xref: /openbmc/linux/arch/m68k/kernel/entry.S (revision 275876e2) 
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	jbsr	do_sigreturn
75	RESTORE_SWITCH_STACK
76	rts
77
78ENTRY(sys_rt_sigreturn)
79	SAVE_SWITCH_STACK
80	jbsr	do_rt_sigreturn
81	RESTORE_SWITCH_STACK
82	rts
83
84ENTRY(buserr)
85	SAVE_ALL_INT
86	GET_CURRENT(%d0)
87	movel	%sp,%sp@-		| stack frame pointer argument
88	jbsr	buserr_c
89	addql	#4,%sp
90	jra	ret_from_exception
91
92ENTRY(trap)
93	SAVE_ALL_INT
94	GET_CURRENT(%d0)
95	movel	%sp,%sp@-		| stack frame pointer argument
96	jbsr	trap_c
97	addql	#4,%sp
98	jra	ret_from_exception
99
100	| After a fork we jump here directly from resume,
101	| so that %d1 contains the previous task
102	| schedule_tail now used regardless of CONFIG_SMP
103ENTRY(ret_from_fork)
104	movel	%d1,%sp@-
105	jsr	schedule_tail
106	addql	#4,%sp
107	jra	ret_from_exception
108
109ENTRY(ret_from_kernel_thread)
110	| a3 contains the kernel thread payload, d7 - its argument
111	movel	%d1,%sp@-
112	jsr	schedule_tail
113	movel	%d7,(%sp)
114	jsr	%a3@
115	addql	#4,%sp
116	jra	ret_from_exception
117
118#if defined(CONFIG_COLDFIRE) || !defined(CONFIG_MMU)
119
120#ifdef TRAP_DBG_INTERRUPT
121
122.globl dbginterrupt
123ENTRY(dbginterrupt)
124	SAVE_ALL_INT
125	GET_CURRENT(%d0)
126	movel	%sp,%sp@- 		/* stack frame pointer argument */
127	jsr	dbginterrupt_c
128	addql	#4,%sp
129	jra	ret_from_exception
130#endif
131
132ENTRY(reschedule)
133	/* save top of frame */
134	pea	%sp@
135	jbsr	set_esp0
136	addql	#4,%sp
137	pea	ret_from_exception
138	jmp	schedule
139
140ENTRY(ret_from_user_signal)
141	moveq #__NR_sigreturn,%d0
142	trap #0
143
144ENTRY(ret_from_user_rt_signal)
145	movel #__NR_rt_sigreturn,%d0
146	trap #0
147
148#else
149
150do_trace_entry:
151	movel	#-ENOSYS,%sp@(PT_OFF_D0)| needed for strace
152	subql	#4,%sp
153	SAVE_SWITCH_STACK
154	jbsr	syscall_trace
155	RESTORE_SWITCH_STACK
156	addql	#4,%sp
157	movel	%sp@(PT_OFF_ORIG_D0),%d0
158	cmpl	#NR_syscalls,%d0
159	jcs	syscall
160badsys:
161	movel	#-ENOSYS,%sp@(PT_OFF_D0)
162	jra	ret_from_syscall
163
164do_trace_exit:
165	subql	#4,%sp
166	SAVE_SWITCH_STACK
167	jbsr	syscall_trace
168	RESTORE_SWITCH_STACK
169	addql	#4,%sp
170	jra	.Lret_from_exception
171
172ENTRY(ret_from_signal)
173	movel	%curptr@(TASK_STACK),%a1
174	tstb	%a1@(TINFO_FLAGS+2)
175	jge	1f
176	jbsr	syscall_trace
1771:	RESTORE_SWITCH_STACK
178	addql	#4,%sp
179/* on 68040 complete pending writebacks if any */
180#ifdef CONFIG_M68040
181	bfextu	%sp@(PT_OFF_FORMATVEC){#0,#4},%d0
182	subql	#7,%d0				| bus error frame ?
183	jbne	1f
184	movel	%sp,%sp@-
185	jbsr	berr_040cleanup
186	addql	#4,%sp
1871:
188#endif
189	jra	.Lret_from_exception
190
191ENTRY(system_call)
192	SAVE_ALL_SYS
193
194	GET_CURRENT(%d1)
195	movel	%d1,%a1
196
197	| save top of frame
198	movel	%sp,%curptr@(TASK_THREAD+THREAD_ESP0)
199
200	| syscall trace?
