arch/avr32/kernel/entry-avr32b.S - LeafOS-Devices/android_kernel_samsung_universal7904 - Gitiles

 /*
  * Copyright (C) 2004-2006 Atmel Corporation
  *
  * 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.
  */

 /*
  * This file contains the low-level entry-points into the kernel, that is,
  * exception handlers, debug trap handlers, interrupt handlers and the
  * system call handler.
  */
 #include <linux/errno.h>

 #include <asm/asm.h>
 #include <asm/hardirq.h>
 #include <asm/irq.h>
 #include <asm/ocd.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/ptrace.h>
 #include <asm/sysreg.h>
 #include <asm/thread_info.h>
 #include <asm/unistd.h>

 #ifdef CONFIG_PREEMPT
 # define preempt_stop		mask_interrupts
 #else
 # define preempt_stop
 # define fault_resume_kernel	fault_restore_all
 #endif

 #define __MASK(x)	((1 << (x)) - 1)
 #define IRQ_MASK	((__MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT) | \
 			 (__MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT))

 	.section .ex.text,"ax",@progbits
 	.align	2
 exception_vectors:
 	bral	handle_critical
 	.align	2
 	bral	handle_critical
 	.align	2
 	bral	do_bus_error_write
 	.align	2
 	bral	do_bus_error_read
 	.align	2
 	bral	do_nmi_ll
 	.align	2
 	bral	handle_address_fault
 	.align	2
 	bral	handle_protection_fault
 	.align	2
 	bral	handle_debug
 	.align	2
 	bral	do_illegal_opcode_ll
 	.align	2
 	bral	do_illegal_opcode_ll
 	.align	2
 	bral	do_illegal_opcode_ll
 	.align	2
 	bral	do_fpe_ll
 	.align	2
 	bral	do_illegal_opcode_ll
 	.align	2
 	bral	handle_address_fault
 	.align	2
 	bral	handle_address_fault
 	.align	2
 	bral	handle_protection_fault
 	.align	2
 	bral	handle_protection_fault
 	.align	2
 	bral	do_dtlb_modified

 	/*
 	 * r0 :	PGD/PT/PTE
 	 * r1 : Offending address
 	 * r2 : Scratch register
 	 * r3 : Cause (5, 12 or 13)
 	 */
 #define	tlbmiss_save	pushm	r0-r3
 #define tlbmiss_restore	popm	r0-r3

 	.section .tlbx.ex.text,"ax",@progbits
 	.global	itlb_miss
 itlb_miss:
 	tlbmiss_save
 	rjmp	tlb_miss_common

 	.section .tlbr.ex.text,"ax",@progbits
 dtlb_miss_read:
 	tlbmiss_save
 	rjmp	tlb_miss_common

 	.section .tlbw.ex.text,"ax",@progbits
 dtlb_miss_write:
 	tlbmiss_save

 	.global	tlb_miss_common
 tlb_miss_common:
 	mfsr	r0, SYSREG_TLBEAR
 	mfsr	r1, SYSREG_PTBR

 	/* Is it the vmalloc space? */
 	bld	r0, 31
 	brcs	handle_vmalloc_miss

 	/* First level lookup */
 pgtbl_lookup:
 	lsr	r2, r0, PGDIR_SHIFT
 	ld.w	r3, r1[r2 << 2]
 	bfextu	r1, r0, PAGE_SHIFT, PGDIR_SHIFT - PAGE_SHIFT
 	bld	r3, _PAGE_BIT_PRESENT
 	brcc	page_table_not_present

 	/* Translate to virtual address in P1. */
 	andl	r3, 0xf000
 	sbr	r3, 31

 	/* Second level lookup */
 	ld.w	r2, r3[r1 << 2]
 	mfsr	r0, SYSREG_TLBARLO
 	bld	r2, _PAGE_BIT_PRESENT
 	brcc	page_not_present

 	/* Mark the page as accessed */
 	sbr	r2, _PAGE_BIT_ACCESSED
 	st.w	r3[r1 << 2], r2

 	/* Drop software flags */
 	andl	r2, _PAGE_FLAGS_HARDWARE_MASK & 0xffff
 	mtsr	SYSREG_TLBELO, r2

 	/* Figure out which entry we want to replace */
 	mfsr	r1, SYSREG_MMUCR
 	clz	r2, r0
 	brcc	1f
 	mov	r3, -1			/* All entries have been accessed, */
 	mov	r2, 0			/* so start at 0 */
 	mtsr	SYSREG_TLBARLO, r3	/* and reset TLBAR */

 1:	bfins	r1, r2, SYSREG_DRP_OFFSET, SYSREG_DRP_SIZE
 	mtsr	SYSREG_MMUCR, r1
 	tlbw

 	tlbmiss_restore
 	rete

 handle_vmalloc_miss:
 	/* Simply do the lookup in init's page table */
 	mov	r1, lo(swapper_pg_dir)
 	orh	r1, hi(swapper_pg_dir)
 	rjmp	pgtbl_lookup


 	/* ---                    System Call                    --- */

 	.section .scall.text,"ax",@progbits
 system_call:
 #ifdef CONFIG_PREEMPT
 	mask_interrupts
 #endif
 	pushm	r12		/* r12_orig */
 	stmts	--sp, r0-lr

 	mfsr	r0, SYSREG_RAR_SUP
 	mfsr	r1, SYSREG_RSR_SUP
 #ifdef CONFIG_PREEMPT
 	unmask_interrupts
 #endif
 	zero_fp
 	stm	--sp, r0-r1

 	/* check for syscall tracing */
 	get_thread_info r0
 	ld.w	r1, r0[TI_flags]
 	bld	r1, TIF_SYSCALL_TRACE
 	brcs	syscall_trace_enter

 syscall_trace_cont:
 	cp.w	r8, NR_syscalls
 	brhs	syscall_badsys

 	lddpc   lr, syscall_table_addr
 	ld.w    lr, lr[r8 << 2]
 	mov	r8, r5		/* 5th argument (6th is pushed by stub) */
 	icall   lr

