xref: /openbmc/linux/arch/arm/kernel/entry-common.S (revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2) 
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#include <linux/config.h>
11
12#include <asm/thread_info.h>
13#include <asm/ptrace.h>
14#include <asm/unistd.h>
15
16#include "entry-header.S"
17
18/*
19 * We rely on the fact that R0 is at the bottom of the stack (due to
20 * slow/fast restore user regs).
21 */
22#if S_R0 != 0
23#error "Please fix"
24#endif
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	disable_irq r1				@ disable interrupts
34	ldr	r1, [tsk, #TI_FLAGS]
35	tst	r1, #_TIF_WORK_MASK
36	bne	fast_work_pending
37	fast_restore_user_regs
38
39/*
40 * Ok, we need to do extra processing, enter the slow path.
41 */
42fast_work_pending:
43	str	r0, [sp, #S_R0+S_OFF]!		@ returned r0
44work_pending:
45	tst	r1, #_TIF_NEED_RESCHED
46	bne	work_resched
47	tst	r1, #_TIF_NOTIFY_RESUME | _TIF_SIGPENDING
48	beq	no_work_pending
49	mov	r0, sp				@ 'regs'
50	mov	r2, why				@ 'syscall'
51	bl	do_notify_resume
52	disable_irq r1				@ disable interrupts
53	b	no_work_pending
54
55work_resched:
56	bl	schedule
57/*
58 * "slow" syscall return path.  "why" tells us if this was a real syscall.
59 */
60ENTRY(ret_to_user)
61ret_slow_syscall:
62	disable_irq r1				@ disable interrupts
63	ldr	r1, [tsk, #TI_FLAGS]
64	tst	r1, #_TIF_WORK_MASK
65	bne	work_pending
66no_work_pending:
67	slow_restore_user_regs
68
69/*
70 * This is how we return from a fork.
71 */
72ENTRY(ret_from_fork)
73	bl	schedule_tail
74	get_thread_info tsk
75	ldr	r1, [tsk, #TI_FLAGS]		@ check for syscall tracing
76	mov	why, #1
77	tst	r1, #_TIF_SYSCALL_TRACE		@ are we tracing syscalls?
78	beq	ret_slow_syscall
79	mov	r1, sp
80	mov	r0, #1				@ trace exit [IP = 1]
81	bl	syscall_trace
82	b	ret_slow_syscall
83
84
85#include "calls.S"
86
87/*=============================================================================
88 * SWI handler
89 *-----------------------------------------------------------------------------
90 */
91
92	/* If we're optimising for StrongARM the resulting code won't
93	   run on an ARM7 and we can save a couple of instructions.
94								--pb */
95#ifdef CONFIG_CPU_ARM710
96	.macro	arm710_bug_check, instr, temp
97	and	\temp, \instr, #0x0f000000	@ check for SWI
98	teq	\temp, #0x0f000000
99	bne	.Larm700bug
100	.endm
101
102.Larm700bug:
103	ldr	r0, [sp, #S_PSR]		@ Get calling cpsr
104	sub	lr, lr, #4
105	str	lr, [r8]
106	msr	spsr_cxsf, r0
107	ldmia	sp, {r0 - lr}^			@ Get calling r0 - lr
108	mov	r0, r0
109	ldr	lr, [sp, #S_PC]			@ Get PC
110	add	sp, sp, #S_FRAME_SIZE
111	movs	pc, lr
112#else
113	.macro	arm710_bug_check, instr, temp
114	.endm
115#endif
116
117	.align	5
118ENTRY(vector_swi)
119	save_user_regs
120	zero_fp
121	get_scno
122	arm710_bug_check scno, ip
123
124#ifdef CONFIG_ALIGNMENT_TRAP
125	ldr	ip, __cr_alignment
126	ldr	ip, [ip]
127	mcr	p15, 0, ip, c1, c0		@ update control register
128#endif
129	enable_irq ip
130
131	str	r4, [sp, #-S_OFF]!		@ push fifth arg
132
133	get_thread_info tsk
134	ldr	ip, [tsk, #TI_FLAGS]		@ check for syscall tracing
135	bic	scno, scno, #0xff000000		@ mask off SWI op-code
136	eor	scno, scno, #OS_NUMBER << 20	@ check OS number
137	adr	tbl, sys_call_table		@ load syscall table pointer
138	tst	ip, #_TIF_SYSCALL_TRACE		@ are we tracing syscalls?
