xref: /openbmc/linux/arch/arm/kernel/entry-common.S (revision a1e58bbd) 
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/arch/entry-macro.S>
13
14#include "entry-header.S"
15
16
17	.align	5
18/*
19 * This is the fast syscall return path.  We do as little as
20 * possible here, and this includes saving r0 back into the SVC
21 * stack.
22 */
23ret_fast_syscall:
24	disable_irq				@ disable interrupts
25	ldr	r1, [tsk, #TI_FLAGS]
26	tst	r1, #_TIF_WORK_MASK
27	bne	fast_work_pending
28
29	/* perform architecture specific actions before user return */
30	arch_ret_to_user r1, lr
31
32	@ fast_restore_user_regs
33	ldr	r1, [sp, #S_OFF + S_PSR]	@ get calling cpsr
34	ldr	lr, [sp, #S_OFF + S_PC]!	@ get pc
35	msr	spsr_cxsf, r1			@ save in spsr_svc
36	ldmdb	sp, {r1 - lr}^			@ get calling r1 - lr
37	mov	r0, r0
38	add	sp, sp, #S_FRAME_SIZE - S_PC
39	movs	pc, lr				@ return & move spsr_svc into cpsr
40
41/*
42 * Ok, we need to do extra processing, enter the slow path.
43 */
44fast_work_pending:
45	str	r0, [sp, #S_R0+S_OFF]!		@ returned r0
46work_pending:
47	tst	r1, #_TIF_NEED_RESCHED
48	bne	work_resched
49	tst	r1, #_TIF_SIGPENDING
50	beq	no_work_pending
51	mov	r0, sp				@ 'regs'
52	mov	r2, why				@ 'syscall'
53	bl	do_notify_resume
54	b	ret_slow_syscall		@ Check work again
55
56work_resched:
57	bl	schedule
58/*
59 * "slow" syscall return path.  "why" tells us if this was a real syscall.
60 */
61ENTRY(ret_to_user)
62ret_slow_syscall:
63	disable_irq				@ disable interrupts
64	ldr	r1, [tsk, #TI_FLAGS]
65	tst	r1, #_TIF_WORK_MASK
66	bne	work_pending
67no_work_pending:
68	/* perform architecture specific actions before user return */
69	arch_ret_to_user r1, lr
70
71	@ slow_restore_user_regs
72	ldr	r1, [sp, #S_PSR]		@ get calling cpsr
73	ldr	lr, [sp, #S_PC]!		@ get pc
74	msr	spsr_cxsf, r1			@ save in spsr_svc
75	ldmdb	sp, {r0 - lr}^			@ get calling r0 - lr
76	mov	r0, r0
77	add	sp, sp, #S_FRAME_SIZE - S_PC
78	movs	pc, lr				@ return & move spsr_svc into cpsr
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
94
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/*=============================================================================
103 * SWI handler
104 *-----------------------------------------------------------------------------
105 */
106
107	/* If we're optimising for StrongARM the resulting code won't
108	   run on an ARM7 and we can save a couple of instructions.
109								--pb */
110#ifdef CONFIG_CPU_ARM710
111#define A710(code...) code
112.Larm710bug:
113	ldmia	sp, {r0 - lr}^			@ Get calling r0 - lr
114	mov	r0, r0
115	add	sp, sp, #S_FRAME_SIZE
116	subs	pc, lr, #4
117#else
118#define A710(code...)
119#endif
120
121	.align	5
122ENTRY(vector_swi)
123	sub	sp, sp, #S_FRAME_SIZE
124	stmia	sp, {r0 - r12}			@ Calling r0 - r12
125	add	r8, sp, #S_PC
126	stmdb	r8, {sp, lr}^			@ Calling sp, lr
127	mrs	r8, spsr			@ called from non-FIQ mode, so ok.
128	str	lr, [sp, #S_PC]			@ Save calling PC
129	str	r8, [sp, #S_PSR]		@ Save CPSR
130	str	r0, [sp, #S_OLD_R0]		@ Save OLD_R0
131	zero_fp
132
133	/*
134	 * Get the system call number.
135	 */
136
137#if defined(CONFIG_OABI_COMPAT)
138
139	/*
140	 * If we have CONFIG_OABI_COMPAT then we need to look at the swi
141	 * value to determine if it is an EABI or an old ABI call.