 	.global	syscall_return
 syscall_return:
 	get_thread_info r0
 	mask_interrupts		/* make sure we don't miss an interrupt
 				   setting need_resched or sigpending
 				   between sampling and the rets */

 	/* Store the return value so that the correct value is loaded below */
 	stdsp   sp[REG_R12], r12

 	ld.w	r1, r0[TI_flags]
 	andl	r1, _TIF_ALLWORK_MASK, COH
 	brne	syscall_exit_work

 syscall_exit_cont:
 	popm	r8-r9
 	mtsr	SYSREG_RAR_SUP, r8
 	mtsr	SYSREG_RSR_SUP, r9
 	ldmts	sp++, r0-lr
 	sub	sp, -4		/* r12_orig */
 	rets

 	.align	2
 syscall_table_addr:
 	.long   sys_call_table

 syscall_badsys:
 	mov	r12, -ENOSYS
 	rjmp	syscall_return

 	.global ret_from_fork
 ret_from_fork:
 	rcall   schedule_tail

 	/* check for syscall tracing */
 	get_thread_info r0
 	ld.w	r1, r0[TI_flags]
 	andl	r1, _TIF_ALLWORK_MASK, COH
 	brne	syscall_exit_work
 	rjmp    syscall_exit_cont

 syscall_trace_enter:
 	pushm	r8-r12
 	rcall	syscall_trace
 	popm	r8-r12
 	rjmp	syscall_trace_cont

 syscall_exit_work:
 	bld	r1, TIF_SYSCALL_TRACE
 	brcc	1f
 	unmask_interrupts
 	rcall	syscall_trace
 	mask_interrupts
 	ld.w	r1, r0[TI_flags]

 1:	bld	r1, TIF_NEED_RESCHED
 	brcc	2f
 	unmask_interrupts
 	rcall	schedule
 	mask_interrupts
 	ld.w	r1, r0[TI_flags]
 	rjmp	1b

 2:	mov	r2, _TIF_SIGPENDING | _TIF_RESTORE_SIGMASK
 	tst	r1, r2
 	breq	3f
 	unmask_interrupts
 	mov	r12, sp
 	mov	r11, r0
 	rcall	do_notify_resume
 	mask_interrupts
 	ld.w	r1, r0[TI_flags]
 	rjmp	1b

 3:	bld	r1, TIF_BREAKPOINT
 	brcc	syscall_exit_cont
 	mfsr	r3, SYSREG_TLBEHI
 	lddsp	r2, sp[REG_PC]
 	andl	r3, 0xff, COH
 	lsl	r3, 1
 	sbr	r3, 30
 	sbr	r3, 0
 	mtdr	DBGREG_BWA2A, r2
 	mtdr	DBGREG_BWC2A, r3
 	rjmp	syscall_exit_cont


 	/* The slow path of the TLB miss handler */
 page_table_not_present:
 page_not_present:
 	tlbmiss_restore
 	sub	sp, 4
 	stmts	--sp, r0-lr
 	rcall	save_full_context_ex
 	mfsr	r12, SYSREG_ECR
 	mov	r11, sp
 	rcall	do_page_fault
 	rjmp	ret_from_exception

 	/* This function expects to find offending PC in SYSREG_RAR_EX */
 save_full_context_ex:
 	mfsr	r8, SYSREG_RSR_EX
 	mov	r12, r8
 	andh	r8, (MODE_MASK >> 16), COH
 	mfsr	r11, SYSREG_RAR_EX
 	brne	2f

 1:	pushm	r11, r12	/* PC and SR */
 	unmask_exceptions
 	ret	r12

 2:	sub	r10, sp, -(FRAME_SIZE_FULL - REG_LR)
 	stdsp	sp[4], r10	/* replace saved SP */
 	rjmp	1b

 	/* Low-level exception handlers */
 handle_critical:
 	pushm	r12
 	pushm	r0-r12
 	rcall	save_full_context_ex
 	mfsr	r12, SYSREG_ECR
 	mov	r11, sp
 	rcall	do_critical_exception

 	/* We should never get here... */
 bad_return:
 	sub	r12, pc, (. - 1f)
 	bral	panic
 	.align	2
 1:	.asciz	"Return from critical exception!"

 	.align	1
 do_bus_error_write:
 	sub	sp, 4
 	stmts	--sp, r0-lr
 	rcall	save_full_context_ex
 	mov	r11, 1
 	rjmp	1f

 do_bus_error_read:
 	sub	sp, 4
 	stmts	--sp, r0-lr
 	rcall	save_full_context_ex
 	mov	r11, 0
 1:	mfsr	r12, SYSREG_BEAR
 	mov	r10, sp
 	rcall	do_bus_error
 	rjmp	ret_from_exception

 	.align	1
 do_nmi_ll:
 	sub	sp, 4
 	stmts	--sp, r0-lr
 	mfsr	r9, SYSREG_RSR_NMI
 	mfsr	r8, SYSREG_RAR_NMI
 	bfextu	r0, r9, MODE_SHIFT, 3
 	brne	2f

 1:	pushm	r8, r9	/* PC and SR */
 	mfsr	r12, SYSREG_ECR
 	mov	r11, sp
 	rcall	do_nmi
 	popm	r8-r9
 	mtsr	SYSREG_RAR_NMI, r8
 	tst	r0, r0
 	mtsr	SYSREG_RSR_NMI, r9
 	brne	3f

 	ldmts	sp++, r0-lr
 	sub	sp, -4		/* skip r12_orig */
 	rete

 2:	sub	r10, sp, -(FRAME_SIZE_FULL - REG_LR)
 	stdsp	sp[4], r10	/* replace saved SP */
 	rjmp	1b

