summaryrefslogtreecommitdiff
path: root/arch/arm/kernel/entry-common.S
blob: aae802ee12f86bad23e8fd2430ce5d206da28036 (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
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
/*
 *  linux/arch/arm/kernel/entry-common.S
 *
 *  Copyright (C) 2000 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <asm/unistd.h>
#include <asm/ftrace.h>
#include <mach/entry-macro.S>
#include <asm/unwind.h>

#include "entry-header.S"


	.align	5
/*
 * This is the fast syscall return path.  We do as little as
 * possible here, and this includes saving r0 back into the SVC
 * stack.
 */
ret_fast_syscall:
 UNWIND(.fnstart	)
 UNWIND(.cantunwind	)
	disable_irq				@ disable interrupts
	ldr	r1, [tsk, #TI_FLAGS]
	tst	r1, #_TIF_WORK_MASK
	bne	fast_work_pending

	/* perform architecture specific actions before user return */
	arch_ret_to_user r1, lr

	restore_user_regs fast = 1, offset = S_OFF
 UNWIND(.fnend		)

/*
 * Ok, we need to do extra processing, enter the slow path.
 */
fast_work_pending:
	str	r0, [sp, #S_R0+S_OFF]!		@ returned r0
work_pending:
	tst	r1, #_TIF_NEED_RESCHED
	bne	work_resched
	tst	r1, #_TIF_SIGPENDING|_TIF_NOTIFY_RESUME
	beq	no_work_pending
	mov	r0, sp				@ 'regs'
	mov	r2, why				@ 'syscall'
	tst	r1, #_TIF_SIGPENDING		@ delivering a signal?
	movne	why, #0				@ prevent further restarts
	bl	do_notify_resume
	b	ret_slow_syscall		@ Check work again

work_resched:
	bl	schedule
/*
 * "slow" syscall return path.  "why" tells us if this was a real syscall.
 */
ENTRY(ret_to_user)
ret_slow_syscall:
	disable_irq				@ disable interrupts
	ldr	r1, [tsk, #TI_FLAGS]
	tst	r1, #_TIF_WORK_MASK
	bne	work_pending
no_work_pending:
	/* perform architecture specific actions before user return */
	arch_ret_to_user r1, lr

	restore_user_regs fast = 0, offset = 0
ENDPROC(ret_to_user)

/*
 * This is how we return from a fork.
 */
ENTRY(ret_from_fork)
	bl	schedule_tail
	get_thread_info tsk
	ldr	r1, [tsk, #TI_FLAGS]		@ check for syscall tracing
	mov	why, #1
	tst	r1, #_TIF_SYSCALL_TRACE		@ are we tracing syscalls?
	beq	ret_slow_syscall
	mov	r1, sp
	mov	r0, #1				@ trace exit [IP = 1]
	bl	syscall_trace
	b	ret_slow_syscall
ENDPROC(ret_from_fork)

	.equ NR_syscalls,0
#define CALL(x) .equ NR_syscalls,NR_syscalls+1
#include "calls.S"
#undef CALL
#define CALL(x) .long x

#ifdef CONFIG_FUNCTION_TRACER
/*
 * When compiling with -pg, gcc inserts a call to the mcount routine at the
 * start of every function.  In mcount, apart from the function's address (in
 * lr), we need to get hold of the function's caller's address.
 *
 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
 *
 *	bl	mcount
 *
 * These versions have the limitation that in order for the mcount routine to
 * be able to determine the function's caller's address, an APCS-style frame
 * pointer (which is set up with something like the code below) is required.
 *
 *	mov     ip, sp
 *	push    {fp, ip, lr, pc}
 *	sub     fp, ip, #4
 *
 * With EABI, these frame pointers are not available unless -mapcs-frame is
 * specified, and if building as Thumb-2, not even then.
 *
 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
 * with call sites like:
 *
 *	push	{lr}
 *	bl	__gnu_mcount_nc
 *
 * With these compilers, frame pointers are not necessary.
 *
 * mcount can be thought of as a function called in the middle of a subroutine
 * call.  As such, it needs to be transparent for both the caller and the
 * callee: the original lr needs to be restored when leaving mcount, and no
 * registers should be clobbered.  (In the __gnu_mcount_nc implementation, we
 * clobber the ip register.  This is OK because the ARM calling convention
 * allows it to be clobbered in subroutines and doesn't use it to hold
 * parameters.)
 *
 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
 * arch/arm/kernel/ftrace.c).
 */

