xref: /linux/arch/m68k/kernel/entry.S (revision 4b660dbd9ee2059850fd30e0df420ca7a38a1856) 
1/* SPDX-License-Identifier: GPL-2.0-or-later
2 * -*- mode: asm -*-
3 *
4 *  linux/arch/m68k/kernel/entry.S
5 *
6 *  Copyright (C) 1991, 1992  Linus Torvalds
7 *
8 * Linux/m68k support by Hamish Macdonald
9 *
10 * 68060 fixes by Jesper Skov
11 *
12 */
13
14/*
15 * entry.S  contains the system-call and fault low-level handling routines.
16 * This also contains the timer-interrupt handler, as well as all interrupts
17 * and faults that can result in a task-switch.
18 *
19 * NOTE: This code handles signal-recognition, which happens every time
20 * after a timer-interrupt and after each system call.
21 *
22 */
23
24/*
25 * 12/03/96 Jes: Currently we only support m68k single-cpu systems, so
26 *               all pointers that used to be 'current' are now entry
27 *               number 0 in the 'current_set' list.
28 *
29 *  6/05/00 RZ:	 addedd writeback completion after return from sighandler
30 *		 for 68040
31 */
32
33#include <linux/linkage.h>
34#include <asm/errno.h>
35#include <asm/setup.h>
36#include <asm/traps.h>
37#include <asm/unistd.h>
38#include <asm/asm-offsets.h>
39#include <asm/entry.h>
40
41.globl system_call, buserr, trap, resume
42.globl sys_call_table
43.globl __sys_fork, __sys_clone, __sys_vfork
44.globl bad_interrupt
45.globl auto_irqhandler_fixup
46.globl user_irqvec_fixup
47
48.text
49ENTRY(__sys_fork)
50	SAVE_SWITCH_STACK
51	jbsr	sys_fork
52	lea     %sp@(24),%sp
53	rts
54
55ENTRY(__sys_clone)
56	SAVE_SWITCH_STACK
57	pea	%sp@(SWITCH_STACK_SIZE)
58	jbsr	m68k_clone
59	lea     %sp@(28),%sp
60	rts
61
62ENTRY(__sys_vfork)
63	SAVE_SWITCH_STACK
64	jbsr	sys_vfork
65	lea     %sp@(24),%sp
66	rts
67
68ENTRY(__sys_clone3)
69	SAVE_SWITCH_STACK
70	pea	%sp@(SWITCH_STACK_SIZE)
71	jbsr	m68k_clone3
72	lea	%sp@(28),%sp
73	rts
74
75ENTRY(sys_sigreturn)
76	SAVE_SWITCH_STACK
77	movel	%sp,%a1			  	| switch_stack pointer
78	lea	%sp@(SWITCH_STACK_SIZE),%a0	| pt_regs pointer
79	lea     %sp@(-84),%sp			| leave a gap
80	movel	%a1,%sp@-
81	movel	%a0,%sp@-
82	jbsr	do_sigreturn
83	jra	1f				| shared with rt_sigreturn()
84
85ENTRY(sys_rt_sigreturn)
86	SAVE_SWITCH_STACK
87	movel	%sp,%a1			  	| switch_stack pointer
88	lea	%sp@(SWITCH_STACK_SIZE),%a0	| pt_regs pointer
89	lea     %sp@(-84),%sp			| leave a gap
90	movel	%a1,%sp@-
91	movel	%a0,%sp@-
92	| stack contents:
93	|   [original pt_regs address] [original switch_stack address]
94	|   [gap] [switch_stack] [pt_regs] [exception frame]
95	jbsr	do_rt_sigreturn
96
971:
98	| stack contents now:
99	|   [original pt_regs address] [original switch_stack address]
100	|   [unused part of the gap] [moved switch_stack] [moved pt_regs]
101	|   [replacement exception frame]
102	| return value of do_{rt_,}sigreturn() points to moved switch_stack.