 3:	popm	lr
 	sub	sp, -4		/* skip sp */
 	popm	r0-r12
 	sub	sp, -4		/* skip r12_orig */
 	rete

 handle_address_fault:
 	sub	sp, 4
 	stmts	--sp, r0-lr
 	rcall	save_full_context_ex
 	mfsr	r12, SYSREG_ECR
 	mov	r11, sp
 	rcall	do_address_exception
 	rjmp	ret_from_exception

 handle_protection_fault:
 	sub	sp, 4
 	stmts	--sp, r0-lr
 	rcall	save_full_context_ex
 	mfsr	r12, SYSREG_ECR
 	mov	r11, sp
 	rcall	do_page_fault
 	rjmp	ret_from_exception

 	.align	1
 do_illegal_opcode_ll:
 	sub	sp, 4
 	stmts	--sp, r0-lr
 	rcall	save_full_context_ex
 	mfsr	r12, SYSREG_ECR
 	mov	r11, sp
 	rcall	do_illegal_opcode
 	rjmp	ret_from_exception

 do_dtlb_modified:
 	pushm	r0-r3
 	mfsr	r1, SYSREG_TLBEAR
 	mfsr	r0, SYSREG_PTBR
 	lsr	r2, r1, PGDIR_SHIFT
 	ld.w	r0, r0[r2 << 2]
 	lsl	r1, (32 - PGDIR_SHIFT)
 	lsr	r1, (32 - PGDIR_SHIFT) + PAGE_SHIFT

 	/* Translate to virtual address in P1 */
 	andl	r0, 0xf000
 	sbr	r0, 31
 	add	r2, r0, r1 << 2
 	ld.w	r3, r2[0]
 	sbr	r3, _PAGE_BIT_DIRTY
 	mov	r0, r3
 	st.w	r2[0], r3

 	/* The page table is up-to-date. Update the TLB entry as well */
 	andl	r0, lo(_PAGE_FLAGS_HARDWARE_MASK)
 	mtsr	SYSREG_TLBELO, r0

 	/* MMUCR[DRP] is updated automatically, so let's go... */
 	tlbw

 	popm	r0-r3
 	rete

 do_fpe_ll:
 	sub	sp, 4
 	stmts	--sp, r0-lr
 	rcall	save_full_context_ex
 	unmask_interrupts
 	mov	r12, 26
 	mov	r11, sp
 	rcall	do_fpe
 	rjmp	ret_from_exception

 ret_from_exception:
 	mask_interrupts
 	lddsp	r4, sp[REG_SR]
 	andh	r4, (MODE_MASK >> 16), COH
 	brne	fault_resume_kernel

 	get_thread_info r0
 	ld.w	r1, r0[TI_flags]
 	andl	r1, _TIF_WORK_MASK, COH
 	brne	fault_exit_work

 fault_resume_user:
 	popm	r8-r9
 	mask_exceptions
 	mtsr	SYSREG_RAR_EX, r8
 	mtsr	SYSREG_RSR_EX, r9
 	ldmts	sp++, r0-lr
 	sub	sp, -4
 	rete

 fault_resume_kernel:
 #ifdef CONFIG_PREEMPT
 	get_thread_info	r0
 	ld.w	r2, r0[TI_preempt_count]
 	cp.w	r2, 0
 	brne	1f
 	ld.w	r1, r0[TI_flags]
 	bld	r1, TIF_NEED_RESCHED
 	brcc	1f
 	lddsp	r4, sp[REG_SR]
 	bld	r4, SYSREG_GM_OFFSET
 	brcs	1f
 	rcall	preempt_schedule_irq
 1:
 #endif

 	popm	r8-r9
 	mask_exceptions
 	mfsr	r1, SYSREG_SR
 	mtsr	SYSREG_RAR_EX, r8
 	mtsr	SYSREG_RSR_EX, r9
 	popm	lr
 	sub	sp, -4		/* ignore SP */
 	popm	r0-r12
 	sub	sp, -4		/* ignore r12_orig */
 	rete

 irq_exit_work:
 	/* Switch to exception mode so that we can share the same code. */
 	mfsr	r8, SYSREG_SR
 	cbr	r8, SYSREG_M0_OFFSET
 	orh	r8, hi(SYSREG_BIT(M1) | SYSREG_BIT(M2))
 	mtsr	SYSREG_SR, r8
 	sub	pc, -2
 	get_thread_info r0
 	ld.w	r1, r0[TI_flags]

 fault_exit_work:
 	bld	r1, TIF_NEED_RESCHED
 	brcc	1f
 	unmask_interrupts
 	rcall	schedule
 	mask_interrupts
 	ld.w	r1, r0[TI_flags]
 	rjmp	fault_exit_work

 1:	mov	r2, _TIF_SIGPENDING | _TIF_RESTORE_SIGMASK
 	tst	r1, r2
 	breq	2f
 	unmask_interrupts
 	mov	r12, sp
 	mov	r11, r0
 	rcall	do_notify_resume
 	mask_interrupts
 	ld.w	r1, r0[TI_flags]
 	rjmp	fault_exit_work

 2:	bld	r1, TIF_BREAKPOINT
 	brcc	fault_resume_user
 	mfsr	r3, SYSREG_TLBEHI
 	lddsp	r2, sp[REG_PC]
 	andl	r3, 0xff, COH
 	lsl	r3, 1
 	sbr	r3, 30
 	sbr	r3, 0
 	mtdr	DBGREG_BWA2A, r2
 	mtdr	DBGREG_BWC2A, r3
 	rjmp	fault_resume_user

 	/* If we get a debug trap from privileged context we end up here */
 handle_debug_priv:
 	/* Fix up LR and SP in regs. r11 contains the mode we came from */
 	mfsr	r8, SYSREG_SR
 	mov	r9, r8
 	andh	r8, hi(~MODE_MASK)
 	or	r8, r11
 	mtsr	SYSREG_SR, r8
 	sub	pc, -2
 	stdsp	sp[REG_LR], lr
 	mtsr	SYSREG_SR, r9
 	sub	pc, -2
 	sub	r10, sp, -FRAME_SIZE_FULL
 	stdsp	sp[REG_SP], r10
 	mov	r12, sp
 	rcall	do_debug_priv

