xref: /openbmc/linux/arch/m68k/kernel/entry.S (revision 36de991e) 
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/traps.h>
40#include <asm/unistd.h>
41#include <asm/asm-offsets.h>
42#include <asm/entry.h>
43
44.globl system_call, buserr, trap, resume
45.globl sys_call_table
46.globl __sys_fork, __sys_clone, __sys_vfork
47.globl bad_interrupt
48.globl auto_irqhandler_fixup
49.globl user_irqvec_fixup
50
51.text
52ENTRY(__sys_fork)
53	SAVE_SWITCH_STACK
54	jbsr	sys_fork
55	lea     %sp@(24),%sp
56	rts
57
58ENTRY(__sys_clone)
59	SAVE_SWITCH_STACK
60	pea	%sp@(SWITCH_STACK_SIZE)
61	jbsr	m68k_clone
62	lea     %sp@(28),%sp
63	rts
64
65ENTRY(__sys_vfork)
66	SAVE_SWITCH_STACK
67	jbsr	sys_vfork
68	lea     %sp@(24),%sp
69	rts
70
71ENTRY(__sys_clone3)
72	SAVE_SWITCH_STACK
73	pea	%sp@(SWITCH_STACK_SIZE)
74	jbsr	m68k_clone3
75	lea	%sp@(28),%sp
76	rts
77
78ENTRY(sys_sigreturn)
79	SAVE_SWITCH_STACK
80	movel	%sp,%a1			  	| switch_stack pointer
81	lea	%sp@(SWITCH_STACK_SIZE),%a0	| pt_regs pointer
82	lea     %sp@(-84),%sp			| leave a gap
83	movel	%a1,%sp@-
84	movel	%a0,%sp@-
85	jbsr	do_sigreturn
86	jra	1f				| shared with rt_sigreturn()
87
88ENTRY(sys_rt_sigreturn)
89	SAVE_SWITCH_STACK
90	movel	%sp,%a1			  	| switch_stack pointer
91	lea	%sp@(SWITCH_STACK_SIZE),%a0	| pt_regs pointer
92	lea     %sp@(-84),%sp			| leave a gap
93	movel	%a1,%sp@-
94	movel	%a0,%sp@-
95	| stack contents:
96	|   [original pt_regs address] [original switch_stack address]
97	|   [gap] [switch_stack] [pt_regs] [exception frame]
98	jbsr	do_rt_sigreturn
99
1001:
101	| stack contents now:
102	|   [original pt_regs address] [original switch_stack address]
103	|   [unused part of the gap] [moved switch_stack] [moved pt_regs]
104	|   [replacement exception frame]
105	| return value of do_{rt_,}sigreturn() points to moved switch_stack.
106
107	movel	%d0,%sp				| discard the leftover junk
108	RESTORE_SWITCH_STACK
109	| stack contents now is just [syscall return address] [pt_regs] [frame]
110	| return pt_regs.d0
111	movel	%sp@(PT_OFF_D0+4),%d0
112	rts
113
114ENTRY(buserr)
115	SAVE_ALL_INT
116	GET_CURRENT(%d0)
117	movel	%sp,%sp@-		| stack frame pointer argument
118	jbsr	buserr_c
119	addql	#4,%sp
120	jra	ret_from_exception
121
122ENTRY(trap)
123	SAVE_ALL_INT
124	GET_CURRENT(%d0)
125	movel	%sp,%sp@-		| stack frame pointer argument
126	jbsr	trap_c
127	addql	#4,%sp
128	jra	ret_from_exception
129
130	| After a fork we jump here directly from resume,
131	| so that %d1 contains the previous task
132	| schedule_tail now used regardless of CONFIG_SMP
133ENTRY(ret_from_fork)
134	movel	%d1,%sp@-
135	jsr	schedule_tail
136	addql	#4,%sp
137	jra	ret_from_exception
138
139ENTRY(ret_from_kernel_thread)
140	| a3 contains the kernel thread payload, d7 - its argument
141	movel	%d1,%sp@-
142	jsr	schedule_tail
143	movel	%d7,(%sp)
144	jsr	%a3@
145	addql	#4,%sp
146	jra	ret_from_exception
147
148#if defined(CONFIG_COLDFIRE) || !defined(CONFIG_MMU)
149
150#ifdef TRAP_DBG_INTERRUPT
151
152.globl dbginterrupt
153ENTRY(dbginterrupt)
154	SAVE_ALL_INT
155	GET_CURRENT(%d0)
156	movel	%sp,%sp@- 		/* stack frame pointer argument */
157	jsr	dbginterrupt_c
158	addql	#4,%sp
159	jra	ret_from_exception
160#endif
161
162ENTRY(reschedule)
163	/* save top of frame */
164	pea	%sp@
165	jbsr	set_esp0
166	addql	#4,%sp
167	pea	ret_from_exception
168	jmp	schedule
169
170ENTRY(ret_from_user_signal)
171	moveq #__NR_sigreturn,%d0
172	trap #0
173
174ENTRY(ret_from_user_rt_signal)
175	movel #__NR_rt_sigreturn,%d0
176	trap #0
177
178#else
179
180do_trace_entry:
181	movel	#-ENOSYS,%sp@(PT_OFF_D0)| needed for strace
182	subql	#4,%sp
183	SAVE_SWITCH_STACK
184	jbsr	syscall_trace
185	RESTORE_SWITCH_STACK
186	addql	#4,%sp
187	movel	%sp@(PT_OFF_ORIG_D0),%d0
188	cmpl	#NR_syscalls,%d0
189	jcs	syscall
190badsys:
191	movel	#-ENOSYS,%sp@(PT_OFF_D0)
192	jra	ret_from_syscall
193
194do_trace_exit:
195	subql	#4,%sp
196	SAVE_SWITCH_STACK
197	jbsr	syscall_trace
198	RESTORE_SWITCH_STACK
199	addql	#4,%sp
200	jra	.Lret_from_exception
201
202ENTRY(system_call)
203	SAVE_ALL_SYS
204
205	GET_CURRENT(%d1)
206	movel	%d1,%a1
207
208	| save top of frame
209	movel	%sp,%curptr@(TASK_THREAD+THREAD_ESP0)
210
211	| syscall trace?
