/* * 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) * * 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. * * 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() nolonger 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 excpetion 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>	/* {EXTRY,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 gauranteed that 'j somewhere' * will use the 'j limm' form of the intrsuction 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_LEVELSVECTOR   handle_interrupt_level2#elseVECTOR   handle_interrupt_level1#endif .rept   28VECTOR   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, Intruction TLB miss   (0x21)VECTOR   EV_TLBMissD             ; 0x110, Data TLB miss         (0x22)VECTOR   EV_TLBProtV             ; 0x118, Protection Violation  (0x23)				 ;         or Misaligned AccessVECTOR   EV_PrivilegeV           ; 0x120, Privilege Violation   (0x24)VECTOR   EV_Trap                 ; 0x128, Trap exception        (0x25)VECTOR   EV_Extension            ; 0x130, Extn Intruction Excp  (0x26) .rept   24VECTOR   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, 4int1_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, 4int2_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 seperate 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	rtie1:	bl  do_memory_error	b   ret_from_exceptionEND(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_exceptionEND(handle_interrupt_level1) ;################### Non TLB Exception Handling ############################# ; ---------------------------------------------; Protection Violation Exception Handler; --------------------------------------------- ENTRY(EV_TLBProtV) 	EXCEPTION_PROLOGUE 	mov r2, r9	; ECR set into r9 already	lr  r0, [efa]	; Faulting Data address (not part of pt_regs saved above) 	; Exception auto-disables further Intr/exceptions.	; Re-enable them by pretending to return from exception	; (so rest of handler executes in pure K mode) 	FAKE_RET_FROM_EXCPN 	mov   r1, sp	; Handle to pt_regs 	;------ (5) Type of Protection Violation? ----------	;	; ProtV Hardware Exception is triggered for Access Faults of 2 types	;   -Access Violaton	: 00_23_(00|01|02|03)_00	;			         x  r  w  r+w	;   -Unaligned Access	: 00_23_04_00	;	bbit1 r2, 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	lr  r0, [efa]	; Faulting Data address	mov   r1, sp	FAKE_RET_FROM_EXCPN 	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: 	# 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 	lr	r10, [status32] 	; Restore REG File. In case multiple Events outstanding,	; use the same priorty 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 interruptdebug_marker_l2:	rtie not_level2_interrupt: #endif 	INTERRUPT_EPILOGUE 1	; return from level 1 interruptdebug_marker_l1:	rtie .Lexcep_or_pure_K_ret: 	;this case is for syscalls or Exceptions or pure kernel mode 	EXCEPTION_EPILOGUEdebug_marker_syscall:	rtie END(ret_from_exception)