xref: /openbmc/linux/arch/arm/kernel/entry-common.S (revision 9cdb81c7) 
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 <asm/unwind.h>
14
15#ifdef CONFIG_NEED_RET_TO_USER
16#include <mach/entry-macro.S>
17#else
18	.macro  arch_ret_to_user, tmp1, tmp2
19	.endm
20#endif
21
22#include "entry-header.S"
23
24
25	.align	5
26/*
27 * This is the fast syscall return path.  We do as little as
28 * possible here, and this includes saving r0 back into the SVC
29 * stack.
30 */
31ret_fast_syscall:
32 UNWIND(.fnstart	)
33 UNWIND(.cantunwind	)
34	disable_irq				@ disable interrupts
35	ldr	r1, [tsk, #TI_FLAGS]
36	tst	r1, #_TIF_WORK_MASK
37	bne	fast_work_pending
38#if defined(CONFIG_IRQSOFF_TRACER)
39	asm_trace_hardirqs_on
40#endif
41
42	/* perform architecture specific actions before user return */
43	arch_ret_to_user r1, lr
44
45	restore_user_regs fast = 1, offset = S_OFF
46 UNWIND(.fnend		)
47
48/*
49 * Ok, we need to do extra processing, enter the slow path.
50 */
51fast_work_pending:
52	str	r0, [sp, #S_R0+S_OFF]!		@ returned r0
53work_pending:
54	tst	r1, #_TIF_NEED_RESCHED
55	bne	work_resched
56	tst	r1, #_TIF_SIGPENDING|_TIF_NOTIFY_RESUME
57	beq	no_work_pending
58	mov	r0, sp				@ 'regs'
59	mov	r2, why				@ 'syscall'
60	tst	r1, #_TIF_SIGPENDING		@ delivering a signal?
61	movne	why, #0				@ prevent further restarts
62	bl	do_notify_resume
63	b	ret_slow_syscall		@ Check work again
64
65work_resched:
66	bl	schedule
67/*
68 * "slow" syscall return path.  "why" tells us if this was a real syscall.
69 */
70ENTRY(ret_to_user)
71ret_slow_syscall:
72	disable_irq				@ disable interrupts
73ENTRY(ret_to_user_from_irq)
74	ldr	r1, [tsk, #TI_FLAGS]
75	tst	r1, #_TIF_WORK_MASK
76	bne	work_pending
77no_work_pending:
78#if defined(CONFIG_IRQSOFF_TRACER)
79	asm_trace_hardirqs_on
80#endif
81	/* perform architecture specific actions before user return */
82	arch_ret_to_user r1, lr
83
84	restore_user_regs fast = 0, offset = 0
85ENDPROC(ret_to_user_from_irq)
86ENDPROC(ret_to_user)
87
88/*
89 * This is how we return from a fork.
90 */
91ENTRY(ret_from_fork)
92	bl	schedule_tail
93	get_thread_info tsk
94	ldr	r1, [tsk, #TI_FLAGS]		@ check for syscall tracing
95	mov	why, #1
96	tst	r1, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
97	beq	ret_slow_syscall
98	mov	r1, sp
99	mov	r0, #1				@ trace exit [IP = 1]
100	bl	syscall_trace
101	b	ret_slow_syscall
102ENDPROC(ret_from_fork)
103
104	.equ NR_syscalls,0
105#define CALL(x) .equ NR_syscalls,NR_syscalls+1
106#include "calls.S"
107#undef CALL
108#define CALL(x) .long x
109
110#ifdef CONFIG_FUNCTION_TRACER
111/*
112 * When compiling with -pg, gcc inserts a call to the mcount routine at the
113 * start of every function.  In mcount, apart from the function's address (in
114 * lr), we need to get hold of the function's caller's address.
115 *
116 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
117 *
118 *	bl	mcount
119 *
120 * These versions have the limitation that in order for the mcount routine to
121 * be able to determine the function's caller's address, an APCS-style frame
122 * pointer (which is set up with something like the code below) is required.
123 *
124 *	mov     ip, sp
125 *	push    {fp, ip, lr, pc}
126 *	sub     fp, ip, #4
127 *
128 * With EABI, these frame pointers are not available unless -mapcs-frame is
129 * specified, and if building as Thumb-2, not even then.
130 *
131 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
132 * with call sites like:
133 *
134 *	push	{lr}
135 *	bl	__gnu_mcount_nc
136 *
137 * With these compilers, frame pointers are not necessary.
