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1/* -*- mode: asm -*-
2 *
3 *  linux/arch/m68k/kernel/entry.S
4 *
5 *  Copyright (C) 1991, 1992  Linus Torvalds
6 *
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
9 * for more details.
10 *
11 * Linux/m68k support by Hamish Macdonald
12 *
13 * 68060 fixes by Jesper Skov
14 *
15 */
16
17/*
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.
21 *
22 * NOTE: This code handles signal-recognition, which happens every time
23 * after a timer-interrupt and after each system call.
24 *
25 */
26
27/*
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.
31 *
32 *  6/05/00 RZ:	 addedd writeback completion after return from sighandler
33 *		 for 68040
34 */
35
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>
44
45.globl system_call, buserr, trap, resume
46.globl sys_call_table
47.globl __sys_fork, __sys_clone, __sys_vfork
48.globl bad_interrupt
49.globl auto_irqhandler_fixup
50.globl user_irqvec_fixup
51
52.text
53ENTRY(__sys_fork)
54	SAVE_SWITCH_STACK
55	jbsr	sys_fork
56	lea     %sp@(24),%sp
57	rts
58
59ENTRY(__sys_clone)
60	SAVE_SWITCH_STACK
61	pea	%sp@(SWITCH_STACK_SIZE)
62	jbsr	m68k_clone
63	lea     %sp@(28),%sp
64	rts
65
66ENTRY(__sys_vfork)
67	SAVE_SWITCH_STACK
68	jbsr	sys_vfork
69	lea     %sp@(24),%sp
70	rts
71
72ENTRY(sys_sigreturn)
73	SAVE_SWITCH_STACK
74	movel	%sp,%sp@-		  | switch_stack pointer
75	pea	%sp@(SWITCH_STACK_SIZE+4) | pt_regs pointer
76	jbsr	do_sigreturn
77	addql	#8,%sp
78	RESTORE_SWITCH_STACK
79	rts
80
81ENTRY(sys_rt_sigreturn)
82	SAVE_SWITCH_STACK
83	movel	%sp,%sp@-		  | switch_stack pointer
84	pea	%sp@(SWITCH_STACK_SIZE+4) | pt_regs pointer
85	jbsr	do_rt_sigreturn
86	addql	#8,%sp
87	RESTORE_SWITCH_STACK
88	rts
89
90ENTRY(buserr)
91	SAVE_ALL_INT
92	GET_CURRENT(%d0)
93	movel	%sp,%sp@-		| stack frame pointer argument
94	jbsr	buserr_c
95	addql	#4,%sp
96	jra	ret_from_exception
97
98ENTRY(trap)
99	SAVE_ALL_INT
100	GET_CURRENT(%d0)
101	movel	%sp,%sp@-		| stack frame pointer argument
102	jbsr	trap_c
103	addql	#4,%sp
104	jra	ret_from_exception
105
106	| After a fork we jump here directly from resume,
107	| so that %d1 contains the previous task
108	| schedule_tail now used regardless of CONFIG_SMP
109ENTRY(ret_from_fork)
110	movel	%d1,%sp@-
111	jsr	schedule_tail
112	addql	#4,%sp
113	jra	ret_from_exception
114
115ENTRY(ret_from_kernel_thread)
116	| a3 contains the kernel thread payload, d7 - its argument
117	movel	%d1,%sp@-
118	jsr	schedule_tail
119	movel	%d7,(%sp)
120	jsr	%a3@
121	addql	#4,%sp
122	jra	ret_from_exception
123
124#if defined(CONFIG_COLDFIRE) || !defined(CONFIG_MMU)
125
126#ifdef TRAP_DBG_INTERRUPT
127
128.globl dbginterrupt
129ENTRY(dbginterrupt)
130	SAVE_ALL_INT
131	GET_CURRENT(%d0)
132	movel	%sp,%sp@- 		/* stack frame pointer argument */
133	jsr	dbginterrupt_c
134	addql	#4,%sp
135	jra	ret_from_exception
136#endif
137
138ENTRY(reschedule)
139	/* save top of frame */
140	pea	%sp@
141	jbsr	set_esp0
142	addql	#4,%sp
143	pea	ret_from_exception
144	jmp	schedule
145
146ENTRY(ret_from_user_signal)
147	moveq #__NR_sigreturn,%d0
148	trap #0
149
150ENTRY(ret_from_user_rt_signal)
151	movel #__NR_rt_sigreturn,%d0
152	trap #0
153
154#else
155
156do_trace_entry:
157	movel	#-ENOSYS,%sp@(PT_OFF_D0)| needed for strace
158	subql	#4,%sp
159	SAVE_SWITCH_STACK
160	jbsr	syscall_trace
161	RESTORE_SWITCH_STACK
162	addql	#4,%sp
163	addql	#1,%d0			| optimization for cmpil #-1,%d0
164	jeq	ret_from_syscall
165	movel	%sp@(PT_OFF_ORIG_D0),%d0
166	cmpl	#NR_syscalls,%d0
167	jcs	syscall
168	jra	ret_from_syscall
169badsys:
170	movel	#-ENOSYS,%sp@(PT_OFF_D0)
171	jra	ret_from_syscall
172
173do_trace_exit:
174	subql	#4,%sp
175	SAVE_SWITCH_STACK
176	jbsr	syscall_trace
177	RESTORE_SWITCH_STACK
178	addql	#4,%sp
179	jra	.Lret_from_exception
180
181ENTRY(ret_from_signal)
182	movel	%curptr@(TASK_STACK),%a1
183	tstb	%a1@(TINFO_FLAGS+2)
184	jge	1f
185	jbsr	syscall_trace
1861:	RESTORE_SWITCH_STACK
187	addql	#4,%sp
188/* on 68040 complete pending writebacks if any */
189#ifdef CONFIG_M68040
190	bfextu	%sp@(PT_OFF_FORMATVEC){#0,#4},%d0
191	subql	#7,%d0				| bus error frame ?
