xref: /openbmc/linux/arch/arm/kernel/entry-common.S (revision 565d76cb) 
1/*
2 *  linux/arch/arm/kernel/entry-common.S
3 *
4 *  Copyright (C) 2000 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <asm/unistd.h>
12#include <asm/ftrace.h>
13#include <mach/entry-macro.S>
14#include <asm/unwind.h>
15
16#include "entry-header.S"
17
18
19	.align	5
20/*
21 * This is the fast syscall return path.  We do as little as
22 * possible here, and this includes saving r0 back into the SVC
23 * stack.
24 */
25ret_fast_syscall:
26 UNWIND(.fnstart	)
27 UNWIND(.cantunwind	)
28	disable_irq				@ disable interrupts
29	ldr	r1, [tsk, #TI_FLAGS]
30	tst	r1, #_TIF_WORK_MASK
31	bne	fast_work_pending
32#if defined(CONFIG_IRQSOFF_TRACER)
33	asm_trace_hardirqs_on
34#endif
35
36	/* perform architecture specific actions before user return */
37	arch_ret_to_user r1, lr
38
39	restore_user_regs fast = 1, offset = S_OFF
40 UNWIND(.fnend		)
41
42/*
43 * Ok, we need to do extra processing, enter the slow path.
44 */
45fast_work_pending:
46	str	r0, [sp, #S_R0+S_OFF]!		@ returned r0
47work_pending:
48	tst	r1, #_TIF_NEED_RESCHED
49	bne	work_resched
50	tst	r1, #_TIF_SIGPENDING|_TIF_NOTIFY_RESUME
51	beq	no_work_pending
52	mov	r0, sp				@ 'regs'
53	mov	r2, why				@ 'syscall'
54	tst	r1, #_TIF_SIGPENDING		@ delivering a signal?
55	movne	why, #0				@ prevent further restarts
56	bl	do_notify_resume
57	b	ret_slow_syscall		@ Check work again
58
59work_resched:
60	bl	schedule
61/*
62 * "slow" syscall return path.  "why" tells us if this was a real syscall.
63 */
64ENTRY(ret_to_user)
65ret_slow_syscall:
66	disable_irq				@ disable interrupts
67	ldr	r1, [tsk, #TI_FLAGS]
68	tst	r1, #_TIF_WORK_MASK
69	bne	work_pending
70no_work_pending:
71#if defined(CONFIG_IRQSOFF_TRACER)
72	asm_trace_hardirqs_on
73#endif
74	/* perform architecture specific actions before user return */
75	arch_ret_to_user r1, lr
76
77	restore_user_regs fast = 0, offset = 0
78ENDPROC(ret_to_user)
79
80/*
81 * This is how we return from a fork.
82 */
83ENTRY(ret_from_fork)
84	bl	schedule_tail
85	get_thread_info tsk
86	ldr	r1, [tsk, #TI_FLAGS]		@ check for syscall tracing
87	mov	why, #1
88	tst	r1, #_TIF_SYSCALL_TRACE		@ are we tracing syscalls?
89	beq	ret_slow_syscall
90	mov	r1, sp
91	mov	r0, #1				@ trace exit [IP = 1]
92	bl	syscall_trace
93	b	ret_slow_syscall
94ENDPROC(ret_from_fork)
95
96	.equ NR_syscalls,0
97#define CALL(x) .equ NR_syscalls,NR_syscalls+1
98#include "calls.S"
99#undef CALL
100#define CALL(x) .long x
101
102#ifdef CONFIG_FUNCTION_TRACER
103/*
104 * When compiling with -pg, gcc inserts a call to the mcount routine at the
105 * start of every function.  In mcount, apart from the function's address (in
106 * lr), we need to get hold of the function's caller's address.
107 *
108 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
109 *
110 *	bl	mcount
111 *
112 * These versions have the limitation that in order for the mcount routine to
113 * be able to determine the function's caller's address, an APCS-style frame
114 * pointer (which is set up with something like the code below) is required.
115 *
116 *	mov     ip, sp
117 *	push    {fp, ip, lr, pc}
118 *	sub     fp, ip, #4
119 *
120 * With EABI, these frame pointers are not available unless -mapcs-frame is
121 * specified, and if building as Thumb-2, not even then.
122 *
123 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
124 * with call sites like:
125 *
126 *	push	{lr}
127 *	bl	__gnu_mcount_nc
128 *
129 * With these compilers, frame pointers are not necessary.
