/*
 *  arch/ppc64/kernel/entry.S
 *
 *  PowerPC version 
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *  Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP
 *    Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
 *  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 "ppc_asm.h"
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/thread_info.h>
#include <linux/errno.h>
#include <linux/sys.h>
#include <linux/config.h>

#ifdef CONFIG_PPC_ISERIES
#define DO_SOFT_DISABLE
#endif

#undef SHOW_SYSCALLS
#undef SHOW_SYSCALLS_TASK

#ifdef SHOW_SYSCALLS_TASK
	.data
show_syscalls_task:
	.long	-1
#endif

	.section	".toc","aw"
.SYS_CALL_TABLE:
	.tc .sys_call_table[TC],.sys_call_table

.SYS_CALL_TABLE32:
	.tc .sys_call_table32[TC],.sys_call_table32

	.section	".text"
	.align 3

/*
 * Handle a system call.
 */
_GLOBAL(DoSyscall)
	ld	r11,_CCR(r1)	/* Clear SO bit in CR */
	lis	r10,0x1000
	andc	r11,r11,r10
	std	r11,_CCR(r1)
#ifdef SHOW_SYSCALLS
#ifdef SHOW_SYSCALLS_TASK
	LOADBASE(r31,show_syscalls_task)
	ld	r31,show_syscalls_task@l(r31)
	ld	r10,PACACURRENT(r13)
	cmp	0,r10,r31
	bne	1f
#endif
	LOADADDR(r3,7f)
	ld	r4,GPR0(r1)
	ld	r5,GPR3(r1)
	ld	r6,GPR4(r1)
	ld	r7,GPR5(r1)
	ld	r8,GPR6(r1)
	ld	r9,GPR7(r1)
	bl	.printk
	LOADADDR(r3,77f)
	ld	r4,GPR8(r1)
	ld	r5,GPR9(r1)
	ld	r6, PACACURRENT(r13)
	bl	.printk
	ld	r0,GPR0(r1)
	ld	r3,GPR3(r1)
	ld	r4,GPR4(r1)
	ld	r5,GPR5(r1)
	ld	r6,GPR6(r1)
	ld	r7,GPR7(r1)
	ld	r8,GPR8(r1)
1:
#endif /* SHOW_SYSCALLS */
	clrrdi	r10,r1,THREAD_SHIFT
	ld	r10,TI_FLAGS(r10)
	andi.	r11,r10,_TIF_SYSCALL_TRACE
	bne-	50f
	cmpli	0,r0,NR_syscalls
	bge-	66f
/*
 * Need to vector to 32 Bit or default sys_call_table here,
 * based on caller's run-mode / personality.
 */
#ifdef CONFIG_BINFMT_ELF32
	andi.	r11,r10,_TIF_32BIT
	beq-	15f
	ld	r10,.SYS_CALL_TABLE32@toc(2)
/*
 * Now mung the first 4 parameters into shape, by making certain that
 * the high bits (most significant 32 bits in 64 bit reg) are 0
 * for the first 4 parameter regs(3-6).
 */
	clrldi	r3,r3,32
	clrldi	r4,r4,32
	clrldi	r5,r5,32
	clrldi	r6,r6,32
	b	17f
15:
#endif
	ld	r10,.SYS_CALL_TABLE@toc(2)
17:	slwi	r0,r0,3
	ldx	r10,r10,r0	/* Fetch system call handler [ptr] */
	mtlr	r10
	addi	r9,r1,STACK_FRAME_OVERHEAD
	blrl			/* Call handler */
_GLOBAL(ret_from_syscall_1)
20:	std	r3,RESULT(r1)	/* Save result */
#ifdef SHOW_SYSCALLS
#ifdef SHOW_SYSCALLS_TASK
	ld	r10, PACACURRENT(13)
	cmp	0,r10,r31
	bne	91f
#endif
	mr	r4,r3
	LOADADDR(r3,79f)
	bl	.printk
	ld	r3,RESULT(r1)
91:
#endif
	li	r10,-_LAST_ERRNO
	cmpl	0,r3,r10
	blt	30f
	neg	r3,r3
	cmpi	0,r3,ERESTARTNOHAND
	bne	22f
	li	r3,EINTR
22:	ld	r10,_CCR(r1)	/* Set SO bit in CR */
	oris	r10,r10,0x1000
	std	r10,_CCR(r1)
30:	std	r3,GPR3(r1)	/* Update return value */
	b	.ret_from_except
66:	li	r3,ENOSYS
	b	22b
        