201	tstb	%a1@(TINFO_FLAGS+2)
202	jmi	do_trace_entry
203	cmpl	#NR_syscalls,%d0
204	jcc	badsys
205syscall:
206	jbsr	@(sys_call_table,%d0:l:4)@(0)
207	movel	%d0,%sp@(PT_OFF_D0)	| save the return value
208ret_from_syscall:
209	|oriw	#0x0700,%sr
210	movel	%curptr@(TASK_STACK),%a1
211	movew	%a1@(TINFO_FLAGS+2),%d0
212	jne	syscall_exit_work
2131:	RESTORE_ALL
214
215syscall_exit_work:
216	btst	#5,%sp@(PT_OFF_SR)	| check if returning to kernel
217	bnes	1b			| if so, skip resched, signals
218	lslw	#1,%d0
219	jcs	do_trace_exit
220	jmi	do_delayed_trace
221	lslw	#8,%d0
222	jne	do_signal_return
223	pea	resume_userspace
224	jra	schedule
225
226
227ENTRY(ret_from_exception)
228.Lret_from_exception:
229	btst	#5,%sp@(PT_OFF_SR)	| check if returning to kernel
230	bnes	1f			| if so, skip resched, signals
231	| only allow interrupts when we are really the last one on the
232	| kernel stack, otherwise stack overflow can occur during
233	| heavy interrupt load
234	andw	#ALLOWINT,%sr
235
236resume_userspace:
237	movel	%curptr@(TASK_STACK),%a1
238	moveb	%a1@(TINFO_FLAGS+3),%d0
239	jne	exit_work
2401:	RESTORE_ALL
241
242exit_work:
243	| save top of frame
244	movel	%sp,%curptr@(TASK_THREAD+THREAD_ESP0)
245	lslb	#1,%d0
246	jne	do_signal_return
247	pea	resume_userspace
248	jra	schedule
249
250
251do_signal_return:
252	|andw	#ALLOWINT,%sr
253	subql	#4,%sp			| dummy return address
254	SAVE_SWITCH_STACK
255	pea	%sp@(SWITCH_STACK_SIZE)
256	bsrl	do_notify_resume
257	addql	#4,%sp
258	RESTORE_SWITCH_STACK
259	addql	#4,%sp
260	jbra	resume_userspace
261
262do_delayed_trace:
263	bclr	#7,%sp@(PT_OFF_SR)	| clear trace bit in SR
264	pea	1			| send SIGTRAP
265	movel	%curptr,%sp@-
266	pea	LSIGTRAP
267	jbsr	send_sig
268	addql	#8,%sp
269	addql	#4,%sp
270	jbra	resume_userspace
271
272
273/* This is the main interrupt handler for autovector interrupts */
274
275ENTRY(auto_inthandler)
276	SAVE_ALL_INT
277	GET_CURRENT(%d0)
278					|  put exception # in d0
279	bfextu	%sp@(PT_OFF_FORMATVEC){#4,#10},%d0
280	subw	#VEC_SPUR,%d0
281
282	movel	%sp,%sp@-
283	movel	%d0,%sp@-		|  put vector # on stack
284auto_irqhandler_fixup = . + 2
285	jsr	do_IRQ			|  process the IRQ
286	addql	#8,%sp			|  pop parameters off stack
287	jra	ret_from_exception
288
289/* Handler for user defined interrupt vectors */
290
291ENTRY(user_inthandler)
292	SAVE_ALL_INT
293	GET_CURRENT(%d0)
294					|  put exception # in d0
295	bfextu	%sp@(PT_OFF_FORMATVEC){#4,#10},%d0
296user_irqvec_fixup = . + 2
297	subw	#VEC_USER,%d0
298
299	movel	%sp,%sp@-
300	movel	%d0,%sp@-		|  put vector # on stack
301	jsr	do_IRQ			|  process the IRQ
302	addql	#8,%sp			|  pop parameters off stack
303	jra	ret_from_exception
304
305/* Handler for uninitialized and spurious interrupts */
306
307ENTRY(bad_inthandler)
308	SAVE_ALL_INT
309	GET_CURRENT(%d0)
310
311	movel	%sp,%sp@-
312	jsr	handle_badint
313	addql	#4,%sp
314	jra	ret_from_exception
315
316resume:
317	/*
318	 * Beware - when entering resume, prev (the current task) is
319	 * in a0, next (the new task) is in a1,so don't change these
320	 * registers until their contents are no longer needed.