192	jbne	1f
193	movel	%sp,%sp@-
194	jbsr	berr_040cleanup
195	addql	#4,%sp
1961:
197#endif
198	jra	.Lret_from_exception
199
200ENTRY(system_call)
201	SAVE_ALL_SYS
202
203	GET_CURRENT(%d1)
204	movel	%d1,%a1
205
206	| save top of frame
207	movel	%sp,%curptr@(TASK_THREAD+THREAD_ESP0)
208
209	| syscall trace?
210	tstb	%a1@(TINFO_FLAGS+2)
211	jmi	do_trace_entry
212	cmpl	#NR_syscalls,%d0
213	jcc	badsys
214syscall:
215	jbsr	@(sys_call_table,%d0:l:4)@(0)
216	movel	%d0,%sp@(PT_OFF_D0)	| save the return value
217ret_from_syscall:
218	|oriw	#0x0700,%sr
219	movel	%curptr@(TASK_STACK),%a1
220	movew	%a1@(TINFO_FLAGS+2),%d0
221	jne	syscall_exit_work
2221:	RESTORE_ALL
223
224syscall_exit_work:
225	btst	#5,%sp@(PT_OFF_SR)	| check if returning to kernel
226	bnes	1b			| if so, skip resched, signals
227	lslw	#1,%d0
228	jcs	do_trace_exit
229	jmi	do_delayed_trace
230	lslw	#8,%d0
231	jne	do_signal_return
232	pea	resume_userspace
233	jra	schedule
234
235
236ENTRY(ret_from_exception)
237.Lret_from_exception:
238	btst	#5,%sp@(PT_OFF_SR)	| check if returning to kernel
239	bnes	1f			| if so, skip resched, signals
240	| only allow interrupts when we are really the last one on the
241	| kernel stack, otherwise stack overflow can occur during
242	| heavy interrupt load
243	andw	#ALLOWINT,%sr
244
245resume_userspace:
246	movel	%curptr@(TASK_STACK),%a1
247	moveb	%a1@(TINFO_FLAGS+3),%d0
248	jne	exit_work
2491:	RESTORE_ALL
250
251exit_work:
252	| save top of frame
253	movel	%sp,%curptr@(TASK_THREAD+THREAD_ESP0)
254	lslb	#1,%d0
255	jne	do_signal_return
256	pea	resume_userspace
257	jra	schedule
258
259
260do_signal_return:
261	|andw	#ALLOWINT,%sr
262	subql	#4,%sp			| dummy return address
263	SAVE_SWITCH_STACK
264	pea	%sp@(SWITCH_STACK_SIZE)
265	bsrl	do_notify_resume
266	addql	#4,%sp
267	RESTORE_SWITCH_STACK
268	addql	#4,%sp
269	jbra	resume_userspace
270
271do_delayed_trace:
272	bclr	#7,%sp@(PT_OFF_SR)	| clear trace bit in SR
273	pea	1			| send SIGTRAP
274	movel	%curptr,%sp@-
275	pea	LSIGTRAP
276	jbsr	send_sig
277	addql	#8,%sp
278	addql	#4,%sp
279	jbra	resume_userspace
280
281
282/* This is the main interrupt handler for autovector interrupts */
283
284ENTRY(auto_inthandler)
285	SAVE_ALL_INT
286	GET_CURRENT(%d0)
287					|  put exception # in d0
288	bfextu	%sp@(PT_OFF_FORMATVEC){#4,#10},%d0
289	subw	#VEC_SPUR,%d0
290
291	movel	%sp,%sp@-
292	movel	%d0,%sp@-		|  put vector # on stack
293auto_irqhandler_fixup = . + 2
294	jsr	do_IRQ			|  process the IRQ
295	addql	#8,%sp			|  pop parameters off stack
296	jra	ret_from_exception
297
298/* Handler for user defined interrupt vectors */
299
300ENTRY(user_inthandler)
301	SAVE_ALL_INT
302	GET_CURRENT(%d0)
303					|  put exception # in d0
304	bfextu	%sp@(PT_OFF_FORMATVEC){#4,#10},%d0
305user_irqvec_fixup = . + 2
306	subw	#VEC_USER,%d0
307
308	movel	%sp,%sp@-
309	movel	%d0,%sp@-		|  put vector # on stack
310	jsr	do_IRQ			|  process the IRQ
311	addql	#8,%sp			|  pop parameters off stack
312	jra	ret_from_exception
313
314/* Handler for uninitialized and spurious interrupts */
315
316ENTRY(bad_inthandler)
317	SAVE_ALL_INT
318	GET_CURRENT(%d0)
319
320	movel	%sp,%sp@-
321	jsr	handle_badint
322	addql	#4,%sp
323	jra	ret_from_exception
324
325resume:
326	/*
327	 * Beware - when entering resume, prev (the current task) is
328	 * in a0, next (the new task) is in a1,so don't change these
329	 * registers until their contents are no longer needed.