 	/* Now, put everything back */
 	ssrf	SR_EM_BIT
 	popm	r10, r11
 	mtsr	SYSREG_RAR_DBG, r10
 	mtsr	SYSREG_RSR_DBG, r11
 	mfsr	r8, SYSREG_SR
 	mov	r9, r8
 	andh	r8, hi(~MODE_MASK)
 	andh	r11, hi(MODE_MASK)
 	or	r8, r11
 	mtsr	SYSREG_SR, r8
 	sub	pc, -2
 	popm	lr
 	mtsr	SYSREG_SR, r9
 	sub	pc, -2
 	sub	sp, -4		/* skip SP */
 	popm	r0-r12
 	sub	sp, -4
 	retd

 	/*
 	 * At this point, everything is masked, that is, interrupts,
 	 * exceptions and debugging traps. We might get called from
 	 * interrupt or exception context in some rare cases, but this
 	 * will be taken care of by do_debug(), so we're not going to
 	 * do a 100% correct context save here.
 	 */
 handle_debug:
 	sub	sp, 4		/* r12_orig */
 	stmts	--sp, r0-lr
 	mfsr	r10, SYSREG_RAR_DBG
 	mfsr	r11, SYSREG_RSR_DBG
 	unmask_exceptions
 	pushm	r10,r11
 	andh	r11, (MODE_MASK >> 16), COH
 	brne	handle_debug_priv

 	mov	r12, sp
 	rcall	do_debug

 	lddsp	r10, sp[REG_SR]
 	andh	r10, (MODE_MASK >> 16), COH
 	breq	debug_resume_user

 debug_restore_all:
 	popm	r10,r11
 	mask_exceptions
 	mtsr	SYSREG_RSR_DBG, r11
 	mtsr	SYSREG_RAR_DBG, r10
 	ldmts	sp++, r0-lr
 	sub	sp, -4
 	retd

 debug_resume_user:
 	get_thread_info r0
 	mask_interrupts

 	ld.w	r1, r0[TI_flags]
 	andl	r1, _TIF_DBGWORK_MASK, COH
 	breq	debug_restore_all

 1:	bld	r1, TIF_NEED_RESCHED
 	brcc	2f
 	unmask_interrupts
 	rcall	schedule
 	mask_interrupts
 	ld.w	r1, r0[TI_flags]
 	rjmp	1b

 2:	mov	r2, _TIF_SIGPENDING | _TIF_RESTORE_SIGMASK
 	tst	r1, r2
 	breq	3f
 	unmask_interrupts
 	mov	r12, sp
 	mov	r11, r0
 	rcall	do_notify_resume
 	mask_interrupts
 	ld.w	r1, r0[TI_flags]
 	rjmp	1b

 3:	bld	r1, TIF_SINGLE_STEP
 	brcc	debug_restore_all
 	mfdr	r2, DBGREG_DC
 	sbr	r2, DC_SS_BIT
 	mtdr	DBGREG_DC, r2
 	rjmp	debug_restore_all

 	.set	rsr_int0,	SYSREG_RSR_INT0
 	.set	rsr_int1,	SYSREG_RSR_INT1
 	.set	rsr_int2,	SYSREG_RSR_INT2
 	.set	rsr_int3,	SYSREG_RSR_INT3
 	.set	rar_int0,	SYSREG_RAR_INT0
 	.set	rar_int1,	SYSREG_RAR_INT1
 	.set	rar_int2,	SYSREG_RAR_INT2
 	.set	rar_int3,	SYSREG_RAR_INT3

 	.macro	IRQ_LEVEL level
 	.type	irq_level\level, @function
 irq_level\level:
 	sub	sp, 4		/* r12_orig */
 	stmts	--sp,r0-lr
 	mfsr	r8, rar_int\level
 	mfsr	r9, rsr_int\level

 #ifdef CONFIG_PREEMPT
 	sub	r11, pc, (. - system_call)
 	cp.w	r11, r8
 	breq	4f
 #endif

 	pushm	r8-r9

 	mov	r11, sp
 	mov	r12, \level

 	rcall	do_IRQ

 	lddsp	r4, sp[REG_SR]
 	bfextu	r4, r4, SYSREG_M0_OFFSET, 3
 	cp.w	r4, MODE_SUPERVISOR >> SYSREG_M0_OFFSET
 	breq	2f
 	cp.w	r4, MODE_USER >> SYSREG_M0_OFFSET
 #ifdef CONFIG_PREEMPT
 	brne	3f
 #else
 	brne	1f
 #endif

 	get_thread_info	r0
 	ld.w	r1, r0[TI_flags]
 	andl	r1, _TIF_WORK_MASK, COH
 	brne	irq_exit_work

 1:	popm	r8-r9
 	mtsr	rar_int\level, r8
 	mtsr	rsr_int\level, r9
 	ldmts	sp++,r0-lr
 	sub	sp, -4		/* ignore r12_orig */
 	rete

 #ifdef CONFIG_PREEMPT
 4:	mask_interrupts
 	mfsr	r8, rsr_int\level
 	sbr	r8, 16
 	mtsr	rsr_int\level, r8
 	ldmts	sp++, r0-lr
 	sub	sp, -4		/* ignore r12_orig */
 	rete
 #endif

 2:	get_thread_info	r0
 	ld.w	r1, r0[TI_flags]
 	bld	r1, TIF_CPU_GOING_TO_SLEEP
 #ifdef CONFIG_PREEMPT
 	brcc	3f
 #else
 	brcc	1b
 #endif
 	sub	r1, pc, . - cpu_idle_skip_sleep
 	stdsp	sp[REG_PC], r1
 #ifdef CONFIG_PREEMPT
 3:	get_thread_info r0
 	ld.w	r2, r0[TI_preempt_count]
 	cp.w	r2, 0
 	brne	1b
 	ld.w	r1, r0[TI_flags]
 	bld	r1, TIF_NEED_RESCHED
 	brcc	1b
 	lddsp	r4, sp[REG_SR]
 	bld	r4, SYSREG_GM_OFFSET
 	brcs	1b
 	rcall	preempt_schedule_irq
 #endif
 	rjmp	1b
 	.endm