#ifndef CONFIG_OLD_MCOUNT
#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
#endif
#endif

.macro __mcount suffix
	mcount_enter
	ldr	r0, =ftrace_trace_function
	ldr	r2, [r0]
	adr	r0, .Lftrace_stub
	cmp	r0, r2
	bne	1f

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	ldr     r1, =ftrace_graph_return
	ldr     r2, [r1]
	cmp     r0, r2
	bne     ftrace_graph_caller\suffix

	ldr     r1, =ftrace_graph_entry
	ldr     r2, [r1]
	ldr     r0, =ftrace_graph_entry_stub
	cmp     r0, r2
	bne     ftrace_graph_caller\suffix
#endif

	mcount_exit

1: 	mcount_get_lr	r1			@ lr of instrumented func
	mov	r0, lr				@ instrumented function
	sub	r0, r0, #MCOUNT_INSN_SIZE
	adr	lr, BSYM(2f)
	mov	pc, r2
2:	mcount_exit
.endm

.macro __ftrace_caller suffix
	mcount_enter

	mcount_get_lr	r1			@ lr of instrumented func
	mov	r0, lr				@ instrumented function
	sub	r0, r0, #MCOUNT_INSN_SIZE

	.globl ftrace_call\suffix
ftrace_call\suffix:
	bl	ftrace_stub

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	.globl ftrace_graph_call\suffix
ftrace_graph_call\suffix:
	mov	r0, r0
#endif

	mcount_exit
.endm

.macro __ftrace_graph_caller
	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)
#ifdef CONFIG_DYNAMIC_FTRACE
	@ called from __ftrace_caller, saved in mcount_enter
	ldr	r1, [sp, #16]		@ instrumented routine (func)
#else
	@ called from __mcount, untouched in lr
	mov	r1, lr			@ instrumented routine (func)
#endif
	sub	r1, r1, #MCOUNT_INSN_SIZE
	mov	r2, fp			@ frame pointer
	bl	prepare_ftrace_return
	mcount_exit
.endm

#ifdef CONFIG_OLD_MCOUNT
/*
 * mcount
 */

.macro mcount_enter
	stmdb	sp!, {r0-r3, lr}
.endm

.macro mcount_get_lr reg
	ldr	\reg, [fp, #-4]
.endm

.macro mcount_exit
	ldr	lr, [fp, #-4]
	ldmia	sp!, {r0-r3, pc}
.endm

ENTRY(mcount)
#ifdef CONFIG_DYNAMIC_FTRACE
	stmdb	sp!, {lr}
	ldr	lr, [fp, #-4]
	ldmia	sp!, {pc}
#else
	__mcount _old
#endif
ENDPROC(mcount)

#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(ftrace_caller_old)
	__ftrace_caller _old
ENDPROC(ftrace_caller_old)
#endif

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller_old)
	__ftrace_graph_caller
ENDPROC(ftrace_graph_caller_old)
#endif

.purgem mcount_enter
.purgem mcount_get_lr
.purgem mcount_exit
#endif

/*
 * __gnu_mcount_nc
 */

.macro mcount_enter
	stmdb	sp!, {r0-r3, lr}
.endm

.macro mcount_get_lr reg
	ldr	\reg, [sp, #20]
.endm

.macro mcount_exit
	ldmia	sp!, {r0-r3, ip, lr}
	mov	pc, ip
.endm

ENTRY(__gnu_mcount_nc)
#ifdef CONFIG_DYNAMIC_FTRACE
	mov	ip, lr
	ldmia	sp!, {lr}
	mov	pc, ip
#else
	__mcount
#endif
ENDPROC(__gnu_mcount_nc)

