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
121 jra ret_from_exception
123 #if defined(CONFIG_COLDFIRE) || !defined(CONFIG_MMU)
125 #ifdef TRAP_DBG_INTERRUPT
131 movel %sp,%sp@- /* stack frame pointer argument */
134 jra ret_from_exception
138 /* save top of frame */
142 pea ret_from_exception
145 ENTRY(ret_from_user_signal)
146 moveq #__NR_sigreturn,%d0
149 ENTRY(ret_from_user_rt_signal)
150 movel #__NR_rt_sigreturn,%d0
156 movel #-ENOSYS,%sp@(PT_OFF_D0)| needed for strace
162 movel %sp@(PT_OFF_ORIG_D0),%d0
163 cmpl #NR_syscalls,%d0
166 movel #-ENOSYS,%sp@(PT_OFF_D0)
175 jra .Lret_from_exception
177 ENTRY(ret_from_signal)
178 movel %curptr@(TASK_STACK),%a1
179 tstb %a1@(TINFO_FLAGS+2)
182 1: RESTORE_SWITCH_STACK
184 /* on 68040 complete pending writebacks if any */
186 bfextu %sp@(PT_OFF_FORMATVEC){#0,#4},%d0
187 subql #7,%d0 | bus error frame ?
194 jra .Lret_from_exception
203 movel %sp,%curptr@(TASK_THREAD+THREAD_ESP0)
206 tstb %a1@(TINFO_FLAGS+2)
208 cmpl #NR_syscalls,%d0
211 jbsr @(sys_call_table,%d0:l:4)@(0)
212 movel %d0,%sp@(PT_OFF_D0) | save the return value
215 movel %curptr@(TASK_STACK),%a1
216 movew %a1@(TINFO_FLAGS+2),%d0
217 jne syscall_exit_work
221 btst #5,%sp@(PT_OFF_SR) | check if returning to kernel
222 bnes 1b | if so, skip resched, signals
232 ENTRY(ret_from_exception)
233 .Lret_from_exception:
234 btst #5,%sp@(PT_OFF_SR) | check if returning to kernel
235 bnes 1f | if so, skip resched, signals
236 | only allow interrupts when we are really the last one on the
237 | kernel stack, otherwise stack overflow can occur during
238 | heavy interrupt load
242 movel %curptr@(TASK_STACK),%a1
243 moveb %a1@(TINFO_FLAGS+3),%d0
249 movel %sp,%curptr@(TASK_THREAD+THREAD_ESP0)
258 subql #4,%sp | dummy return address
260 pea %sp@(SWITCH_STACK_SIZE)
261 bsrl do_notify_resume
265 jbra resume_userspace
268 bclr #7,%sp@(PT_OFF_SR) | clear trace bit in SR
275 jbra resume_userspace
278 /* This is the main interrupt handler for autovector interrupts */
280 ENTRY(auto_inthandler)
284 addqb #1,%a1@(TINFO_PREEMPT+1)
285 | put exception # in d0
286 bfextu %sp@(PT_OFF_FORMATVEC){#4,#10},%d0
290 movel %d0,%sp@- | put vector # on stack
291 auto_irqhandler_fixup = . + 2
292 jsr do_IRQ | process the IRQ
293 addql #8,%sp | pop parameters off stack
296 movel %curptr@(TASK_STACK),%a1
297 subqb #1,%a1@(TINFO_PREEMPT+1)
298 jeq ret_from_last_interrupt
302 ret_from_last_interrupt:
303 moveq #(~ALLOWINT>>8)&0xff,%d0
304 andb %sp@(PT_OFF_SR),%d0
307 /* check if we need to do software interrupts */
308 tstl irq_stat+CPUSTAT_SOFTIRQ_PENDING
309 jeq .Lret_from_exception
310 pea ret_from_exception
313 /* Handler for user defined interrupt vectors */
315 ENTRY(user_inthandler)
319 addqb #1,%a1@(TINFO_PREEMPT+1)
320 | put exception # in d0
321 bfextu %sp@(PT_OFF_FORMATVEC){#4,#10},%d0
322 user_irqvec_fixup = . + 2
326 movel %d0,%sp@- | put vector # on stack
327 jsr do_IRQ | process the IRQ
328 addql #8,%sp | pop parameters off stack
330 movel %curptr@(TASK_STACK),%a1
331 subqb #1,%a1@(TINFO_PREEMPT+1)
332 jeq ret_from_last_interrupt
335 /* Handler for uninitialized and spurious interrupts */
337 ENTRY(bad_inthandler)
341 addqb #1,%a1@(TINFO_PREEMPT+1)
347 movel %curptr@(TASK_STACK),%a1
348 subqb #1,%a1@(TINFO_PREEMPT+1)
349 jeq ret_from_last_interrupt
355 * Beware - when entering resume, prev (the current task) is
356 * in a0, next (the new task) is in a1,so don't change these
357 * registers until their contents are no longer needed.