 	.section .irq.text,"ax",@progbits

 .global cpu_idle_sleep
 cpu_idle_sleep:
 	mask_interrupts
 	get_thread_info r8
 	ld.w	r9, r8[TI_flags]
 	bld	r9, TIF_NEED_RESCHED
 	brcs	cpu_idle_enable_int_and_exit
 	sbr	r9, TIF_CPU_GOING_TO_SLEEP
 	st.w	r8[TI_flags], r9
 	unmask_interrupts
 	sleep 0
 cpu_idle_skip_sleep:
 	mask_interrupts
 	ld.w	r9, r8[TI_flags]
 	cbr	r9, TIF_CPU_GOING_TO_SLEEP
 	st.w	r8[TI_flags], r9
 cpu_idle_enable_int_and_exit:
 	unmask_interrupts
 	retal	r12

 	.global	irq_level0
 	.global	irq_level1
 	.global	irq_level2
 	.global	irq_level3
 	IRQ_LEVEL 0
 	IRQ_LEVEL 1
 	IRQ_LEVEL 2
 	IRQ_LEVEL 3
	/*
	* Copyright (C) 2004-2006 Atmel Corporation
	*
	* 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.
	*/

	/*
	* This file contains the low-level entry-points into the kernel, that is,
	* exception handlers, debug trap handlers, interrupt handlers and the
	* system call handler.
	*/
	#include <linux/errno.h>

	#include <asm/asm.h>
	#include <asm/hardirq.h>
	#include <asm/irq.h>
	#include <asm/ocd.h>
	#include <asm/page.h>
	#include <asm/pgtable.h>
	#include <asm/ptrace.h>
	#include <asm/sysreg.h>
	#include <asm/thread_info.h>
	#include <asm/unistd.h>

	#ifdef CONFIG_PREEMPT
	# define preempt_stop mask_interrupts
	#else
	# define preempt_stop
	# define fault_resume_kernel fault_restore_all
	#endif

	#define __MASK(x) ((1 << (x)) - 1)
	#define IRQ_MASK ((__MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT) \| \
	(__MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT))

	.section .ex.text,"ax",@progbits
	.align 2
	exception_vectors:
	bral handle_critical
	.align 2
	bral handle_critical
	.align 2
	bral do_bus_error_write
	.align 2
	bral do_bus_error_read
	.align 2
	bral do_nmi_ll
	.align 2
	bral handle_address_fault
	.align 2
	bral handle_protection_fault
	.align 2
	bral handle_debug
	.align 2
	bral do_illegal_opcode_ll
	.align 2
	bral do_illegal_opcode_ll
	.align 2
	bral do_illegal_opcode_ll
	.align 2
	bral do_fpe_ll
	.align 2
	bral do_illegal_opcode_ll
	.align 2
	bral handle_address_fault
	.align 2
	bral handle_address_fault
	.align 2
	bral handle_protection_fault
	.align 2
	bral handle_protection_fault
	.align 2
	bral do_dtlb_modified

	/*
	* r0 : PGD/PT/PTE
	* r1 : Offending address
	* r2 : Scratch register
	* r3 : Cause (5, 12 or 13)
	*/
	#define tlbmiss_save pushm r0-r3
	#define tlbmiss_restore popm r0-r3

	.section .tlbx.ex.text,"ax",@progbits
	.global itlb_miss
	itlb_miss:
	tlbmiss_save
	rjmp tlb_miss_common

	.section .tlbr.ex.text,"ax",@progbits
	dtlb_miss_read:
	tlbmiss_save
	rjmp tlb_miss_common

	.section .tlbw.ex.text,"ax",@progbits
	dtlb_miss_write:
	tlbmiss_save

	.global tlb_miss_common
	tlb_miss_common:
	mfsr r0, SYSREG_TLBEAR
	mfsr r1, SYSREG_PTBR

	/* Is it the vmalloc space? */
	bld r0, 31
	brcs handle_vmalloc_miss

	/* First level lookup */
	pgtbl_lookup:
	lsr r2, r0, PGDIR_SHIFT
	ld.w r3, r1[r2 << 2]
	bfextu r1, r0, PAGE_SHIFT, PGDIR_SHIFT - PAGE_SHIFT
	bld r3, _PAGE_BIT_PRESENT
	brcc page_table_not_present

	/* Translate to virtual address in P1. */
	andl r3, 0xf000
	sbr r3, 31

	/* Second level lookup */
	ld.w r2, r3[r1 << 2]
	mfsr r0, SYSREG_TLBARLO
	bld r2, _PAGE_BIT_PRESENT
	brcc page_not_present

	/* Mark the page as accessed */
	sbr r2, _PAGE_BIT_ACCESSED
	st.w r3[r1 << 2], r2

	/* Drop software flags */
	andl r2, _PAGE_FLAGS_HARDWARE_MASK & 0xffff
	mtsr SYSREG_TLBELO, r2

	/* Figure out which entry we want to replace */
	mfsr r1, SYSREG_MMUCR
	clz r2, r0
	brcc 1f
	mov r3, -1 /* All entries have been accessed, */
	mov r2, 0 /* so start at 0 */
	mtsr SYSREG_TLBARLO, r3 /* and reset TLBAR */

	1: bfins r1, r2, SYSREG_DRP_OFFSET, SYSREG_DRP_SIZE
	mtsr SYSREG_MMUCR, r1
	tlbw

	tlbmiss_restore
	rete

	handle_vmalloc_miss:
	/* Simply do the lookup in init's page table */
	mov r1, lo(swapper_pg_dir)
	orh r1, hi(swapper_pg_dir)
	rjmp pgtbl_lookup