142	 */
143#ifdef CONFIG_ARM_THUMB
144	tst	r8, #PSR_T_BIT
145	movne	r10, #0				@ no thumb OABI emulation
146	ldreq	r10, [lr, #-4]			@ get SWI instruction
147#else
148	ldr	r10, [lr, #-4]			@ get SWI instruction
149  A710(	and	ip, r10, #0x0f000000		@ check for SWI		)
150  A710(	teq	ip, #0x0f000000						)
151  A710(	bne	.Larm710bug						)
152#endif
153
154#elif defined(CONFIG_AEABI)
155
156	/*
157	 * Pure EABI user space always put syscall number into scno (r7).
158	 */
159  A710(	ldr	ip, [lr, #-4]			@ get SWI instruction	)
160  A710(	and	ip, ip, #0x0f000000		@ check for SWI		)
161  A710(	teq	ip, #0x0f000000						)
162  A710(	bne	.Larm710bug						)
163
164#elif defined(CONFIG_ARM_THUMB)
165
166	/* Legacy ABI only, possibly thumb mode. */
167	tst	r8, #PSR_T_BIT			@ this is SPSR from save_user_regs
168	addne	scno, r7, #__NR_SYSCALL_BASE	@ put OS number in
169	ldreq	scno, [lr, #-4]
170
171#else
172
173	/* Legacy ABI only. */
174	ldr	scno, [lr, #-4]			@ get SWI instruction
175  A710(	and	ip, scno, #0x0f000000		@ check for SWI		)
176  A710(	teq	ip, #0x0f000000						)
177  A710(	bne	.Larm710bug						)
178
179#endif
180
181#ifdef CONFIG_ALIGNMENT_TRAP
182	ldr	ip, __cr_alignment
183	ldr	ip, [ip]
184	mcr	p15, 0, ip, c1, c0		@ update control register
185#endif
186	enable_irq
187
188	get_thread_info tsk
189	adr	tbl, sys_call_table		@ load syscall table pointer
190	ldr	ip, [tsk, #TI_FLAGS]		@ check for syscall tracing
191
192#if defined(CONFIG_OABI_COMPAT)
193	/*
194	 * If the swi argument is zero, this is an EABI call and we do nothing.
195	 *
196	 * If this is an old ABI call, get the syscall number into scno and
197	 * get the old ABI syscall table address.
198	 */
199	bics	r10, r10, #0xff000000
200	eorne	scno, r10, #__NR_OABI_SYSCALL_BASE
201	ldrne	tbl, =sys_oabi_call_table
202#elif !defined(CONFIG_AEABI)
203	bic	scno, scno, #0xff000000		@ mask off SWI op-code
204	eor	scno, scno, #__NR_SYSCALL_BASE	@ check OS number
205#endif
206
207	stmdb	sp!, {r4, r5}			@ push fifth and sixth args
208	tst	ip, #_TIF_SYSCALL_TRACE		@ are we tracing syscalls?
209	bne	__sys_trace
210
211	cmp	scno, #NR_syscalls		@ check upper syscall limit
212	adr	lr, ret_fast_syscall		@ return address
213	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
214
215	add	r1, sp, #S_OFF
2162:	mov	why, #0				@ no longer a real syscall
217	cmp	scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
218	eor	r0, scno, #__NR_SYSCALL_BASE	@ put OS number back
219	bcs	arm_syscall
220	b	sys_ni_syscall			@ not private func
221
222	/*
223	 * This is the really slow path.  We're going to be doing
224	 * context switches, and waiting for our parent to respond.
225	 */
226__sys_trace:
227	mov	r2, scno
228	add	r1, sp, #S_OFF
229	mov	r0, #0				@ trace entry [IP = 0]
230	bl	syscall_trace
231
232	adr	lr, __sys_trace_return		@ return address
233	mov	scno, r0			@ syscall number (possibly new)
234	add	r1, sp, #S_R0 + S_OFF		@ pointer to regs
235	cmp	scno, #NR_syscalls		@ check upper syscall limit
236	ldmccia	r1, {r0 - r3}			@ have to reload r0 - r3
237	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
238	b	2b
239
240__sys_trace_return:
241	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0
242	mov	r2, scno
243	mov	r1, sp
244	mov	r0, #1				@ trace exit [IP = 1]
245	bl	syscall_trace
246	b	ret_slow_syscall
247
248	.align	5
249#ifdef CONFIG_ALIGNMENT_TRAP
250	.type	__cr_alignment, #object
251__cr_alignment:
252	.word	cr_alignment
253#endif
254	.ltorg
255
256/*
257 * This is the syscall table declaration for native ABI syscalls.
