3 * linux/arch/m68k/kernel/entry.S
5 * Copyright (C) 1991, 1992 Linus Torvalds
7 * This file is subject to the terms and conditions of the GNU General Public
8 * License. See the file README.legal in the main directory of this archive
11 * Linux/m68k support by Hamish Macdonald
13 * 68060 fixes by Jesper Skov
18 * entry.S contains the system-call and fault low-level handling routines.
19 * This also contains the timer-interrupt handler, as well as all interrupts
20 * and faults that can result in a task-switch.
22 * NOTE: This code handles signal-recognition, which happens every time
23 * after a timer-interrupt and after each system call.
28 * 12/03/96 Jes: Currently we only support m68k single-cpu systems, so
29 * all pointers that used to be 'current' are now entry
30 * number 0 in the 'current_set' list.
32 * 6/05/00 RZ: addedd writeback completion after return from sighandler
36 #include <linux/linkage.h>
37 #include <asm/errno.h>
38 #include <asm/setup.h>
39 #include <asm/segment.h>
40 #include <asm/traps.h>
41 #include <asm/unistd.h>
42 #include <asm/asm-offsets.h>
43 #include <asm/entry.h>
45 .globl system_call, buserr, trap, resume
47 .globl sys_fork, sys_clone, sys_vfork
48 .globl ret_from_interrupt, bad_interrupt
49 .globl auto_irqhandler_fixup
50 .globl user_irqvec_fixup
55 pea %sp@(SWITCH_STACK_SIZE)
63 pea %sp@(SWITCH_STACK_SIZE)
71 pea %sp@(SWITCH_STACK_SIZE)
83 ENTRY(sys_rt_sigreturn)
92 movel %sp,%sp@- | stack frame pointer argument
95 jra ret_from_exception
100 movel %sp,%sp@- | stack frame pointer argument
103 jra ret_from_exception
105 | After a fork we jump here directly from resume,
106 | so that %d1 contains the previous task
107 | schedule_tail now used regardless of CONFIG_SMP
112 jra ret_from_exception
114 ENTRY(ret_from_kernel_thread)
115 | a3 contains the kernel thread payload, d7 - its argument
125 ENTRY(ret_from_kernel_execve)
128 jra ret_from_exception
130 #if defined(CONFIG_COLDFIRE) || !defined(CONFIG_MMU)
132 #ifdef TRAP_DBG_INTERRUPT
138 movel %sp,%sp@- /* stack frame pointer argument */
141 jra ret_from_exception
145 /* save top of frame */
149 pea ret_from_exception
152 ENTRY(ret_from_user_signal)
153 moveq #__NR_sigreturn,%d0
156 ENTRY(ret_from_user_rt_signal)
157 movel #__NR_rt_sigreturn,%d0
163 movel #-ENOSYS,%sp@(PT_OFF_D0)| needed for strace
169 movel %sp@(PT_OFF_ORIG_D0),%d0
170 cmpl #NR_syscalls,%d0
173 movel #-ENOSYS,%sp@(PT_OFF_D0)
182 jra .Lret_from_exception
184 ENTRY(ret_from_signal)
185 movel %curptr@(TASK_STACK),%a1
186 tstb %a1@(TINFO_FLAGS+2)
189 1: RESTORE_SWITCH_STACK
191 /* on 68040 complete pending writebacks if any */
193 bfextu %sp@(PT_OFF_FORMATVEC){#0,#4},%d0
194 subql #7,%d0 | bus error frame ?
201 jra .Lret_from_exception
210 movel %sp,%curptr@(TASK_THREAD+THREAD_ESP0)
213 tstb %a1@(TINFO_FLAGS+2)
215 cmpl #NR_syscalls,%d0
218 jbsr @(sys_call_table,%d0:l:4)@(0)
219 movel %d0,%sp@(PT_OFF_D0) | save the return value
222 movel %curptr@(TASK_STACK),%a1
223 movew %a1@(TINFO_FLAGS+2),%d0
224 jne syscall_exit_work
228 btst #5,%sp@(PT_OFF_SR) | check if returning to kernel
229 bnes 1b | if so, skip resched, signals
239 ENTRY(ret_from_exception)
240 .Lret_from_exception:
241 btst #5,%sp@(PT_OFF_SR) | check if returning to kernel
242 bnes 1f | if so, skip resched, signals
243 | only allow interrupts when we are really the last one on the
244 | kernel stack, otherwise stack overflow can occur during
245 | heavy interrupt load
249 movel %curptr@(TASK_STACK),%a1
250 moveb %a1@(TINFO_FLAGS+3),%d0
256 movel %sp,%curptr@(TASK_THREAD+THREAD_ESP0)
265 subql #4,%sp | dummy return address
267 pea %sp@(SWITCH_STACK_SIZE)
268 bsrl do_notify_resume
272 jbra resume_userspace
275 bclr #7,%sp@(PT_OFF_SR) | clear trace bit in SR
282 jbra resume_userspace