330	 */
331
332	/* save sr */
333	movew	%sr,%a0@(TASK_THREAD+THREAD_SR)
334
335	/* save fs (sfc,%dfc) (may be pointing to kernel memory) */
336	movec	%sfc,%d0
337	movew	%d0,%a0@(TASK_THREAD+THREAD_FS)
338
339	/* save usp */
340	/* it is better to use a movel here instead of a movew 8*) */
341	movec	%usp,%d0
342	movel	%d0,%a0@(TASK_THREAD+THREAD_USP)
343
344	/* save non-scratch registers on stack */
345	SAVE_SWITCH_STACK
346
347	/* save current kernel stack pointer */
348	movel	%sp,%a0@(TASK_THREAD+THREAD_KSP)
349
350	/* save floating point context */
351#ifndef CONFIG_M68KFPU_EMU_ONLY
352#ifdef CONFIG_M68KFPU_EMU
353	tstl	m68k_fputype
354	jeq	3f
355#endif
356	fsave	%a0@(TASK_THREAD+THREAD_FPSTATE)
357
358#if defined(CONFIG_M68060)
359#if !defined(CPU_M68060_ONLY)
360	btst	#3,m68k_cputype+3
361	beqs	1f
362#endif
363	/* The 060 FPU keeps status in bits 15-8 of the first longword */
364	tstb	%a0@(TASK_THREAD+THREAD_FPSTATE+2)
365	jeq	3f
366#if !defined(CPU_M68060_ONLY)
367	jra	2f
368#endif
369#endif /* CONFIG_M68060 */
370#if !defined(CPU_M68060_ONLY)
3711:	tstb	%a0@(TASK_THREAD+THREAD_FPSTATE)
372	jeq	3f
373#endif
3742:	fmovemx	%fp0-%fp7,%a0@(TASK_THREAD+THREAD_FPREG)
375	fmoveml	%fpcr/%fpsr/%fpiar,%a0@(TASK_THREAD+THREAD_FPCNTL)
3763:
377#endif	/* CONFIG_M68KFPU_EMU_ONLY */
378	/* Return previous task in %d1 */
379	movel	%curptr,%d1
380
381	/* switch to new task (a1 contains new task) */
382	movel	%a1,%curptr
383
384	/* restore floating point context */
385#ifndef CONFIG_M68KFPU_EMU_ONLY
386#ifdef CONFIG_M68KFPU_EMU
387	tstl	m68k_fputype
388	jeq	4f
389#endif
390#if defined(CONFIG_M68060)
391#if !defined(CPU_M68060_ONLY)
392	btst	#3,m68k_cputype+3
393	beqs	1f
394#endif
395	/* The 060 FPU keeps status in bits 15-8 of the first longword */
396	tstb	%a1@(TASK_THREAD+THREAD_FPSTATE+2)
397	jeq	3f
398#if !defined(CPU_M68060_ONLY)
399	jra	2f
400#endif
401#endif /* CONFIG_M68060 */
402#if !defined(CPU_M68060_ONLY)
4031:	tstb	%a1@(TASK_THREAD+THREAD_FPSTATE)
404	jeq	3f
405#endif
4062:	fmovemx	%a1@(TASK_THREAD+THREAD_FPREG),%fp0-%fp7
407	fmoveml	%a1@(TASK_THREAD+THREAD_FPCNTL),%fpcr/%fpsr/%fpiar
4083:	frestore %a1@(TASK_THREAD+THREAD_FPSTATE)
4094:
410#endif	/* CONFIG_M68KFPU_EMU_ONLY */
411
412	/* restore the kernel stack pointer */
413	movel	%a1@(TASK_THREAD+THREAD_KSP),%sp
414
415	/* restore non-scratch registers */
416	RESTORE_SWITCH_STACK
417
418	/* restore user stack pointer */
419	movel	%a1@(TASK_THREAD+THREAD_USP),%a0
420	movel	%a0,%usp
421
422	/* restore fs (sfc,%dfc) */
423	movew	%a1@(TASK_THREAD+THREAD_FS),%a0
424	movec	%a0,%sfc
425	movec	%a0,%dfc
426
427	/* restore status register */
428	movew	%a1@(TASK_THREAD+THREAD_SR),%sr
429
430	rts
431
432#endif /* CONFIG_MMU && !CONFIG_COLDFIRE */
433