entry_32.S

/*
 *  PowerPC version
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *  Rewritten by Cort Dougan (cort@fsmlabs.com) for PReP
 *    Copyright (C) 1996 Cort Dougan <cort@fsmlabs.com>
 *  Adapted for Power Macintosh by Paul Mackerras.
 *  Low-level exception handlers and MMU support
 *  rewritten by Paul Mackerras.
 *    Copyright (C) 1996 Paul Mackerras.
 *  MPC8xx modifications Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
 *
 *  This file contains the system call entry code, context switch
 *  code, and exception/interrupt return code for PowerPC.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 */

#include <linux/errno.h>
#include <linux/sys.h>
#include <linux/threads.h>
#include <asm/reg.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/cputable.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/unistd.h>

#undef SHOW_SYSCALLS
#undef SHOW_SYSCALLS_TASK

/*
 * MSR_KERNEL is > 0x10000 on 4xx/Book-E since it include MSR_CE.
 */
#if MSR_KERNEL >= 0x10000
#define LOAD_MSR_KERNEL(r, x)	lis r,(x)@h; ori r,r,(x)@l
#else
#define LOAD_MSR_KERNEL(r, x)	li r,(x)
#endif

#ifdef CONFIG_BOOKE
#include "head_booke.h"
#define TRANSFER_TO_HANDLER_EXC_LEVEL(exc_level)	\
	mtspr	exc_level##_SPRG,r8;			\
	BOOKE_LOAD_EXC_LEVEL_STACK(exc_level);		\
	lwz	r0,GPR10-INT_FRAME_SIZE(r8);		\
	stw	r0,GPR10(r11);				\
	lwz	r0,GPR11-INT_FRAME_SIZE(r8);		\
	stw	r0,GPR11(r11);				\
	mfspr	r8,exc_level##_SPRG

	.globl	mcheck_transfer_to_handler
mcheck_transfer_to_handler:
	TRANSFER_TO_HANDLER_EXC_LEVEL(MCHECK)
	b	transfer_to_handler_full

	.globl	debug_transfer_to_handler
debug_transfer_to_handler:
	TRANSFER_TO_HANDLER_EXC_LEVEL(DEBUG)
	b	transfer_to_handler_full

	.globl	crit_transfer_to_handler
crit_transfer_to_handler:
	TRANSFER_TO_HANDLER_EXC_LEVEL(CRIT)
	/* fall through */
#endif

#ifdef CONFIG_40x
	.globl	crit_transfer_to_handler
crit_transfer_to_handler:
	lwz	r0,crit_r10@l(0)
	stw	r0,GPR10(r11)
	lwz	r0,crit_r11@l(0)
	stw	r0,GPR11(r11)
	/* fall through */
#endif

/*
 * This code finishes saving the registers to the exception frame
 * and jumps to the appropriate handler for the exception, turning
 * on address translation.
 * Note that we rely on the caller having set cr0.eq iff the exception
 * occurred in kernel mode (i.e. MSR:PR = 0).
 */
	.globl	transfer_to_handler_full
transfer_to_handler_full:
	SAVE_NVGPRS(r11)
	/* fall through */

	.globl	transfer_to_handler
transfer_to_handler:
	stw	r2,GPR2(r11)
	stw	r12,_NIP(r11)
	stw	r9,_MSR(r11)
	andi.	r2,r9,MSR_PR
	mfctr	r12
	mfspr	r2,SPRN_XER
	stw	r12,_CTR(r11)
	stw	r2,_XER(r11)
	mfspr	r12,SPRN_SPRG3
	addi	r2,r12,-THREAD
	tovirt(r2,r2)			/* set r2 to current */
	beq	2f			/* if from user, fix up THREAD.regs */
	addi	r11,r1,STACK_FRAME_OVERHEAD
	stw	r11,PT_REGS(r12)
#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
	/* Check to see if the dbcr0 register is set up to debug.  Use the
	   internal debug mode bit to do this. */
	lwz	r12,THREAD_DBCR0(r12)
	andis.	r12,r12,DBCR0_IDM@h
	beq+	3f
	/* From user and task is ptraced - load up global dbcr0 */
	li	r12,-1			/* clear all pending debug events */
	mtspr	SPRN_DBSR,r12
	lis	r11,global_dbcr0@ha
	tophys(r11,r11)
	addi	r11,r11,global_dbcr0@l
#ifdef CONFIG_SMP
	rlwinm	r9,r1,0,0,(31-THREAD_SHIFT)
	lwz	r9,TI_CPU(r9)
	slwi	r9,r9,3
	add	r11,r11,r9
#endif
	lwz	r12,0(r11)
	mtspr	SPRN_DBCR0,r12
	lwz	r12,4(r11)
	addi	r12,r12,-1
	stw	r12,4(r11)
#endif
	b	3f