212	tstb	%a1@(TINFO_FLAGS+2)
213	jmi	do_trace_entry
214	cmpl	#NR_syscalls,%d0
215	jcc	badsys
216syscall:
217	jbsr	@(sys_call_table,%d0:l:4)@(0)
218	movel	%d0,%sp@(PT_OFF_D0)	| save the return value
219ret_from_syscall:
220	|oriw	#0x0700,%sr
221	movel	%curptr@(TASK_STACK),%a1
222	movew	%a1@(TINFO_FLAGS+2),%d0
223	jne	syscall_exit_work
2241:	RESTORE_ALL
225
226syscall_exit_work:
227	btst	#5,%sp@(PT_OFF_SR)	| check if returning to kernel
228	bnes	1b			| if so, skip resched, signals
229	lslw	#1,%d0
230	jcs	do_trace_exit
231	jmi	do_delayed_trace
232	lslw	#8,%d0
233	jne	do_signal_return
234	pea	resume_userspace
235	jra	schedule
236
237
238ENTRY(ret_from_exception)
239.Lret_from_exception:
240	btst	#5,%sp@(PT_OFF_SR)	| check if returning to kernel
241	bnes	1f			| if so, skip resched, signals
242	| only allow interrupts when we are really the last one on the
243	| kernel stack, otherwise stack overflow can occur during
244	| heavy interrupt load
245	andw	#ALLOWINT,%sr
246
247resume_userspace:
248	movel	%curptr@(TASK_STACK),%a1
249	moveb	%a1@(TINFO_FLAGS+3),%d0
250	jne	exit_work
2511:	RESTORE_ALL
252
253exit_work:
254	| save top of frame
255	movel	%sp,%curptr@(TASK_THREAD+THREAD_ESP0)
256	lslb	#1,%d0
257	jne	do_signal_return
258	pea	resume_userspace
259	jra	schedule
260
261
262do_signal_return:
263	|andw	#ALLOWINT,%sr
264	subql	#4,%sp			| dummy return address
265	SAVE_SWITCH_STACK
266	pea	%sp@(SWITCH_STACK_SIZE)
267	bsrl	do_notify_resume
268	addql	#4,%sp
269	RESTORE_SWITCH_STACK
270	addql	#4,%sp
271	jbra	resume_userspace
272
273do_delayed_trace:
274	bclr	#7,%sp@(PT_OFF_SR)	| clear trace bit in SR
275	pea	1			| send SIGTRAP
276	movel	%curptr,%sp@-
277	pea	LSIGTRAP
278	jbsr	send_sig
279	addql	#8,%sp
280	addql	#4,%sp
281	jbra	resume_userspace
282
283
284/* This is the main interrupt handler for autovector interrupts */
285
286ENTRY(auto_inthandler)
287	SAVE_ALL_INT
288	GET_CURRENT(%d0)
289					|  put exception # in d0
290	bfextu	%sp@(PT_OFF_FORMATVEC){#4,#10},%d0
291	subw	#VEC_SPUR,%d0
292
293	movel	%sp,%sp@-
294	movel	%d0,%sp@-		|  put vector # on stack
295auto_irqhandler_fixup = . + 2
296	jsr	do_IRQ			|  process the IRQ
297	addql	#8,%sp			|  pop parameters off stack
298	jra	ret_from_exception
299
300/* Handler for user defined interrupt vectors */
301
302ENTRY(user_inthandler)
303	SAVE_ALL_INT
304	GET_CURRENT(%d0)
305					|  put exception # in d0
306	bfextu	%sp@(PT_OFF_FORMATVEC){#4,#10},%d0
307user_irqvec_fixup = . + 2
308	subw	#VEC_USER,%d0
309
310	movel	%sp,%sp@-
311	movel	%d0,%sp@-		|  put vector # on stack
312	jsr	do_IRQ			|  process the IRQ
313	addql	#8,%sp			|  pop parameters off stack
314	jra	ret_from_exception
315
316/* Handler for uninitialized and spurious interrupts */
317
318ENTRY(bad_inthandler)
319	SAVE_ALL_INT
320	GET_CURRENT(%d0)
321
322	movel	%sp,%sp@-
323	jsr	handle_badint
324	addql	#4,%sp
325	jra	ret_from_exception
326
327resume:
328	/*
329	 * Beware - when entering resume, prev (the current task) is
330	 * in a0, next (the new task) is in a1,so don't change these
331	 * registers until their contents are no longer needed.
