summaryrefslogtreecommitdiffstats
path: root/arch/mips/kernel/scall_o32.S
blob: d7c107599c7b8104b9f614bed5e88eb28c499c8f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1997, 1998, 1999, 2000 by Ralf Baechle
 */
#include <asm/asm.h>
#include <linux/errno.h>
#include <asm/current.h>
#include <asm/mipsregs.h>
#include <asm/regdef.h>
#include <asm/stackframe.h>
#include <asm/isadep.h>
#include <asm/unistd.h>

/* This duplicates the definition from <linux/sched.h> */
#define PT_TRACESYS	0x00000002	/* tracing system calls */

/* This duplicates the definition from <asm/signal.h> */
#define SIGILL		4		/* Illegal instruction (ANSI).  */

/* Highest syscall used of any syscall flavour */
#define MAX_SYSCALL_NO	__NR_Linux + __NR_Linux_syscalls

	.align  5
NESTED(handle_sys, PT_SIZE, sp)
	.set	noat
	SAVE_SOME
	STI
	.set	at

	lw	t1, PT_EPC(sp)		# skip syscall on return

	sltiu	t0, v0, MAX_SYSCALL_NO + 1 # check syscall number
	addiu	t1, 4			# skip to next instruction
	beqz	t0, illegal_syscall
	sw	t1, PT_EPC(sp)

	/* XXX Put both in one cacheline, should save a bit. */
	sll	t0, v0, 2
	lw	t2, sys_call_table(t0)	# syscall routine
	lbu	t3, sys_narg_table(v0)	# number of arguments
	beqz	t2, illegal_syscall;

	subu	t0, t3, 5		# 5 or more arguments?
	sw	a3, PT_R26(sp)		# save a3 for syscall restarting
	bgez	t0, stackargs

stack_done:
        sw      a3, PT_R26(sp)          # save for syscall restart
	lw	t0, TASK_PTRACE($28)	# syscall tracing enabled?
	andi	t0, PT_TRACESYS
	bnez	t0, trace_a_syscall

	jalr	t2			# Do The Real Thing (TM)

	li	t0, -EMAXERRNO - 1	# error?
	sltu	t0, t0, v0
	sw	t0, PT_R7(sp)		# set error flag
	beqz	t0, 1f

	negu	v0			# error
	sw	v0, PT_R0(sp)		# set flag for syscall restarting
1:	sw	v0, PT_R2(sp)		# result

EXPORT(o32_ret_from_sys_call)
	la	t1, irq_stat		# softirq_active
#ifdef CONFIG_SMP
	lw	t0, TASK_PROCESSOR($28)
        sll	t0, t0, 5
	addu	t1, t0
#endif
	lw	t0, 0(t1)		# softirq_active
	lw	t1, 4(t1)		# softirq_mask.  unused delay slot
	and	t0, t1
	bnez	t0, o32_handle_softirq

9:	lw	t0,PT_STATUS(sp)	# returning to kernel mode?
	andi	t1, t0, KU_USER
	lw	t2, TASK_NEED_RESCHED($28)
	beqz	t1, o32_return		# -> yes
	bnez	t2, o32_reschedule
	lw	v0, TASK_SIGPENDING($28)
	move	a0, zero
	beqz	v0, o32_return
	move	a1, sp
	SAVE_STATIC
	jal	do_signal

o32_return:
	RESTORE_SOME
	RESTORE_SP_AND_RET

o32_handle_softirq:
	jal	do_softirq
	b	9b
o32_reschedule:
	SAVE_STATIC
	jal	schedule
	b	o32_ret_from_sys_call

/* ------------------------------------------------------------------------ */

trace_a_syscall:
	SAVE_STATIC
	sw	t2, PT_R1(sp)
	jal	syscall_trace
	lw	t2, PT_R1(sp)

	lw	a0, PT_R4(sp)		# Restore argument registers
	lw	a1, PT_R5(sp)
	lw	a2, PT_R6(sp)
	lw	a3, PT_R7(sp)
	jalr	t2

	li	t0, -EMAXERRNO - 1	# error?
	sltu	t0, t0, v0
	sw	t0, PT_R7(sp)		# set error flag
	beqz	t0, 1f

	negu	v0			# error
	sw	v0, PT_R0(sp)		# set flag for syscall restarting
1:	sw	v0, PT_R2(sp)		# result

	jal	syscall_trace
	j	ret_from_sys_call

/* ------------------------------------------------------------------------ */

	/*
	 * More than four arguments.  Try to deal with it by copying the
	 * stack arguments from the user stack to the kernel stack.
	 * This Sucks (TM).
	 */
stackargs:
	lw	t0, PT_R29(sp)		# get old user stack pointer
	subu	t3, 4
	sll	t1, t3, 2		# stack valid?

	addu	t1, t0			# end address
	or	t0, t1
	bltz	t0, bad_stack		# -> sp is bad

	lw	t0, PT_R29(sp)		# get old user stack pointer
	la	t1, 3f			# copy 1 to 2 arguments
	sll	t3, t3, 4
	subu	t1, t3
	jr	t1

	/* Ok, copy the args from the luser stack to the kernel stack */
	/*
	 * I know Ralf doesn't like nops but this avoids code
	 * duplication for R3000 targets (and this is the
	 * only place where ".set reorder" doesn't help).
	 * Harald.
	 */
	.set    push
	.set    noreorder
1:	lw	t1, 20(t0)		# argument #6 from usp
	nop
	sw	t1, 20(sp)
	nop
2:	lw	t1, 16(t0)		# argument #5 from usp
	nop
	sw	t1, 16(sp)
	nop
	.set	pop

3:	j	stack_done		# go back

	.section __ex_table,"a"
	PTR	1b,bad_stack
	PTR	2b,bad_stack
	.previous

	/*
	 * The stackpointer for a call with more than 4 arguments is bad.
	 * We probably should handle this case a bit more drastic.
	 */
bad_stack:
	negu	v0				# error
	sw	v0, PT_R0(sp)
	sw	v0, PT_R2(sp)
	li	t0, 1				# set error flag
	sw	t0, PT_R7(sp)
	j	ret_from_sys_call

	/*
	 * The system call does not exist in this kernel
	 */
illegal_syscall:
	li	v0, ENOSYS			# error
	sw	v0, PT_R2(sp)
	li	t0, 1				# set error flag
	sw	t0, PT_R7(sp)
	j	ret_from_sys_call
	END(handle_sys)