285 /* This is the main interrupt handler for autovector interrupts */
287 ENTRY(auto_inthandler)
291 addqb #1,%a1@(TINFO_PREEMPT+1)
292 | put exception # in d0
293 bfextu %sp@(PT_OFF_FORMATVEC){#4,#10},%d0
297 movel %d0,%sp@- | put vector # on stack
298 auto_irqhandler_fixup = . + 2
299 jsr do_IRQ | process the IRQ
300 addql #8,%sp | pop parameters off stack
303 movel %curptr@(TASK_STACK),%a1
304 subqb #1,%a1@(TINFO_PREEMPT+1)
305 jeq ret_from_last_interrupt
309 ret_from_last_interrupt:
310 moveq #(~ALLOWINT>>8)&0xff,%d0
311 andb %sp@(PT_OFF_SR),%d0
314 /* check if we need to do software interrupts */
315 tstl irq_stat+CPUSTAT_SOFTIRQ_PENDING
316 jeq .Lret_from_exception
317 pea ret_from_exception
320 /* Handler for user defined interrupt vectors */
322 ENTRY(user_inthandler)
326 addqb #1,%a1@(TINFO_PREEMPT+1)
327 | put exception # in d0
328 bfextu %sp@(PT_OFF_FORMATVEC){#4,#10},%d0
329 user_irqvec_fixup = . + 2
333 movel %d0,%sp@- | put vector # on stack
334 jsr do_IRQ | process the IRQ
335 addql #8,%sp | pop parameters off stack
337 movel %curptr@(TASK_STACK),%a1
338 subqb #1,%a1@(TINFO_PREEMPT+1)
339 jeq ret_from_last_interrupt
342 /* Handler for uninitialized and spurious interrupts */
344 ENTRY(bad_inthandler)
348 addqb #1,%a1@(TINFO_PREEMPT+1)
354 movel %curptr@(TASK_STACK),%a1
355 subqb #1,%a1@(TINFO_PREEMPT+1)
356 jeq ret_from_last_interrupt
362 * Beware - when entering resume, prev (the current task) is
363 * in a0, next (the new task) is in a1,so don't change these
364 * registers until their contents are no longer needed.
368 movew %sr,%a0@(TASK_THREAD+THREAD_SR)
370 /* save fs (sfc,%dfc) (may be pointing to kernel memory) */
372 movew %d0,%a0@(TASK_THREAD+THREAD_FS)
375 /* it is better to use a movel here instead of a movew 8*) */
377 movel %d0,%a0@(TASK_THREAD+THREAD_USP)
379 /* save non-scratch registers on stack */
382 /* save current kernel stack pointer */
383 movel %sp,%a0@(TASK_THREAD+THREAD_KSP)
385 /* save floating point context */
386 #ifndef CONFIG_M68KFPU_EMU_ONLY
387 #ifdef CONFIG_M68KFPU_EMU
391 fsave %a0@(TASK_THREAD+THREAD_FPSTATE)
393 #if defined(CONFIG_M68060)
394 #if !defined(CPU_M68060_ONLY)
395 btst #3,m68k_cputype+3
398 /* The 060 FPU keeps status in bits 15-8 of the first longword */
399 tstb %a0@(TASK_THREAD+THREAD_FPSTATE+2)
401 #if !defined(CPU_M68060_ONLY)
404 #endif /* CONFIG_M68060 */
405 #if !defined(CPU_M68060_ONLY)
406 1: tstb %a0@(TASK_THREAD+THREAD_FPSTATE)
409 2: fmovemx %fp0-%fp7,%a0@(TASK_THREAD+THREAD_FPREG)
410 fmoveml %fpcr/%fpsr/%fpiar,%a0@(TASK_THREAD+THREAD_FPCNTL)
412 #endif /* CONFIG_M68KFPU_EMU_ONLY */
413 /* Return previous task in %d1 */
416 /* switch to new task (a1 contains new task) */
419 /* restore floating point context */
420 #ifndef CONFIG_M68KFPU_EMU_ONLY
421 #ifdef CONFIG_M68KFPU_EMU
425 #if defined(CONFIG_M68060)
426 #if !defined(CPU_M68060_ONLY)
427 btst #3,m68k_cputype+3
430 /* The 060 FPU keeps status in bits 15-8 of the first longword */
431 tstb %a1@(TASK_THREAD+THREAD_FPSTATE+2)
433 #if !defined(CPU_M68060_ONLY)
436 #endif /* CONFIG_M68060 */
437 #if !defined(CPU_M68060_ONLY)
438 1: tstb %a1@(TASK_THREAD+THREAD_FPSTATE)
441 2: fmovemx %a1@(TASK_THREAD+THREAD_FPREG),%fp0-%fp7
442 fmoveml %a1@(TASK_THREAD+THREAD_FPCNTL),%fpcr/%fpsr/%fpiar
443 3: frestore %a1@(TASK_THREAD+THREAD_FPSTATE)
445 #endif /* CONFIG_M68KFPU_EMU_ONLY */
447 /* restore the kernel stack pointer */
448 movel %a1@(TASK_THREAD+THREAD_KSP),%sp
450 /* restore non-scratch registers */
453 /* restore user stack pointer */
454 movel %a1@(TASK_THREAD+THREAD_USP),%a0
457 /* restore fs (sfc,%dfc) */
458 movew %a1@(TASK_THREAD+THREAD_FS),%a0
462 /* restore status register */
463 movew %a1@(TASK_THREAD+THREAD_SR),%sr
467 #endif /* CONFIG_MMU && !CONFIG_COLDFIRE */