aboutsummaryrefslogtreecommitdiffstats
path: root/arch/sh/kernel/entry-common.S
blob: 926b2e7b11c13a602fcce925c07439e1cdb09229 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
/* $Id: entry.S,v 1.37 2004/06/11 13:02:46 doyu Exp $
 *
 *  linux/arch/sh/entry.S
 *
 *  Copyright (C) 1999, 2000, 2002  Niibe Yutaka
 *  Copyright (C) 2003  Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 */

! NOTE:
! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address
! to be jumped is too far, but it causes illegal slot exception.

/*	
 * entry.S contains the system-call and fault low-level handling routines.
 * This also contains the timer-interrupt handler, as well as all interrupts
 * and faults that can result in a task-switch.
 *
 * NOTE: This code handles signal-recognition, which happens every time
 * after a timer-interrupt and after each system call.
 *
 * NOTE: This code uses a convention that instructions in the delay slot
 * of a transfer-control instruction are indented by an extra space, thus:
 *
 *    jmp	@k0	    ! control-transfer instruction
 *     ldc	k1, ssr     ! delay slot
 *
 * Stack layout in 'ret_from_syscall':
 * 	ptrace needs to have all regs on the stack.
 *	if the order here is changed, it needs to be
 *	updated in ptrace.c and ptrace.h
 *
 *	r0
 *      ...
 *	r15 = stack pointer
 *	spc
 *	pr
 *	ssr
 *	gbr
 *	mach
 *	macl
 *	syscall #
 *
 */

#if defined(CONFIG_PREEMPT)
#  define preempt_stop()	cli
#else
#  define preempt_stop()
#  define resume_kernel		__restore_all
#endif


	.align	2
ENTRY(exception_error)
	!
#ifdef CONFIG_TRACE_IRQFLAGS
	mov.l	2f, r0
	jsr	@r0
	 nop
#endif
	sti
	mov.l	1f, r0
	jmp	@r0
	 nop

	.align	2
1:	.long	do_exception_error
#ifdef CONFIG_TRACE_IRQFLAGS
2:	.long	trace_hardirqs_on
#endif

	.align	2
ret_from_exception:
	preempt_stop()
#ifdef CONFIG_TRACE_IRQFLAGS
	mov.l	4f, r0
	jsr	@r0
	 nop
#endif
ENTRY(ret_from_irq)
	!
	mov	#OFF_SR, r0
	mov.l	@(r0,r15), r0	! get status register
	shll	r0
	shll	r0		! kernel space?
	get_current_thread_info r8, r0
	bt	resume_kernel	! Yes, it's from kernel, go back soon

#ifdef CONFIG_PREEMPT
	bra	resume_userspace
	 nop
ENTRY(resume_kernel)
	mov.l	@(TI_PRE_COUNT,r8), r0	! current_thread_info->preempt_count
	tst	r0, r0
	bf	noresched
need_resched:
	mov.l	@(TI_FLAGS,r8), r0	! current_thread_info->flags
	tst	#_TIF_NEED_RESCHED, r0	! need_resched set?
	bt	noresched

	mov	#OFF_SR, r0
	mov.l	@(r0,r15), r0		! get status register
	and	#0xf0, r0		! interrupts off (exception path)?
	cmp/eq	#0xf0, r0
	bt	noresched

	mov.l	1f, r0
	mov.l	r0, @(TI_PRE_COUNT,r8)

#ifdef CONFIG_TRACE_IRQFLAGS
	mov.l	3f, r0
	jsr	@r0
	 nop
#endif
	sti
	mov.l	2f, r0
	jsr	@r0
	 nop
	mov	#0, r0
	mov.l	r0, @(TI_PRE_COUNT,r8)
	cli
#ifdef CONFIG_TRACE_IRQFLAGS
	mov.l	4f, r0
	jsr	@r0
	 nop
#endif

	bra	need_resched
	 nop

noresched:
	bra	__restore_all
	 nop

	.align 2
1:	.long	PREEMPT_ACTIVE
2:	.long	schedule
#ifdef CONFIG_TRACE_IRQFLAGS
3:	.long	trace_hardirqs_on
4:	.long	trace_hardirqs_off
#endif
#endif

