entry.s

microwindows移植到S3C44B0的源码

/* -*- mode: asm -*-
 *
 *  linux/arch/m68knommu/platform/5307/entry.S
 *
 *  Copyright (C) 1999  Greg Ungerer ([e-mail])
 *  Copyright (C) 1998  D. Jeff Dionne <[e-mail]>,
 *                      Kenneth Albanowski <[e-mail]>,
 *  Copyright (C) 2000  Lineo Inc. (www.lineo.com) 
 *
 * Based on:
 *
 *  linux/arch/m68k/kernel/entry.S
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file README.legal 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 ([e-mail])
 * 5307 fixes by David W. Miller
 * linux 2.4 support David McCullough <[e-mail]>
 */

/*
 * entry.S  contains the system-call and fault low-level handling routines.
 * This also contains the timer-interrupt handler, as well as all interrupts
 * and faults that can result in a task-switch.
 *
 * NOTE: This code handles signal-recognition, which happens every time
 * after a timer-interrupt and after each system call.
 *
 * Stack layout in 'ret_from_exception':
 *
 *	This allows access to the syscall arguments in registers d1-d5
 *
 *	 0(sp) - d1
 *	 4(sp) - d2
 *	 8(sp) - d3
 *	 C(sp) - d4
 *	10(sp) - d5
 *	14(sp) - a0
 *	18(sp) - a1
 *	1C(sp) - a2
 *	20(sp) - d0
 *	24(sp) - orig_d0
 *	28(sp) - stack adjustment
 *	2C(sp) - format & vector      }
 *	2E(sp) - sr                   } different to m68k
 *	30(sp) - pc                   }
 */

#include <linux/sys.h>
#include <linux/config.h>
#include <linux/linkage.h>
#include <asm/setup.h>
#include <asm/segment.h>

#include "m68k_defs.h"

LENOSYS = 38

/* the following macro is used when enabling interrupts */
#define ALLOWINT 0xf8ff
#define	MAX_NOINT_IPL	0


LD0			= 0x20
LORIG_D0	= 0x24
LFORMATVEC	= 0x2c
LSR			= 0x2e
LPC			= 0x30

/*
 * This defines the normal kernel pt-regs layout.
 *
 * regs are a2-a6 and d6-d7 preserved by C code
 * the kernel doesn't mess with usp unless it needs to
 *
 *	This is made a little more tricky on the ColdFire. There is no
 *	separate kernel and user stack pointers. Need to artificially
 *	construct a usp in software... When doing this we need to disable
 *	interrupts, otherwise bad things could happen.
 */
#define SAVE_ALL						\
	move	#0x2700,%sr;		/* disable intrs */	\
	btst	#5,%sp@(2);		/* from user? */	\
	bnes	6f;			/* no, skip */		\
	movel	%sp,sw_usp;		/* save user sp */	\
	addql	#8,sw_usp;		/* remove exception */	\
	movel	sw_ksp,%sp;		/* kernel sp */		\
	subql	#8,%sp;			/* room for exception */\
	clrl	%sp@-;			/* stk_adj */		\
	movel	%d0,%sp@-;		/* orig d0 */		\
	movel	%d0,%sp@-;		/* d0 */		\
	subl	#32,%sp;		/* space for 8 regs */	\
	moveml	%d1-%d5/%a0-%a2,%sp@;				\
	movel	sw_usp,%a0;		/* get usp */		\
	moveml	%a0@(-8),%d1-%d2;	/* get exception */	\
	moveml	%d1-%d2,%sp@(LFORMATVEC); /* copy exception */	\
	bra	7f;						\
	6:							\
	clrl	%sp@-;			/* stk_adj */		\
	movel	%d0,%sp@-;		/* orig d0 */		\
	movel	%d0,%sp@-;		/* d0 */		\
	subl	#32,%sp;		/* space for 7 regs */	\
	moveml	%d1-%d5/%a0-%a2,%sp@;				\
	7:

#define RESTORE_ALL						\
	btst	#5,%sp@(LSR);		/* going user? */	\
	bnes	8f;			/* no, skip */		\
	move	#0x2700,%sr;		/* disable intrs */	\
	movel	sw_usp,%a0;		/* get usp */		\
	moveml	%sp@(LFORMATVEC),%d1-%d2; /* copy exception */	\
	moveml	%d1-%d2,%a0@(-8);				\
	moveml	%sp@,%d1-%d5/%a0-%a2;				\
	addl	#32,%sp;		/* space for 8 regs */	\
	movel	%sp@+,%d0;					\
	addql	#4,%sp;			/* orig d0 */		\
	addl	%sp@+,%sp;		/* stk adj */		\
	addql	#8,%sp;			/* remove exception */	\
	movel	%sp,sw_ksp;		/* save ksp */		\
	subql	#8,sw_usp;		/* set exception */	\
	movel	sw_usp,%sp;		/* restore usp */	\
	rte;							\
	8:							\
	moveml	%sp@,%d1-%d5/%a0-%a2;				\
	addl	#32,%sp;		/* space for 8 regs */	\
	movel	%sp@+,%d0;					\
	addql	#4,%sp;			/* orig d0 */		\
	addl	%sp@+,%sp;		/* stk adj */		\
	rte

/*
 *	Quick exception save, use current stack only.
 */
#define SAVE_LOCAL						\
	move	#0x2700,%sr;		/* disable intrs */	\
	clrl	%sp@-;			/* stk_adj */		\
	movel	%d0,%sp@-;		/* orig d0 */		\
	movel	%d0,%sp@-;		/* d0 */		\
	subl	#32,%sp;		/* space for 8 regs */	\
	moveml	%d1-%d5/%a0-%a2,%sp@;

#define RESTORE_LOCAL						\
	moveml	%sp@,%d1-%d5/%a0-%a2;				\
	addl	#32,%sp;		/* space for 8 regs */	\
	movel	%sp@+,%d0;					\
	addql	#4,%sp;			/* orig d0 */		\
	addl	%sp@+,%sp;		/* stk adj */		\
	rte


#define SWITCH_STACK_SIZE (6*4+4)	/* includes return address */

#define SAVE_SWITCH_STACK		\
	subl    #24,%sp; /* 6 regs */	\
	moveml	%a3-%a6/%d6-%d7,%sp@

#define RESTORE_SWITCH_STACK		\
	moveml	%sp@,%a3-%a6/%d6-%d7;	\
	addl	#24,%sp /* 6 regs */

/*
 *	Software copy of the user and kernel stack pointers... Ugh...
 *	Need these to get around ColdFire not having separate kernel
 *	and user stack pointers.
 */
.globl SYMBOL_NAME(sw_usp)
.globl SYMBOL_NAME(sw_ksp)

.data

sw_ksp:
.long	0

sw_usp:
.long	0

.text


.globl SYMBOL_NAME(buserr)
.globl SYMBOL_NAME(trap)
.globl SYMBOL_NAME(system_call)
.globl SYMBOL_NAME(resume), SYMBOL_NAME(ret_from_exception)
.globl SYMBOL_NAME(ret_from_signal)
.globl SYMBOL_NAME(sys_call_table)
.globl SYMBOL_NAME(sys_fork), SYMBOL_NAME(sys_clone), SYMBOL_NAME(sys_vfork)
.globl SYMBOL_NAME(ret_from_interrupt)
.globl SYMBOL_NAME(inthandler)
.globl SYMBOL_NAME(fasthandler)

#ifdef TRAP_DBG_INTERRUPT
.globl SYMBOL_NAME(dbginterrupt)
#endif

.text

ENTRY(buserr)
	SAVE_ALL
	moveq	#-1,%d0
	movel	%d0,%sp@(LORIG_D0)	| a -1 in the ORIG_D0 field
								| signifies that the stack frame
								| is NOT for syscall

	movel	%sp,%sp@- 			| stack frame pointer argument
	jsr	SYMBOL_NAME(buserr_c)
	addql	#4,%sp
	jra	SYMBOL_NAME(ret_from_exception)