138 *
139 * mcount can be thought of as a function called in the middle of a subroutine
140 * call.  As such, it needs to be transparent for both the caller and the
141 * callee: the original lr needs to be restored when leaving mcount, and no
142 * registers should be clobbered.  (In the __gnu_mcount_nc implementation, we
143 * clobber the ip register.  This is OK because the ARM calling convention
144 * allows it to be clobbered in subroutines and doesn't use it to hold
145 * parameters.)
146 *
147 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
148 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
149 * arch/arm/kernel/ftrace.c).
150 */
151
152#ifndef CONFIG_OLD_MCOUNT
153#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
154#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
155#endif
156#endif
157
158.macro mcount_adjust_addr rd, rn
159	bic	\rd, \rn, #1		@ clear the Thumb bit if present
160	sub	\rd, \rd, #MCOUNT_INSN_SIZE
161.endm
162
163.macro __mcount suffix
164	mcount_enter
165	ldr	r0, =ftrace_trace_function
166	ldr	r2, [r0]
167	adr	r0, .Lftrace_stub
168	cmp	r0, r2
169	bne	1f
170
171#ifdef CONFIG_FUNCTION_GRAPH_TRACER
172	ldr     r1, =ftrace_graph_return
173	ldr     r2, [r1]
174	cmp     r0, r2
175	bne     ftrace_graph_caller\suffix
176
177	ldr     r1, =ftrace_graph_entry
178	ldr     r2, [r1]
179	ldr     r0, =ftrace_graph_entry_stub
180	cmp     r0, r2
181	bne     ftrace_graph_caller\suffix
182#endif
183
184	mcount_exit
185
1861: 	mcount_get_lr	r1			@ lr of instrumented func
187	mcount_adjust_addr	r0, lr		@ instrumented function
188	adr	lr, BSYM(2f)
189	mov	pc, r2
1902:	mcount_exit
191.endm
192
193.macro __ftrace_caller suffix
194	mcount_enter
195
196	mcount_get_lr	r1			@ lr of instrumented func
197	mcount_adjust_addr	r0, lr		@ instrumented function
198
199	.globl ftrace_call\suffix
200ftrace_call\suffix:
201	bl	ftrace_stub
202
203#ifdef CONFIG_FUNCTION_GRAPH_TRACER
204	.globl ftrace_graph_call\suffix
205ftrace_graph_call\suffix:
206	mov	r0, r0
207#endif
208
209	mcount_exit
210.endm
211
212.macro __ftrace_graph_caller
213	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)
214#ifdef CONFIG_DYNAMIC_FTRACE
215	@ called from __ftrace_caller, saved in mcount_enter
216	ldr	r1, [sp, #16]		@ instrumented routine (func)
217	mcount_adjust_addr	r1, r1
218#else
219	@ called from __mcount, untouched in lr
220	mcount_adjust_addr	r1, lr	@ instrumented routine (func)
221#endif
222	mov	r2, fp			@ frame pointer
223	bl	prepare_ftrace_return
224	mcount_exit
225.endm
226
227#ifdef CONFIG_OLD_MCOUNT
228/*
229 * mcount
230 */
231
232.macro mcount_enter
233	stmdb	sp!, {r0-r3, lr}
234.endm
235
236.macro mcount_get_lr reg
237	ldr	\reg, [fp, #-4]
238.endm
239
240.macro mcount_exit
241	ldr	lr, [fp, #-4]
242	ldmia	sp!, {r0-r3, pc}
243.endm
244
245ENTRY(mcount)
246#ifdef CONFIG_DYNAMIC_FTRACE
247	stmdb	sp!, {lr}
248	ldr	lr, [fp, #-4]
249	ldmia	sp!, {pc}
250#else
251	__mcount _old
252#endif
253ENDPROC(mcount)
254
255#ifdef CONFIG_DYNAMIC_FTRACE
256ENTRY(ftrace_caller_old)
257	__ftrace_caller _old
258ENDPROC(ftrace_caller_old)
259#endif
260
261#ifdef CONFIG_FUNCTION_GRAPH_TRACER
262ENTRY(ftrace_graph_caller_old)