ENTRY(resume_userspace)
	! r8: current_thread_info
	cli
#ifdef CONFIG_TRACE_IRQFLAGS
	mov.l	5f, r0
	jsr	@r0
	 nop
#endif
	mov.l	@(TI_FLAGS,r8), r0		! current_thread_info->flags
	tst	#_TIF_WORK_MASK, r0
	bt/s	__restore_all
	 tst	#_TIF_NEED_RESCHED, r0

	.align	2
work_pending:
	! r0: current_thread_info->flags
	! r8: current_thread_info
	! t:  result of "tst	#_TIF_NEED_RESCHED, r0"
	bf/s	work_resched
	 tst	#(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0
work_notifysig:
	bt/s	__restore_all
	 mov	r15, r4
	mov	r12, r5		! set arg1(save_r0)
	mov	r0, r6
	mov.l	2f, r1
	mov.l	3f, r0
	jmp	@r1
	 lds	r0, pr
work_resched:
	mov.l	1f, r1
	jsr	@r1				! schedule
	 nop
	cli
#ifdef CONFIG_TRACE_IRQFLAGS
	mov.l	5f, r0
	jsr	@r0
	 nop
#endif
	!
	mov.l	@(TI_FLAGS,r8), r0		! current_thread_info->flags
	tst	#_TIF_WORK_MASK, r0
	bt	__restore_all
	bra	work_pending
	 tst	#_TIF_NEED_RESCHED, r0

	.align	2
1:	.long	schedule
2:	.long	do_notify_resume
3:	.long	restore_all
#ifdef CONFIG_TRACE_IRQFLAGS
4:	.long	trace_hardirqs_on
5:	.long	trace_hardirqs_off
#endif

	.align	2
syscall_exit_work:
	! r0: current_thread_info->flags
	! r8: current_thread_info
	tst	#_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP | _TIF_SYSCALL_AUDIT, r0
	bt/s	work_pending
	 tst	#_TIF_NEED_RESCHED, r0
#ifdef CONFIG_TRACE_IRQFLAGS
	mov.l	5f, r0
	jsr	@r0
	 nop
#endif
	sti
	! XXX setup arguments...
	mov	r15, r4
	mov	#1, r5
	mov.l	4f, r0			! do_syscall_trace
	jsr	@r0
	 nop
	bra	resume_userspace
	 nop

	.align	2
syscall_trace_entry:
	!                     	Yes it is traced.
	! XXX setup arguments...
	mov     r15, r4
	mov     #0, r5
	mov.l	4f, r11		! Call do_syscall_trace which notifies
	jsr	@r11	    	! superior (will chomp R[0-7])
	 nop
	!			Reload R0-R4 from kernel stack, where the
	!   	    	    	parent may have modified them using
	!   	    	    	ptrace(POKEUSR).  (Note that R0-R2 are
	!   	    	    	used by the system call handler directly
	!   	    	    	from the kernel stack anyway, so don't need
	!   	    	    	to be reloaded here.)  This allows the parent
	!   	    	    	to rewrite system calls and args on the fly.
	mov.l	@(OFF_R4,r15), r4   ! arg0
	mov.l	@(OFF_R5,r15), r5
	mov.l	@(OFF_R6,r15), r6
	mov.l	@(OFF_R7,r15), r7   ! arg3
	mov.l	@(OFF_R3,r15), r3   ! syscall_nr
	!
	mov.l	2f, r10			! Number of syscalls
	cmp/hs	r10, r3
	bf	syscall_call
	mov	#-ENOSYS, r0
	bra	syscall_exit
	 mov.l	r0, @(OFF_R0,r15)	! Return value

__restore_all:
	mov.l	1f, r0
	jmp	@r0
	 nop

	.align	2
1:	.long	restore_all

	.align	2
syscall_badsys:			! Bad syscall number
	mov	#-ENOSYS, r0
	bra	resume_userspace
	 mov.l	r0, @(OFF_R0,r15)	! Return value