130 *
131 * mcount can be thought of as a function called in the middle of a subroutine
132 * call.  As such, it needs to be transparent for both the caller and the
133 * callee: the original lr needs to be restored when leaving mcount, and no
134 * registers should be clobbered.  (In the __gnu_mcount_nc implementation, we
135 * clobber the ip register.  This is OK because the ARM calling convention
136 * allows it to be clobbered in subroutines and doesn't use it to hold
137 * parameters.)
138 *
139 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
140 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
141 * arch/arm/kernel/ftrace.c).
142 */
143
144#ifndef CONFIG_OLD_MCOUNT
145#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
146#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
147#endif
148#endif
149
150.macro __mcount suffix
151	mcount_enter
152	ldr	r0, =ftrace_trace_function
153	ldr	r2, [r0]
154	adr	r0, .Lftrace_stub
155	cmp	r0, r2
156	bne	1f
157
158#ifdef CONFIG_FUNCTION_GRAPH_TRACER
159	ldr     r1, =ftrace_graph_return
160	ldr     r2, [r1]
161	cmp     r0, r2
162	bne     ftrace_graph_caller\suffix
163
164	ldr     r1, =ftrace_graph_entry
165	ldr     r2, [r1]
166	ldr     r0, =ftrace_graph_entry_stub
167	cmp     r0, r2
168	bne     ftrace_graph_caller\suffix
169#endif
170
171	mcount_exit
172
1731: 	mcount_get_lr	r1			@ lr of instrumented func
174	mov	r0, lr				@ instrumented function
175	sub	r0, r0, #MCOUNT_INSN_SIZE
176	adr	lr, BSYM(2f)
177	mov	pc, r2
1782:	mcount_exit
179.endm
180
181.macro __ftrace_caller suffix
182	mcount_enter
183
184	mcount_get_lr	r1			@ lr of instrumented func
185	mov	r0, lr				@ instrumented function
186	sub	r0, r0, #MCOUNT_INSN_SIZE
187
188	.globl ftrace_call\suffix
189ftrace_call\suffix:
190	bl	ftrace_stub
191
192#ifdef CONFIG_FUNCTION_GRAPH_TRACER
193	.globl ftrace_graph_call\suffix
194ftrace_graph_call\suffix:
195	mov	r0, r0
196#endif
197
198	mcount_exit
199.endm
200
201.macro __ftrace_graph_caller
202	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)
203#ifdef CONFIG_DYNAMIC_FTRACE
204	@ called from __ftrace_caller, saved in mcount_enter
205	ldr	r1, [sp, #16]		@ instrumented routine (func)
206#else
207	@ called from __mcount, untouched in lr
208	mov	r1, lr			@ instrumented routine (func)
209#endif
210	sub	r1, r1, #MCOUNT_INSN_SIZE
211	mov	r2, fp			@ frame pointer
212	bl	prepare_ftrace_return
213	mcount_exit
214.endm
215
216#ifdef CONFIG_OLD_MCOUNT
217/*
218 * mcount
219 */
220
221.macro mcount_enter
222	stmdb	sp!, {r0-r3, lr}
223.endm
224
225.macro mcount_get_lr reg
226	ldr	\reg, [fp, #-4]
227.endm
228
229.macro mcount_exit
230	ldr	lr, [fp, #-4]
231	ldmia	sp!, {r0-r3, pc}
232.endm
233
234ENTRY(mcount)
235#ifdef CONFIG_DYNAMIC_FTRACE
236	stmdb	sp!, {lr}
237	ldr	lr, [fp, #-4]
238	ldmia	sp!, {pc}
239#else
240	__mcount _old
241#endif
242ENDPROC(mcount)
243
244#ifdef CONFIG_DYNAMIC_FTRACE
245ENTRY(ftrace_caller_old)
246	__ftrace_caller _old
247ENDPROC(ftrace_caller_old)
248#endif
249
250#ifdef CONFIG_FUNCTION_GRAPH_TRACER
251ENTRY(ftrace_graph_caller_old)
252	__ftrace_graph_caller