/* Traced system call support */
50:	bl	.do_syscall_trace
	ld	r0,GPR0(r1)	/* Restore original registers */
	ld	r3,GPR3(r1)
	ld	r4,GPR4(r1)
	ld	r5,GPR5(r1)
	ld	r6,GPR6(r1)
	ld	r7,GPR7(r1)
	ld	r8,GPR8(r1)
	/* XXX check this - Anton */
	ld	r9,GPR9(r1)
	cmpli	0,r0,NR_syscalls
	bge-	66f
/*
 * Need to vector to 32 Bit or default sys_call_table here,
 * based on caller's run-mode / personality.
 */
#ifdef CONFIG_BINFMT_ELF32
	clrrdi	r10,r1,THREAD_SHIFT
	ld	r10,TI_FLAGS(r10)
	andi.	r11,r10,_TIF_32BIT
	beq-	55f
	ld	r10,.SYS_CALL_TABLE32@toc(2)
/*
 * Now mung the first 4 parameters into shape, by making certain that
 * the high bits (most significant 32 bits in 64 bit reg) are 0
 * for the first 4 parameter regs(3-6).
 */
	clrldi	r3,r3,32
	clrldi	r4,r4,32
	clrldi	r5,r5,32
	clrldi	r6,r6,32
	b	57f
55:
#endif
	ld	r10,.SYS_CALL_TABLE@toc(2)
57:
	slwi	r0,r0,3
	ldx	r10,r10,r0	/* Fetch system call handler [ptr] */
	mtlr	r10
	addi	r9,r1,STACK_FRAME_OVERHEAD
	blrl			/* Call handler */
_GLOBAL(ret_from_syscall_2)
58:	std	r3,RESULT(r1)	/* Save result */	
	std	r3,GPR0(r1)	/* temporary gross hack to make strace work */
	li	r10,-_LAST_ERRNO
	cmpl	0,r3,r10
	blt	60f
	neg	r3,r3
	cmpi	0,r3,ERESTARTNOHAND
	bne	57f
	li	r3,EINTR
57:	ld	r10,_CCR(r1)	/* Set SO bit in CR */
	oris	r10,r10,0x1000
	std	r10,_CCR(r1)
60:	std	r3,GPR3(r1)	/* Update return value */
	bl	.do_syscall_trace
	b	.ret_from_except
66:	li	r3,ENOSYS
	b	57b
#ifdef SHOW_SYSCALLS
7:	.string	"syscall %d(%x, %x, %x, %x, %x, "
77:	.string	"%x, %x), current=%p\n"
79:	.string	" -> %x\n"
	.align	2,0
#endif

_GLOBAL(ppc32_sigreturn)
	bl	.sys32_sigreturn
	b	80f

_GLOBAL(ppc32_rt_sigreturn)
	bl	.sys32_rt_sigreturn
	b	80f

_GLOBAL(ppc64_sigreturn)
	bl	.sys_sigreturn
	b	80f

_GLOBAL(ppc64_rt_sigreturn)
	bl	.sys_rt_sigreturn

80:	clrrdi	r4,r1,THREAD_SHIFT
	ld	r4,TI_FLAGS(r4)
	andi.	r4,r4,_TIF_SYSCALL_TRACE
	bne-	81f
	cmpi	0,r3,0
	bge	.ret_from_except
	b	20b
81:	cmpi	0,r3,0
	blt	58b
	bl	.do_syscall_trace
	b	.ret_from_except

/*
 * 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, via ret_from_except.
 * On entry, r3 points to the THREAD for the current task, r4
 * points to the THREAD for the new task.
 *
 * 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/ppc64/kernel/process.c
 */
_GLOBAL(_switch)
	mflr	r0
	std	r0,16(r1)
	stdu	r1,-SWITCH_FRAME_SIZE(r1)
	/* r3-r13 are caller saved -- Cort */
	SAVE_8GPRS(14, r1)
	SAVE_10GPRS(22, r1)
	mflr	r20		/* Return to switch caller */
	mfmsr	r22
	andi.	r21, r22, MSR_FP
	beq+	1f
	li	r6,MSR_FP	/* Disable floating-point */
	andc	r22,r22,r6
	mtmsrd	r22
	isync
1:	std	r20,_NIP(r1)
	mfcr	r23
	std	r23,_CCR(r1)
	std	r1,KSP(r3)	/* Set old stack pointer */

	addi	r6,r4,-THREAD	/* Convert THREAD to 'current' */
	std	r6,PACACURRENT(r13)	/* Set new 'current' */