258 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
259 */
260#define ABI(native, compat) native
261#ifdef CONFIG_AEABI
262#define OBSOLETE(syscall) sys_ni_syscall
263#else
264#define OBSOLETE(syscall) syscall
265#endif
266
267	.type	sys_call_table, #object
268ENTRY(sys_call_table)
269#include "calls.S"
270#undef ABI
271#undef OBSOLETE
272
273/*============================================================================
274 * Special system call wrappers
275 */
276@ r0 = syscall number
277@ r8 = syscall table
278		.type	sys_syscall, #function
279sys_syscall:
280		bic	scno, r0, #__NR_OABI_SYSCALL_BASE
281		cmp	scno, #__NR_syscall - __NR_SYSCALL_BASE
282		cmpne	scno, #NR_syscalls	@ check range
283		stmloia	sp, {r5, r6}		@ shuffle args
284		movlo	r0, r1
285		movlo	r1, r2
286		movlo	r2, r3
287		movlo	r3, r4
288		ldrlo	pc, [tbl, scno, lsl #2]
289		b	sys_ni_syscall
290
291sys_fork_wrapper:
292		add	r0, sp, #S_OFF
293		b	sys_fork
294
295sys_vfork_wrapper:
296		add	r0, sp, #S_OFF
297		b	sys_vfork
298
299sys_execve_wrapper:
300		add	r3, sp, #S_OFF
301		b	sys_execve
302
303sys_clone_wrapper:
304		add	ip, sp, #S_OFF
305		str	ip, [sp, #4]
306		b	sys_clone
307
308sys_sigsuspend_wrapper:
309		add	r3, sp, #S_OFF
310		b	sys_sigsuspend
311
312sys_rt_sigsuspend_wrapper:
313		add	r2, sp, #S_OFF
314		b	sys_rt_sigsuspend
315
316sys_sigreturn_wrapper:
317		add	r0, sp, #S_OFF
318		b	sys_sigreturn
319
320sys_rt_sigreturn_wrapper:
321		add	r0, sp, #S_OFF
322		b	sys_rt_sigreturn
323
324sys_sigaltstack_wrapper:
325		ldr	r2, [sp, #S_OFF + S_SP]
326		b	do_sigaltstack
327
328sys_statfs64_wrapper:
329		teq	r1, #88
330		moveq	r1, #84
331		b	sys_statfs64
332
333sys_fstatfs64_wrapper:
334		teq	r1, #88
335		moveq	r1, #84
336		b	sys_fstatfs64
337
338/*
339 * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
340 * offset, we return EINVAL.
341 */
342sys_mmap2:
343#if PAGE_SHIFT > 12
344		tst	r5, #PGOFF_MASK
345		moveq	r5, r5, lsr #PAGE_SHIFT - 12
346		streq	r5, [sp, #4]
347		beq	do_mmap2
348		mov	r0, #-EINVAL
349		mov	pc, lr
350#else
351		str	r5, [sp, #4]
352		b	do_mmap2
353#endif
354
355#ifdef CONFIG_OABI_COMPAT
356
357/*
358 * These are syscalls with argument register differences
359 */
360
361sys_oabi_pread64:
362		stmia	sp, {r3, r4}
363		b	sys_pread64
364
365sys_oabi_pwrite64:
366		stmia	sp, {r3, r4}
367		b	sys_pwrite64
368
369sys_oabi_truncate64:
370		mov	r3, r2
371		mov	r2, r1
372		b	sys_truncate64
373
374sys_oabi_ftruncate64:
375		mov	r3, r2
376		mov	r2, r1
377		b	sys_ftruncate64
378
379sys_oabi_readahead:
380		str	r3, [sp]
381		mov	r3, r2
382		mov	r2, r1
383		b	sys_readahead
384
385/*
386 * Let's declare a second syscall table for old ABI binaries
387 * using the compatibility syscall entries.
388 */
389#define ABI(native, compat) compat
390#define OBSOLETE(syscall) syscall
391
392	.type	sys_oabi_call_table, #object
393ENTRY(sys_oabi_call_table)
394#include "calls.S"
395#undef ABI
396#undef OBSOLETE
397
398#endif
399
400