361 movew %sr,%a0@(TASK_THREAD+THREAD_SR)
363 /* save fs (sfc,%dfc) (may be pointing to kernel memory) */
365 movew %d0,%a0@(TASK_THREAD+THREAD_FS)
368 /* it is better to use a movel here instead of a movew 8*) */
370 movel %d0,%a0@(TASK_THREAD+THREAD_USP)
372 /* save non-scratch registers on stack */
375 /* save current kernel stack pointer */
376 movel %sp,%a0@(TASK_THREAD+THREAD_KSP)
378 /* save floating point context */
379 #ifndef CONFIG_M68KFPU_EMU_ONLY
380 #ifdef CONFIG_M68KFPU_EMU
384 fsave %a0@(TASK_THREAD+THREAD_FPSTATE)
386 #if defined(CONFIG_M68060)
387 #if !defined(CPU_M68060_ONLY)
388 btst #3,m68k_cputype+3
391 /* The 060 FPU keeps status in bits 15-8 of the first longword */
392 tstb %a0@(TASK_THREAD+THREAD_FPSTATE+2)
394 #if !defined(CPU_M68060_ONLY)
397 #endif /* CONFIG_M68060 */
398 #if !defined(CPU_M68060_ONLY)
399 1: tstb %a0@(TASK_THREAD+THREAD_FPSTATE)
402 2: fmovemx %fp0-%fp7,%a0@(TASK_THREAD+THREAD_FPREG)
403 fmoveml %fpcr/%fpsr/%fpiar,%a0@(TASK_THREAD+THREAD_FPCNTL)
405 #endif /* CONFIG_M68KFPU_EMU_ONLY */
406 /* Return previous task in %d1 */
409 /* switch to new task (a1 contains new task) */
412 /* restore floating point context */
413 #ifndef CONFIG_M68KFPU_EMU_ONLY
414 #ifdef CONFIG_M68KFPU_EMU
418 #if defined(CONFIG_M68060)
419 #if !defined(CPU_M68060_ONLY)
420 btst #3,m68k_cputype+3
423 /* The 060 FPU keeps status in bits 15-8 of the first longword */
424 tstb %a1@(TASK_THREAD+THREAD_FPSTATE+2)
426 #if !defined(CPU_M68060_ONLY)
429 #endif /* CONFIG_M68060 */
430 #if !defined(CPU_M68060_ONLY)
431 1: tstb %a1@(TASK_THREAD+THREAD_FPSTATE)
434 2: fmovemx %a1@(TASK_THREAD+THREAD_FPREG),%fp0-%fp7
435 fmoveml %a1@(TASK_THREAD+THREAD_FPCNTL),%fpcr/%fpsr/%fpiar
436 3: frestore %a1@(TASK_THREAD+THREAD_FPSTATE)
438 #endif /* CONFIG_M68KFPU_EMU_ONLY */
440 /* restore the kernel stack pointer */
441 movel %a1@(TASK_THREAD+THREAD_KSP),%sp
443 /* restore non-scratch registers */
446 /* restore user stack pointer */
447 movel %a1@(TASK_THREAD+THREAD_USP),%a0
450 /* restore fs (sfc,%dfc) */
451 movew %a1@(TASK_THREAD+THREAD_FS),%a0
455 /* restore status register */
456 movew %a1@(TASK_THREAD+THREAD_SR),%sr
460 #endif /* CONFIG_MMU && !CONFIG_COLDFIRE */