103
104	movel	%d0,%sp				| discard the leftover junk
105	RESTORE_SWITCH_STACK
106	| stack contents now is just [syscall return address] [pt_regs] [frame]
107	| return pt_regs.d0
108	movel	%sp@(PT_OFF_D0+4),%d0
109	rts
110
111ENTRY(buserr)
112	SAVE_ALL_INT
113	GET_CURRENT(%d0)
114	movel	%sp,%sp@-		| stack frame pointer argument
115	jbsr	buserr_c
116	addql	#4,%sp
117	jra	ret_from_exception
118
119ENTRY(trap)
120	SAVE_ALL_INT
121	GET_CURRENT(%d0)
122	movel	%sp,%sp@-		| stack frame pointer argument
123	jbsr	trap_c
124	addql	#4,%sp
125	jra	ret_from_exception
126
127	| After a fork we jump here directly from resume,
128	| so that %d1 contains the previous task
129	| schedule_tail now used regardless of CONFIG_SMP
130ENTRY(ret_from_fork)
131	movel	%d1,%sp@-
132	jsr	schedule_tail
133	addql	#4,%sp
134	jra	ret_from_exception
135
136ENTRY(ret_from_kernel_thread)
137	| a3 contains the kernel thread payload, d7 - its argument
138	movel	%d1,%sp@-
139	jsr	schedule_tail
140	movel	%d7,(%sp)
141	jsr	%a3@
142	addql	#4,%sp
143	jra	ret_from_exception
144
145#if defined(CONFIG_COLDFIRE) || !defined(CONFIG_MMU)
146
147#ifdef TRAP_DBG_INTERRUPT
148
149.globl dbginterrupt
150ENTRY(dbginterrupt)
151	SAVE_ALL_INT
152	GET_CURRENT(%d0)
153	movel	%sp,%sp@- 		/* stack frame pointer argument */
154	jsr	dbginterrupt_c
155	addql	#4,%sp
156	jra	ret_from_exception
157#endif
158
159ENTRY(reschedule)
160	/* save top of frame */
161	pea	%sp@
162	jbsr	set_esp0
163	addql	#4,%sp
164	pea	ret_from_exception
165	jmp	schedule
166
167ENTRY(ret_from_user_signal)
168	moveq #__NR_sigreturn,%d0
169	trap #0
170
171ENTRY(ret_from_user_rt_signal)
172	movel #__NR_rt_sigreturn,%d0
173	trap #0
174
175#else
176
177do_trace_entry:
178	movel	#-ENOSYS,%sp@(PT_OFF_D0)| needed for strace
179	subql	#4,%sp
180	SAVE_SWITCH_STACK
181	jbsr	syscall_trace_enter
182	RESTORE_SWITCH_STACK
183	addql	#4,%sp
184	addql	#1,%d0			| optimization for cmpil #-1,%d0
185	jeq	ret_from_syscall
186	movel	%sp@(PT_OFF_ORIG_D0),%d0
187	cmpl	#NR_syscalls,%d0
188	jcs	syscall
189	jra	ret_from_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_leave
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	| seccomp filter active?
