/* * linux/arch/nios2/kernel/entry.S * * Copyright (C) 2013-2014  Altera Corporation * Copyright (C) 2009, Wind River Systems Inc * * Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com * *  Copyright (C) 1999-2002, Greg Ungerer (gerg@snapgear.com) *  Copyright (C) 1998  D. Jeff Dionne <jeff@lineo.ca>, *                      Kenneth Albanowski <kjahds@kjahds.com>, *  Copyright (C) 2000  Lineo Inc. (www.lineo.com) *  Copyright (C) 2004  Microtronix Datacom Ltd. * * This file is subject to the terms and conditions of the GNU General Public * License.  See the file "COPYING" in the main directory of this archive * for more details. * * Linux/m68k support by Hamish Macdonald * * 68060 fixes by Jesper Skov * ColdFire support by Greg Ungerer (gerg@snapgear.com) * 5307 fixes by David W. Miller * linux 2.4 support David McCullough <davidm@snapgear.com> */ #include <linux/sys.h>#include <linux/linkage.h>#include <asm/asm-offsets.h>#include <asm/asm-macros.h>#include <asm/thread_info.h>#include <asm/errno.h>#include <asm/setup.h>#include <asm/entry.h>#include <asm/unistd.h>#include <asm/processor.h> .macro GET_THREAD_INFO reg.if THREAD_SIZE & 0xffff0000	andhi	\reg, sp, %hi(~(THREAD_SIZE-1)).else	addi	\reg, r0, %lo(~(THREAD_SIZE-1))	and	\reg, \reg, sp.endif.endm .macro	kuser_cmpxchg_check	/*	 * Make sure our user space atomic helper is restarted if it was	 * interrupted in a critical region.	 * ea-4 = address of interrupted insn (ea must be preserved).	 * sp = saved regs.	 * cmpxchg_ldw = first critical insn, cmpxchg_stw = last critical insn.	 * If ea <= cmpxchg_stw and ea > cmpxchg_ldw then saved EA is set to	 * cmpxchg_ldw + 4.	*/	/* et = cmpxchg_stw + 4 */	movui   et, (KUSER_BASE + 4 + (cmpxchg_stw - __kuser_helper_start))	bgtu	ea, et, 1f 	subi	et, et, (cmpxchg_stw - cmpxchg_ldw) /* et = cmpxchg_ldw + 4 */	bltu	ea, et, 1f	stw	et, PT_EA(sp)	/* fix up EA */	mov	ea, et1:.endm .section .rodata.align 4exception_table:	.word unhandled_exception	/* 0 - Reset */	.word unhandled_exception	/* 1 - Processor-only Reset */	.word external_interrupt	/* 2 - Interrupt */	.word handle_trap		/* 3 - Trap Instruction */ 	.word instruction_trap		/* 4 - Unimplemented instruction */	.word handle_illegal		/* 5 - Illegal instruction */	.word handle_unaligned		/* 6 - Misaligned data access */	.word handle_unaligned		/* 7 - Misaligned destination address */ 	.word handle_diverror		/* 8 - Division error */	.word protection_exception_ba	/* 9 - Supervisor-only instr. address */	.word protection_exception_instr /* 10 - Supervisor only instruction */	.word protection_exception_ba	/* 11 - Supervisor only data address */ 	.word unhandled_exception	/* 12 - Double TLB miss (data) */	.word protection_exception_pte	/* 13 - TLB permission violation (x) */	.word protection_exception_pte	/* 14 - TLB permission violation (r) */	.word protection_exception_pte	/* 15 - TLB permission violation (w) */ 	.word unhandled_exception	/* 16 - MPU region violation */ trap_table:	.word	handle_system_call	/* 0  */	.word	handle_trap_1		/* 1  */	.word	handle_trap_2		/* 2  */	.word	handle_trap_3		/* 3  */	.word	handle_trap_reserved	/* 4  */	.word	handle_trap_reserved	/* 5  */	.word	handle_trap_reserved	/* 6  */	.word	handle_trap_reserved	/* 7  */	.word	handle_trap_reserved	/* 8  */	.word	handle_trap_reserved	/* 