xref: /openbmc/linux/arch/arm/kernel/entry-common.S (revision 81d67439) 
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
67ENTRY(ret_to_user_from_irq)
68	ldr	r1, [tsk, #TI_FLAGS]
69	tst	r1, #_TIF_WORK_MASK
70	bne	work_pending
71no_work_pending:
72#if defined(CONFIG_IRQSOFF_TRACER)
73	asm_trace_hardirqs_on
74#endif
75	/* perform architecture specific actions before user return */
76	arch_ret_to_user r1, lr
77
78	restore_user_regs fast = 0, offset = 0
79ENDPROC(ret_to_user_from_irq)
80ENDPROC(ret_to_user)
81
82/*
83 * This is how we return from a fork.
84 */
85ENTRY(ret_from_fork)
86	bl	schedule_tail
87	get_thread_info tsk
88	ldr	r1, [tsk, #TI_FLAGS]		@ check for syscall tracing
89	mov	why, #1
90	tst	r1, #_TIF_SYSCALL_TRACE		@ are we tracing syscalls?
91	beq	ret_slow_syscall
92	mov	r1, sp
93	mov	r0, #1				@ trace exit [IP = 1]
94	bl	syscall_trace
95	b	ret_slow_syscall
96ENDPROC(ret_from_fork)
97
98	.equ NR_syscalls,0
99#define CALL(x) .equ NR_syscalls,NR_syscalls+1
100#include "calls.S"
101#undef CALL
102#define CALL(x) .long x
103
104#ifdef CONFIG_FUNCTION_TRACER
105/*
106 * When compiling with -pg, gcc inserts a call to the mcount routine at the
107 * start of every function.  In mcount, apart from the function's address (in
108 * lr), we need to get hold of the function's caller's address.
109 *
110 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
111 *
112 *	bl	mcount
113 *
114 * These versions have the limitation that in order for the mcount routine to
115 * be able to determine the function's caller's address, an APCS-style frame
116 * pointer (which is set up with something like the code below) is required.
117 *
118 *	mov     ip, sp
119 *	push    {fp, ip, lr, pc}
120 *	sub     fp, ip, #4
121 *
122 * With EABI, these frame pointers are not available unless -mapcs-frame is
123 * specified, and if building as Thumb-2, not even then.
124 *
125 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
126 * with call sites like:
127 *
128 *	push	{lr}
129 *	bl	__gnu_mcount_nc
130 *
131 * With these compilers, frame pointers are not necessary.
132 *
133 * mcount can be thought of as a function called in the middle of a subroutine
134 * call.  As such, it needs to be transparent for both the caller and the
135 * callee: the original lr needs to be restored when leaving mcount, and no
136 * registers should be clobbered.  (In the __gnu_mcount_nc implementation, we
137 * clobber the ip register.  This is OK because the ARM calling convention
138 * allows it to be clobbered in subroutines and doesn't use it to hold
139 * parameters.)
140 *
141 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
142 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
143 * arch/arm/kernel/ftrace.c).