2:	/* if from kernel, check interrupted DOZE/NAP mode and
         * check for stack overflow
         */
	lwz	r9,KSP_LIMIT(r12)
	cmplw	r1,r9			/* if r1 <= ksp_limit */
	ble-	stack_ovf		/* then the kernel stack overflowed */
5:
#ifdef CONFIG_6xx
	rlwinm	r9,r1,0,0,31-THREAD_SHIFT
	tophys(r9,r9)			/* check local flags */
	lwz	r12,TI_LOCAL_FLAGS(r9)
	mtcrf	0x01,r12
	bt-	31-TLF_NAPPING,4f
#endif /* CONFIG_6xx */
	.globl transfer_to_handler_cont
transfer_to_handler_cont:
3:
	mflr	r9
	lwz	r11,0(r9)		/* virtual address of handler */
	lwz	r9,4(r9)		/* where to go when done */
	mtspr	SPRN_SRR0,r11
	mtspr	SPRN_SRR1,r10
	mtlr	r9
	SYNC
	RFI				/* jump to handler, enable MMU */

#ifdef CONFIG_6xx
4:	rlwinm	r12,r12,0,~_TLF_NAPPING
	stw	r12,TI_LOCAL_FLAGS(r9)
	b	power_save_6xx_restore
#endif

/*
 * On kernel stack overflow, load up an initial stack pointer
 * and call StackOverflow(regs), which should not return.
 */
stack_ovf:
	/* sometimes we use a statically-allocated stack, which is OK. */
	lis	r12,_end@h
	ori	r12,r12,_end@l
	cmplw	r1,r12
	ble	5b			/* r1 <= &_end is OK */
	SAVE_NVGPRS(r11)
	addi	r3,r1,STACK_FRAME_OVERHEAD
	lis	r1,init_thread_union@ha
	addi	r1,r1,init_thread_union@l
	addi	r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD
	lis	r9,StackOverflow@ha
	addi	r9,r9,StackOverflow@l
	LOAD_MSR_KERNEL(r10,MSR_KERNEL)
	FIX_SRR1(r10,r12)
	mtspr	SPRN_SRR0,r9
	mtspr	SPRN_SRR1,r10
	SYNC
	RFI

/*
 * Handle a system call.
 */
	.stabs	"arch/powerpc/kernel/",N_SO,0,0,0f
	.stabs	"entry_32.S",N_SO,0,0,0f
0:

_GLOBAL(DoSyscall)
	stw	r3,ORIG_GPR3(r1)
	li	r12,0
	stw	r12,RESULT(r1)
	lwz	r11,_CCR(r1)	/* Clear SO bit in CR */
	rlwinm	r11,r11,0,4,2
	stw	r11,_CCR(r1)
#ifdef SHOW_SYSCALLS
	bl	do_show_syscall
#endif /* SHOW_SYSCALLS */
	rlwinm	r10,r1,0,0,(31-THREAD_SHIFT)	/* current_thread_info() */
	lwz	r11,TI_FLAGS(r10)
	andi.	r11,r11,_TIF_SYSCALL_T_OR_A
	bne-	syscall_dotrace
syscall_dotrace_cont:
	cmplwi	0,r0,NR_syscalls
	lis	r10,sys_call_table@h
	ori	r10,r10,sys_call_table@l
	slwi	r0,r0,2
	bge-	66f
	lwzx	r10,r10,r0	/* Fetch system call handler [ptr] */
	mtlr	r10
	addi	r9,r1,STACK_FRAME_OVERHEAD
	PPC440EP_ERR42
	blrl			/* Call handler */
	.globl	ret_from_syscall
ret_from_syscall:
#ifdef SHOW_SYSCALLS
	bl	do_show_syscall_exit
#endif
	mr	r6,r3
	rlwinm	r12,r1,0,0,(31-THREAD_SHIFT)	/* current_thread_info() */
	/* disable interrupts so current_thread_info()->flags can't change */
	LOAD_MSR_KERNEL(r10,MSR_KERNEL)	/* doesn't include MSR_EE */
	SYNC
	MTMSRD(r10)
	lwz	r9,TI_FLAGS(r12)
	li	r8,-_LAST_ERRNO
	andi.	r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
	bne-	syscall_exit_work
	cmplw	0,r3,r8
	blt+	syscall_exit_cont
	lwz	r11,_CCR(r1)			/* Load CR */
	neg	r3,r3
	oris	r11,r11,0x1000	/* Set SO bit in CR */
	stw	r11,_CCR(r1)
syscall_exit_cont:
#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
	/* If the process has its own DBCR0 value, load it up.  The internal
	   debug mode bit tells us that dbcr0 should be loaded. */
	lwz	r0,THREAD+THREAD_DBCR0(r2)
	andis.	r10,r0,DBCR0_IDM@h
	bnel-	load_dbcr0
#endif
#ifdef CONFIG_44x
	lis	r4,icache_44x_need_flush@ha
	lwz	r5,icache_44x_need_flush@l(r4)
	cmplwi	cr0,r5,0
	bne-	2f
1:
#endif /* CONFIG_44x */
BEGIN_FTR_SECTION
	lwarx	r7,0,r1
END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
	stwcx.	r0,0,r1			/* to clear the reservation */
	lwz	r4,_LINK(r1)
	lwz	r5,_CCR(r1)
	mtlr	r4
	mtcr	r5
	lwz	r7,_NIP(r1)
	lwz	r8,_MSR(r1)
	FIX_SRR1(r8, r0)
	lwz	r2,GPR2(r1)
	lwz	r1,GPR1(r1)
	mtspr	SPRN_SRR0,r7
	mtspr	SPRN_SRR1,r8
	SYNC
	RFI
#ifdef CONFIG_44x
2:	li	r7,0
	iccci	r0,r0
	stw	r7,icache_44x_need_flush@l(r4)
	b	1b
#endif  /* CONFIG_44x */