9  */	.word	handle_trap_reserved	/* 10 */	.word	handle_trap_reserved	/* 11 */	.word	handle_trap_reserved	/* 12 */	.word	handle_trap_reserved	/* 13 */	.word	handle_trap_reserved	/* 14 */	.word	handle_trap_reserved	/* 15 */	.word	handle_trap_reserved	/* 16 */	.word	handle_trap_reserved	/* 17 */	.word	handle_trap_reserved	/* 18 */	.word	handle_trap_reserved	/* 19 */	.word	handle_trap_reserved	/* 20 */	.word	handle_trap_reserved	/* 21 */	.word	handle_trap_reserved	/* 22 */	.word	handle_trap_reserved	/* 23 */	.word	handle_trap_reserved	/* 24 */	.word	handle_trap_reserved	/* 25 */	.word	handle_trap_reserved	/* 26 */	.word	handle_trap_reserved	/* 27 */	.word	handle_trap_reserved	/* 28 */	.word	handle_trap_reserved	/* 29 */#ifdef CONFIG_KGDB	.word	handle_kgdb_breakpoint	/* 30 KGDB breakpoint */#else	.word	instruction_trap		/* 30 */#endif	.word	handle_breakpoint	/* 31 */ .text.set noat.set nobreak ENTRY(inthandler)	SAVE_ALL 	kuser_cmpxchg_check 	/* Clear EH bit before we get a new excpetion in the kernel	 * and after we have saved it to the exception frame. This is done	 * whether it's trap, tlb-miss or interrupt. If we don't do this	 * estatus is not updated the next exception.	 */	rdctl	r24, status	movi	r9, %lo(~STATUS_EH)	and	r24, r24, r9	wrctl	status, r24 	/* Read cause and vector and branch to the associated handler */	mov	r4, sp	rdctl	r5, exception	movia	r9, exception_table	add	r24, r9, r5	ldw	r24, 0(r24)	jmp	r24  /*********************************************************************** * Handle traps *********************************************************************** */ENTRY(handle_trap)	ldwio	r24, -4(ea)	/* instruction that caused the exception */	srli	r24, r24, 4	andi	r24, r24, 0x7c	movia	r9,trap_table	add	r24, r24, r9	ldw	r24, 0(r24)	jmp	r24  /*********************************************************************** * Handle system calls *********************************************************************** */ENTRY(handle_system_call)	/* Enable interrupts */	rdctl	r10, status	ori	r10, r10, STATUS_PIE	wrctl	status, r10 	/* Reload registers destroyed by common code. */	ldw	r4, PT_R4(sp)	ldw	r5, PT_R5(sp) local_restart:	stw	r2, PT_ORIG_R2(sp)	/* Check that the requested system call is within limits */	movui	r1, __NR_syscalls	bgeu	r2, r1, ret_invsyscall	slli	r1, r2, 2	movhi	r11, %hiadj(sys_call_table)	add	r1, r1, r11	ldw	r1, %lo(sys_call_table)(r1) 	/* Check if we are being traced */	GET_THREAD_INFO r11	ldw	r11,TI_FLAGS(r11)	BTBNZ   r11,r11,TIF_SYSCALL_TRACE,traced_system_call 	/* Execute the system call */	callr	r1 	/* If the syscall returns a negative result:	 *   Set r7 to 1 to indicate error,	 *   Negate r2 to get a positive error code	 * If the syscall returns zero or a positive value:	 *   Set r7 to 0.	 * The sigreturn system calls will skip the code below by	 * adding to register ra. To avoid destroying registers	 */translate_rc_and_ret:	movi	r1, 0	bge	r2, zero, 3f	ldw	r1, PT_ORIG_R2(sp)	addi	r1, r1, 1	beq	r1, zero, 3f	sub	r2, zero, r2	movi	r1, 13:	stw	r2, PT_R2(sp)	stw	r1, PT_R7(sp)end_translate_rc_and_ret: ret_from_exception:	ldw	r1, PT_ESTATUS(sp)	/* if so, skip resched, signals */	TSTBNZ	r1, r1, ESTATUS_EU, Luser_return restore_all:	rdctl	r10, status			/* disable intrs */	andi	r10, r10, %lo(~STATUS_PIE)	wrctl	status, r10	RESTORE_ALL	eret 	/* If the syscall number was invalid return ENOSYS */ret_invsyscall:	movi	r2, -ENOSYS	br	translate_rc_and_ret 	/* This implements the same as above, except it calls	 * do_syscall_trace_enter and do_syscall_trace_exit before and after the	 * syscall in order for utilities like strace and gdb to work.	 */traced_system_call:	SAVE_SWITCH_STACK	call	do_syscall_trace_enter	RESTORE_SWITCH_STACK 	/* Create system call register arguments. The 5th and 6th	   arguments on stack are already in place at the beginning	   of pt_regs. */	ldw	r2, PT_R2(sp)	ldw	r4, PT_R4(sp)	ldw	r5, PT_R5(sp)	ldw	r6, PT_R6(sp)	ldw	r7, PT_R7(sp) 	/* Fetch the syscall function. */	movui	r1, __NR_syscalls	bgeu	r2, r1, traced_invsyscall	slli	r1, r2, 2	movhi	r11,%hiadj(sys_call_table)	add	r1, r1, r11	ldw	r1, %lo(sys_call_table)(r1) 	callr	r1 	/* If the syscall returns a negative result:	 *   Set r7 to 1 to indicate error,	 *   Negate r2 to get a positive error code	 * If the syscall returns zero or a positive value:	 *   Set r7 to 0.	 * The sigreturn system calls will skip the code below by	 * adding to register ra. To avoid destroying registers	 */translate_rc_and_ret2:	movi	r1, 0	bge	r2, zero, 4f	ldw	r1, PT_ORIG_R2(sp)	addi	r1, r1, 1	beq	r1, zero, 4f	sub	r2, zero, r2	movi	r1, 14:	stw	r2, PT_R2(sp)	stw	r1, PT_R7(sp)end_translate_rc_and_ret2:	SAVE_SWITCH_STACK	call	do_syscall_trace_exit	RESTORE_SWITCH_STACK	br	ret_from_exception 	/* If the syscall number was invalid return ENOSYS */traced_invsyscall:	movi	r2, -ENOSYS	br	translate_rc_and_ret2 Luser_return:	GET_THREAD_INFO	r11			/* get thread_info pointer */	ldw	r10, TI_FLAGS(r11)		/* get thread_info->flags */	ANDI32	r11, r10, _TIF_WORK_MASK	beq	r11, r0, restore_all		/* Nothing to do */	BTBZ	r1, r10, TIF_NEED_RESCHED, Lsignal_return 	/* Reschedule work */	call	schedule	br	ret_from_exception Lsignal_return:	ANDI32	r1, r10, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME	beq	r1, r0, restore_all	mov	r4, sp			/* pt_regs */	SAVE_SWITCH_STACK	call	do_notify_resume	beq	r2, r0, no_work_pending	RESTORE_SWITCH_STACK	/* prepare restart syscall here without leaving kernel */	ldw	r2, PT_R2(sp)	/* reload syscall number in r2 */	ldw 	r4, PT_R4(sp)	/* reload syscall arguments r4-r9 */	ldw 	r5, PT_R5(sp)	ldw 	r6, PT_R6(sp)	ldw 	r7, PT_R7(sp)	ldw 	r8, PT_R8(sp)	ldw 	r9, PT_R9(sp)	br	local_restart	/* restart syscall */ no_work_pending:	RESTORE_SWITCH_STACK	br	ret_from_exception /*********************************************************************** * Handle external interrupts. *********************************************************************** *//* * This is the generic interrupt handler (for all hardware interrupt * sources). It figures out the vector number and calls the appropriate * interrupt service routine directly. */external_interrupt:	rdctl	r12, ipending	rdctl	r9, ienable	and	r12, r12, r9	/* skip if no interrupt is pending */	beq	r12, r0, ret_from_interrupt 	/*	 * Process an external hardware interrupt.	 */ 	addi	ea, ea, -4	/* re-issue the interrupted instruction */	stw	ea, PT_EA(sp)2:	movi	r4, %lo(-1)	/* Start from bit position 0,					highest priority */				/* This is the IRQ # for handler call */1:	andi	r10, r12, 1	/* Isolate bit we are interested in */	srli	r12, r12, 1	/* shift count is costly without hardware					multiplier */	addi	r4, r4, 1	beq	r10, r0, 1b	mov	r5, sp		/* Setup pt_regs pointer for handler call */	call	do_IRQ	rdctl	r12, ipending	/* check again if irq still pending */	rdctl	r9, ienable	/* Isolate possible interrupts */	and	r12, r12, r9	bne	r12, r0, 2b	/* br	ret_from_interrupt */ /* fall through to ret_from_interrupt */ ENTRY(ret_from_interrupt)	ldw	r1, PT_ESTATUS(sp)	/* check if returning to kernel */	TSTBNZ	r1, r1, ESTATUS_EU, Luser_return #ifdef CONFIG_PREEMPTION	GET_THREAD_INFO	r1	ldw	r4, TI_PREEMPT_COUNT(r1)	bne	r4, r0, restore_all	ldw	r4, TI_FLAGS(r1)		/* ? Need resched set */	BTBZ	r10, r4, TIF_NEED_RESCHED, restore_all	ldw	r4, PT_ESTATUS(sp)	/* ? Interrupts off */	andi	r10, r4, ESTATUS_EPIE	beq	r10, r0, restore_all	call	preempt_schedule_irq#endif	br	restore_all /*********************************************************************** * A few syscall wrappers *********************************************************************** *//* * int clone(unsigned long clone_flags, unsigned long newsp, *		int __user * parent_tidptr, int __user * child_tidptr, *		int tls_val) */ENTRY(sys_clone)	SAVE_SWITCH_STACK	subi    sp, sp, 4 /* make space for tls pointer */	stw     r8, 0(sp) /* pass tls pointer (r8) via stack (5th argument) */	call	nios2_clone	addi    sp, sp, 4	RESTORE_SWITCH_STACK	ret/* long syscall(SYS_clone3, struct clone_args *cl_args, size_t size); */ENTRY(__sys_clone3)	SAVE_SWITCH_STACK	call	sys_clone3	RESTORE_SWITCH_STACK	ret ENTRY(sys_rt_sigreturn)	SAVE_SWITCH_STACK	mov	r4, sp	call	do_rt_sigreturn	RESTORE_SWITCH_STACK	addi	ra, ra, (end_translate_rc_and_ret - translate_rc_and_ret)	ret /*********************************************************************** * A few other wrappers and stubs *********************************************************************** */protection_exception_pte:	rdctl	r6, pteaddr	slli	r6, r6, 10	call	do_page_fault	br	ret_from_exception protection_exception_ba:	rdctl	r6, badaddr	call	do_page_fault	br	ret_from_exception protection_exception_instr:	call	handle_supervisor_instr	br	ret_from_exception handle_breakpoint:	call	breakpoint_c	br	ret_from_exception #ifdef CONFIG_NIOS2_ALIGNMENT_TRAPhandle_unaligned:	SAVE_SWITCH_STACK	call	handle_unaligned_c	RESTORE_SWITCH_STACK	br	ret_from_exception#elsehandle_unaligned:	call	handle_unaligned_c	br	ret_from_exception#endif handle_illegal:	call	handle_illegal_c	br	ret_from_exception handle_diverror:	call	handle_diverror_c	br	ret_from_exception #ifdef CONFIG_KGDBhandle_kgdb_breakpoint:	call	kgdb_breakpoint_c	br	ret_from_exception#endif handle_trap_1:	call	handle_trap_1_c	br	ret_from_exception handle_trap_2:	call	handle_trap_2_c	br	ret_from_exception handle_trap_3:handle_trap_reserved:	call	handle_trap_3_c	br	ret_from_exception /* * Beware - when entering resume, prev (the current task) is * in r4, next (the new task) is in r5, don't change these * registers. */ENTRY(resume) 	rdctl	r7, status			/* save thread status reg */	stw	r7, TASK_THREAD + THREAD_KPSR(r4) 	andi	r7, r7, %lo(~STATUS_PIE)	/* disable interrupts */	wrctl	status, r7 	SAVE_SWITCH_STACK	stw	sp, TASK_THREAD + THREAD_KSP(r4)/* save kernel stack pointer */	ldw	sp, TASK_THREAD + THREAD_KSP(r5)/* restore new thread stack */	movia	r24, _current_thread		/* save thread */	GET_THREAD_INFO r1

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