xref: /openbmc/linux/arch/arm/kernel/entry-common.S (revision d0b5e15f) 
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/assembler.h>
12#include <asm/unistd.h>
13#include <asm/ftrace.h>
14#include <asm/unwind.h>
15
16#ifdef CONFIG_NEED_RET_TO_USER
17#include <mach/entry-macro.S>
18#else
19	.macro  arch_ret_to_user, tmp1, tmp2
20	.endm
21#endif
22
23#include "entry-header.S"
24
25
26	.align	5
27/*
28 * This is the fast syscall return path.  We do as little as
29 * possible here, and this includes saving r0 back into the SVC
30 * stack.
31 */
32ret_fast_syscall:
33 UNWIND(.fnstart	)
34 UNWIND(.cantunwind	)
35	disable_irq				@ disable interrupts
36	ldr	r1, [tsk, #TI_FLAGS]
37	tst	r1, #_TIF_WORK_MASK
38	bne	fast_work_pending
39	asm_trace_hardirqs_on
40
41	/* perform architecture specific actions before user return */
42	arch_ret_to_user r1, lr
43	ct_user_enter
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	mov	r0, sp				@ 'regs'
55	mov	r2, why				@ 'syscall'
56	bl	do_work_pending
57	cmp	r0, #0
58	beq	no_work_pending
59	movlt	scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
60	ldmia	sp, {r0 - r6}			@ have to reload r0 - r6
61	b	local_restart			@ ... and off we go
62
63/*
64 * "slow" syscall return path.  "why" tells us if this was a real syscall.
65 */
66ENTRY(ret_to_user)
67ret_slow_syscall:
68	disable_irq				@ disable interrupts
69ENTRY(ret_to_user_from_irq)
70	ldr	r1, [tsk, #TI_FLAGS]
71	tst	r1, #_TIF_WORK_MASK
72	bne	work_pending
73no_work_pending:
74	asm_trace_hardirqs_on
75
76	/* perform architecture specific actions before user return */
77	arch_ret_to_user r1, lr
78	ct_user_enter save = 0
79
80	restore_user_regs fast = 0, offset = 0
81ENDPROC(ret_to_user_from_irq)
82ENDPROC(ret_to_user)
83
84/*
85 * This is how we return from a fork.
86 */
87ENTRY(ret_from_fork)
88	bl	schedule_tail
89	cmp	r5, #0
90	movne	r0, r4
91	adrne	lr, BSYM(1f)
92	retne	r5
931:	get_thread_info tsk
94	b	ret_slow_syscall
95ENDPROC(ret_from_fork)
96
97	.equ NR_syscalls,0
98#define CALL(x) .equ NR_syscalls,NR_syscalls+1
99#include "calls.S"
100
101/*
102 * Ensure that the system call table is equal to __NR_syscalls,
103 * which is the value the rest of the system sees
104 */
105.ifne NR_syscalls - __NR_syscalls
106.error "__NR_syscalls is not equal to the size of the syscall table"
107.endif
108
109#undef CALL
110#define CALL(x) .long x
111
112/*=============================================================================
113 * SWI handler
114 *-----------------------------------------------------------------------------
115 */
116
117	.align	5
118ENTRY(vector_swi)
119#ifdef CONFIG_CPU_V7M
120	v7m_exception_entry
121#else
122	sub	sp, sp, #S_FRAME_SIZE
123	stmia	sp, {r0 - r12}			@ Calling r0 - r12
124 ARM(	add	r8, sp, #S_PC		)
125 ARM(	stmdb	r8, {sp, lr}^		)	@ Calling sp, lr
126 THUMB(	mov	r8, sp			)
127 THUMB(	store_user_sp_lr r8, r10, S_SP	)	@ calling sp, lr
128	mrs	r8, spsr			@ called from non-FIQ mode, so ok.
129	str	lr, [sp, #S_PC]			@ Save calling PC
130	str	r8, [sp, #S_PSR]		@ Save CPSR
131	str	r0, [sp, #S_OLD_R0]		@ Save OLD_R0
132#endif
133	zero_fp
134	alignment_trap r10, ip, __cr_alignment
135	enable_irq
136	ct_user_exit
137	get_thread_info tsk
138
139	/*
140	 * Get the system call number.