#ifdef CONFIG_PPC_ISERIES
#error fixme
	ld	r7,TI_FLAGS(r4)	/* Get run light flag */
	mfspr	r9,CTRLF
	srdi	r7,r7,1		/* Align to run light bit in CTRL reg */
	insrdi	r9,r7,1,63	/* Insert run light into CTRL */
	mtspr	CTRLT,r9
#endif

	ld	r1,KSP(r4)	/* Load new stack pointer */
	ld	r6,_CCR(r1)
	mtcrf	0xFF,r6
	/* r3-r13 are destroyed -- Cort */
	REST_8GPRS(14, r1)
	REST_10GPRS(22, r1)

	ld	r7,_NIP(r1)	/* Return to _switch caller in new task */
	mtlr	r7
	addi	r1,r1,SWITCH_FRAME_SIZE
	blr

_GLOBAL(ret_from_fork)
#if CONFIG_SMP || CONFIG_PREEMPT
	bl	.schedule_tail
#endif
	clrrdi	r4,r1,THREAD_SHIFT
	ld	r4,TI_FLAGS(r4)
	andi.	r4,r4,_TIF_SYSCALL_TRACE
	beq+	.ret_from_except
	bl	.do_syscall_trace
	b	.ret_from_except

_GLOBAL(ret_from_except)
#ifdef CONFIG_PPC_ISERIES
	ld	r5,SOFTE(r1)
	cmpdi	0,r5,0
	beq	4f
irq_recheck:
	/* Check for pending interrupts (iSeries) */
	CHECKANYINT(r3,r4)
	beq+	4f	/* skip do_IRQ if no interrupts */

#warning FIX ISERIES
	mfspr	r5,SPRG3
	li	r3,0
	stb	r3,PACAPROCENABLED(r5)	/* ensure we are disabled */
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	.do_IRQ
	b	irq_recheck	/* loop back and handle more */
4:
#endif
	/*
	 * Disable interrupts so that current_thread_info()->flags
	 * can't change between when we test it and when we return
	 * from the interrupt.
	 */
recheck:
	mfmsr	r10		/* Get current interrupt state */
	li	r4,0
	ori	r4,r4,MSR_EE|MSR_RI
	andc	r10,r10,r4	/* clear MSR_EE and MSR_RI */
	mtmsrd	r10,1		/* Update machine state */

#ifdef CONFIG_PPC_ISERIES
#error fix iSeries soft disable
#endif

	ld	r3,_MSR(r1)	/* Returning to user mode? */
	andi.	r3,r3,MSR_PR
	beq	restore		/* if not, just restore regs and return */

	/* Check current_thread_info()->flags */
	clrrdi	r3,r1,THREAD_SHIFT
	ld	r3,TI_FLAGS(r3)
	andi.	r0,r3,_TIF_USER_WORK_MASK
	bne	do_work

	addi	r0,r1,INT_FRAME_SIZE	/* size of frame */
	ld	r4,PACACURRENT(r13)
	std	r0,THREAD+KSP(r4)	/* save kernel stack pointer */
	std	r1,PACAKSAVE(r13)	/* save exception stack pointer */

	/*
	 * r13 is our per cpu area, only restore it if we are returning to
	 * userspace
	 */
	REST_GPR(13,r1)

restore:
	ld	r3,_CTR(r1)
	ld	r0,_LINK(r1)
	mtctr	r3
	mtlr	r0
	ld	r3,_XER(r1)
	mtspr	XER,r3

	REST_8GPRS(5, r1)
	REST_10GPRS(14, r1)
	REST_8GPRS(24, r1)

	stdcx.	r0,0,r1		/* to clear the reservation */

#ifdef DO_SOFT_DISABLE
	/* XXX do this in do_work, r13 isnt valid here */
	ld	r0,SOFTE(r1)
	stb	r0,PACAPROCENABLED(r13)
#endif

	ld	r0,_MSR(r1)
	mtspr	SRR1,r0

	ld	r2,_CCR(r1)
	mtcrf	0xFF,r2
	ld	r2,_NIP(r1)
	mtspr	SRR0,r2

	ld	r0,GPR0(r1)
	ld	r2,GPR2(r1)
	ld	r3,GPR3(r1)
	ld	r4,GPR4(r1)
	ld	r1,GPR1(r1)

