summaryrefslogtreecommitdiff
path: root/arch/arm/kernel/entry-common.S
blob: 746565a876dcdd362522d1e546c8404faacfbfe2 (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
/*
 *  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/assembler.h>
#include <asm/unistd.h>
#include <asm/ftrace.h>
#include <asm/unwind.h>
#include <asm/memory.h>
#ifdef CONFIG_AEABI
#include <asm/unistd-oabi.h>
#endif

	.equ	NR_syscalls, __NR_syscalls

#ifdef CONFIG_NEED_RET_TO_USER
#include <mach/entry-macro.S>
#else
	.macro  arch_ret_to_user, tmp1, tmp2
	.endm
#endif

#include "entry-header.S"

saved_psr	.req	r8
#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING)
saved_pc	.req	r9
#define TRACE(x...) x
#else
saved_pc	.req	lr
#define TRACE(x...)
#endif

	.section .entry.text,"ax",%progbits
	.align	5
#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING) || \
	IS_ENABLED(CONFIG_DEBUG_RSEQ))
/*
 * This is the fast syscall return path.  We do as little as possible here,
 * such as avoiding writing r0 to the stack.  We only use this path if we
 * have tracing, context tracking and rseq debug disabled - the overheads
 * from those features make this path too inefficient.
 */
ret_fast_syscall:
__ret_fast_syscall:
 UNWIND(.fnstart	)
 UNWIND(.cantunwind	)
	disable_irq_notrace			@ disable interrupts
	ldr	r2, [tsk, #TI_ADDR_LIMIT]
	cmp	r2, #TASK_SIZE
	blne	addr_limit_check_failed
	ldr	r1, [tsk, #TI_FLAGS]		@ re-check for syscall tracing
	tst	r1, #_TIF_SYSCALL_WORK | _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		)
ENDPROC(ret_fast_syscall)

	/* Ok, we need to do extra processing, enter the slow path. */
fast_work_pending:
	str	r0, [sp, #S_R0+S_OFF]!		@ returned r0
	/* fall through to work_pending */
#else
/*
 * The "replacement" ret_fast_syscall for when tracing, context tracking,
 * or rseq debug is enabled.  As we will need to call out to some C functions,
 * we save r0 first to avoid needing to save registers around each C function
 * call.
 */
ret_fast_syscall:
__ret_fast_syscall:
 UNWIND(.fnstart	)
 UNWIND(.cantunwind	)
	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0
#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
	/* do_rseq_syscall needs interrupts enabled. */
	mov	r0, sp				@ 'regs'
	bl	do_rseq_syscall
#endif
	disable_irq_notrace			@ disable interrupts
	ldr	r2, [tsk, #TI_ADDR_LIMIT]
	cmp	r2, #TASK_SIZE
	blne	addr_limit_check_failed
	ldr	r1, [tsk, #TI_FLAGS]		@ re-check for syscall tracing
	tst	r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
	beq	no_work_pending
 UNWIND(.fnend		)
ENDPROC(ret_fast_syscall)

	/* Slower path - fall through to work_pending */
#endif

	tst	r1, #_TIF_SYSCALL_WORK
	bne	__sys_trace_return_nosave
slow_work_pending:
	mov	r0, sp				@ 'regs'
	mov	r2, why				@ 'syscall'
	bl	do_work_pending
	cmp	r0, #0
	beq	no_work_pending
	movlt	scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
	ldmia	sp, {r0 - r6}			@ have to reload r0 - r6
	b	local_restart			@ ... and off we go
ENDPROC(ret_fast_syscall)

/*
 * "slow" syscall return path.  "why" tells us if this was a real syscall.
 * IRQs may be enabled here, so always disable them.  Note that we use the
 * "notrace" version to avoid calling into the tracing code unnecessarily.
 * do_work_pending() will update this state if necessary.
 */
ENTRY(ret_to_user)
ret_slow_syscall:
#if IS_ENABLED(CONFIG_DEBUG_RSEQ)
	/* do_rseq_syscall needs interrupts enabled. */
	enable_irq_notrace			@ enable interrupts
	mov	r0, sp				@ 'regs'
	bl	do_rseq_syscall
#endif
	disable_irq_notrace			@ disable interrupts
ENTRY(ret_to_user_from_irq)
	ldr	r2, [tsk, #TI_ADDR_LIMIT]
	cmp	r2, #TASK_SIZE
	blne	addr_limit_check_failed
	ldr	r1, [tsk, #TI_FLAGS]
	tst	r1, #_TIF_WORK_MASK
	bne	slow_work_pending
no_work_pending:
	asm_trace_hardirqs_on save = 0

	/* perform architecture specific actions before user return */
	arch_ret_to_user r1, lr
	ct_user_enter save = 0

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

/*
 * This is how we return from a fork.
 */
ENTRY(ret_from_fork)
	bl	schedule_tail
	cmp	r5, #0
	movne	r0, r4
	badrne	lr, 1f
	retne	r5
1:	get_thread_info tsk
	b	ret_slow_syscall
ENDPROC(ret_from_fork)