144 */
145
146#ifndef CONFIG_OLD_MCOUNT
147#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
148#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
149#endif
150#endif
151
152.macro __mcount suffix
153	mcount_enter
154	ldr	r0, =ftrace_trace_function
155	ldr	r2, [r0]
156	adr	r0, .Lftrace_stub
157	cmp	r0, r2
158	bne	1f
159
160#ifdef CONFIG_FUNCTION_GRAPH_TRACER
161	ldr     r1, =ftrace_graph_return
162	ldr     r2, [r1]
163	cmp     r0, r2
164	bne     ftrace_graph_caller\suffix
165
166	ldr     r1, =ftrace_graph_entry
167	ldr     r2, [r1]
168	ldr     r0, =ftrace_graph_entry_stub
169	cmp     r0, r2
170	bne     ftrace_graph_caller\suffix
171#endif
172
173	mcount_exit
174
1751: 	mcount_get_lr	r1			@ lr of instrumented func
176	mov	r0, lr				@ instrumented function
177	sub	r0, r0, #MCOUNT_INSN_SIZE
178	adr	lr, BSYM(2f)
179	mov	pc, r2
1802:	mcount_exit
181.endm
182
183.macro __ftrace_caller suffix
184	mcount_enter
185
186	mcount_get_lr	r1			@ lr of instrumented func
187	mov	r0, lr				@ instrumented function
188	sub	r0, r0, #MCOUNT_INSN_SIZE
189
190	.globl ftrace_call\suffix
191ftrace_call\suffix:
192	bl	ftrace_stub
193
194#ifdef CONFIG_FUNCTION_GRAPH_TRACER
195	.globl ftrace_graph_call\suffix
196ftrace_graph_call\suffix:
197	mov	r0, r0
198#endif
199
200	mcount_exit
201.endm
202
203.macro __ftrace_graph_caller
204	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)
205#ifdef CONFIG_DYNAMIC_FTRACE
206	@ called from __ftrace_caller, saved in mcount_enter
207	ldr	r1, [sp, #16]		@ instrumented routine (func)
208#else
209	@ called from __mcount, untouched in lr
210	mov	r1, lr			@ instrumented routine (func)
211#endif
212	sub	r1, r1, #MCOUNT_INSN_SIZE
213	mov	r2, fp			@ frame pointer
214	bl	prepare_ftrace_return
215	mcount_exit
216.endm
217
218#ifdef CONFIG_OLD_MCOUNT
219/*
220 * mcount
221 */
222
223.macro mcount_enter
224	stmdb	sp!, {r0-r3, lr}
225.endm
226
227.macro mcount_get_lr reg
228	ldr	\reg, [fp, #-4]
229.endm
230
231.macro mcount_exit
232	ldr	lr, [fp, #-4]
233	ldmia	sp!, {r0-r3, pc}
234.endm
235
236ENTRY(mcount)
237#ifdef CONFIG_DYNAMIC_FTRACE
238	stmdb	sp!, {lr}
239	ldr	lr, [fp, #-4]
240	ldmia	sp!, {pc}
241#else
242	__mcount _old
243#endif
244ENDPROC(mcount)
245
246#ifdef CONFIG_DYNAMIC_FTRACE
247ENTRY(ftrace_caller_old)
248	__ftrace_caller _old
249ENDPROC(ftrace_caller_old)
250#endif
251
252#ifdef CONFIG_FUNCTION_GRAPH_TRACER
253ENTRY(ftrace_graph_caller_old)
254	__ftrace_graph_caller
255ENDPROC(ftrace_graph_caller_old)
256#endif
257
258.purgem mcount_enter
259.purgem mcount_get_lr
260.purgem mcount_exit
261#endif
262
263/*
264 * __gnu_mcount_nc
265 */
266
267.macro mcount_enter
268	stmdb	sp!, {r0-r3, lr}
269.endm
270
271.macro mcount_get_lr reg
272	ldr	\reg, [sp, #20]
273.endm
274
275.macro mcount_exit
276	ldmia	sp!, {r0-r3, ip, lr}
277	mov	pc, ip
278.endm
279
280ENTRY(__gnu_mcount_nc)
281#ifdef CONFIG_DYNAMIC_FTRACE
282	mov	ip, lr
283	ldmia	sp!, {lr}
284	mov	pc, ip
285#else
286	__mcount
287#endif
288ENDPROC(__gnu_mcount_nc)
289
290#ifdef CONFIG_DYNAMIC_FTRACE
291ENTRY(ftrace_caller)
292	__ftrace_caller
293ENDPROC(ftrace_caller)
294#endif
295
296#ifdef CONFIG_FUNCTION_GRAPH_TRACER
297ENTRY(ftrace_graph_caller)
298	__ftrace_graph_caller
299ENDPROC(ftrace_graph_caller)
300#endif
301
302.purgem mcount_enter
303.purgem mcount_get_lr
304.purgem mcount_exit
305
306#ifdef CONFIG_FUNCTION_GRAPH_TRACER
307	.globl return_to_handler
308return_to_handler:
309	stmdb	sp!, {r0-r3}
310	mov	r0, fp			@ frame pointer
311	bl	ftrace_return_to_handler
312	mov	lr, r0			@ r0 has real ret addr
313	ldmia	sp!, {r0-r3}
314	mov	pc, lr
315#endif
316
317ENTRY(ftrace_stub)
318.Lftrace_stub:
319	mov	pc, lr
320ENDPROC(ftrace_stub)
321
322#endif /* CONFIG_FUNCTION_TRACER */
323
324/*=============================================================================
325 * SWI handler
326 *-----------------------------------------------------------------------------
327 */
328
329	/* If we're optimising for StrongARM the resulting code won't
330	   run on an ARM7 and we can save a couple of instructions.