66:	li	r3,-ENOSYS
	b	ret_from_syscall

	.globl	ret_from_fork
ret_from_fork:
	REST_NVGPRS(r1)
	bl	schedule_tail
	li	r3,0
	b	ret_from_syscall

/* Traced system call support */
syscall_dotrace:
	SAVE_NVGPRS(r1)
	li	r0,0xc00
	stw	r0,_TRAP(r1)
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	do_syscall_trace_enter
	lwz	r0,GPR0(r1)	/* Restore original registers */
	lwz	r3,GPR3(r1)
	lwz	r4,GPR4(r1)
	lwz	r5,GPR5(r1)
	lwz	r6,GPR6(r1)
	lwz	r7,GPR7(r1)
	lwz	r8,GPR8(r1)
	REST_NVGPRS(r1)
	b	syscall_dotrace_cont

syscall_exit_work:
	andi.	r0,r9,_TIF_RESTOREALL
	beq+	0f
	REST_NVGPRS(r1)
	b	2f
0:	cmplw	0,r3,r8
	blt+	1f
	andi.	r0,r9,_TIF_NOERROR
	bne-	1f
	lwz	r11,_CCR(r1)			/* Load CR */
	neg	r3,r3
	oris	r11,r11,0x1000	/* Set SO bit in CR */
	stw	r11,_CCR(r1)

1:	stw	r6,RESULT(r1)	/* Save result */
	stw	r3,GPR3(r1)	/* Update return value */
2:	andi.	r0,r9,(_TIF_PERSYSCALL_MASK)
	beq	4f

	/* Clear per-syscall TIF flags if any are set.  */

	li	r11,_TIF_PERSYSCALL_MASK
	addi	r12,r12,TI_FLAGS
3:	lwarx	r8,0,r12
	andc	r8,r8,r11
#ifdef CONFIG_IBM405_ERR77
	dcbt	0,r12
#endif
	stwcx.	r8,0,r12
	bne-	3b
	subi	r12,r12,TI_FLAGS
	
4:	/* Anything which requires enabling interrupts? */
	andi.	r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
	beq	ret_from_except

	/* Re-enable interrupts */
	ori	r10,r10,MSR_EE
	SYNC
	MTMSRD(r10)

	/* Save NVGPRS if they're not saved already */
	lwz	r4,_TRAP(r1)
	andi.	r4,r4,1
	beq	5f
	SAVE_NVGPRS(r1)
	li	r4,0xc00
	stw	r4,_TRAP(r1)
5:
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	do_syscall_trace_leave
	b	ret_from_except_full

#ifdef SHOW_SYSCALLS
do_show_syscall:
#ifdef SHOW_SYSCALLS_TASK
	lis	r11,show_syscalls_task@ha
	lwz	r11,show_syscalls_task@l(r11)
	cmp	0,r2,r11
	bnelr
#endif
	stw	r31,GPR31(r1)
	mflr	r31
	lis	r3,7f@ha
	addi	r3,r3,7f@l
	lwz	r4,GPR0(r1)
	lwz	r5,GPR3(r1)
	lwz	r6,GPR4(r1)
	lwz	r7,GPR5(r1)
	lwz	r8,GPR6(r1)
	lwz	r9,GPR7(r1)
	bl	printk
	lis	r3,77f@ha
	addi	r3,r3,77f@l
	lwz	r4,GPR8(r1)
	mr	r5,r2
	bl	printk
	lwz	r0,GPR0(r1)
	lwz	r3,GPR3(r1)
	lwz	r4,GPR4(r1)
	lwz	r5,GPR5(r1)
	lwz	r6,GPR6(r1)
	lwz	r7,GPR7(r1)
	lwz	r8,GPR8(r1)
	mtlr	r31
	lwz	r31,GPR31(r1)
	blr

do_show_syscall_exit:
#ifdef SHOW_SYSCALLS_TASK
	lis	r11,show_syscalls_task@ha
	lwz	r11,show_syscalls_task@l(r11)
	cmp	0,r2,r11
	bnelr
#endif
	stw	r31,GPR31(r1)
	mflr	r31
	stw	r3,RESULT(r1)	/* Save result */
	mr	r4,r3
	lis	r3,79f@ha
	addi	r3,r3,79f@l
	bl	printk
	lwz	r3,RESULT(r1)
	mtlr	r31
	lwz	r31,GPR31(r1)
	blr

7:	.string	"syscall %d(%x, %x, %x, %x, %x, "
77:	.string	"%x), current=%p\n"
79:	.string	" -> %x\n"
	.align	2,0

#ifdef SHOW_SYSCALLS_TASK
	.data
	.globl	show_syscalls_task
show_syscalls_task:
	.long	-1
	.text
#endif
#endif /* SHOW_SYSCALLS */

/*
 * The fork/clone functions need to copy the full register set into
 * the child process. Therefore we need to save all the nonvolatile
 * registers (r13 - r31) before calling the C code.
 */
	.globl	ppc_fork
ppc_fork:
	SAVE_NVGPRS(r1)
	lwz	r0,_TRAP(r1)
	rlwinm	r0,r0,0,0,30		/* clear LSB to indicate full */
	stw	r0,_TRAP(r1)		/* register set saved */
	b	sys_fork