141	 */
142
143#if defined(CONFIG_OABI_COMPAT)
144
145	/*
146	 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
147	 * value to determine if it is an EABI or an old ABI call.
148	 */
149#ifdef CONFIG_ARM_THUMB
150	tst	r8, #PSR_T_BIT
151	movne	r10, #0				@ no thumb OABI emulation
152 USER(	ldreq	r10, [lr, #-4]		)	@ get SWI instruction
153#else
154 USER(	ldr	r10, [lr, #-4]		)	@ get SWI instruction
155#endif
156 ARM_BE8(rev	r10, r10)			@ little endian instruction
157
158#elif defined(CONFIG_AEABI)
159
160	/*
161	 * Pure EABI user space always put syscall number into scno (r7).
162	 */
163#elif defined(CONFIG_ARM_THUMB)
164	/* Legacy ABI only, possibly thumb mode. */
165	tst	r8, #PSR_T_BIT			@ this is SPSR from save_user_regs
166	addne	scno, r7, #__NR_SYSCALL_BASE	@ put OS number in
167 USER(	ldreq	scno, [lr, #-4]		)
168
169#else
170	/* Legacy ABI only. */
171 USER(	ldr	scno, [lr, #-4]		)	@ get SWI instruction
172#endif
173
174	adr	tbl, sys_call_table		@ load syscall table pointer
175
176#if defined(CONFIG_OABI_COMPAT)
177	/*
178	 * If the swi argument is zero, this is an EABI call and we do nothing.
179	 *
180	 * If this is an old ABI call, get the syscall number into scno and
181	 * get the old ABI syscall table address.
182	 */
183	bics	r10, r10, #0xff000000
184	eorne	scno, r10, #__NR_OABI_SYSCALL_BASE
185	ldrne	tbl, =sys_oabi_call_table
186#elif !defined(CONFIG_AEABI)
187	bic	scno, scno, #0xff000000		@ mask off SWI op-code
188	eor	scno, scno, #__NR_SYSCALL_BASE	@ check OS number
189#endif
190
191local_restart:
192	ldr	r10, [tsk, #TI_FLAGS]		@ check for syscall tracing
193	stmdb	sp!, {r4, r5}			@ push fifth and sixth args
194
195	tst	r10, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
196	bne	__sys_trace
197
198	cmp	scno, #NR_syscalls		@ check upper syscall limit
199	adr	lr, BSYM(ret_fast_syscall)	@ return address
200	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
201
202	add	r1, sp, #S_OFF
2032:	cmp	scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
204	eor	r0, scno, #__NR_SYSCALL_BASE	@ put OS number back
205	bcs	arm_syscall
206	mov	why, #0				@ no longer a real syscall
207	b	sys_ni_syscall			@ not private func
208
209#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
210	/*
211	 * We failed to handle a fault trying to access the page
212	 * containing the swi instruction, but we're not really in a
213	 * position to return -EFAULT. Instead, return back to the
214	 * instruction and re-enter the user fault handling path trying
215	 * to page it in. This will likely result in sending SEGV to the
216	 * current task.
217	 */
2189001:
219	sub	lr, lr, #4
220	str	lr, [sp, #S_PC]
221	b	ret_fast_syscall
222#endif
223ENDPROC(vector_swi)
224
225	/*
226	 * This is the really slow path.  We're going to be doing
227	 * context switches, and waiting for our parent to respond.
228	 */
229__sys_trace:
230	mov	r1, scno
231	add	r0, sp, #S_OFF
232	bl	syscall_trace_enter
233
234	adr	lr, BSYM(__sys_trace_return)	@ return address
235	mov	scno, r0			@ syscall number (possibly new)
236	add	r1, sp, #S_R0 + S_OFF		@ pointer to regs
237	cmp	scno, #NR_syscalls		@ check upper syscall limit
238	ldmccia	r1, {r0 - r6}			@ have to reload r0 - r6
239	stmccia	sp, {r4, r5}			@ and update the stack args
240	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
241	cmp	scno, #-1			@ skip the syscall?