263	__ftrace_graph_caller
264ENDPROC(ftrace_graph_caller_old)
265#endif
266
267.purgem mcount_enter
268.purgem mcount_get_lr
269.purgem mcount_exit
270#endif
271
272/*
273 * __gnu_mcount_nc
274 */
275
276.macro mcount_enter
277	stmdb	sp!, {r0-r3, lr}
278.endm
279
280.macro mcount_get_lr reg
281	ldr	\reg, [sp, #20]
282.endm
283
284.macro mcount_exit
285	ldmia	sp!, {r0-r3, ip, lr}
286	mov	pc, ip
287.endm
288
289ENTRY(__gnu_mcount_nc)
290#ifdef CONFIG_DYNAMIC_FTRACE
291	mov	ip, lr
292	ldmia	sp!, {lr}
293	mov	pc, ip
294#else
295	__mcount
296#endif
297ENDPROC(__gnu_mcount_nc)
298
299#ifdef CONFIG_DYNAMIC_FTRACE
300ENTRY(ftrace_caller)
301	__ftrace_caller
302ENDPROC(ftrace_caller)
303#endif
304
305#ifdef CONFIG_FUNCTION_GRAPH_TRACER
306ENTRY(ftrace_graph_caller)
307	__ftrace_graph_caller
308ENDPROC(ftrace_graph_caller)
309#endif
310
311.purgem mcount_enter
312.purgem mcount_get_lr
313.purgem mcount_exit
314
315#ifdef CONFIG_FUNCTION_GRAPH_TRACER
316	.globl return_to_handler
317return_to_handler:
318	stmdb	sp!, {r0-r3}
319	mov	r0, fp			@ frame pointer
320	bl	ftrace_return_to_handler
321	mov	lr, r0			@ r0 has real ret addr
322	ldmia	sp!, {r0-r3}
323	mov	pc, lr
324#endif
325
326ENTRY(ftrace_stub)
327.Lftrace_stub:
328	mov	pc, lr
329ENDPROC(ftrace_stub)
330
331#endif /* CONFIG_FUNCTION_TRACER */
332
333/*=============================================================================
334 * SWI handler
335 *-----------------------------------------------------------------------------
336 */
337
338	/* If we're optimising for StrongARM the resulting code won't
339	   run on an ARM7 and we can save a couple of instructions.
340								--pb */
341#ifdef CONFIG_CPU_ARM710
342#define A710(code...) code
343.Larm710bug:
344	ldmia	sp, {r0 - lr}^			@ Get calling r0 - lr
345	mov	r0, r0
346	add	sp, sp, #S_FRAME_SIZE
347	subs	pc, lr, #4
348#else
349#define A710(code...)
350#endif
351
352	.align	5
353ENTRY(vector_swi)
354	sub	sp, sp, #S_FRAME_SIZE
355	stmia	sp, {r0 - r12}			@ Calling r0 - r12
356 ARM(	add	r8, sp, #S_PC		)
357 ARM(	stmdb	r8, {sp, lr}^		)	@ Calling sp, lr
358 THUMB(	mov	r8, sp			)
359 THUMB(	store_user_sp_lr r8, r10, S_SP	)	@ calling sp, lr
360	mrs	r8, spsr			@ called from non-FIQ mode, so ok.
361	str	lr, [sp, #S_PC]			@ Save calling PC
362	str	r8, [sp, #S_PSR]		@ Save CPSR
363	str	r0, [sp, #S_OLD_R0]		@ Save OLD_R0
364	zero_fp
365
366	/*
367	 * Get the system call number.
368	 */
369
370#if defined(CONFIG_OABI_COMPAT)
371
372	/*
373	 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
374	 * value to determine if it is an EABI or an old ABI call.
375	 */
376#ifdef CONFIG_ARM_THUMB
377	tst	r8, #PSR_T_BIT
378	movne	r10, #0				@ no thumb OABI emulation
379	ldreq	r10, [lr, #-4]			@ get SWI instruction
380#else
381	ldr	r10, [lr, #-4]			@ get SWI instruction
382  A710(	and	ip, r10, #0x0f000000		@ check for SWI		)
383  A710(	teq	ip, #0x0f000000						)
384  A710(	bne	.Larm710bug						)
385#endif
386#ifdef CONFIG_CPU_ENDIAN_BE8
387	rev	r10, r10			@ little endian instruction
388#endif
389
390#elif defined(CONFIG_AEABI)
391
392	/*
393	 * Pure EABI user space always put syscall number into scno (r7).