	.globl	ppc_vfork
ppc_vfork:
	SAVE_NVGPRS(r1)
	lwz	r0,_TRAP(r1)
	rlwinm	r0,r0,0,0,30		/* clear LSB to indicate full */
	stw	r0,_TRAP(r1)		/* register set saved */
	b	sys_vfork

	.globl	ppc_clone
ppc_clone:
	SAVE_NVGPRS(r1)
	lwz	r0,_TRAP(r1)
	rlwinm	r0,r0,0,0,30		/* clear LSB to indicate full */
	stw	r0,_TRAP(r1)		/* register set saved */
	b	sys_clone

	.globl	ppc_swapcontext
ppc_swapcontext:
	SAVE_NVGPRS(r1)
	lwz	r0,_TRAP(r1)
	rlwinm	r0,r0,0,0,30		/* clear LSB to indicate full */
	stw	r0,_TRAP(r1)		/* register set saved */
	b	sys_swapcontext

/*
 * Top-level page fault handling.
 * This is in assembler because if do_page_fault tells us that
 * it is a bad kernel page fault, we want to save the non-volatile
 * registers before calling bad_page_fault.
 */
	.globl	handle_page_fault
handle_page_fault:
	stw	r4,_DAR(r1)
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	do_page_fault
	cmpwi	r3,0
	beq+	ret_from_except
	SAVE_NVGPRS(r1)
	lwz	r0,_TRAP(r1)
	clrrwi	r0,r0,1
	stw	r0,_TRAP(r1)
	mr	r5,r3
	addi	r3,r1,STACK_FRAME_OVERHEAD
	lwz	r4,_DAR(r1)
	bl	bad_page_fault
	b	ret_from_except_full

/*
 * This routine switches between two different tasks.  The process
 * state of one is saved on its kernel stack.  Then the state
 * of the other is restored from its kernel stack.  The memory
 * management hardware is updated to the second process's state.
 * Finally, we can return to the second process.
 * On entry, r3 points to the THREAD for the current task, r4
 * points to the THREAD for the new task.
 *
 * This routine is always called with interrupts disabled.
 *
 * Note: there are two ways to get to the "going out" portion
 * of this code; either by coming in via the entry (_switch)
 * or via "fork" which must set up an environment equivalent
 * to the "_switch" path.  If you change this , you'll have to
 * change the fork code also.
 *
 * The code which creates the new task context is in 'copy_thread'
 * in arch/ppc/kernel/process.c
 */
_GLOBAL(_switch)
	stwu	r1,-INT_FRAME_SIZE(r1)
	mflr	r0
	stw	r0,INT_FRAME_SIZE+4(r1)
	/* r3-r12 are caller saved -- Cort */
	SAVE_NVGPRS(r1)
	stw	r0,_NIP(r1)	/* Return to switch caller */
	mfmsr	r11
	li	r0,MSR_FP	/* Disable floating-point */
#ifdef CONFIG_ALTIVEC
BEGIN_FTR_SECTION
	oris	r0,r0,MSR_VEC@h	/* Disable altivec */
	mfspr	r12,SPRN_VRSAVE	/* save vrsave register value */
	stw	r12,THREAD+THREAD_VRSAVE(r2)
END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
BEGIN_FTR_SECTION
	oris	r0,r0,MSR_SPE@h	 /* Disable SPE */
	mfspr	r12,SPRN_SPEFSCR /* save spefscr register value */
	stw	r12,THREAD+THREAD_SPEFSCR(r2)
END_FTR_SECTION_IFSET(CPU_FTR_SPE)
#endif /* CONFIG_SPE */
	and.	r0,r0,r11	/* FP or altivec or SPE enabled? */
	beq+	1f
	andc	r11,r11,r0
	MTMSRD(r11)
	isync
1:	stw	r11,_MSR(r1)
	mfcr	r10
	stw	r10,_CCR(r1)
	stw	r1,KSP(r3)	/* Set old stack pointer */

#ifdef CONFIG_SMP
	/* We need a sync somewhere here to make sure that if the
	 * previous task gets rescheduled on another CPU, it sees all
	 * stores it has performed on this one.
	 */
	sync
#endif /* CONFIG_SMP */

	tophys(r0,r4)
	CLR_TOP32(r0)
	mtspr	SPRN_SPRG3,r0	/* Update current THREAD phys addr */
	lwz	r1,KSP(r4)	/* Load new stack pointer */

	/* save the old current 'last' for return value */
	mr	r3,r2
	addi	r2,r4,-THREAD	/* Update current */

#ifdef CONFIG_ALTIVEC
BEGIN_FTR_SECTION
	lwz	r0,THREAD+THREAD_VRSAVE(r2)
	mtspr	SPRN_VRSAVE,r0		/* if G4, restore VRSAVE reg */
END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
BEGIN_FTR_SECTION
	lwz	r0,THREAD+THREAD_SPEFSCR(r2)
	mtspr	SPRN_SPEFSCR,r0		/* restore SPEFSCR reg */
END_FTR_SECTION_IFSET(CPU_FTR_SPE)
#endif /* CONFIG_SPE */

	lwz	r0,_CCR(r1)
	mtcrf	0xFF,r0
	/* r3-r12 are destroyed -- Cort */
	REST_NVGPRS(r1)

	lwz	r4,_NIP(r1)	/* Return to _switch caller in new task */
	mtlr	r4
	addi	r1,r1,INT_FRAME_SIZE
	blr