215	btst	#5,%a1@(TINFO_FLAGS+2)
216	bnes	do_trace_entry
217	cmpl	#NR_syscalls,%d0
218	jcc	badsys
219syscall:
220	jbsr	@(sys_call_table,%d0:l:4)@(0)
221	movel	%d0,%sp@(PT_OFF_D0)	| save the return value
222ret_from_syscall:
223	|oriw	#0x0700,%sr
224	movel	%curptr@(TASK_STACK),%a1
225	movew	%a1@(TINFO_FLAGS+2),%d0
226	jne	syscall_exit_work
2271:	RESTORE_ALL
228
229syscall_exit_work:
230	btst	#5,%sp@(PT_OFF_SR)	| check if returning to kernel
231	bnes	1b			| if so, skip resched, signals
232	lslw	#1,%d0
233	jcs	do_trace_exit
234	jmi	do_delayed_trace
235	lslw	#8,%d0
236	jne	do_signal_return
237	pea	resume_userspace
238	jra	schedule
239
240
241ENTRY(ret_from_exception)
242.Lret_from_exception:
243	btst	#5,%sp@(PT_OFF_SR)	| check if returning to kernel
244	bnes	1f			| if so, skip resched, signals
245	| only allow interrupts when we are really the last one on the
246	| kernel stack, otherwise stack overflow can occur during
247	| heavy interrupt load
248	andw	#ALLOWINT,%sr
249
250resume_userspace:
251	movel	%curptr@(TASK_STACK),%a1
252	moveb	%a1@(TINFO_FLAGS+3),%d0
253	jne	exit_work
2541:	RESTORE_ALL
255
256exit_work:
257	| save top of frame
258	movel	%sp,%curptr@(TASK_THREAD+THREAD_ESP0)
259	lslb	#1,%d0
260	jne	do_signal_return
261	pea	resume_userspace
262	jra	schedule
263
264
265do_signal_return:
266	|andw	#ALLOWINT,%sr
267	subql	#4,%sp			| dummy return address
268	SAVE_SWITCH_STACK
269	pea	%sp@(SWITCH_STACK_SIZE)
270	bsrl	do_notify_resume
271	addql	#4,%sp
272	RESTORE_SWITCH_STACK
273	addql	#4,%sp
274	jbra	resume_userspace
275
276do_delayed_trace:
277	bclr	#7,%sp@(PT_OFF_SR)	| clear trace bit in SR
278	pea	1			| send SIGTRAP
279	movel	%curptr,%sp@-
280	pea	LSIGTRAP
281	jbsr	send_sig
282	addql	#8,%sp
283	addql	#4,%sp
284	jbra	resume_userspace
285
286
287/* This is the main interrupt handler for autovector interrupts */
288
289ENTRY(auto_inthandler)
290	SAVE_ALL_INT
291	GET_CURRENT(%d0)
292					|  put exception # in d0
293	bfextu	%sp@(PT_OFF_FORMATVEC){#4,#10},%d0
294	subw	#VEC_SPUR,%d0
295
296	movel	%sp,%sp@-
297	movel	%d0,%sp@-		|  put vector # on stack
298auto_irqhandler_fixup = . + 2
299	jsr	do_IRQ			|  process the IRQ
300	addql	#8,%sp			|  pop parameters off stack
301	jra	ret_from_exception
302
303/* Handler for user defined interrupt vectors */
304
305ENTRY(user_inthandler)
306	SAVE_ALL_INT
307	GET_CURRENT(%d0)
308					|  put exception # in d0
309	bfextu	%sp@(PT_OFF_FORMATVEC){#4,#10},%d0
310user_irqvec_fixup = . + 2
311	subw	#VEC_USER,%d0
312
313	movel	%sp,%sp@-
314	movel	%d0,%sp@-		|  put vector # on stack
315	jsr	do_IRQ			|  process the IRQ
316	addql	#8,%sp			|  pop parameters off stack
317	jra	ret_from_exception
318
319/* Handler for uninitialized and spurious interrupts */
320
321ENTRY(bad_inthandler)
322	SAVE_ALL_INT
323	GET_CURRENT(%d0)
324
325	movel	%sp,%sp@-
326	jsr	handle_badint
327	addql	#4,%sp
328	jra	ret_from_exception
329
330resume:
331	/*
332	 * Beware - when entering resume, prev (the current task) is
333	 * in a0, next (the new task) is in a1,so don't change these
334	 * registers until their contents are no longer needed.