332	 */
333
334	/* save sr */
335	movew	%sr,%a0@(TASK_THREAD+THREAD_SR)
336
337	/* save fs (sfc,%dfc) (may be pointing to kernel memory) */
338	movec	%sfc,%d0
339	movew	%d0,%a0@(TASK_THREAD+THREAD_FC)
340
341	/* save usp */
342	/* it is better to use a movel here instead of a movew 8*) */
343	movec	%usp,%d0
344	movel	%d0,%a0@(TASK_THREAD+THREAD_USP)
345
346	/* save non-scratch registers on stack */
347	SAVE_SWITCH_STACK
348
349	/* save current kernel stack pointer */
350	movel	%sp,%a0@(TASK_THREAD+THREAD_KSP)
351
352	/* save floating point context */
353#ifndef CONFIG_M68KFPU_EMU_ONLY
354#ifdef CONFIG_M68KFPU_EMU
355	tstl	m68k_fputype
356	jeq	3f
357#endif
358	fsave	%a0@(TASK_THREAD+THREAD_FPSTATE)
359
360#if defined(CONFIG_M68060)
361#if !defined(CPU_M68060_ONLY)
362	btst	#3,m68k_cputype+3
363	beqs	1f
364#endif
365	/* The 060 FPU keeps status in bits 15-8 of the first longword */
366	tstb	%a0@(TASK_THREAD+THREAD_FPSTATE+2)
367	jeq	3f
368#if !defined(CPU_M68060_ONLY)
369	jra	2f
370#endif
371#endif /* CONFIG_M68060 */
372#if !defined(CPU_M68060_ONLY)
3731:	tstb	%a0@(TASK_THREAD+THREAD_FPSTATE)
374	jeq	3f
375#endif
3762:	fmovemx	%fp0-%fp7,%a0@(TASK_THREAD+THREAD_FPREG)
377	fmoveml	%fpcr/%fpsr/%fpiar,%a0@(TASK_THREAD+THREAD_FPCNTL)
3783:
379#endif	/* CONFIG_M68KFPU_EMU_ONLY */
380	/* Return previous task in %d1 */
381	movel	%curptr,%d1
382
383	/* switch to new task (a1 contains new task) */
384	movel	%a1,%curptr
385
386	/* restore floating point context */
387#ifndef CONFIG_M68KFPU_EMU_ONLY
388#ifdef CONFIG_M68KFPU_EMU
389	tstl	m68k_fputype
390	jeq	4f
391#endif
392#if defined(CONFIG_M68060)
393#if !defined(CPU_M68060_ONLY)
394	btst	#3,m68k_cputype+3
395	beqs	1f
396#endif
397	/* The 060 FPU keeps status in bits 15-8 of the first longword */
398	tstb	%a1@(TASK_THREAD+THREAD_FPSTATE+2)
399	jeq	3f
400#if !defined(CPU_M68060_ONLY)
401	jra	2f
402#endif
403#endif /* CONFIG_M68060 */
404#if !defined(CPU_M68060_ONLY)
4051:	tstb	%a1@(TASK_THREAD+THREAD_FPSTATE)
406	jeq	3f
407#endif
4082:	fmovemx	%a1@(TASK_THREAD+THREAD_FPREG),%fp0-%fp7
409	fmoveml	%a1@(TASK_THREAD+THREAD_FPCNTL),%fpcr/%fpsr/%fpiar
4103:	frestore %a1@(TASK_THREAD+THREAD_FPSTATE)
4114:
412#endif	/* CONFIG_M68KFPU_EMU_ONLY */
413
414	/* restore the kernel stack pointer */
415	movel	%a1@(TASK_THREAD+THREAD_KSP),%sp
416
417	/* restore non-scratch registers */
418	RESTORE_SWITCH_STACK
419
420	/* restore user stack pointer */
421	movel	%a1@(TASK_THREAD+THREAD_USP),%a0
422	movel	%a0,%usp
423
424	/* restore fs (sfc,%dfc) */
425	movew	%a1@(TASK_THREAD+THREAD_FC),%a0
426	movec	%a0,%sfc
427	movec	%a0,%dfc
428
429	/* restore status register */
430	movew	%a1@(TASK_THREAD+THREAD_SR),%sr
431
432	rts
433
434#endif /* CONFIG_MMU && !CONFIG_COLDFIRE */
435