	/* --- System Call --- */

	.section .scall.text,"ax",@progbits
	system_call:
	#ifdef CONFIG_PREEMPT
	mask_interrupts
	#endif
	pushm r12 /* r12_orig */
	stmts --sp, r0-lr

	mfsr r0, SYSREG_RAR_SUP
	mfsr r1, SYSREG_RSR_SUP
	#ifdef CONFIG_PREEMPT
	unmask_interrupts
	#endif
	zero_fp
	stm --sp, r0-r1

	/* check for syscall tracing */
	get_thread_info r0
	ld.w r1, r0[TI_flags]
	bld r1, TIF_SYSCALL_TRACE
	brcs syscall_trace_enter

	syscall_trace_cont:
	cp.w r8, NR_syscalls
	brhs syscall_badsys

	lddpc lr, syscall_table_addr
	ld.w lr, lr[r8 << 2]
	mov r8, r5 /* 5th argument (6th is pushed by stub) */
	icall lr

	.global syscall_return
	syscall_return:
	get_thread_info r0
	mask_interrupts /* make sure we don't miss an interrupt
	setting need_resched or sigpending
	between sampling and the rets */

	/* Store the return value so that the correct value is loaded below */
	stdsp sp[REG_R12], r12

	ld.w r1, r0[TI_flags]
	andl r1, _TIF_ALLWORK_MASK, COH
	brne syscall_exit_work

	syscall_exit_cont:
	popm r8-r9
	mtsr SYSREG_RAR_SUP, r8
	mtsr SYSREG_RSR_SUP, r9
	ldmts sp++, r0-lr
	sub sp, -4 /* r12_orig */
	rets

	.align 2
	syscall_table_addr:
	.long sys_call_table

	syscall_badsys:
	mov r12, -ENOSYS
	rjmp syscall_return

	.global ret_from_fork
	ret_from_fork:
	rcall schedule_tail

	/* check for syscall tracing */
	get_thread_info r0
	ld.w r1, r0[TI_flags]
	andl r1, _TIF_ALLWORK_MASK, COH
	brne syscall_exit_work
	rjmp syscall_exit_cont

	syscall_trace_enter:
	pushm r8-r12
	rcall syscall_trace
	popm r8-r12
	rjmp syscall_trace_cont

	syscall_exit_work:
	bld r1, TIF_SYSCALL_TRACE
	brcc 1f
	unmask_interrupts
	rcall syscall_trace
	mask_interrupts
	ld.w r1, r0[TI_flags]

	1: bld r1, TIF_NEED_RESCHED
	brcc 2f
	unmask_interrupts
	rcall schedule
	mask_interrupts
	ld.w r1, r0[TI_flags]
	rjmp 1b

	2: mov r2, _TIF_SIGPENDING \| _TIF_RESTORE_SIGMASK
	tst r1, r2
	breq 3f
	unmask_interrupts
	mov r12, sp
	mov r11, r0
	rcall do_notify_resume
	mask_interrupts
	ld.w r1, r0[TI_flags]
	rjmp 1b

	3: bld r1, TIF_BREAKPOINT
	brcc syscall_exit_cont
	mfsr r3, SYSREG_TLBEHI
	lddsp r2, sp[REG_PC]
	andl r3, 0xff, COH
	lsl r3, 1
	sbr r3, 30
	sbr r3, 0
	mtdr DBGREG_BWA2A, r2
	mtdr DBGREG_BWC2A, r3
	rjmp syscall_exit_cont


	/* The slow path of the TLB miss handler */
	page_table_not_present:
	page_not_present:
	tlbmiss_restore
	sub sp, 4
	stmts --sp, r0-lr
	rcall save_full_context_ex
	mfsr r12, SYSREG_ECR
	mov r11, sp
	rcall do_page_fault
	rjmp ret_from_exception

	/* This function expects to find offending PC in SYSREG_RAR_EX */
	save_full_context_ex:
	mfsr r8, SYSREG_RSR_EX
	mov r12, r8
	andh r8, (MODE_MASK >> 16), COH
	mfsr r11, SYSREG_RAR_EX
	brne 2f

	1: pushm r11, r12 /* PC and SR */
	unmask_exceptions
	ret r12

	2: sub r10, sp, -(FRAME_SIZE_FULL - REG_LR)
	stdsp sp[4], r10 /* replace saved SP */
	rjmp 1b

	/* Low-level exception handlers */
	handle_critical:
	pushm r12
	pushm r0-r12
	rcall save_full_context_ex
	mfsr r12, SYSREG_ECR
	mov r11, sp
	rcall do_critical_exception

	/* We should never get here... */
	bad_return:
	sub r12, pc, (. - 1f)
	bral panic
	.align 2
	1: .asciz "Return from critical exception!"

	.align 1
	do_bus_error_write:
	sub sp, 4
	stmts --sp, r0-lr
	rcall save_full_context_ex
	mov r11, 1
	rjmp 1f

	do_bus_error_read:
	sub sp, 4
	stmts --sp, r0-lr
	rcall save_full_context_ex
	mov r11, 0
	1: mfsr r12, SYSREG_BEAR
	mov r10, sp
	rcall do_bus_error
	rjmp ret_from_exception

	.align 1
	do_nmi_ll:
	sub sp, 4
	stmts --sp, r0-lr
	mfsr r9, SYSREG_RSR_NMI
	mfsr r8, SYSREG_RAR_NMI
	bfextu r0, r9, MODE_SHIFT, 3
	brne 2f

	1: pushm r8, r9 /* PC and SR */
	mfsr r12, SYSREG_ECR
	mov r11, sp
	rcall do_nmi
	popm r8-r9
	mtsr SYSREG_RAR_NMI, r8
	tst r0, r0
	mtsr SYSREG_RSR_NMI, r9
	brne 3f

	ldmts sp++, r0-lr
	sub sp, -4 /* skip r12_orig */
	rete

	2: sub r10, sp, -(FRAME_SIZE_FULL - REG_LR)
	stdsp sp[4], r10 /* replace saved SP */
	rjmp 1b

