1/*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License.  See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * Copyright (C) 1995-99, 2000- 02, 06 Ralf Baechle <ralf@linux-mips.org>
7 * Copyright (C) 2001 MIPS Technologies, Inc.
8 * Copyright (C) 2004 Thiemo Seufer
9 * Copyright (C) 2014 Imagination Technologies Ltd.
10 */
11#include <linux/errno.h>
12#include <asm/asm.h>
13#include <asm/asmmacro.h>
14#include <asm/irqflags.h>
15#include <asm/mipsregs.h>
16#include <asm/regdef.h>
17#include <asm/stackframe.h>
18#include <asm/isadep.h>
19#include <asm/sysmips.h>
20#include <asm/thread_info.h>
21#include <asm/unistd.h>
22#include <asm/asm-offsets.h>
23
24	.align	5
25NESTED(handle_sys, PT_SIZE, sp)
26	.set	noat
27	SAVE_SOME
28	TRACE_IRQS_ON_RELOAD
29	STI
30	.set	at
31
32	lw	t1, PT_EPC(sp)		# skip syscall on return
33
34	addiu	t1, 4			# skip to next instruction
35	sw	t1, PT_EPC(sp)
36
37	sw	a3, PT_R26(sp)		# save a3 for syscall restarting
38
39	/*
40	 * More than four arguments.  Try to deal with it by copying the
41	 * stack arguments from the user stack to the kernel stack.
42	 * This Sucks (TM).
43	 */
44	lw	t0, PT_R29(sp)		# get old user stack pointer
45
46	/*
47	 * We intentionally keep the kernel stack a little below the top of
48	 * userspace so we don't have to do a slower byte accurate check here.
49	 */
50	addu	t4, t0, 32
51	bltz	t4, bad_stack		# -> sp is bad
52
53	/*
54	 * Ok, copy the args from the luser stack to the kernel stack.
55	 */
56
57	.set    push
58	.set    noreorder
59	.set	nomacro
60
61load_a4: user_lw(t5, 16(t0))		# argument #5 from usp
62load_a5: user_lw(t6, 20(t0))		# argument #6 from usp
63load_a6: user_lw(t7, 24(t0))		# argument #7 from usp
64load_a7: user_lw(t8, 28(t0))		# argument #8 from usp
65loads_done:
66
67	sw	t5, 16(sp)		# argument #5 to ksp
68	sw	t6, 20(sp)		# argument #6 to ksp
69	sw	t7, 24(sp)		# argument #7 to ksp
70	sw	t8, 28(sp)		# argument #8 to ksp
71	.set	pop
72
73	.section __ex_table,"a"
74	PTR_WD	load_a4, bad_stack_a4
75	PTR_WD	load_a5, bad_stack_a5
76	PTR_WD	load_a6, bad_stack_a6
77	PTR_WD	load_a7, bad_stack_a7
78	.previous
79
80	/*
81	 * syscall number is in v0 unless we called syscall(__NR_###)
82	 * where the real syscall number is in a0
83	 */
84	subu	t2, v0,  __NR_O32_Linux
85	bnez	t2, 1f /* __NR_syscall at offset 0 */
86	LONG_S	a0, TI_SYSCALL($28)	# Save a0 as syscall number
87	b	2f
881:
89	LONG_S	v0, TI_SYSCALL($28)	# Save v0 as syscall number
902:
91
92	lw	t0, TI_FLAGS($28)	# syscall tracing enabled?
93	li	t1, _TIF_WORK_SYSCALL_ENTRY
94	and	t0, t1
95	bnez	t0, syscall_trace_entry # -> yes
96syscall_common:
97	subu	v0, v0, __NR_O32_Linux	# check syscall number
98	sltiu	t0, v0, __NR_O32_Linux_syscalls
99	beqz	t0, illegal_syscall
100
101	sll	t0, v0, 2
102	la	t1, sys_call_table
103	addu	t1, t0
104	lw	t2, (t1)		# syscall routine
105
106	beqz	t2, illegal_syscall
107
108	jalr	t2			# Do The Real Thing (TM)
109
110	li	t0, -EMAXERRNO - 1	# error?