331								--pb */
332#ifdef CONFIG_CPU_ARM710
333#define A710(code...) code
334.Larm710bug:
335	ldmia	sp, {r0 - lr}^			@ Get calling r0 - lr
336	mov	r0, r0
337	add	sp, sp, #S_FRAME_SIZE
338	subs	pc, lr, #4
339#else
340#define A710(code...)
341#endif
342
343	.align	5
344ENTRY(vector_swi)
345	sub	sp, sp, #S_FRAME_SIZE
346	stmia	sp, {r0 - r12}			@ Calling r0 - r12
347 ARM(	add	r8, sp, #S_PC		)
348 ARM(	stmdb	r8, {sp, lr}^		)	@ Calling sp, lr
349 THUMB(	mov	r8, sp			)
350 THUMB(	store_user_sp_lr r8, r10, S_SP	)	@ calling sp, lr
351	mrs	r8, spsr			@ called from non-FIQ mode, so ok.
352	str	lr, [sp, #S_PC]			@ Save calling PC
353	str	r8, [sp, #S_PSR]		@ Save CPSR
354	str	r0, [sp, #S_OLD_R0]		@ Save OLD_R0
355	zero_fp
356
357	/*
358	 * Get the system call number.
359	 */
360
361#if defined(CONFIG_OABI_COMPAT)
362
363	/*
364	 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
365	 * value to determine if it is an EABI or an old ABI call.
366	 */
367#ifdef CONFIG_ARM_THUMB
368	tst	r8, #PSR_T_BIT
369	movne	r10, #0				@ no thumb OABI emulation
370	ldreq	r10, [lr, #-4]			@ get SWI instruction
371#else
372	ldr	r10, [lr, #-4]			@ get SWI instruction
373  A710(	and	ip, r10, #0x0f000000		@ check for SWI		)
374  A710(	teq	ip, #0x0f000000						)
375  A710(	bne	.Larm710bug						)
376#endif
377#ifdef CONFIG_CPU_ENDIAN_BE8
378	rev	r10, r10			@ little endian instruction
379#endif
380
381#elif defined(CONFIG_AEABI)
382
383	/*
384	 * Pure EABI user space always put syscall number into scno (r7).
385	 */
386  A710(	ldr	ip, [lr, #-4]			@ get SWI instruction	)
387  A710(	and	ip, ip, #0x0f000000		@ check for SWI		)
388  A710(	teq	ip, #0x0f000000						)
389  A710(	bne	.Larm710bug						)
390
391#elif defined(CONFIG_ARM_THUMB)
392
393	/* Legacy ABI only, possibly thumb mode. */
394	tst	r8, #PSR_T_BIT			@ this is SPSR from save_user_regs
395	addne	scno, r7, #__NR_SYSCALL_BASE	@ put OS number in
396	ldreq	scno, [lr, #-4]
397
398#else
399
400	/* Legacy ABI only. */
401	ldr	scno, [lr, #-4]			@ get SWI instruction
402  A710(	and	ip, scno, #0x0f000000		@ check for SWI		)
403  A710(	teq	ip, #0x0f000000						)
404  A710(	bne	.Larm710bug						)
405
406#endif
407
408#ifdef CONFIG_ALIGNMENT_TRAP
409	ldr	ip, __cr_alignment
410	ldr	ip, [ip]
411	mcr	p15, 0, ip, c1, c0		@ update control register
412#endif
413	enable_irq
414
415	get_thread_info tsk
416	adr	tbl, sys_call_table		@ load syscall table pointer
417
418#if defined(CONFIG_OABI_COMPAT)
419	/*
420	 * If the swi argument is zero, this is an EABI call and we do nothing.