139	bne	__sys_trace
140
141	adr	lr, ret_fast_syscall		@ return address
142	cmp	scno, #NR_syscalls		@ check upper syscall limit
143	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
144
145	add	r1, sp, #S_OFF
1462:	mov	why, #0				@ no longer a real syscall
147	cmp	scno, #ARMSWI_OFFSET
148	eor	r0, scno, #OS_NUMBER << 20	@ put OS number back
149	bcs	arm_syscall
150	b	sys_ni_syscall			@ not private func
151
152	/*
153	 * This is the really slow path.  We're going to be doing
154	 * context switches, and waiting for our parent to respond.
155	 */
156__sys_trace:
157	add	r1, sp, #S_OFF
158	mov	r0, #0				@ trace entry [IP = 0]
159	bl	syscall_trace
160
161	adr	lr, __sys_trace_return		@ return address
162	add	r1, sp, #S_R0 + S_OFF		@ pointer to regs
163	cmp	scno, #NR_syscalls		@ check upper syscall limit
164	ldmccia	r1, {r0 - r3}			@ have to reload r0 - r3
165	ldrcc	pc, [tbl, scno, lsl #2]		@ call sys_* routine
166	b	2b
167
168__sys_trace_return:
169	str	r0, [sp, #S_R0 + S_OFF]!	@ save returned r0
170	mov	r1, sp
171	mov	r0, #1				@ trace exit [IP = 1]
172	bl	syscall_trace
173	b	ret_slow_syscall
174
175	.align	5
176#ifdef CONFIG_ALIGNMENT_TRAP
177	.type	__cr_alignment, #object
178__cr_alignment:
179	.word	cr_alignment
180#endif
181
182	.type	sys_call_table, #object
183ENTRY(sys_call_table)
184#include "calls.S"
185
186/*============================================================================
187 * Special system call wrappers
188 */
189@ r0 = syscall number
190@ r5 = syscall table
191		.type	sys_syscall, #function
192sys_syscall:
193		eor	scno, r0, #OS_NUMBER << 20
194		cmp	scno, #__NR_syscall - __NR_SYSCALL_BASE
195		cmpne	scno, #NR_syscalls	@ check range
196		stmloia	sp, {r5, r6}		@ shuffle args
197		movlo	r0, r1
198		movlo	r1, r2
199		movlo	r2, r3
200		movlo	r3, r4
201		ldrlo	pc, [tbl, scno, lsl #2]
202		b	sys_ni_syscall
203
204sys_fork_wrapper:
205		add	r0, sp, #S_OFF
206		b	sys_fork
207
208sys_vfork_wrapper:
209		add	r0, sp, #S_OFF
210		b	sys_vfork
211
212sys_execve_wrapper:
213		add	r3, sp, #S_OFF
214		b	sys_execve
215
216sys_clone_wrapper:
217		add	ip, sp, #S_OFF
218		str	ip, [sp, #4]
219		b	sys_clone
220
221sys_sigsuspend_wrapper:
222		add	r3, sp, #S_OFF
223		b	sys_sigsuspend
224
225sys_rt_sigsuspend_wrapper:
226		add	r2, sp, #S_OFF
227		b	sys_rt_sigsuspend
228
229sys_sigreturn_wrapper:
230		add	r0, sp, #S_OFF
231		b	sys_sigreturn
232
233sys_rt_sigreturn_wrapper:
234		add	r0, sp, #S_OFF
235		b	sys_rt_sigreturn
236
237sys_sigaltstack_wrapper:
238		ldr	r2, [sp, #S_OFF + S_SP]
239		b	do_sigaltstack
240
241sys_futex_wrapper:
242		str	r5, [sp, #4]		@ push sixth arg
243		b	sys_futex
244
245/*
246 * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
247 * offset, we return EINVAL.
248 */
249sys_mmap2:
250#if PAGE_SHIFT > 12
251		tst	r5, #PGOFF_MASK
252		moveq	r5, r5, lsr #PAGE_SHIFT - 12
253		streq	r5, [sp, #4]
254		beq	do_mmap2
255		mov	r0, #-EINVAL
256		RETINSTR(mov,pc, lr)
257#else
258		str	r5, [sp, #4]
259		b	do_mmap2
260#endif
261