242	bne	2b
243	add	sp, sp, #S_OFF			@ restore stack
244	b	ret_slow_syscall
245
246__sys_trace_return:
247	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0
248	mov	r0, sp
249	bl	syscall_trace_exit
250	b	ret_slow_syscall
251
252	.align	5
253#ifdef CONFIG_ALIGNMENT_TRAP
254	.type	__cr_alignment, #object
255__cr_alignment:
256	.word	cr_alignment
257#endif
258	.ltorg
259
260/*
261 * This is the syscall table declaration for native ABI syscalls.
262 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
263 */
264#define ABI(native, compat) native
265#ifdef CONFIG_AEABI
266#define OBSOLETE(syscall) sys_ni_syscall
267#else
268#define OBSOLETE(syscall) syscall
269#endif
270
271	.type	sys_call_table, #object
272ENTRY(sys_call_table)
273#include "calls.S"
274#undef ABI
275#undef OBSOLETE
276
277/*============================================================================
278 * Special system call wrappers
279 */
280@ r0 = syscall number
281@ r8 = syscall table
282sys_syscall:
283		bic	scno, r0, #__NR_OABI_SYSCALL_BASE
284		cmp	scno, #__NR_syscall - __NR_SYSCALL_BASE
285		cmpne	scno, #NR_syscalls	@ check range
286		stmloia	sp, {r5, r6}		@ shuffle args
287		movlo	r0, r1
288		movlo	r1, r2
289		movlo	r2, r3
290		movlo	r3, r4
291		ldrlo	pc, [tbl, scno, lsl #2]
292		b	sys_ni_syscall
293ENDPROC(sys_syscall)
294
295sys_sigreturn_wrapper:
296		add	r0, sp, #S_OFF
297		mov	why, #0		@ prevent syscall restart handling
298		b	sys_sigreturn
299ENDPROC(sys_sigreturn_wrapper)
300
301sys_rt_sigreturn_wrapper:
302		add	r0, sp, #S_OFF
303		mov	why, #0		@ prevent syscall restart handling
304		b	sys_rt_sigreturn
305ENDPROC(sys_rt_sigreturn_wrapper)
306
307sys_statfs64_wrapper:
308		teq	r1, #88
309		moveq	r1, #84
310		b	sys_statfs64
311ENDPROC(sys_statfs64_wrapper)
312
313sys_fstatfs64_wrapper:
314		teq	r1, #88
315		moveq	r1, #84
316		b	sys_fstatfs64
317ENDPROC(sys_fstatfs64_wrapper)
318
319/*
320 * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
321 * offset, we return EINVAL.
322 */
323sys_mmap2:
324#if PAGE_SHIFT > 12
325		tst	r5, #PGOFF_MASK
326		moveq	r5, r5, lsr #PAGE_SHIFT - 12
327		streq	r5, [sp, #4]
328		beq	sys_mmap_pgoff
329		mov	r0, #-EINVAL
330		ret	lr
331#else
332		str	r5, [sp, #4]
333		b	sys_mmap_pgoff
334#endif
335ENDPROC(sys_mmap2)
336
337#ifdef CONFIG_OABI_COMPAT
338
339/*
340 * These are syscalls with argument register differences
341 */
342
343sys_oabi_pread64:
344		stmia	sp, {r3, r4}
345		b	sys_pread64
346ENDPROC(sys_oabi_pread64)
347
348sys_oabi_pwrite64:
349		stmia	sp, {r3, r4}
350		b	sys_pwrite64
351ENDPROC(sys_oabi_pwrite64)
352
353sys_oabi_truncate64:
354		mov	r3, r2
355		mov	r2, r1
356		b	sys_truncate64
357ENDPROC(sys_oabi_truncate64)
358
359sys_oabi_ftruncate64:
360		mov	r3, r2
361		mov	r2, r1
362		b	sys_ftruncate64
363ENDPROC(sys_oabi_ftruncate64)
364
365sys_oabi_readahead:
366		str	r3, [sp]
367		mov	r3, r2
368		mov	r2, r1
369		b	sys_readahead
370ENDPROC(sys_oabi_readahead)
371
372/*
373 * Let's declare a second syscall table for old ABI binaries
374 * using the compatibility syscall entries.
375 */
376#define ABI(native, compat) compat
377#define OBSOLETE(syscall) syscall
378
379	.type	sys_oabi_call_table, #object
380ENTRY(sys_oabi_call_table)
381#include "calls.S"
382#undef ABI
383#undef OBSOLETE
384
385#endif
386
387