253ENDPROC(ftrace_graph_caller_old)
254#endif
255
256.purgem mcount_enter
257.purgem mcount_get_lr
258.purgem mcount_exit
259#endif
260
261/*
262 * __gnu_mcount_nc
263 */
264
265.macro mcount_enter
266	stmdb	sp!, {r0-r3, lr}
267.endm
268
269.macro mcount_get_lr reg
270	ldr	\reg, [sp, #20]
271.endm
272
273.macro mcount_exit
274	ldmia	sp!, {r0-r3, ip, lr}
275	mov	pc, ip
276.endm
277
278ENTRY(__gnu_mcount_nc)
279#ifdef CONFIG_DYNAMIC_FTRACE
280	mov	ip, lr
281	ldmia	sp!, {lr}
282	mov	pc, ip
283#else
284	__mcount
285#endif
286ENDPROC(__gnu_mcount_nc)
287
288#ifdef CONFIG_DYNAMIC_FTRACE
289ENTRY(ftrace_caller)
290	__ftrace_caller
291ENDPROC(ftrace_caller)
292#endif
293
294#ifdef CONFIG_FUNCTION_GRAPH_TRACER
295ENTRY(ftrace_graph_caller)
296	__ftrace_graph_caller
297ENDPROC(ftrace_graph_caller)
298#endif
299
300.purgem mcount_enter
301.purgem mcount_get_lr
302.purgem mcount_exit
303
304#ifdef CONFIG_FUNCTION_GRAPH_TRACER
305	.globl return_to_handler
306return_to_handler:
307	stmdb	sp!, {r0-r3}
308	mov	r0, fp			@ frame pointer
309	bl	ftrace_return_to_handler
310	mov	lr, r0			@ r0 has real ret addr
311	ldmia	sp!, {r0-r3}
312	mov	pc, lr
313#endif
314
315ENTRY(ftrace_stub)
316.Lftrace_stub:
317	mov	pc, lr
318ENDPROC(ftrace_stub)
319
320#endif /* CONFIG_FUNCTION_TRACER */
321
322/*=============================================================================
323 * SWI handler
324 *-----------------------------------------------------------------------------
325 */
326
327	/* If we're optimising for StrongARM the resulting code won't
328	   run on an ARM7 and we can save a couple of instructions.
329								--pb */
330#ifdef CONFIG_CPU_ARM710
331#define A710(code...) code
332.Larm710bug:
333	ldmia	sp, {r0 - lr}^			@ Get calling r0 - lr
334	mov	r0, r0
335	add	sp, sp, #S_FRAME_SIZE
336	subs	pc, lr, #4
337#else
338#define A710(code...)
339#endif
340
341	.align	5
342ENTRY(vector_swi)
343	sub	sp, sp, #S_FRAME_SIZE
344	stmia	sp, {r0 - r12}			@ Calling r0 - r12
345 ARM(	add	r8, sp, #S_PC		)
346 ARM(	stmdb	r8, {sp, lr}^		)	@ Calling sp, lr
347 THUMB(	mov	r8, sp			)
348 THUMB(	store_user_sp_lr r8, r10, S_SP	)	@ calling sp, lr
349	mrs	r8, spsr			@ called from non-FIQ mode, so ok.
350	str	lr, [sp, #S_PC]			@ Save calling PC
351	str	r8, [sp, #S_PSR]		@ Save CPSR
352	str	r0, [sp, #S_OLD_R0]		@ Save OLD_R0
353	zero_fp
354
355	/*
356	 * Get the system call number.
357	 */
358
359#if defined(CONFIG_OABI_COMPAT)
360
361	/*
362	 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
363	 * value to determine if it is an EABI or an old ABI call.
364	 */
365#ifdef CONFIG_ARM_THUMB
366	tst	r8, #PSR_T_BIT
367	movne	r10, #0				@ no thumb OABI emulation
368	ldreq	r10, [lr, #-4]			@ get SWI instruction
369#else
370	ldr	r10, [lr, #-4]			@ get SWI instruction
371  A710(	and	ip, r10, #0x0f000000		@ check for SWI		)
372  A710(	teq	ip, #0x0f000000						)
373  A710(	bne	.Larm710bug						)
374#endif
375#ifdef CONFIG_CPU_ENDIAN_BE8
376	rev	r10, r10			@ little endian instruction
377#endif
378
379#elif defined(CONFIG_AEABI)
380
381	/*
382	 * Pure EABI user space always put syscall number into scno (r7).