	3: popm lr
	sub sp, -4 /* skip sp */
	popm r0-r12
	sub sp, -4 /* skip r12_orig */
	rete

	handle_address_fault:
	sub sp, 4
	stmts --sp, r0-lr
	rcall save_full_context_ex
	mfsr r12, SYSREG_ECR
	mov r11, sp
	rcall do_address_exception
	rjmp ret_from_exception

	handle_protection_fault:
	sub sp, 4
	stmts --sp, r0-lr
	rcall save_full_context_ex
	mfsr r12, SYSREG_ECR
	mov r11, sp
	rcall do_page_fault
	rjmp ret_from_exception

	.align 1
	do_illegal_opcode_ll:
	sub sp, 4
	stmts --sp, r0-lr
	rcall save_full_context_ex
	mfsr r12, SYSREG_ECR
	mov r11, sp
	rcall do_illegal_opcode
	rjmp ret_from_exception

	do_dtlb_modified:
	pushm r0-r3
	mfsr r1, SYSREG_TLBEAR
	mfsr r0, SYSREG_PTBR
	lsr r2, r1, PGDIR_SHIFT
	ld.w r0, r0[r2 << 2]
	lsl r1, (32 - PGDIR_SHIFT)
	lsr r1, (32 - PGDIR_SHIFT) + PAGE_SHIFT

	/* Translate to virtual address in P1 */
	andl r0, 0xf000
	sbr r0, 31
	add r2, r0, r1 << 2
	ld.w r3, r2[0]
	sbr r3, _PAGE_BIT_DIRTY
	mov r0, r3
	st.w r2[0], r3

	/* The page table is up-to-date. Update the TLB entry as well */
	andl r0, lo(_PAGE_FLAGS_HARDWARE_MASK)
	mtsr SYSREG_TLBELO, r0

	/* MMUCR[DRP] is updated automatically, so let's go... */
	tlbw

	popm r0-r3
	rete

	do_fpe_ll:
	sub sp, 4
	stmts --sp, r0-lr
	rcall save_full_context_ex
	unmask_interrupts
	mov r12, 26
	mov r11, sp
	rcall do_fpe
	rjmp ret_from_exception

	ret_from_exception:
	mask_interrupts
	lddsp r4, sp[REG_SR]
	andh r4, (MODE_MASK >> 16), COH
	brne fault_resume_kernel

	get_thread_info r0
	ld.w r1, r0[TI_flags]
	andl r1, _TIF_WORK_MASK, COH
	brne fault_exit_work

	fault_resume_user:
	popm r8-r9
	mask_exceptions
	mtsr SYSREG_RAR_EX, r8
	mtsr SYSREG_RSR_EX, r9
	ldmts sp++, r0-lr
	sub sp, -4
	rete

	fault_resume_kernel:
	#ifdef CONFIG_PREEMPT
	get_thread_info r0
	ld.w r2, r0[TI_preempt_count]
	cp.w r2, 0
	brne 1f
	ld.w r1, r0[TI_flags]
	bld r1, TIF_NEED_RESCHED
	brcc 1f
	lddsp r4, sp[REG_SR]
	bld r4, SYSREG_GM_OFFSET
	brcs 1f
	rcall preempt_schedule_irq
	1:
	#endif

	popm r8-r9
	mask_exceptions
	mfsr r1, SYSREG_SR
	mtsr SYSREG_RAR_EX, r8
	mtsr SYSREG_RSR_EX, r9
	popm lr
	sub sp, -4 /* ignore SP */
	popm r0-r12
	sub sp, -4 /* ignore r12_orig */
	rete

	irq_exit_work:
	/* Switch to exception mode so that we can share the same code. */
	mfsr r8, SYSREG_SR
	cbr r8, SYSREG_M0_OFFSET
	orh r8, hi(SYSREG_BIT(M1) \| SYSREG_BIT(M2))
	mtsr SYSREG_SR, r8
	sub pc, -2
	get_thread_info r0
	ld.w r1, r0[TI_flags]

	fault_exit_work:
	bld r1, TIF_NEED_RESCHED
	brcc 1f
	unmask_interrupts
	rcall schedule
	mask_interrupts
	ld.w r1, r0[TI_flags]
	rjmp fault_exit_work

	1: mov r2, _TIF_SIGPENDING \| _TIF_RESTORE_SIGMASK
	tst r1, r2
	breq 2f
	unmask_interrupts
	mov r12, sp
	mov r11, r0
	rcall do_notify_resume
	mask_interrupts
	ld.w r1, r0[TI_flags]
	rjmp fault_exit_work

	2: bld r1, TIF_BREAKPOINT
	brcc fault_resume_user
	mfsr r3, SYSREG_TLBEHI
	lddsp r2, sp[REG_PC]
	andl r3, 0xff, COH
	lsl r3, 1
	sbr r3, 30
	sbr r3, 0
	mtdr DBGREG_BWA2A, r2
	mtdr DBGREG_BWC2A, r3
	rjmp fault_resume_user

	/* If we get a debug trap from privileged context we end up here */
	handle_debug_priv:
	/* Fix up LR and SP in regs. r11 contains the mode we came from */
	mfsr r8, SYSREG_SR
	mov r9, r8
	andh r8, hi(~MODE_MASK)
	or r8, r11
	mtsr SYSREG_SR, r8
	sub pc, -2
	stdsp sp[REG_LR], lr
	mtsr SYSREG_SR, r9
	sub pc, -2
	sub r10, sp, -FRAME_SIZE_FULL
	stdsp sp[REG_SP], r10
	mov r12, sp
	rcall do_debug_priv

	/* Now, put everything back */
	ssrf SR_EM_BIT
	popm r10, r11
	mtsr SYSREG_RAR_DBG, r10
	mtsr SYSREG_RSR_DBG, r11
	mfsr r8, SYSREG_SR
	mov r9, r8
	andh r8, hi(~MODE_MASK)
	andh r11, hi(MODE_MASK)
	or r8, r11
	mtsr SYSREG_SR, r8
	sub pc, -2
	popm lr
	mtsr SYSREG_SR, r9
	sub pc, -2
	sub sp, -4 /* skip SP */
	popm r0-r12
	sub sp, -4
	retd