#ifdef TRAP_DBG_INTERRUPT
ENTRY(dbginterrupt)
	SAVE_ALL
	moveq	#-1,%d0
	movel	%d0,%sp@(LORIG_D0)	| a -1 in the ORIG_D0 field
								| signifies that the stack frame
								| is NOT for syscall

	movel	%sp,%sp@- 			| stack frame pointer argument
	jsr	SYMBOL_NAME(dbginterrupt_c)
	addql	#4,%sp
	jra	SYMBOL_NAME(ret_from_exception)
#endif


ENTRY(reschedule)
	| save top of frame
	pea	%sp@
	jbsr	SYMBOL_NAME(set_esp0)
	addql	#4,%sp

	pea	SYMBOL_NAME(ret_from_exception)
	jmp	SYMBOL_NAME(schedule)

	| After a fork we jump here directly from resume,
	| so that %d1 contains the previous task
	| Theoretically only needed on SMP, but lets watch
	| what happens in schedule_tail() in future...
ENTRY(ret_from_fork)
	movel	%d1,%sp@-
	jsr	SYMBOL_NAME(schedule_tail)
	addql	#4,%sp
	jra	SYMBOL_NAME(ret_from_exception)

ENTRY(system_call)
	SAVE_ALL
	move	#0x2000,%sr;		| enable intrs again

	movel	#-LENOSYS,%d2
	movel	%d2,LD0(%sp)		| default return value in d0
					| original D0 is in orig_d0
	movel	%d0,%d2

	| save top of frame
	pea	%sp@
	jbsr	SYMBOL_NAME(set_esp0)
	addql	#4,%sp

	cmpl	#NR_syscalls,%d2
	jcc	SYMBOL_NAME(ret_from_exception)
	lea	SYMBOL_NAME(sys_call_table),%a0
	lsll	#2,%d2		| movel	%a0@(%d2:l:4),%d3
	movel	%a0@(%d2),%d3
	jeq	SYMBOL_NAME(ret_from_exception)
	lsrl	#2,%d2
	movel	SYMBOL_NAME(_current_task),%a0
	btst	#1,%a0@(TASK_PTRACE+3)	| PT_TRACESYS
	bnes	1f
	movel	%d3,%a0
	jbsr	%a0@
	movel	%d0,%sp@(LD0)		| save the return value
	jra	SYMBOL_NAME(ret_from_exception)
1:
	subql	#4,%sp
	SAVE_SWITCH_STACK
	jbsr	SYMBOL_NAME(syscall_trace)
	RESTORE_SWITCH_STACK
	addql	#4,%sp
	movel	%d3,%a0
	jbsr	%a0@
	movel	%d0,%sp@(LD0)		| save the return value
	subql	#4,%sp			| dummy return address
	SAVE_SWITCH_STACK
	jbsr	SYMBOL_NAME(syscall_trace)

SYMBOL_NAME_LABEL(ret_from_signal)
	RESTORE_SWITCH_STACK
	addql	#4,%sp

SYMBOL_NAME_LABEL(ret_from_exception)
	btst	#5,%sp@(LSR)		| check if returning to kernel
	bnes	2f			| if so, skip resched, signals
	| tstl	SYMBOL_NAME(need_resched)
	| jne	SYMBOL_NAME(reschedule)
	movel	SYMBOL_NAME(_current_task),%a0
	tstl	%a0@(TASK_NEEDRESCHED)
	jne	SYMBOL_NAME(reschedule)

#if 0 /* as per m68k */
	cmpl	#SYMBOL_NAME(task),%a0	| task[0] cannot have signals
	jeq	2f
#endif

	bclr	#2,%a0@(TASK_PTRACE+3)	| check for delayed trace
	jeq	1f
	bclr	#7,%sp@(LSR)		| clear trace bit in SR
	pea	1			| send SIGTRAP
	movel	%a0,%sp@-
	pea	5
	jbsr	SYMBOL_NAME(send_sig)
	addql	#8,%sp
	addql	#4,%sp
	movel	SYMBOL_NAME(_current_task),%a0

1:
	tstl	%a0@(TASK_STATE)	| state
	jne	SYMBOL_NAME(reschedule)
	tstl	%a0@(TASK_COUNTER)	| counter
	jeq	SYMBOL_NAME(reschedule)

	movel	%a0@(TASK_BLOCKED),%d0
	notl	%d0
	btst	#0,%a0@(TASK_PTRACE+3)	| PT_PTRACED
	jeq	1f
	moveq	#-1,%d0			| let the debugger see all signals
1:	andl	%a0@(TASK_SIGPENDING),%d0
	jne	Lsignal_return
2:	RESTORE_ALL			| Does RTE