335	 */
336
337	/* save sr */
338	movew	%sr,%a0@(TASK_THREAD+THREAD_SR)
339
340	/* save fs (sfc,%dfc) (may be pointing to kernel memory) */
341	movec	%sfc,%d0
342	movew	%d0,%a0@(TASK_THREAD+THREAD_FC)
343
344	/* save usp */
345	/* it is better to use a movel here instead of a movew 8*) */
346	movec	%usp,%d0
347	movel	%d0,%a0@(TASK_THREAD+THREAD_USP)
348
349	/* save non-scratch registers on stack */
350	SAVE_SWITCH_STACK
351
352	/* save current kernel stack pointer */
353	movel	%sp,%a0@(TASK_THREAD+THREAD_KSP)
354
355	/* save floating point context */
356#ifndef CONFIG_M68KFPU_EMU_ONLY
357#ifdef CONFIG_M68KFPU_EMU
358	tstl	m68k_fputype
359	jeq	3f
360#endif
361	fsave	%a0@(TASK_THREAD+THREAD_FPSTATE)
362
363#if defined(CONFIG_M68060)
364#if !defined(CPU_M68060_ONLY)
365	btst	#3,m68k_cputype+3
366	beqs	1f
367#endif
368	/* The 060 FPU keeps status in bits 15-8 of the first longword */
369	tstb	%a0@(TASK_THREAD+THREAD_FPSTATE+2)
370	jeq	3f
371#if !defined(CPU_M68060_ONLY)
372	jra	2f
373#endif
374#endif /* CONFIG_M68060 */
375#if !defined(CPU_M68060_ONLY)
3761:	tstb	%a0@(TASK_THREAD+THREAD_FPSTATE)
377	jeq	3f
378#endif
3792:	fmovemx	%fp0-%fp7,%a0@(TASK_THREAD+THREAD_FPREG)
380	fmoveml	%fpcr/%fpsr/%fpiar,%a0@(TASK_THREAD+THREAD_FPCNTL)
3813:
382#endif	/* CONFIG_M68KFPU_EMU_ONLY */
383	/* Return previous task in %d1 */
384	movel	%curptr,%d1
385
386	/* switch to new task (a1 contains new task) */
387	movel	%a1,%curptr
388
389	/* restore floating point context */
390#ifndef CONFIG_M68KFPU_EMU_ONLY
391#ifdef CONFIG_M68KFPU_EMU
392	tstl	m68k_fputype
393	jeq	4f
394#endif
395#if defined(CONFIG_M68060)
396#if !defined(CPU_M68060_ONLY)
397	btst	#3,m68k_cputype+3
398	beqs	1f
399#endif
400	/* The 060 FPU keeps status in bits 15-8 of the first longword */
401	tstb	%a1@(TASK_THREAD+THREAD_FPSTATE+2)
402	jeq	3f
403#if !defined(CPU_M68060_ONLY)
404	jra	2f
405#endif
406#endif /* CONFIG_M68060 */
407#if !defined(CPU_M68060_ONLY)
4081:	tstb	%a1@(TASK_THREAD+THREAD_FPSTATE)
409	jeq	3f
410#endif
4112:	fmovemx	%a1@(TASK_THREAD+THREAD_FPREG),%fp0-%fp7
412	fmoveml	%a1@(TASK_THREAD+THREAD_FPCNTL),%fpcr/%fpsr/%fpiar
4133:	frestore %a1@(TASK_THREAD+THREAD_FPSTATE)
4144:
415#endif	/* CONFIG_M68KFPU_EMU_ONLY */
416
417	/* restore the kernel stack pointer */
418	movel	%a1@(TASK_THREAD+THREAD_KSP),%sp
419
420	/* restore non-scratch registers */
421	RESTORE_SWITCH_STACK
422
423	/* restore user stack pointer */
424	movel	%a1@(TASK_THREAD+THREAD_USP),%a0
425	movel	%a0,%usp
426
427	/* restore fs (sfc,%dfc) */
428	movew	%a1@(TASK_THREAD+THREAD_FC),%a0
429	movec	%a0,%sfc
430	movec	%a0,%dfc
431
432	/* restore status register */
433	movew	%a1@(TASK_THREAD+THREAD_SR),%sr
434
435	rts
436
437#endif /* CONFIG_MMU && !CONFIG_COLDFIRE */
438