	/*
	* At this point, everything is masked, that is, interrupts,
	* exceptions and debugging traps. We might get called from
	* interrupt or exception context in some rare cases, but this
	* will be taken care of by do_debug(), so we're not going to
	* do a 100% correct context save here.
	*/
	handle_debug:
	sub sp, 4 /* r12_orig */
	stmts --sp, r0-lr
	mfsr r10, SYSREG_RAR_DBG
	mfsr r11, SYSREG_RSR_DBG
	unmask_exceptions
	pushm r10,r11
	andh r11, (MODE_MASK >> 16), COH
	brne handle_debug_priv

	mov r12, sp
	rcall do_debug

	lddsp r10, sp[REG_SR]
	andh r10, (MODE_MASK >> 16), COH
	breq debug_resume_user

	debug_restore_all:
	popm r10,r11
	mask_exceptions
	mtsr SYSREG_RSR_DBG, r11
	mtsr SYSREG_RAR_DBG, r10
	ldmts sp++, r0-lr
	sub sp, -4
	retd

	debug_resume_user:
	get_thread_info r0
	mask_interrupts

	ld.w r1, r0[TI_flags]
	andl r1, _TIF_DBGWORK_MASK, COH
	breq debug_restore_all

	1: bld r1, TIF_NEED_RESCHED
	brcc 2f
	unmask_interrupts
	rcall schedule
	mask_interrupts
	ld.w r1, r0[TI_flags]
	rjmp 1b

	2: mov r2, _TIF_SIGPENDING \| _TIF_RESTORE_SIGMASK
	tst r1, r2
	breq 3f
	unmask_interrupts
	mov r12, sp
	mov r11, r0
	rcall do_notify_resume
	mask_interrupts
	ld.w r1, r0[TI_flags]
	rjmp 1b

	3: bld r1, TIF_SINGLE_STEP
	brcc debug_restore_all
	mfdr r2, DBGREG_DC
	sbr r2, DC_SS_BIT
	mtdr DBGREG_DC, r2
	rjmp debug_restore_all

	.set rsr_int0, SYSREG_RSR_INT0
	.set rsr_int1, SYSREG_RSR_INT1
	.set rsr_int2, SYSREG_RSR_INT2
	.set rsr_int3, SYSREG_RSR_INT3
	.set rar_int0, SYSREG_RAR_INT0
	.set rar_int1, SYSREG_RAR_INT1
	.set rar_int2, SYSREG_RAR_INT2
	.set rar_int3, SYSREG_RAR_INT3

	.macro IRQ_LEVEL level
	.type irq_level\level, @function
	irq_level\level:
	sub sp, 4 /* r12_orig */
	stmts --sp,r0-lr
	mfsr r8, rar_int\level
	mfsr r9, rsr_int\level

	#ifdef CONFIG_PREEMPT
	sub r11, pc, (. - system_call)
	cp.w r11, r8
	breq 4f
	#endif

	pushm r8-r9

	mov r11, sp
	mov r12, \level

	rcall do_IRQ

	lddsp r4, sp[REG_SR]
	bfextu r4, r4, SYSREG_M0_OFFSET, 3
	cp.w r4, MODE_SUPERVISOR >> SYSREG_M0_OFFSET
	breq 2f
	cp.w r4, MODE_USER >> SYSREG_M0_OFFSET
	#ifdef CONFIG_PREEMPT
	brne 3f
	#else
	brne 1f
	#endif

	get_thread_info r0
	ld.w r1, r0[TI_flags]
	andl r1, _TIF_WORK_MASK, COH
	brne irq_exit_work

	1: popm r8-r9
	mtsr rar_int\level, r8
	mtsr rsr_int\level, r9
	ldmts sp++,r0-lr
	sub sp, -4 /* ignore r12_orig */
	rete

	#ifdef CONFIG_PREEMPT
	4: mask_interrupts
	mfsr r8, rsr_int\level
	sbr r8, 16
	mtsr rsr_int\level, r8
	ldmts sp++, r0-lr
	sub sp, -4 /* ignore r12_orig */
	rete
	#endif

	2: get_thread_info r0
	ld.w r1, r0[TI_flags]
	bld r1, TIF_CPU_GOING_TO_SLEEP
	#ifdef CONFIG_PREEMPT
	brcc 3f
	#else
	brcc 1b
	#endif
	sub r1, pc, . - cpu_idle_skip_sleep
	stdsp sp[REG_PC], r1
	#ifdef CONFIG_PREEMPT
	3: get_thread_info r0
	ld.w r2, r0[TI_preempt_count]
	cp.w r2, 0
	brne 1b
	ld.w r1, r0[TI_flags]
	bld r1, TIF_NEED_RESCHED
	brcc 1b
	lddsp r4, sp[REG_SR]
	bld r4, SYSREG_GM_OFFSET
	brcs 1b
	rcall preempt_schedule_irq
	#endif
	rjmp 1b
	.endm

	.section .irq.text,"ax",@progbits

	.global cpu_idle_sleep
	cpu_idle_sleep:
	mask_interrupts
	get_thread_info r8
	ld.w r9, r8[TI_flags]
	bld r9, TIF_NEED_RESCHED
	brcs cpu_idle_enable_int_and_exit
	sbr r9, TIF_CPU_GOING_TO_SLEEP
	st.w r8[TI_flags], r9
	unmask_interrupts
	sleep 0
	cpu_idle_skip_sleep:
	mask_interrupts
	ld.w r9, r8[TI_flags]
	cbr r9, TIF_CPU_GOING_TO_SLEEP
	st.w r8[TI_flags], r9
	cpu_idle_enable_int_and_exit:
	unmask_interrupts
	retal r12

	.global irq_level0
	.global irq_level1
	.global irq_level2
	.global irq_level3
	IRQ_LEVEL 0
	IRQ_LEVEL 1
	IRQ_LEVEL 2
	IRQ_LEVEL 3