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

	.align	5
ENTRY(vector_swi)
#ifdef CONFIG_CPU_V7M
	v7m_exception_entry
#else
	sub	sp, sp, #PT_REGS_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	saved_psr, spsr			@ called from non-FIQ mode, so ok.
 TRACE(	mov	saved_pc, lr		)
	str	saved_pc, [sp, #S_PC]		@ Save calling PC
	str	saved_psr, [sp, #S_PSR]		@ Save CPSR
	str	r0, [sp, #S_OLD_R0]		@ Save OLD_R0
#endif
	zero_fp
	alignment_trap r10, ip, __cr_alignment
	asm_trace_hardirqs_on save=0
	enable_irq_notrace
	ct_user_exit save=0

	/*
	 * 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	saved_psr, #PSR_T_BIT
	movne	r10, #0				@ no thumb OABI emulation
 USER(	ldreq	r10, [saved_pc, #-4]	)	@ get SWI instruction
#else
 USER(	ldr	r10, [saved_pc, #-4]	)	@ get SWI instruction
#endif
 ARM_BE8(rev	r10, r10)			@ little endian instruction

#elif defined(CONFIG_AEABI)

	/*
	 * Pure EABI user space always put syscall number into scno (r7).
	 */
#elif defined(CONFIG_ARM_THUMB)
	/* Legacy ABI only, possibly thumb mode. */
	tst	saved_psr, #PSR_T_BIT		@ this is SPSR from save_user_regs
	addne	scno, r7, #__NR_SYSCALL_BASE	@ put OS number in
 USER(	ldreq	scno, [saved_pc, #-4]	)

#else
	/* Legacy ABI only. */
 USER(	ldr	scno, [saved_pc, #-4]	)	@ get SWI instruction
#endif

	/* saved_psr and saved_pc are now dead */

	uaccess_disable tbl

	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
	get_thread_info tsk
	/*
	 * Reload the registers that may have been corrupted on entry to
	 * the syscall assembly (by tracing or context tracking.)
	 */
 TRACE(	ldmia	sp, {r0 - r3}		)

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

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

	invoke_syscall tbl, scno, r10, __ret_fast_syscall

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

#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
	/*
	 * We failed to handle a fault trying to access the page
	 * containing the swi instruction, but we're not really in a
	 * position to return -EFAULT. Instead, return back to the
	 * instruction and re-enter the user fault handling path trying
	 * to page it in. This will likely result in sending SEGV to the
	 * current task.
	 */
9001:
	sub	lr, saved_pc, #4
	str	lr, [sp, #S_PC]
	get_thread_info tsk
	b	ret_fast_syscall
#endif
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	r1, scno
	add	r0, sp, #S_OFF
	bl	syscall_trace_enter
	mov	scno, r0
	invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1
	cmp	scno, #-1			@ skip the syscall?
	bne	2b
	add	sp, sp, #S_OFF			@ restore stack
	b	ret_slow_syscall

__sys_trace_return:
	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0
	mov	r0, sp
	bl	syscall_trace_exit
	b	ret_slow_syscall

__sys_trace_return_nosave:
	enable_irq_notrace
	mov	r0, sp
	bl	syscall_trace_exit
	b	ret_slow_syscall

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

	.macro	syscall_table_start, sym
	.equ	__sys_nr, 0
	.type	\sym, #object
ENTRY(\sym)
	.endm

	.macro	syscall, nr, func
	.ifgt	__sys_nr - \nr
	.error	"Duplicated/unorded system call entry"
	.endif
	.rept	\nr - __sys_nr
	.long	sys_ni_syscall
	.endr
	.long	\func
	.equ	__sys_nr, \nr + 1
	.endm

	.macro	syscall_table_end, sym
	.ifgt	__sys_nr - __NR_syscalls
	.error	"System call table too big"
	.endif
	.rept	__NR_syscalls - __sys_nr
	.long	sys_ni_syscall
	.endr
	.size	\sym, . - \sym
	.endm

#define NATIVE(nr, func) syscall nr, func

/*
 * This is the syscall table declaration for native ABI syscalls.
 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
 */
	syscall_table_start sys_call_table
#define COMPAT(nr, native, compat) syscall nr, native
#ifdef CONFIG_AEABI
#include <calls-eabi.S>
#else
#include <calls-oabi.S>
#endif
#undef COMPAT
	syscall_table_end sys_call_table

/*============================================================================
 * 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
#ifdef CONFIG_CPU_SPECTRE
		movhs	scno, #0
		csdb
#endif
		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_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_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:
		str	r5, [sp, #4]
		b	sys_mmap_pgoff
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.
 */
	syscall_table_start sys_oabi_call_table
#define COMPAT(nr, native, compat) syscall nr, compat
#include <calls-oabi.S>
	syscall_table_end sys_oabi_call_table

#endif