#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(ftrace_caller)
	__ftrace_caller
ENDPROC(ftrace_caller)
#endif

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller)
	__ftrace_graph_caller
ENDPROC(ftrace_graph_caller)
#endif

.purgem mcount_enter
.purgem mcount_get_lr
.purgem mcount_exit

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	.globl return_to_handler
return_to_handler:
	stmdb	sp!, {r0-r3}
	mov	r0, fp			@ frame pointer
	bl	ftrace_return_to_handler
	mov	lr, r0			@ r0 has real ret addr
	ldmia	sp!, {r0-r3}
	mov	pc, lr
#endif

ENTRY(ftrace_stub)
.Lftrace_stub:
	mov	pc, lr
ENDPROC(ftrace_stub)

#endif /* CONFIG_FUNCTION_TRACER */

/*=============================================================================
 * SWI handler
 *-----------------------------------------------------------------------------
 */

	/* If we're optimising for StrongARM the resulting code won't 
	   run on an ARM7 and we can save a couple of instructions.  
								--pb */
#ifdef CONFIG_CPU_ARM710
#define A710(code...) code
.Larm710bug:
	ldmia	sp, {r0 - lr}^			@ Get calling r0 - lr
	mov	r0, r0
	add	sp, sp, #S_FRAME_SIZE
	subs	pc, lr, #4
#else
#define A710(code...)
#endif

	.align	5
ENTRY(vector_swi)
	sub	sp, sp, #S_FRAME_SIZE
	stmia	sp, {r0 - r12}			@ Calling r0 - r12
 ARM(	add	r8, sp, #S_PC		)
 ARM(	stmdb	r8, {sp, lr}^		)	@ Calling sp, lr
 THUMB(	mov	r8, sp			)
 THUMB(	store_user_sp_lr r8, r10, S_SP	)	@ calling sp, lr
	mrs	r8, spsr			@ called from non-FIQ mode, so ok.
	str	lr, [sp, #S_PC]			@ Save calling PC
	str	r8, [sp, #S_PSR]		@ Save CPSR
	str	r0, [sp, #S_OLD_R0]		@ Save OLD_R0
	zero_fp

	/*
	 * Get the system call number.
	 */

#if defined(CONFIG_OABI_COMPAT)

	/*
	 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
	 * value to determine if it is an EABI or an old ABI call.
	 */
#ifdef CONFIG_ARM_THUMB
	tst	r8, #PSR_T_BIT
	movne	r10, #0				@ no thumb OABI emulation
	ldreq	r10, [lr, #-4]			@ get SWI instruction
#else
	ldr	r10, [lr, #-4]			@ get SWI instruction
  A710(	and	ip, r10, #0x0f000000		@ check for SWI		)
  A710(	teq	ip, #0x0f000000						)
  A710(	bne	.Larm710bug						)
#endif
#ifdef CONFIG_CPU_ENDIAN_BE8
	rev	r10, r10			@ little endian instruction
#endif

#elif defined(CONFIG_AEABI)

	/*
	 * Pure EABI user space always put syscall number into scno (r7).
	 */
  A710(	ldr	ip, [lr, #-4]			@ get SWI instruction	)
  A710(	and	ip, ip, #0x0f000000		@ check for SWI		)
  A710(	teq	ip, #0x0f000000						)
  A710(	bne	.Larm710bug						)

#elif defined(CONFIG_ARM_THUMB)

	/* Legacy ABI only, possibly thumb mode. */
	tst	r8, #PSR_T_BIT			@ this is SPSR from save_user_regs
	addne	scno, r7, #__NR_SYSCALL_BASE	@ put OS number in
	ldreq	scno, [lr, #-4]