Lsignal_return:
	subql	#4,%sp			| dummy return address
	SAVE_SWITCH_STACK
	pea	%sp@(SWITCH_STACK_SIZE)
	clrl	%sp@-
	jsr	SYMBOL_NAME(do_signal)
	addql	#8,%sp
	RESTORE_SWITCH_STACK
	addql	#4,%sp

	btst    #5,%sp@(LSR);	/* going user? */   
	bnes    not_user;	/* no, skip */      
	move    #0x2700,%sr;	/* disable intrs */ 
	movel   sw_usp,%a0;	/* get usp */       
	moveml  %sp@(LFORMATVEC),%d1-%d2; /* copy exception */  
	moveml  %d1-%d2,%a0@(-8);               
	bclr    #5,%a0@(-8);  /* clear format byte, bit 5 to make stack appear modulo 4 which it WILL be when we do the rte because it was generated in setup_frame */
	bclr    #4,%a0@(-8);  /* clear format byte, bit 4 to make stack appear modulo 4 which it WILL be when we do the rte because it was generated in setup_frame */

	/*
	 * if an app is getting tricky and using "a5",  the signal handler
	 * may trigger while "a5" is invalid,  so we have to set it here
	 */
	jsr 	SYMBOL_NAME(get_pic_a5)
	movel	%d0, %a5

	moveml  %sp@,%d1-%d5/%a0-%a2;               
	addl    #32,%sp;        /* space for 8 regs */  
	movel   %sp@+,%d0;                  
	addql   #4,%sp;         /* orig d0 */       
	addl    %sp@+,%sp;      /* stk adj */       
	addql   #8,%sp;         /* remove exception */  
	movel   %sp,sw_ksp;     /* save ksp */      
	movel   sw_usp,%sp;     /* restore usp */   
	subql   #8,%sp;         /* set exception */ 
	rte;                            
not_user:                          
	moveml  %sp@,%d1-%d5/%a0-%a2;               
	addl    #32,%sp;        /* space for 8 regs */  
	movel   %sp@+,%d0;                  
	addql   #4,%sp;         /* orig d0 */       
	addl    %sp@+,%sp;      /* stk adj */       
	rte

/*--------------------------------------------------------------------------*/

/*
 *	Common ColdFire trap handler. Most traps come through here first.
 */
ENTRY(trap)
	SAVE_ALL
	moveq	#-1,%d0
	movel	%d0,%sp@(LORIG_D0)	| a -1 in the ORIG_D0 field
					| signifies that the stack frame
					| is NOT for syscall
	movel	%sp,%sp@- 		| stack frame pointer argument
	jsr	SYMBOL_NAME(trap_c)
	addql	#4,%sp
	jra	SYMBOL_NAME(ret_from_exception)

/*
 *	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.
 */
SYMBOL_NAME_LABEL(inthandler)
	SAVE_ALL
	moveq	#-1,%d0
	movel	%d0,%sp@(LORIG_D0)	| a -1 in the ORIG_D0 field
					| signifies that the stack frame
					| is NOT for syscall
	addql	#1,SYMBOL_NAME(local_irq_count)
					| put exception # in d0
	movew   %sp@(LFORMATVEC),%d0
	andl	#0x03fc,%d0		| mask out vector only

	movel	SYMBOL_NAME(mach_kstat_irqs),%a0
					| get addr of kstat struct
	addql	#1,%a0@(%d0)		| incr irq intr count

	lsrl	#2,%d0			| calculate real vector #
	movel	%d0,%d1			| calculate array offset
	lsll	#4,%d1
	lea	SYMBOL_NAME(irq_list),%a0
	addl	%d1,%a0			| pointer to array struct

	movel	%sp,%sp@-		| push regs arg onto stack
	movel	%a0@(8),%sp@-		| push devid arg
	movel	%d0,%sp@- 		| push vector # on stack