid check, given A1 was active when A2 happened, preempt count
; must not be 0 because we would have incremented it.
; If this does happen we simply HALT as it means a BUG !!!
cmp r9, 0
bnz 2f
flag 1
2:
sub r9, r9, 1
st r9, [r10, THREAD_INFO_PREEMPT_COUNT]
149:
INTERRUPT_EPILOGUE 2 ; return from level 2 interrupt
debug_marker_l2:
rtie
not_level2_interrupt:
#endif
INTERRUPT_EPILOGUE 1 ; return from level 1 interrupt
debug_marker_l1:
rtie
.Lexcep_or_pure_K_ret:
;this case is for syscalls or Exceptions or pure kernel mode
EXCEPTION_EPILOGUE
debug_marker_syscall:
rtie
END(ret_from_exception)