394	 */
395  A710(	ldr	ip, [lr, #-4]			@ get SWI instruction	)
396  A710(	and	ip, ip, #0x0f000000		@ check for SWI		)
397  A710(	teq	ip, #0x0f000000						)
398  A710(	bne	.Larm710bug						)
399
400#elif defined(CONFIG_ARM_THUMB)
401
402	/* Legacy ABI only, possibly thumb mode. */
403	tst	r8, #PSR_T_BIT			@ this is SPSR from save_user_regs
404	addne	scno, r7, #__NR_SYSCALL_BASE	@ put OS number in
405	ldreq	scno, [lr, #-4]
406
407#else
408
409	/* Legacy ABI only. */
410	ldr	scno, [lr, #-4]			@ get SWI instruction
411  A710(	and	ip, scno, #0x0f000000		@ check for SWI		)
412  A710(	teq	ip, #0x0f000000						)
413  A710(	bne	.Larm710bug						)
414
415#endif
416
417#ifdef CONFIG_ALIGNMENT_TRAP
418	ldr	ip, __cr_alignment
419	ldr	ip, [ip]
420	mcr	p15, 0, ip, c1, c0		@ update control register
421#endif
422	enable_irq
423
424	get_thread_info tsk
425	adr	tbl, sys_call_table		@ load syscall table pointer
426
427#if defined(CONFIG_OABI_COMPAT)
428	/*
429	 * If the swi argument is zero, this is an EABI call and we do nothing.
430	 *
431	 * If this is an old ABI call, get the syscall number into scno and
432	 * get the old ABI syscall table address.
433	 */
434	bics	r10, r10, #0xff000000
435	eorne	scno, r10, #__NR_OABI_SYSCALL_BASE
436	ldrne	tbl, =sys_oabi_call_table
437#elif !defined(CONFIG_AEABI)
438	bic	scno, scno, #0xff000000		@ mask off SWI op-code
439	eor	scno, scno, #__NR_SYSCALL_BASE	@ check OS number
440#endif
441
442	ldr	r10, [tsk, #TI_FLAGS]		@ check for syscall tracing
443	stmdb	sp!, {r4, r5}			@ push fifth and sixth args
444
445#ifdef CONFIG_SECCOMP
446	tst	r10, #_TIF_SECCOMP
447	beq	1f
448	mov	r0, scno
449	bl	__secure_computing
450	add	r0, sp, #S_R0 + S_OFF		@ pointer to regs
451	ldmia	r0, {r0 - r3}			@ have to reload r0 - r3
4521:
453#endif
454
455	tst	r10, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
456	bne	__sys_trace
457
458	cmp	scno, #NR_syscalls		@ check upper syscall limit
459	adr	lr, BSYM(ret_fast_syscall)	@ return address
460	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
461
462	add	r1, sp, #S_OFF
4632:	mov	why, #0				@ no longer a real syscall
464	cmp	scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
465	eor	r0, scno, #__NR_SYSCALL_BASE	@ put OS number back
466	bcs	arm_syscall
467	b	sys_ni_syscall			@ not private func
468ENDPROC(vector_swi)
469
470	/*
471	 * This is the really slow path.  We're going to be doing
472	 * context switches, and waiting for our parent to respond.
473	 */
474__sys_trace:
475	mov	r2, scno
476	add	r1, sp, #S_OFF
477	mov	r0, #0				@ trace entry [IP = 0]
478	bl	syscall_trace
479
480	adr	lr, BSYM(__sys_trace_return)	@ return address
481	mov	scno, r0			@ syscall number (possibly new)
482	add	r1, sp, #S_R0 + S_OFF		@ pointer to regs
483	cmp	scno, #NR_syscalls		@ check upper syscall limit
484	ldmccia	r1, {r0 - r3}			@ have to reload r0 - r3
485	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
486	b	2b
487
488__sys_trace_return:
489	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0
490	mov	r2, scno
491	mov	r1, sp
492	mov	r0, #1				@ trace exit [IP = 1]
493	bl	syscall_trace
494	b	ret_slow_syscall
495
496	.align	5
497#ifdef CONFIG_ALIGNMENT_TRAP
498	.type	__cr_alignment, #object
499__cr_alignment:
500	.word	cr_alignment
501#endif
502	.ltorg
503
504/*
505 * This is the syscall table declaration for native ABI syscalls.