	.globl	fast_exception_return
fast_exception_return:
#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
	andi.	r10,r9,MSR_RI		/* check for recoverable interrupt */
	beq	1f			/* if not, we've got problems */
#endif

2:	REST_4GPRS(3, r11)
	lwz	r10,_CCR(r11)
	REST_GPR(1, r11)
	mtcr	r10
	lwz	r10,_LINK(r11)
	mtlr	r10
	REST_GPR(10, r11)
	mtspr	SPRN_SRR1,r9
	mtspr	SPRN_SRR0,r12
	REST_GPR(9, r11)
	REST_GPR(12, r11)
	lwz	r11,GPR11(r11)
	SYNC
	RFI

#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
/* check if the exception happened in a restartable section */
1:	lis	r3,exc_exit_restart_end@ha
	addi	r3,r3,exc_exit_restart_end@l
	cmplw	r12,r3
	bge	3f
	lis	r4,exc_exit_restart@ha
	addi	r4,r4,exc_exit_restart@l
	cmplw	r12,r4
	blt	3f
	lis	r3,fee_restarts@ha
	tophys(r3,r3)
	lwz	r5,fee_restarts@l(r3)
	addi	r5,r5,1
	stw	r5,fee_restarts@l(r3)
	mr	r12,r4		/* restart at exc_exit_restart */
	b	2b

	.section .bss
	.align	2
fee_restarts:
	.space	4
	.previous

/* aargh, a nonrecoverable interrupt, panic */
/* aargh, we don't know which trap this is */
/* but the 601 doesn't implement the RI bit, so assume it's OK */
3:
BEGIN_FTR_SECTION
	b	2b
END_FTR_SECTION_IFSET(CPU_FTR_601)
	li	r10,-1
	stw	r10,_TRAP(r11)
	addi	r3,r1,STACK_FRAME_OVERHEAD
	lis	r10,MSR_KERNEL@h
	ori	r10,r10,MSR_KERNEL@l
	bl	transfer_to_handler_full
	.long	nonrecoverable_exception
	.long	ret_from_except
#endif

	.globl	ret_from_except_full
ret_from_except_full:
	REST_NVGPRS(r1)
	/* fall through */

	.globl	ret_from_except
ret_from_except:
	/* Hard-disable interrupts so that current_thread_info()->flags
	 * can't change between when we test it and when we return
	 * from the interrupt. */
	LOAD_MSR_KERNEL(r10,MSR_KERNEL)
	SYNC			/* Some chip revs have problems here... */
	MTMSRD(r10)		/* disable interrupts */

	lwz	r3,_MSR(r1)	/* Returning to user mode? */
	andi.	r0,r3,MSR_PR
	beq	resume_kernel

user_exc_return:		/* r10 contains MSR_KERNEL here */
	/* Check current_thread_info()->flags */
	rlwinm	r9,r1,0,0,(31-THREAD_SHIFT)
	lwz	r9,TI_FLAGS(r9)
	andi.	r0,r9,(_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK|_TIF_NEED_RESCHED)
	bne	do_work

restore_user:
#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
	/* Check whether this process has its own DBCR0 value.  The internal
	   debug mode bit tells us that dbcr0 should be loaded. */
	lwz	r0,THREAD+THREAD_DBCR0(r2)
	andis.	r10,r0,DBCR0_IDM@h
	bnel-	load_dbcr0
#endif

#ifdef CONFIG_PREEMPT
	b	restore

/* N.B. the only way to get here is from the beq following ret_from_except. */
resume_kernel:
	/* check current_thread_info->preempt_count */
	rlwinm	r9,r1,0,0,(31-THREAD_SHIFT)
	lwz	r0,TI_PREEMPT(r9)
	cmpwi	0,r0,0		/* if non-zero, just restore regs and return */
	bne	restore
	lwz	r0,TI_FLAGS(r9)
	andi.	r0,r0,_TIF_NEED_RESCHED
	beq+	restore
	andi.	r0,r3,MSR_EE	/* interrupts off? */
	beq	restore		/* don't schedule if so */
1:	bl	preempt_schedule_irq
	rlwinm	r9,r1,0,0,(31-THREAD_SHIFT)
	lwz	r3,TI_FLAGS(r9)
	andi.	r0,r3,_TIF_NEED_RESCHED
	bne-	1b
#else
resume_kernel:
#endif /* CONFIG_PREEMPT */

	/* interrupts are hard-disabled at this point */
restore:
#ifdef CONFIG_44x
	lis	r4,icache_44x_need_flush@ha
	lwz	r5,icache_44x_need_flush@l(r4)
	cmplwi	cr0,r5,0
	beq+	1f
	li	r6,0
	iccci	r0,r0
	stw	r6,icache_44x_need_flush@l(r4)
1:
#endif  /* CONFIG_44x */
	lwz	r0,GPR0(r1)
	lwz	r2,GPR2(r1)
	REST_4GPRS(3, r1)
	REST_2GPRS(7, r1)

	lwz	r10,_XER(r1)
	lwz	r11,_CTR(r1)
	mtspr	SPRN_XER,r10
	mtctr	r11

	PPC405_ERR77(0,r1)
BEGIN_FTR_SECTION
	lwarx	r11,0,r1
END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
	stwcx.	r0,0,r1			/* to clear the reservation */

