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kernel/linux-rt-4.4.41/arch/m68k/68360/entry.S 3.78 KB
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  /*
   *  entry.S - non-mmu 68360 interrupt and exceptions entry points
   *
   *  Copyright (C) 1991, 1992  Linus Torvalds
   *  Copyright (C) 2001 SED Systems, a Division of Calian Ltd.
   *
   * 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
   * M68360 Port by SED Systems, and Lineo.
   */
  
  #include <linux/linkage.h>
  #include <asm/thread_info.h>
  #include <asm/unistd.h>
  #include <asm/errno.h>
  #include <asm/setup.h>
  #include <asm/segment.h>
  #include <asm/traps.h>
  #include <asm/asm-offsets.h>
  #include <asm/entry.h>
  
  .text
  
  .globl system_call
  .globl resume
  .globl ret_from_exception
  .globl ret_from_signal
  .globl sys_call_table
  .globl bad_interrupt
  .globl inthandler
  
  badsys:
  	movel	#-ENOSYS,%sp@(PT_OFF_D0)
  	jra	ret_from_exception
  
  do_trace:
  	movel	#-ENOSYS,%sp@(PT_OFF_D0) /* needed for strace*/
  	subql	#4,%sp
  	SAVE_SWITCH_STACK
  	jbsr	syscall_trace_enter
  	RESTORE_SWITCH_STACK
  	addql	#4,%sp
  	movel	%sp@(PT_OFF_ORIG_D0),%d1
  	movel	#-ENOSYS,%d0
  	cmpl	#NR_syscalls,%d1
  	jcc	1f
  	lsl	#2,%d1
  	lea	sys_call_table, %a0
  	jbsr	%a0@(%d1)
  
  1:	movel	%d0,%sp@(PT_OFF_D0)	/* save the return value */
  	subql	#4,%sp			/* dummy return address */
  	SAVE_SWITCH_STACK
  	jbsr	syscall_trace_leave
  
  ret_from_signal:
  	RESTORE_SWITCH_STACK
  	addql	#4,%sp
  	jra	ret_from_exception
  
  ENTRY(system_call)
  	SAVE_ALL_SYS
  
  	/* save top of frame*/
  	pea	%sp@
  	jbsr	set_esp0
  	addql	#4,%sp
  
  	movel	%sp@(PT_OFF_ORIG_D0),%d0
  
  	movel	%sp,%d1			/* get thread_info pointer */
  	andl	#-THREAD_SIZE,%d1
  	movel	%d1,%a2
  	btst	#(TIF_SYSCALL_TRACE%8),%a2@(TINFO_FLAGS+(31-TIF_SYSCALL_TRACE)/8)
  	jne	do_trace
  	cmpl	#NR_syscalls,%d0
  	jcc	badsys
  	lsl	#2,%d0
  	lea	sys_call_table,%a0
  	movel	%a0@(%d0), %a0
  	jbsr	%a0@
  	movel	%d0,%sp@(PT_OFF_D0)	/* save the return value*/
  
  ret_from_exception:
  	btst	#5,%sp@(PT_OFF_SR)	/* check if returning to kernel*/
  	jeq	Luser_return		/* if so, skip resched, signals*/
  
  Lkernel_return:
  	RESTORE_ALL
  
  Luser_return:
  	/* only allow interrupts when we are really the last one on the*/
  	/* kernel stack, otherwise stack overflow can occur during*/
  	/* heavy interrupt load*/
  	andw	#ALLOWINT,%sr
  
  	movel	%sp,%d1			/* get thread_info pointer */
  	andl	#-THREAD_SIZE,%d1
  	movel	%d1,%a2
  1:
  	move	%a2@(TINFO_FLAGS),%d1	/* thread_info->flags */
  	jne	Lwork_to_do
  	RESTORE_ALL
  
  Lwork_to_do:
  	movel	%a2@(TINFO_FLAGS),%d1	/* thread_info->flags */
  	btst	#TIF_NEED_RESCHED,%d1
  	jne	reschedule
  
  Lsignal_return:
  	subql	#4,%sp			/* dummy return address*/
  	SAVE_SWITCH_STACK
  	pea	%sp@(SWITCH_STACK_SIZE)
  	bsrw	do_notify_resume
  	addql	#4,%sp
  	RESTORE_SWITCH_STACK
  	addql	#4,%sp
  	jra	1b
  
  /*
   * This is the main interrupt handler, responsible for calling do_IRQ()
   */
  inthandler:
  	SAVE_ALL_INT
  	movew	%sp@(PT_OFF_FORMATVEC), %d0
  	and.l	#0x3ff, %d0
  	lsr.l   #0x02,  %d0
  
  	movel	%sp,%sp@-
  	movel	%d0,%sp@- 		/*  put vector # on stack*/
  	jbsr	do_IRQ			/*  process the IRQ */
  	addql	#8,%sp			/*  pop parameters off stack*/
  	jra	ret_from_exception
  
  /*
   * Handler for uninitialized and spurious interrupts.
   */
  bad_interrupt:
  	addql	#1,irq_err_count
  	rte
  
  /*
   * Beware - when entering resume, prev (the current task) is
   * in a0, next (the new task) is in a1, so don't change these
   * registers until their contents are no longer needed.
   */
  ENTRY(resume)
  	movel	%a0,%d1				/* save prev thread in d1 */
  	movew	%sr,%a0@(TASK_THREAD+THREAD_SR)	/* save sr */
  	SAVE_SWITCH_STACK
  	movel	%sp,%a0@(TASK_THREAD+THREAD_KSP) /* save kernel stack */
  	movel	%usp,%a3			/* save usp */
  	movel	%a3,%a0@(TASK_THREAD+THREAD_USP)
  
  	movel	%a1@(TASK_THREAD+THREAD_USP),%a3 /* restore user stack */
  	movel	%a3,%usp
  	movel	%a1@(TASK_THREAD+THREAD_KSP),%sp /* restore new thread stack */
  	RESTORE_SWITCH_STACK
  	movew	%a1@(TASK_THREAD+THREAD_SR),%sr	/* restore thread status reg */
  	rts