#else

	/* Legacy ABI only. */
	ldr	scno, [lr, #-4]			@ get SWI instruction
  A710(	and	ip, scno, #0x0f000000		@ check for SWI		)
  A710(	teq	ip, #0x0f000000						)
  A710(	bne	.Larm710bug						)

#endif

#ifdef CONFIG_ALIGNMENT_TRAP
	ldr	ip, __cr_alignment
	ldr	ip, [ip]
	mcr	p15, 0, ip, c1, c0		@ update control register
#endif
	enable_irq

	get_thread_info tsk
	adr	tbl, sys_call_table		@ load syscall table pointer

#if defined(CONFIG_OABI_COMPAT)
	/*
	 * If the swi argument is zero, this is an EABI call and we do nothing.
	 *
	 * If this is an old ABI call, get the syscall number into scno and
	 * get the old ABI syscall table address.
	 */
	bics	r10, r10, #0xff000000
	eorne	scno, r10, #__NR_OABI_SYSCALL_BASE
	ldrne	tbl, =sys_oabi_call_table
#elif !defined(CONFIG_AEABI)
	bic	scno, scno, #0xff000000		@ mask off SWI op-code
	eor	scno, scno, #__NR_SYSCALL_BASE	@ check OS number
#endif

	ldr	r10, [tsk, #TI_FLAGS]		@ check for syscall tracing
	stmdb	sp!, {r4, r5}			@ push fifth and sixth args

#ifdef CONFIG_SECCOMP
	tst	r10, #_TIF_SECCOMP
	beq	1f
	mov	r0, scno
	bl	__secure_computing	
	add	r0, sp, #S_R0 + S_OFF		@ pointer to regs
	ldmia	r0, {r0 - r3}			@ have to reload r0 - r3
1:
#endif

	tst	r10, #_TIF_SYSCALL_TRACE		@ are we tracing syscalls?
	bne	__sys_trace

	cmp	scno, #NR_syscalls		@ check upper syscall limit
	adr	lr, BSYM(ret_fast_syscall)	@ return address
	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine

	add	r1, sp, #S_OFF
2:	mov	why, #0				@ no longer a real syscall
	cmp	scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
	eor	r0, scno, #__NR_SYSCALL_BASE	@ put OS number back
	bcs	arm_syscall	
	b	sys_ni_syscall			@ not private func
ENDPROC(vector_swi)

	/*
	 * This is the really slow path.  We're going to be doing
	 * context switches, and waiting for our parent to respond.
	 */
__sys_trace:
	mov	r2, scno
	add	r1, sp, #S_OFF
	mov	r0, #0				@ trace entry [IP = 0]
	bl	syscall_trace

	adr	lr, BSYM(__sys_trace_return)	@ return address
	mov	scno, r0			@ syscall number (possibly new)
	add	r1, sp, #S_R0 + S_OFF		@ pointer to regs
	cmp	scno, #NR_syscalls		@ check upper syscall limit
	ldmccia	r1, {r0 - r3}			@ have to reload r0 - r3
	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
	b	2b

__sys_trace_return:
	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0
	mov	r2, scno
	mov	r1, sp
	mov	r0, #1				@ trace exit [IP = 1]
	bl	syscall_trace
	b	ret_slow_syscall

	.align	5
#ifdef CONFIG_ALIGNMENT_TRAP
	.type	__cr_alignment, #object
__cr_alignment:
	.word	cr_alignment
#endif
	.ltorg

/*
 * This is the syscall table declaration for native ABI syscalls.
 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
 */
#define ABI(native, compat) native
#ifdef CONFIG_AEABI
#define OBSOLETE(syscall) sys_ni_syscall
#else
#define OBSOLETE(syscall) syscall
#endif

	.type	sys_call_table, #object
ENTRY(sys_call_table)
#include "calls.S"
#undef ABI
#undef OBSOLETE