506 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
507 */
508#define ABI(native, compat) native
509#ifdef CONFIG_AEABI
510#define OBSOLETE(syscall) sys_ni_syscall
511#else
512#define OBSOLETE(syscall) syscall
513#endif
514
515	.type	sys_call_table, #object
516ENTRY(sys_call_table)
517#include "calls.S"
518#undef ABI
519#undef OBSOLETE
520
521/*============================================================================
522 * Special system call wrappers
523 */
524@ r0 = syscall number
525@ r8 = syscall table
526sys_syscall:
527		bic	scno, r0, #__NR_OABI_SYSCALL_BASE
528		cmp	scno, #__NR_syscall - __NR_SYSCALL_BASE
529		cmpne	scno, #NR_syscalls	@ check range
530		stmloia	sp, {r5, r6}		@ shuffle args
531		movlo	r0, r1
532		movlo	r1, r2
533		movlo	r2, r3
534		movlo	r3, r4
535		ldrlo	pc, [tbl, scno, lsl #2]
536		b	sys_ni_syscall
537ENDPROC(sys_syscall)
538
539sys_fork_wrapper:
540		add	r0, sp, #S_OFF
541		b	sys_fork
542ENDPROC(sys_fork_wrapper)
543
544sys_vfork_wrapper:
545		add	r0, sp, #S_OFF
546		b	sys_vfork
547ENDPROC(sys_vfork_wrapper)
548
549sys_execve_wrapper:
550		add	r3, sp, #S_OFF
551		b	sys_execve
552ENDPROC(sys_execve_wrapper)
553
554sys_clone_wrapper:
555		add	ip, sp, #S_OFF
556		str	ip, [sp, #4]
557		b	sys_clone
558ENDPROC(sys_clone_wrapper)
559
560sys_sigreturn_wrapper:
561		add	r0, sp, #S_OFF
562		mov	why, #0		@ prevent syscall restart handling
563		b	sys_sigreturn
564ENDPROC(sys_sigreturn_wrapper)
565
566sys_rt_sigreturn_wrapper:
567		add	r0, sp, #S_OFF
568		mov	why, #0		@ prevent syscall restart handling
569		b	sys_rt_sigreturn
570ENDPROC(sys_rt_sigreturn_wrapper)
571
572sys_sigaltstack_wrapper:
573		ldr	r2, [sp, #S_OFF + S_SP]
574		b	do_sigaltstack
575ENDPROC(sys_sigaltstack_wrapper)
576
577sys_statfs64_wrapper:
578		teq	r1, #88
579		moveq	r1, #84
580		b	sys_statfs64
581ENDPROC(sys_statfs64_wrapper)
582
583sys_fstatfs64_wrapper:
584		teq	r1, #88
585		moveq	r1, #84
586		b	sys_fstatfs64
587ENDPROC(sys_fstatfs64_wrapper)
588
589/*
590 * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
591 * offset, we return EINVAL.
592 */
593sys_mmap2:
594#if PAGE_SHIFT > 12
595		tst	r5, #PGOFF_MASK
596		moveq	r5, r5, lsr #PAGE_SHIFT - 12
597		streq	r5, [sp, #4]
598		beq	sys_mmap_pgoff
599		mov	r0, #-EINVAL
600		mov	pc, lr
601#else
602		str	r5, [sp, #4]
603		b	sys_mmap_pgoff
604#endif
605ENDPROC(sys_mmap2)
606
607#ifdef CONFIG_OABI_COMPAT
608
609/*
610 * These are syscalls with argument register differences
611 */
612
613sys_oabi_pread64:
614		stmia	sp, {r3, r4}
615		b	sys_pread64
616ENDPROC(sys_oabi_pread64)
617
618sys_oabi_pwrite64:
619		stmia	sp, {r3, r4}
620		b	sys_pwrite64
621ENDPROC(sys_oabi_pwrite64)
622
623sys_oabi_truncate64:
624		mov	r3, r2
625		mov	r2, r1
626		b	sys_truncate64
627ENDPROC(sys_oabi_truncate64)
628
629sys_oabi_ftruncate64:
630		mov	r3, r2
631		mov	r2, r1
632		b	sys_ftruncate64
633ENDPROC(sys_oabi_ftruncate64)
634
635sys_oabi_readahead:
636		str	r3, [sp]
637		mov	r3, r2
638		mov	r2, r1
639		b	sys_readahead
640ENDPROC(sys_oabi_readahead)
641
642/*
643 * Let's declare a second syscall table for old ABI binaries
644 * using the compatibility syscall entries.
645 */
646#define ABI(native, compat) compat
647#define OBSOLETE(syscall) syscall
648
649	.type	sys_oabi_call_table, #object
650ENTRY(sys_oabi_call_table)
651#include "calls.S"
652#undef ABI
653#undef OBSOLETE
654
655#endif
656
657