111	sltu	t0, t0, v0
112	sw	t0, PT_R7(sp)		# set error flag
113	beqz	t0, 1f
114
115	lw	t1, PT_R2(sp)		# syscall number
116	negu	v0			# error
117	sw	t1, PT_R0(sp)		# save it for syscall restarting
1181:	sw	v0, PT_R2(sp)		# result
119
120o32_syscall_exit:
121	j	syscall_exit_partial
122
123/* ------------------------------------------------------------------------ */
124
125syscall_trace_entry:
126	SAVE_STATIC
127	move	a0, sp
128
129	jal	syscall_trace_enter
130
131	bltz	v0, 1f			# seccomp failed? Skip syscall
132
133	RESTORE_STATIC
134	lw	v0, PT_R2(sp)		# Restore syscall (maybe modified)
135	lw	a0, PT_R4(sp)		# Restore argument registers
136	lw	a1, PT_R5(sp)
137	lw	a2, PT_R6(sp)
138	lw	a3, PT_R7(sp)
139	j	syscall_common
140
1411:	j	syscall_exit
142
143/* ------------------------------------------------------------------------ */
144
145	/*
146	 * Our open-coded access area sanity test for the stack pointer
147	 * failed. We probably should handle this case a bit more drastic.
148	 */
149bad_stack:
150	li	v0, EFAULT
151	sw	v0, PT_R2(sp)
152	li	t0, 1				# set error flag
153	sw	t0, PT_R7(sp)
154	j	o32_syscall_exit
155
156bad_stack_a4:
157	li	t5, 0
158	b	load_a5
159
160bad_stack_a5:
161	li	t6, 0
162	b	load_a6
163
164bad_stack_a6:
165	li	t7, 0
166	b	load_a7
167
168bad_stack_a7:
169	li	t8, 0
170	b	loads_done
171
172	/*
173	 * The system call does not exist in this kernel
174	 */
175illegal_syscall:
176	li	v0, ENOSYS			# error
177	sw	v0, PT_R2(sp)
178	li	t0, 1				# set error flag
179	sw	t0, PT_R7(sp)
180	j	o32_syscall_exit
181	END(handle_sys)
182
183	LEAF(sys_syscall)
184	subu	t0, a0, __NR_O32_Linux	# check syscall number
185	sltiu	v0, t0, __NR_O32_Linux_syscalls
186	beqz	t0, einval		# do not recurse
187	sll	t1, t0, 2
188	beqz	v0, einval
189	lw	t2, sys_call_table(t1)		# syscall routine
190
191	move	a0, a1				# shift argument registers
192	move	a1, a2
193	move	a2, a3
194	lw	a3, 16(sp)
195	lw	t4, 20(sp)
196	lw	t5, 24(sp)
197	lw	t6, 28(sp)
198	sw	t4, 16(sp)
199	sw	t5, 20(sp)
200	sw	t6, 24(sp)
201	jr	t2
202	/* Unreached */
203
204einval: li	v0, -ENOSYS
205	jr	ra
206	END(sys_syscall)
207
208#ifdef CONFIG_MIPS_MT_FPAFF
209	/*
210	 * For FPU affinity scheduling on MIPS MT processors, we need to
211	 * intercept sys_sched_xxxaffinity() calls until we get a proper hook
212	 * in kernel/sched/core.c.  Considered only temporary we only support
213	 * these hooks for the 32-bit kernel - there is no MIPS64 MT processor
214	 * atm.
215	 */
216#define sys_sched_setaffinity	mipsmt_sys_sched_setaffinity
217#define sys_sched_getaffinity	mipsmt_sys_sched_getaffinity
218#endif /* CONFIG_MIPS_MT_FPAFF */
219
220#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, native)
221#define __SYSCALL(nr, entry) 	PTR_WD entry
222	.align	2
223	.type	sys_call_table, @object
224EXPORT(sys_call_table)
225#include <asm/syscall_table_o32.h>
226