/*============================================================================
 * Special system call wrappers
 */
@ r0 = syscall number
@ r8 = syscall table
sys_syscall:
		bic	scno, r0, #__NR_OABI_SYSCALL_BASE
		cmp	scno, #__NR_syscall - __NR_SYSCALL_BASE
		cmpne	scno, #NR_syscalls	@ check range
		stmloia	sp, {r5, r6}		@ shuffle args
		movlo	r0, r1
		movlo	r1, r2
		movlo	r2, r3
		movlo	r3, r4
		ldrlo	pc, [tbl, scno, lsl #2]
		b	sys_ni_syscall
ENDPROC(sys_syscall)

sys_fork_wrapper:
		add	r0, sp, #S_OFF
		b	sys_fork
ENDPROC(sys_fork_wrapper)

sys_vfork_wrapper:
		add	r0, sp, #S_OFF
		b	sys_vfork
ENDPROC(sys_vfork_wrapper)

sys_execve_wrapper:
		add	r3, sp, #S_OFF
		b	sys_execve
ENDPROC(sys_execve_wrapper)

sys_clone_wrapper:
		add	ip, sp, #S_OFF
		str	ip, [sp, #4]
		b	sys_clone
ENDPROC(sys_clone_wrapper)

sys_sigreturn_wrapper:
		add	r0, sp, #S_OFF
		mov	why, #0		@ prevent syscall restart handling
		b	sys_sigreturn
ENDPROC(sys_sigreturn_wrapper)

sys_rt_sigreturn_wrapper:
		add	r0, sp, #S_OFF
		mov	why, #0		@ prevent syscall restart handling
		b	sys_rt_sigreturn
ENDPROC(sys_rt_sigreturn_wrapper)

sys_sigaltstack_wrapper:
		ldr	r2, [sp, #S_OFF + S_SP]
		b	do_sigaltstack
ENDPROC(sys_sigaltstack_wrapper)

sys_statfs64_wrapper:
		teq	r1, #88
		moveq	r1, #84
		b	sys_statfs64
ENDPROC(sys_statfs64_wrapper)

sys_fstatfs64_wrapper:
		teq	r1, #88
		moveq	r1, #84
		b	sys_fstatfs64
ENDPROC(sys_fstatfs64_wrapper)

/*
 * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
 * offset, we return EINVAL.
 */
sys_mmap2:
#if PAGE_SHIFT > 12
		tst	r5, #PGOFF_MASK
		moveq	r5, r5, lsr #PAGE_SHIFT - 12
		streq	r5, [sp, #4]
		beq	sys_mmap_pgoff
		mov	r0, #-EINVAL
		mov	pc, lr
#else
		str	r5, [sp, #4]
		b	sys_mmap_pgoff
#endif
ENDPROC(sys_mmap2)

#ifdef CONFIG_OABI_COMPAT

/*
 * These are syscalls with argument register differences
 */

sys_oabi_pread64:
		stmia	sp, {r3, r4}
		b	sys_pread64
ENDPROC(sys_oabi_pread64)

sys_oabi_pwrite64:
		stmia	sp, {r3, r4}
		b	sys_pwrite64
ENDPROC(sys_oabi_pwrite64)

sys_oabi_truncate64:
		mov	r3, r2
		mov	r2, r1
		b	sys_truncate64
ENDPROC(sys_oabi_truncate64)

sys_oabi_ftruncate64:
		mov	r3, r2
		mov	r2, r1
		b	sys_ftruncate64
ENDPROC(sys_oabi_ftruncate64)

sys_oabi_readahead:
		str	r3, [sp]
		mov	r3, r2
		mov	r2, r1
		b	sys_readahead
ENDPROC(sys_oabi_readahead)

/*
 * Let's declare a second syscall table for old ABI binaries
 * using the compatibility syscall entries.
 */
#define ABI(native, compat) compat
#define OBSOLETE(syscall) syscall

	.type	sys_oabi_call_table, #object
ENTRY(sys_oabi_call_table)
#include "calls.S"
#undef ABI
#undef OBSOLETE

#endif