421	 *
422	 * If this is an old ABI call, get the syscall number into scno and
423	 * get the old ABI syscall table address.
424	 */
425	bics	r10, r10, #0xff000000
426	eorne	scno, r10, #__NR_OABI_SYSCALL_BASE
427	ldrne	tbl, =sys_oabi_call_table
428#elif !defined(CONFIG_AEABI)
429	bic	scno, scno, #0xff000000		@ mask off SWI op-code
430	eor	scno, scno, #__NR_SYSCALL_BASE	@ check OS number
431#endif
432
433	ldr	r10, [tsk, #TI_FLAGS]		@ check for syscall tracing
434	stmdb	sp!, {r4, r5}			@ push fifth and sixth args
435
436#ifdef CONFIG_SECCOMP
437	tst	r10, #_TIF_SECCOMP
438	beq	1f
439	mov	r0, scno
440	bl	__secure_computing
441	add	r0, sp, #S_R0 + S_OFF		@ pointer to regs
442	ldmia	r0, {r0 - r3}			@ have to reload r0 - r3
4431:
444#endif
445
446	tst	r10, #_TIF_SYSCALL_TRACE		@ are we tracing syscalls?
447	bne	__sys_trace
448
449	cmp	scno, #NR_syscalls		@ check upper syscall limit
450	adr	lr, BSYM(ret_fast_syscall)	@ return address
451	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
452
453	add	r1, sp, #S_OFF
4542:	mov	why, #0				@ no longer a real syscall
455	cmp	scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
456	eor	r0, scno, #__NR_SYSCALL_BASE	@ put OS number back
457	bcs	arm_syscall
458	b	sys_ni_syscall			@ not private func
459ENDPROC(vector_swi)
460
461	/*
462	 * This is the really slow path.  We're going to be doing
463	 * context switches, and waiting for our parent to respond.
464	 */
465__sys_trace:
466	mov	r2, scno
467	add	r1, sp, #S_OFF
468	mov	r0, #0				@ trace entry [IP = 0]
469	bl	syscall_trace
470
471	adr	lr, BSYM(__sys_trace_return)	@ return address
472	mov	scno, r0			@ syscall number (possibly new)
473	add	r1, sp, #S_R0 + S_OFF		@ pointer to regs
474	cmp	scno, #NR_syscalls		@ check upper syscall limit
475	ldmccia	r1, {r0 - r3}			@ have to reload r0 - r3
476	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
477	b	2b
478
479__sys_trace_return:
480	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0
481	mov	r2, scno
482	mov	r1, sp
483	mov	r0, #1				@ trace exit [IP = 1]
484	bl	syscall_trace
485	b	ret_slow_syscall
486
487	.align	5
488#ifdef CONFIG_ALIGNMENT_TRAP
489	.type	__cr_alignment, #object
490__cr_alignment:
491	.word	cr_alignment
492#endif
493	.ltorg
494
495/*
496 * This is the syscall table declaration for native ABI syscalls.