383	 */
384  A710(	ldr	ip, [lr, #-4]			@ get SWI instruction	)
385  A710(	and	ip, ip, #0x0f000000		@ check for SWI		)
386  A710(	teq	ip, #0x0f000000						)
387  A710(	bne	.Larm710bug						)
388
389#elif defined(CONFIG_ARM_THUMB)
390
391	/* Legacy ABI only, possibly thumb mode. */
392	tst	r8, #PSR_T_BIT			@ this is SPSR from save_user_regs
393	addne	scno, r7, #__NR_SYSCALL_BASE	@ put OS number in
394	ldreq	scno, [lr, #-4]
395
396#else
397
398	/* Legacy ABI only. */
399	ldr	scno, [lr, #-4]			@ get SWI instruction
400  A710(	and	ip, scno, #0x0f000000		@ check for SWI		)
401  A710(	teq	ip, #0x0f000000						)
402  A710(	bne	.Larm710bug						)
403
404#endif
405
406#ifdef CONFIG_ALIGNMENT_TRAP
407	ldr	ip, __cr_alignment
408	ldr	ip, [ip]
409	mcr	p15, 0, ip, c1, c0		@ update control register
410#endif
411	enable_irq
412
413	get_thread_info tsk
414	adr	tbl, sys_call_table		@ load syscall table pointer
415
416#if defined(CONFIG_OABI_COMPAT)
417	/*
418	 * If the swi argument is zero, this is an EABI call and we do nothing.
419	 *
420	 * If this is an old ABI call, get the syscall number into scno and
421	 * get the old ABI syscall table address.
422	 */
423	bics	r10, r10, #0xff000000
424	eorne	scno, r10, #__NR_OABI_SYSCALL_BASE
425	ldrne	tbl, =sys_oabi_call_table
426#elif !defined(CONFIG_AEABI)
427	bic	scno, scno, #0xff000000		@ mask off SWI op-code
428	eor	scno, scno, #__NR_SYSCALL_BASE	@ check OS number
429#endif
430
431	ldr	r10, [tsk, #TI_FLAGS]		@ check for syscall tracing
432	stmdb	sp!, {r4, r5}			@ push fifth and sixth args
433
434#ifdef CONFIG_SECCOMP
435	tst	r10, #_TIF_SECCOMP
436	beq	1f
437	mov	r0, scno
438	bl	__secure_computing
439	add	r0, sp, #S_R0 + S_OFF		@ pointer to regs
440	ldmia	r0, {r0 - r3}			@ have to reload r0 - r3
4411:
442#endif
443
444	tst	r10, #_TIF_SYSCALL_TRACE		@ are we tracing syscalls?
445	bne	__sys_trace
446
447	cmp	scno, #NR_syscalls		@ check upper syscall limit
448	adr	lr, BSYM(ret_fast_syscall)	@ return address
449	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
450
451	add	r1, sp, #S_OFF
4522:	mov	why, #0				@ no longer a real syscall
453	cmp	scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
454	eor	r0, scno, #__NR_SYSCALL_BASE	@ put OS number back
455	bcs	arm_syscall
456	b	sys_ni_syscall			@ not private func
457ENDPROC(vector_swi)
458
459	/*
460	 * This is the really slow path.  We're going to be doing
461	 * context switches, and waiting for our parent to respond.
462	 */
463__sys_trace:
464	mov	r2, scno
465	add	r1, sp, #S_OFF
466	mov	r0, #0				@ trace entry [IP = 0]
467	bl	syscall_trace
468
469	adr	lr, BSYM(__sys_trace_return)	@ return address
470	mov	scno, r0			@ syscall number (possibly new)
471	add	r1, sp, #S_R0 + S_OFF		@ pointer to regs
472	cmp	scno, #NR_syscalls		@ check upper syscall limit
473	ldmccia	r1, {r0 - r3}			@ have to reload r0 - r3
474	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
475	b	2b
476
477__sys_trace_return:
478	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0
479	mov	r2, scno
480	mov	r1, sp
481	mov	r0, #1				@ trace exit [IP = 1]
482	bl	syscall_trace
483	b	ret_slow_syscall
484
485	.align	5
486#ifdef CONFIG_ALIGNMENT_TRAP
487	.type	__cr_alignment, #object
488__cr_alignment:
489	.word	cr_alignment
490#endif
491	.ltorg
492
493/*
494 * This is the syscall table declaration for native ABI syscalls.