321	 */
322
323	/* save sr */
324	movew	%sr,%a0@(TASK_THREAD+THREAD_SR)
325
326	/* save fs (sfc,%dfc) (may be pointing to kernel memory) */
327	movec	%sfc,%d0
328	movew	%d0,%a0@(TASK_THREAD+THREAD_FS)
329
330	/* save usp */
331	/* it is better to use a movel here instead of a movew 8*) */
332	movec	%usp,%d0
333	movel	%d0,%a0@(TASK_THREAD+THREAD_USP)
334
335	/* save non-scratch registers on stack */
336	SAVE_SWITCH_STACK
337
338	/* save current kernel stack pointer */
339	movel	%sp,%a0@(TASK_THREAD+THREAD_KSP)
340
341	/* save floating point context */
342#ifndef CONFIG_M68KFPU_EMU_ONLY
343#ifdef CONFIG_M68KFPU_EMU
344	tstl	m68k_fputype
345	jeq	3f
346#endif
347	fsave	%a0@(TASK_THREAD+THREAD_FPSTATE)
348
349#if defined(CONFIG_M68060)
350#if !defined(CPU_M68060_ONLY)
351	btst	#3,m68k_cputype+3
352	beqs	1f
353#endif
354	/* The 060 FPU keeps status in bits 15-8 of the first longword */
355	tstb	%a0@(TASK_THREAD+THREAD_FPSTATE+2)
356	jeq	3f
357#if !defined(CPU_M68060_ONLY)
358	jra	2f
359#endif
360#endif /* CONFIG_M68060 */
361#if !defined(CPU_M68060_ONLY)
3621:	tstb	%a0@(TASK_THREAD+THREAD_FPSTATE)
363	jeq	3f
364#endif
3652:	fmovemx	%fp0-%fp7,%a0@(TASK_THREAD+THREAD_FPREG)
366	fmoveml	%fpcr/%fpsr/%fpiar,%a0@(TASK_THREAD+THREAD_FPCNTL)
3673:
368#endif	/* CONFIG_M68KFPU_EMU_ONLY */
369	/* Return previous task in %d1 */
370	movel	%curptr,%d1
371
372	/* switch to new task (a1 contains new task) */
373	movel	%a1,%curptr
374
375	/* restore floating point context */
376#ifndef CONFIG_M68KFPU_EMU_ONLY
377#ifdef CONFIG_M68KFPU_EMU
378	tstl	m68k_fputype
379	jeq	4f
380#endif
381#if defined(CONFIG_M68060)
382#if !defined(CPU_M68060_ONLY)
383	btst	#3,m68k_cputype+3
384	beqs	1f
385#endif
386	/* The 060 FPU keeps status in bits 15-8 of the first longword */
387	tstb	%a1@(TASK_THREAD+THREAD_FPSTATE+2)
388	jeq	3f
389#if !defined(CPU_M68060_ONLY)
390	jra	2f
391#endif
392#endif /* CONFIG_M68060 */
393#if !defined(CPU_M68060_ONLY)
3941:	tstb	%a1@(TASK_THREAD+THREAD_FPSTATE)
395	jeq	3f
396#endif
3972:	fmovemx	%a1@(TASK_THREAD+THREAD_FPREG),%fp0-%fp7
398	fmoveml	%a1@(TASK_THREAD+THREAD_FPCNTL),%fpcr/%fpsr/%fpiar
3993:	frestore %a1@(TASK_THREAD+THREAD_FPSTATE)
4004:
401#endif	/* CONFIG_M68KFPU_EMU_ONLY */
402
403	/* restore the kernel stack pointer */
404	movel	%a1@(TASK_THREAD+THREAD_KSP),%sp
405
406	/* restore non-scratch registers */
407	RESTORE_SWITCH_STACK
408
409	/* restore user stack pointer */
410	movel	%a1@(TASK_THREAD+THREAD_USP),%a0
411	movel	%a0,%usp
412
413	/* restore fs (sfc,%dfc) */
414	movew	%a1@(TASK_THREAD+THREAD_FS),%a0
415	movec	%a0,%sfc
416	movec	%a0,%dfc
417
418	/* restore status register */
419	movew	%a1@(TASK_THREAD+THREAD_SR),%sr
420
421	rts
422
423#endif /* CONFIG_MMU && !CONFIG_COLDFIRE */
424