#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
	lwz	r9,_MSR(r1)
	andi.	r10,r9,MSR_RI		/* check if this exception occurred */
	beql	nonrecoverable		/* at a bad place (MSR:RI = 0) */

	lwz	r10,_CCR(r1)
	lwz	r11,_LINK(r1)
	mtcrf	0xFF,r10
	mtlr	r11

	/*
	 * Once we put values in SRR0 and SRR1, we are in a state
	 * where exceptions are not recoverable, since taking an
	 * exception will trash SRR0 and SRR1.  Therefore we clear the
	 * MSR:RI bit to indicate this.  If we do take an exception,
	 * we can't return to the point of the exception but we
	 * can restart the exception exit path at the label
	 * exc_exit_restart below.  -- paulus
	 */
	LOAD_MSR_KERNEL(r10,MSR_KERNEL & ~MSR_RI)
	SYNC
	MTMSRD(r10)		/* clear the RI bit */
	.globl exc_exit_restart
exc_exit_restart:
	lwz	r9,_MSR(r1)
	lwz	r12,_NIP(r1)
	FIX_SRR1(r9,r10)
	mtspr	SPRN_SRR0,r12
	mtspr	SPRN_SRR1,r9
	REST_4GPRS(9, r1)
	lwz	r1,GPR1(r1)
	.globl exc_exit_restart_end
exc_exit_restart_end:
	SYNC
	RFI

#else /* !(CONFIG_4xx || CONFIG_BOOKE) */
	/*
	 * This is a bit different on 4xx/Book-E because it doesn't have
	 * the RI bit in the MSR.
	 * The TLB miss handler checks if we have interrupted
	 * the exception exit path and restarts it if so
	 * (well maybe one day it will... :).
	 */
	lwz	r11,_LINK(r1)
	mtlr	r11
	lwz	r10,_CCR(r1)
	mtcrf	0xff,r10
	REST_2GPRS(9, r1)
	.globl exc_exit_restart
exc_exit_restart:
	lwz	r11,_NIP(r1)
	lwz	r12,_MSR(r1)
exc_exit_start:
	mtspr	SPRN_SRR0,r11
	mtspr	SPRN_SRR1,r12
	REST_2GPRS(11, r1)
	lwz	r1,GPR1(r1)
	.globl exc_exit_restart_end
exc_exit_restart_end:
	PPC405_ERR77_SYNC
	rfi
	b	.			/* prevent prefetch past rfi */

/*
 * Returning from a critical interrupt in user mode doesn't need
 * to be any different from a normal exception.  For a critical
 * interrupt in the kernel, we just return (without checking for
 * preemption) since the interrupt may have happened at some crucial
 * place (e.g. inside the TLB miss handler), and because we will be
 * running with r1 pointing into critical_stack, not the current
 * process's kernel stack (and therefore current_thread_info() will
 * give the wrong answer).
 * We have to restore various SPRs that may have been in use at the
 * time of the critical interrupt.
 *
 */
#ifdef CONFIG_40x
#define PPC_40x_TURN_OFF_MSR_DR						    \
	/* avoid any possible TLB misses here by turning off MSR.DR, we	    \
	 * assume the instructions here are mapped by a pinned TLB entry */ \
	li	r10,MSR_IR;						    \
	mtmsr	r10;							    \
	isync;								    \
	tophys(r1, r1);
#else
#define PPC_40x_TURN_OFF_MSR_DR
#endif

#define RET_FROM_EXC_LEVEL(exc_lvl_srr0, exc_lvl_srr1, exc_lvl_rfi)	\
	REST_NVGPRS(r1);						\
	lwz	r3,_MSR(r1);						\
	andi.	r3,r3,MSR_PR;						\
	LOAD_MSR_KERNEL(r10,MSR_KERNEL);				\
	bne	user_exc_return;					\
	lwz	r0,GPR0(r1);						\
	lwz	r2,GPR2(r1);						\
	REST_4GPRS(3, r1);						\
	REST_2GPRS(7, r1);						\
	lwz	r10,_XER(r1);						\
	lwz	r11,_CTR(r1);						\
	mtspr	SPRN_XER,r10;						\
	mtctr	r11;							\
	PPC405_ERR77(0,r1);						\
	stwcx.	r0,0,r1;		/* to clear the reservation */	\
	lwz	r11,_LINK(r1);						\
	mtlr	r11;							\
	lwz	r10,_CCR(r1);						\
	mtcrf	0xff,r10;						\
	PPC_40x_TURN_OFF_MSR_DR;					\
	lwz	r9,_DEAR(r1);						\
	lwz	r10,_ESR(r1);						\
	mtspr	SPRN_DEAR,r9;						\
	mtspr	SPRN_ESR,r10;						\
	lwz	r11,_NIP(r1);						\
	lwz	r12,_MSR(r1);						\
	mtspr	exc_lvl_srr0,r11;					\
	mtspr	exc_lvl_srr1,r12;					\
	lwz	r9,GPR9(r1);						\
	lwz	r12,GPR12(r1);						\
	lwz	r10,GPR10(r1);						\
	lwz	r11,GPR11(r1);						\
	lwz	r1,GPR1(r1);						\
	PPC405_ERR77_SYNC;						\
	exc_lvl_rfi;							\
	b	.;		/* prevent prefetch past exc_lvl_rfi */