495 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
496 */
497#define ABI(native, compat) native
498#ifdef CONFIG_AEABI
499#define OBSOLETE(syscall) sys_ni_syscall
500#else
501#define OBSOLETE(syscall) syscall
502#endif
503
504	.type	sys_call_table, #object
505ENTRY(sys_call_table)
506#include "calls.S"
507#undef ABI
508#undef OBSOLETE
509
510/*============================================================================
511 * Special system call wrappers
512 */
513@ r0 = syscall number
514@ r8 = syscall table
515sys_syscall:
516		bic	scno, r0, #__NR_OABI_SYSCALL_BASE
517		cmp	scno, #__NR_syscall - __NR_SYSCALL_BASE
518		cmpne	scno, #NR_syscalls	@ check range
519		stmloia	sp, {r5, r6}		@ shuffle args
520		movlo	r0, r1
521		movlo	r1, r2
522		movlo	r2, r3
523		movlo	r3, r4
524		ldrlo	pc, [tbl, scno, lsl #2]
525		b	sys_ni_syscall
526ENDPROC(sys_syscall)
527
528sys_fork_wrapper:
529		add	r0, sp, #S_OFF
530		b	sys_fork
531ENDPROC(sys_fork_wrapper)
532
533sys_vfork_wrapper:
534		add	r0, sp, #S_OFF
535		b	sys_vfork
536ENDPROC(sys_vfork_wrapper)
537
538sys_execve_wrapper:
539		add	r3, sp, #S_OFF
540		b	sys_execve
541ENDPROC(sys_execve_wrapper)
542
543sys_clone_wrapper:
544		add	ip, sp, #S_OFF
545		str	ip, [sp, #4]
546		b	sys_clone
547ENDPROC(sys_clone_wrapper)
548
549sys_sigreturn_wrapper:
550		add	r0, sp, #S_OFF
551		mov	why, #0		@ prevent syscall restart handling
552		b	sys_sigreturn
553ENDPROC(sys_sigreturn_wrapper)
554
555sys_rt_sigreturn_wrapper:
556		add	r0, sp, #S_OFF
557		mov	why, #0		@ prevent syscall restart handling
558		b	sys_rt_sigreturn
559ENDPROC(sys_rt_sigreturn_wrapper)
560
561sys_sigaltstack_wrapper:
562		ldr	r2, [sp, #S_OFF + S_SP]
563		b	do_sigaltstack
564ENDPROC(sys_sigaltstack_wrapper)
565
566sys_statfs64_wrapper:
567		teq	r1, #88
568		moveq	r1, #84
569		b	sys_statfs64
570ENDPROC(sys_statfs64_wrapper)
571
572sys_fstatfs64_wrapper:
573		teq	r1, #88
574		moveq	r1, #84
575		b	sys_fstatfs64
576ENDPROC(sys_fstatfs64_wrapper)
577
578/*
579 * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
580 * offset, we return EINVAL.
581 */
582sys_mmap2:
583#if PAGE_SHIFT > 12
584		tst	r5, #PGOFF_MASK
585		moveq	r5, r5, lsr #PAGE_SHIFT - 12
586		streq	r5, [sp, #4]
587		beq	sys_mmap_pgoff
588		mov	r0, #-EINVAL
589		mov	pc, lr
590#else
591		str	r5, [sp, #4]
592		b	sys_mmap_pgoff
593#endif
594ENDPROC(sys_mmap2)
595
596#ifdef CONFIG_OABI_COMPAT
597
598/*
599 * These are syscalls with argument register differences
600 */
601
602sys_oabi_pread64:
603		stmia	sp, {r3, r4}
604		b	sys_pread64
605ENDPROC(sys_oabi_pread64)
606
607sys_oabi_pwrite64:
608		stmia	sp, {r3, r4}
609		b	sys_pwrite64
610ENDPROC(sys_oabi_pwrite64)
611
612sys_oabi_truncate64:
613		mov	r3, r2
614		mov	r2, r1
615		b	sys_truncate64
616ENDPROC(sys_oabi_truncate64)
617
618sys_oabi_ftruncate64:
619		mov	r3, r2
620		mov	r2, r1
621		b	sys_ftruncate64
622ENDPROC(sys_oabi_ftruncate64)
623
624sys_oabi_readahead:
625		str	r3, [sp]
626		mov	r3, r2
627		mov	r2, r1
628		b	sys_readahead
629ENDPROC(sys_oabi_readahead)
630
631/*
632 * Let's declare a second syscall table for old ABI binaries
633 * using the compatibility syscall entries.
634 */
635#define ABI(native, compat) compat
636#define OBSOLETE(syscall) syscall
637
638	.type	sys_oabi_call_table, #object
639ENTRY(sys_oabi_call_table)
640#include "calls.S"
641#undef ABI
642#undef OBSOLETE
643
644#endif
645
646