497 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
498 */
499#define ABI(native, compat) native
500#ifdef CONFIG_AEABI
501#define OBSOLETE(syscall) sys_ni_syscall
502#else
503#define OBSOLETE(syscall) syscall
504#endif
505
506	.type	sys_call_table, #object
507ENTRY(sys_call_table)
508#include "calls.S"
509#undef ABI
510#undef OBSOLETE
511
512/*============================================================================
513 * Special system call wrappers
514 */
515@ r0 = syscall number
516@ r8 = syscall table
517sys_syscall:
518		bic	scno, r0, #__NR_OABI_SYSCALL_BASE
519		cmp	scno, #__NR_syscall - __NR_SYSCALL_BASE
520		cmpne	scno, #NR_syscalls	@ check range
521		stmloia	sp, {r5, r6}		@ shuffle args
522		movlo	r0, r1
523		movlo	r1, r2
524		movlo	r2, r3
525		movlo	r3, r4
526		ldrlo	pc, [tbl, scno, lsl #2]
527		b	sys_ni_syscall
528ENDPROC(sys_syscall)
529
530sys_fork_wrapper:
531		add	r0, sp, #S_OFF
532		b	sys_fork
533ENDPROC(sys_fork_wrapper)
534
535sys_vfork_wrapper:
536		add	r0, sp, #S_OFF
537		b	sys_vfork
538ENDPROC(sys_vfork_wrapper)
539
540sys_execve_wrapper:
541		add	r3, sp, #S_OFF
542		b	sys_execve
543ENDPROC(sys_execve_wrapper)
544
545sys_clone_wrapper:
546		add	ip, sp, #S_OFF
547		str	ip, [sp, #4]
548		b	sys_clone
549ENDPROC(sys_clone_wrapper)
550
551sys_sigreturn_wrapper:
552		add	r0, sp, #S_OFF
553		mov	why, #0		@ prevent syscall restart handling
554		b	sys_sigreturn
555ENDPROC(sys_sigreturn_wrapper)
556
557sys_rt_sigreturn_wrapper:
558		add	r0, sp, #S_OFF
559		mov	why, #0		@ prevent syscall restart handling
560		b	sys_rt_sigreturn
561ENDPROC(sys_rt_sigreturn_wrapper)
562
563sys_sigaltstack_wrapper:
564		ldr	r2, [sp, #S_OFF + S_SP]
565		b	do_sigaltstack
566ENDPROC(sys_sigaltstack_wrapper)
567
568sys_statfs64_wrapper:
569		teq	r1, #88
570		moveq	r1, #84
571		b	sys_statfs64
572ENDPROC(sys_statfs64_wrapper)
573
574sys_fstatfs64_wrapper:
575		teq	r1, #88
576		moveq	r1, #84
577		b	sys_fstatfs64
578ENDPROC(sys_fstatfs64_wrapper)
579
580/*
581 * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
582 * offset, we return EINVAL.
583 */
584sys_mmap2:
585#if PAGE_SHIFT > 12
586		tst	r5, #PGOFF_MASK
587		moveq	r5, r5, lsr #PAGE_SHIFT - 12
588		streq	r5, [sp, #4]
589		beq	sys_mmap_pgoff
590		mov	r0, #-EINVAL
591		mov	pc, lr
592#else
593		str	r5, [sp, #4]
594		b	sys_mmap_pgoff
595#endif
596ENDPROC(sys_mmap2)
597
598#ifdef CONFIG_OABI_COMPAT
599
600/*
601 * These are syscalls with argument register differences
602 */
603
604sys_oabi_pread64:
605		stmia	sp, {r3, r4}
606		b	sys_pread64
607ENDPROC(sys_oabi_pread64)
608
609sys_oabi_pwrite64:
610		stmia	sp, {r3, r4}
611		b	sys_pwrite64
612ENDPROC(sys_oabi_pwrite64)
613
614sys_oabi_truncate64:
615		mov	r3, r2
616		mov	r2, r1
617		b	sys_truncate64
618ENDPROC(sys_oabi_truncate64)
619
620sys_oabi_ftruncate64:
621		mov	r3, r2
622		mov	r2, r1
623		b	sys_ftruncate64
624ENDPROC(sys_oabi_ftruncate64)
625
626sys_oabi_readahead:
627		str	r3, [sp]
628		mov	r3, r2
629		mov	r2, r1
630		b	sys_readahead
631ENDPROC(sys_oabi_readahead)
632
633/*
634 * Let's declare a second syscall table for old ABI binaries
635 * using the compatibility syscall entries.
636 */
637#define ABI(native, compat) compat
638#define OBSOLETE(syscall) syscall
639
640	.type	sys_oabi_call_table, #object
641ENTRY(sys_oabi_call_table)
642#include "calls.S"
643#undef ABI
644#undef OBSOLETE
645
646#endif
647
648