	.globl	ret_from_crit_exc
ret_from_crit_exc:
	RET_FROM_EXC_LEVEL(SPRN_CSRR0, SPRN_CSRR1, RFCI)

#ifdef CONFIG_BOOKE
	.globl	ret_from_debug_exc
ret_from_debug_exc:
	RET_FROM_EXC_LEVEL(SPRN_DSRR0, SPRN_DSRR1, RFDI)

	.globl	ret_from_mcheck_exc
ret_from_mcheck_exc:
	RET_FROM_EXC_LEVEL(SPRN_MCSRR0, SPRN_MCSRR1, RFMCI)
#endif /* CONFIG_BOOKE */

/*
 * Load the DBCR0 value for a task that is being ptraced,
 * having first saved away the global DBCR0.  Note that r0
 * has the dbcr0 value to set upon entry to this.
 */
load_dbcr0:
	mfmsr	r10		/* first disable debug exceptions */
	rlwinm	r10,r10,0,~MSR_DE
	mtmsr	r10
	isync
	mfspr	r10,SPRN_DBCR0
	lis	r11,global_dbcr0@ha
	addi	r11,r11,global_dbcr0@l
#ifdef CONFIG_SMP
	rlwinm	r9,r1,0,0,(31-THREAD_SHIFT)
	lwz	r9,TI_CPU(r9)
	slwi	r9,r9,3
	add	r11,r11,r9
#endif
	stw	r10,0(r11)
	mtspr	SPRN_DBCR0,r0
	lwz	r10,4(r11)
	addi	r10,r10,1
	stw	r10,4(r11)
	li	r11,-1
	mtspr	SPRN_DBSR,r11	/* clear all pending debug events */
	blr

	.section .bss
	.align	4
global_dbcr0:
	.space	8*NR_CPUS
	.previous
#endif /* !(CONFIG_4xx || CONFIG_BOOKE) */

do_work:			/* r10 contains MSR_KERNEL here */
	andi.	r0,r9,_TIF_NEED_RESCHED
	beq	do_user_signal

do_resched:			/* r10 contains MSR_KERNEL here */
	ori	r10,r10,MSR_EE
	SYNC
	MTMSRD(r10)		/* hard-enable interrupts */
	bl	schedule
recheck:
	LOAD_MSR_KERNEL(r10,MSR_KERNEL)
	SYNC
	MTMSRD(r10)		/* disable interrupts */
	rlwinm	r9,r1,0,0,(31-THREAD_SHIFT)
	lwz	r9,TI_FLAGS(r9)
	andi.	r0,r9,_TIF_NEED_RESCHED
	bne-	do_resched
	andi.	r0,r9,_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK
	beq	restore_user
do_user_signal:			/* r10 contains MSR_KERNEL here */
	ori	r10,r10,MSR_EE
	SYNC
	MTMSRD(r10)		/* hard-enable interrupts */
	/* save r13-r31 in the exception frame, if not already done */
	lwz	r3,_TRAP(r1)
	andi.	r0,r3,1
	beq	2f
	SAVE_NVGPRS(r1)
	rlwinm	r3,r3,0,0,30
	stw	r3,_TRAP(r1)
2:	li	r3,0
	addi	r4,r1,STACK_FRAME_OVERHEAD
	bl	do_signal
	REST_NVGPRS(r1)
	b	recheck

/*
 * We come here when we are at the end of handling an exception
 * that occurred at a place where taking an exception will lose
 * state information, such as the contents of SRR0 and SRR1.
 */
nonrecoverable:
	lis	r10,exc_exit_restart_end@ha
	addi	r10,r10,exc_exit_restart_end@l
	cmplw	r12,r10
	bge	3f
	lis	r11,exc_exit_restart@ha
	addi	r11,r11,exc_exit_restart@l
	cmplw	r12,r11
	blt	3f
	lis	r10,ee_restarts@ha
	lwz	r12,ee_restarts@l(r10)
	addi	r12,r12,1
	stw	r12,ee_restarts@l(r10)
	mr	r12,r11		/* restart at exc_exit_restart */
	blr
3:	/* OK, we can't recover, kill this process */
	/* but the 601 doesn't implement the RI bit, so assume it's OK */
BEGIN_FTR_SECTION
	blr
END_FTR_SECTION_IFSET(CPU_FTR_601)
	lwz	r3,_TRAP(r1)
	andi.	r0,r3,1
	beq	4f
	SAVE_NVGPRS(r1)
	rlwinm	r3,r3,0,0,30
	stw	r3,_TRAP(r1)
4:	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	nonrecoverable_exception
	/* shouldn't return */
	b	4b