	/*
	 *  What if we took an exception and stole this segment, we may
	 * fault on the above addresses and globber SRR0/1. Should check RI
	 * bit and repeat - Anton
	 */
	rfid

/* Note: this must change if we start using the  TIF_NOTIFY_RESUME bit */
do_work:
	/* Enable interrupts */
	ori	r10,r10,MSR_EE|MSR_RI
	mtmsrd	r10,1

	andi.	r0,r3,_TIF_NEED_RESCHED
	beq	1f
	bl	.schedule
	b	recheck

1:	andi.	r0,r3,_TIF_SIGPENDING
	beq	recheck
	li	r3,0
	addi	r4,r1,STACK_FRAME_OVERHEAD
	bl	.do_signal
	b	recheck

/*
 * On CHRP, the Run-Time Abstraction Services (RTAS) have to be
 * called with the MMU off.
 *
 * In addition, we need to be in 32b mode, at least for now.
 * 
 * Note: r3 is an input parameter to rtas, so don't trash it...
 */
_GLOBAL(enter_rtas)
	mflr	r0
	std	r0,16(r1)
        stdu	r1,-RTAS_FRAME_SIZE(r1)	/* Save SP and create stack space. */

	/* Because RTAS is running in 32b mode, it clobbers the high order half
	 * of all registers that it saves.  We therefore save those registers
	 * RTAS might touch to the stack.  (r0, r3-r13 are caller saved)
   	 */
	SAVE_GPR(2, r1)			/* Save the TOC */
	SAVE_GPR(13, r1)		/* Save paca */
	SAVE_8GPRS(14, r1)		/* Save the non-volatiles */
	SAVE_10GPRS(22, r1)		/* ditto */

	mfcr	r4
	std	r4,_CCR(r1)
	mfctr	r5
	std	r5,_CTR(r1)
	mfspr	r6,XER
	std	r6,_XER(r1)
	mfdar	r7
	std	r7,_DAR(r1)
	mfdsisr	r8
	std	r8,_DSISR(r1)
	mfsrr0	r9
	std	r9,_SRR0(r1)
	mfsrr1	r10
	std	r10,_SRR1(r1)

	/* Unfortunately, the stack pointer and the MSR are also clobbered,
	 * so they are saved in the PACA which allows us to restore
	 * our original state after RTAS returns.
         */
	std	r1,PACAR1(r13)
	mfmsr	r6
        std	r6,PACASAVEDMSR(r13)

	/* Setup our real return addr */	
	SET_REG_TO_LABEL(r4,.rtas_return_loc)
	SET_REG_TO_CONST(r9,KERNELBASE)
	sub	r4,r4,r9
       	mtlr	r4

	li	r0,0
	ori	r0,r0,MSR_EE|MSR_SE|MSR_BE|MSR_RI
	andc	r0,r6,r0
	
        li      r9,1
        rldicr  r9,r9,MSR_SF_LG,(63-MSR_SF_LG)
	ori	r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP|MSR_RI
	andc	r6,r0,r9
	sync				/* disable interrupts so SRR0/1 */
	mtmsrd	r0			/* don't get trashed */

	SET_REG_TO_LABEL(r4,rtas)
	ld	r5,RTASENTRY(r4)	/* get the rtas->entry value */
	ld	r4,RTASBASE(r4)		/* get the rtas->base value */
	
	mtspr	SRR0,r5
	mtspr	SRR1,r6
	rfid

_STATIC(rtas_return_loc)
	/* relocation is off at this point */
	mfspr	r4,SPRG3	        /* Get PACA */
	SET_REG_TO_CONST(r5, KERNELBASE)
        sub     r4,r4,r5                /* RELOC the PACA base pointer */
        
        ld	r1,PACAR1(r4)           /* Restore our SP */
	LOADADDR(r3,.rtas_restore_regs)
        ld	r4,PACASAVEDMSR(r4)     /* Restore our MSR */