/*
 * The main debug trap handler.
 *
 * r8=TRA (not the trap number!)
 *
 * Note: This assumes that the trapa value is left in its original
 * form (without the shlr2 shift) so the calculation for the jump
 * call table offset remains a simple in place mask.
 */
debug_trap:
	mov	r8, r0
	and	#(0xf << 2), r0
	mov.l	1f, r8
	add	r0, r8
	mov.l	@r8, r8
	jmp	@r8
	 nop

	.align	2
1:	.long	debug_trap_table

/*
 * Syscall interface:
 *
 *	Syscall #: R3
 *	Arguments #0 to #3: R4--R7
 *	Arguments #4 to #6: R0, R1, R2
 *	TRA: (number of arguments + ABI revision) x 4
 *
 * This code also handles delegating other traps to the BIOS/gdb stub
 * according to:
 *
 * Trap number
 * (TRA>>2)	Purpose
 * --------	-------
 * 0x00-0x0f	original SH-3/4 syscall ABI (not in general use).
 * 0x10-0x1f	general SH-3/4 syscall ABI.
 * 0x20-0x2f	syscall ABI for SH-2 parts.
 * 0x30-0x3f	debug traps used by the kernel.
 * 0x40-0xff	Not supported by all parts, so left unhandled.
 *
 * Note: When we're first called, the TRA value must be shifted
 * right 2 bits in order to get the value that was used as the "trapa"
 * argument.
 */

	.align	2
	.globl	ret_from_fork
ret_from_fork:
	mov.l	1f, r8
	jsr	@r8
	 mov	r0, r4
	bra	syscall_exit
	 nop
	.align	2
1:	.long	schedule_tail

/*
 * The poorly named main trapa decode and dispatch routine, for
 * system calls and debug traps through their respective jump tables.
 */
ENTRY(system_call)
#if !defined(CONFIG_CPU_SH2)
	mov.l	1f, r9
	mov.l	@r9, r8		! Read from TRA (Trap Address) Register
#endif
	/*
	 * Check the trap type
	 */
	mov	#((0x20 << 2) - 1), r9
	cmp/hi	r9, r8
	bt/s	debug_trap		! it's a debug trap..
	 mov	#OFF_TRA, r9
	add	r15, r9
	mov.l	r8, @r9			! set TRA value to tra
#ifdef CONFIG_TRACE_IRQFLAGS
	mov.l	5f, r10
	jsr	@r10
	 nop
#endif
	sti

	!
	get_current_thread_info r8, r10
	mov.l	@(TI_FLAGS,r8), r8
	mov	#(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT), r10
	tst	r10, r8
	bf	syscall_trace_entry
	!
	mov.l	2f, r8			! Number of syscalls
	cmp/hs	r8, r3
	bt	syscall_badsys
	!
syscall_call:
	shll2	r3		! x4
	mov.l	3f, r8		! Load the address of sys_call_table
	add	r8, r3
	mov.l	@r3, r8
	jsr	@r8	    	! jump to specific syscall handler
	 nop
	mov.l	@(OFF_R0,r15), r12		! save r0
	mov.l	r0, @(OFF_R0,r15)		! save the return value
	!
syscall_exit:
	cli
#ifdef CONFIG_TRACE_IRQFLAGS
	mov.l	6f, r0
	jsr	@r0
	 nop
#endif
	!
	get_current_thread_info r8, r0
	mov.l	@(TI_FLAGS,r8), r0		! current_thread_info->flags
	tst	#_TIF_ALLWORK_MASK, r0
	bf	syscall_exit_work
	bra	__restore_all
	 nop
	.align	2
#if !defined(CONFIG_CPU_SH2)
1:	.long	TRA
#endif
2:	.long	NR_syscalls
3:	.long	sys_call_table
4:	.long	do_syscall_trace
#ifdef CONFIG_TRACE_IRQFLAGS
5:	.long	trace_hardirqs_on
6:	.long	trace_hardirqs_off
#endif