	.section .bss
	.align	2
ee_restarts:
	.space	4
	.previous

/*
 * PROM code for specific machines follows.  Put it
 * here so it's easy to add arch-specific sections later.
 * -- Cort
 */
#ifdef CONFIG_PPC_RTAS
/*
 * On CHRP, the Run-Time Abstraction Services (RTAS) have to be
 * called with the MMU off.
 */
_GLOBAL(enter_rtas)
	stwu	r1,-INT_FRAME_SIZE(r1)
	mflr	r0
	stw	r0,INT_FRAME_SIZE+4(r1)
	LOAD_REG_ADDR(r4, rtas)
	lis	r6,1f@ha	/* physical return address for rtas */
	addi	r6,r6,1f@l
	tophys(r6,r6)
	tophys(r7,r1)
	lwz	r8,RTASENTRY(r4)
	lwz	r4,RTASBASE(r4)
	mfmsr	r9
	stw	r9,8(r1)
	LOAD_MSR_KERNEL(r0,MSR_KERNEL)
	SYNC			/* disable interrupts so SRR0/1 */
	MTMSRD(r0)		/* don't get trashed */
	li	r9,MSR_KERNEL & ~(MSR_IR|MSR_DR)
	mtlr	r6
	mtspr	SPRN_SPRG2,r7
	mtspr	SPRN_SRR0,r8
	mtspr	SPRN_SRR1,r9
	RFI
1:	tophys(r9,r1)
	lwz	r8,INT_FRAME_SIZE+4(r9)	/* get return address */
	lwz	r9,8(r9)	/* original msr value */
	FIX_SRR1(r9,r0)
	addi	r1,r1,INT_FRAME_SIZE
	li	r0,0
	mtspr	SPRN_SPRG2,r0
	mtspr	SPRN_SRR0,r8
	mtspr	SPRN_SRR1,r9
	RFI			/* return to caller */

	.globl	machine_check_in_rtas
machine_check_in_rtas:
	twi	31,0,0
	/* XXX load up BATs and panic */

#endif /* CONFIG_PPC_RTAS */

#ifdef CONFIG_FTRACE
#ifdef CONFIG_DYNAMIC_FTRACE
_GLOBAL(mcount)
_GLOBAL(_mcount)
	stwu	r1,-48(r1)
	stw	r3, 12(r1)
	stw	r4, 16(r1)
	stw	r5, 20(r1)
	stw	r6, 24(r1)
	mflr	r3
	stw	r7, 28(r1)
	mfcr	r5
	stw	r8, 32(r1)
	stw	r9, 36(r1)
	stw	r10,40(r1)
	stw	r3, 44(r1)
	stw	r5, 8(r1)
	.globl mcount_call
mcount_call:
	bl	ftrace_stub
	nop
	lwz	r6, 8(r1)
	lwz	r0, 44(r1)
	lwz	r3, 12(r1)
	mtctr	r0
	lwz	r4, 16(r1)
	mtcr	r6
	lwz	r5, 20(r1)
	lwz	r6, 24(r1)
	lwz	r0, 52(r1)
	lwz	r7, 28(r1)
	lwz	r8, 32(r1)
	mtlr	r0
	lwz	r9, 36(r1)
	lwz	r10,40(r1)
	addi	r1, r1, 48
	bctr

_GLOBAL(ftrace_caller)
	/* Based off of objdump optput from glibc */
	stwu	r1,-48(r1)
	stw	r3, 12(r1)
	stw	r4, 16(r1)
	stw	r5, 20(r1)
	stw	r6, 24(r1)
	mflr	r3
	lwz	r4, 52(r1)
	mfcr	r5
	stw	r7, 28(r1)
	stw	r8, 32(r1)
	stw	r9, 36(r1)
	stw	r10,40(r1)
	stw	r3, 44(r1)
	stw	r5, 8(r1)
.globl ftrace_call
ftrace_call:
	bl	ftrace_stub
	nop
	lwz	r6, 8(r1)
	lwz	r0, 44(r1)
	lwz	r3, 12(r1)
	mtctr	r0
	lwz	r4, 16(r1)
	mtcr	r6
	lwz	r5, 20(r1)
	lwz	r6, 24(r1)
	lwz	r0, 52(r1)
	lwz	r7, 28(r1)
	lwz	r8, 32(r1)
	mtlr	r0
	lwz	r9, 36(r1)
	lwz	r10,40(r1)
	addi	r1, r1, 48
	bctr
#else
_GLOBAL(mcount)
_GLOBAL(_mcount)
	stwu	r1,-48(r1)
	stw	r3, 12(r1)
	stw	r4, 16(r1)
	stw	r5, 20(r1)
	stw	r6, 24(r1)
	mflr	r3
	lwz	r4, 52(r1)
	mfcr	r5
	stw	r7, 28(r1)
	stw	r8, 32(r1)
	stw	r9, 36(r1)
	stw	r10,40(r1)
	stw	r3, 44(r1)
	stw	r5, 8(r1)

	LOAD_REG_ADDR(r5, ftrace_trace_function)
	lwz	r5,0(r5)

	mtctr	r5
	bctrl

	nop

	lwz	r6, 8(r1)
	lwz	r0, 44(r1)
	lwz	r3, 12(r1)
	mtctr	r0
	lwz	r4, 16(r1)
	mtcr	r6
	lwz	r5, 20(r1)
	lwz	r6, 24(r1)
	lwz	r0, 52(r1)
	lwz	r7, 28(r1)
	lwz	r8, 32(r1)
	mtlr	r0
	lwz	r9, 36(r1)
	lwz	r10,40(r1)
	addi	r1, r1, 48
	bctr
#endif

_GLOBAL(ftrace_stub)
	blr

#endif /* CONFIG_MCOUNT */