	mtspr	SRR0,r3
	mtspr	SRR1,r4
	rfid

_STATIC(rtas_restore_regs)
	/* relocation is on at this point */
	REST_GPR(2, r1)			/* Restore the TOC */
	REST_GPR(13, r1)		/* Restore paca */
	REST_8GPRS(14, r1)		/* Restore the non-volatiles */
	REST_10GPRS(22, r1)		/* ditto */

	mfspr	r13,SPRG3

	ld	r4,_CCR(r1)
	mtcr	r4
	ld	r5,_CTR(r1)
	mtctr	r5
	ld	r6,_XER(r1)
	mtspr	XER,r6
	ld	r7,_DAR(r1)
	mtdar	r7
	ld	r8,_DSISR(r1)
	mtdsisr	r8
	ld	r9,_SRR0(r1)
	mtsrr0	r9
	ld	r10,_SRR1(r1)
	mtsrr1	r10

        addi	r1,r1,RTAS_FRAME_SIZE	/* Unstack our frame */
	ld	r0,16(r1)		/* get return address */

	mtlr    r0
        blr				/* return to caller */

_GLOBAL(enter_prom)
	mflr	r0
	std	r0,16(r1)
        stdu	r1,-PROM_FRAME_SIZE(r1)	/* Save SP and create stack space */

	/* Because PROM is running in 32b mode, it clobbers the high order half
	 * of all registers that it saves.  We therefore save those registers
	 * PROM might touch to the stack.  (r0, r3-r13 are caller saved)
   	 */
	SAVE_8GPRS(2, r1)		/* Save the TOC & incoming param(s) */
	SAVE_GPR(13, r1)		/* Save paca */
	SAVE_8GPRS(14, r1)		/* Save the non-volatiles */
	SAVE_10GPRS(22, r1)		/* ditto */

	mfcr	r4
	std	r4,_CCR(r1)
	mfctr	r5
	std	r5,_CTR(r1)
	mfspr	r6,XER
	std	r6,_XER(r1)
	mfdar	r7
	std	r7,_DAR(r1)
	mfdsisr	r8
	std	r8,_DSISR(r1)
	mfsrr0	r9
	std	r9,_SRR0(r1)
	mfsrr1	r10
	std	r10,_SRR1(r1)
	mfmsr	r11
	std	r11,_MSR(r1)

	/* Unfortunatly, the stack pointer is also clobbered, so it is saved
	 * in the SPRG2 which allows us to restore our original state after
	 * PROM returns.
         */
	mtspr	SPRG2,r1

        /* put a relocation offset into r3 */
        bl      .reloc_offset
	LOADADDR(r12,prom)
	sub	r12,r12,r3
	ld	r12,PROMENTRY(r12)	/* get the prom->entry value */
	mtlr	r12

        mfmsr   r11			/* grab the current MSR */
        li      r12,1
        rldicr  r12,r12,MSR_SF_LG,(63-MSR_SF_LG)
        andc    r11,r11,r12
        li      r12,1
        rldicr  r12,r12,MSR_ISF_LG,(63-MSR_ISF_LG)
        andc    r11,r11,r12
        mtmsrd  r11
        isync

	REST_8GPRS(2, r1)		/* Restore the TOC & param(s) */
	REST_GPR(13, r1)		/* Restore paca */
	REST_8GPRS(14, r1)		/* Restore the non-volatiles */
	REST_10GPRS(22, r1)		/* ditto */
	blrl				/* Entering PROM here... */

	mfspr	r1,SPRG2		/* Restore the stack pointer */
	ld	r6,_MSR(r1)		/* Restore the MSR */
	mtmsrd	r6
        isync

	REST_GPR(2, r1)			/* Restore the TOC */
	REST_GPR(13, r1)		/* Restore paca */
	REST_8GPRS(14, r1)		/* Restore the non-volatiles */
	REST_10GPRS(22, r1)		/* ditto */

	ld	r4,_CCR(r1)
	mtcr	r4
	ld	r5,_CTR(r1)
	mtctr	r5
	ld	r6,_XER(r1)
	mtspr	XER,r6
	ld	r7,_DAR(r1)
	mtdar	r7
	ld	r8,_DSISR(r1)
	mtdsisr	r8
	ld	r9,_SRR0(r1)
	mtsrr0	r9
	ld	r10,_SRR1(r1)
	mtsrr1	r10
        addi	r1,r1,PROM_FRAME_SIZE
	ld	r0,16(r1)		/* get return address */

	mtlr    r0
        blr				/* return to caller */
