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 lw t0, TI_FLAGS($28) # syscall tracing enabled?
81 li t1, _TIF_WORK_SYSCALL_ENTRY
82 and t0, t1
83 bnez t0, syscall_trace_entry # -> yes
84syscall_common:
85 subu v0, v0, __NR_O32_Linux # check syscall number
86 sltiu t0, v0, __NR_O32_Linux_syscalls
87 beqz t0, illegal_syscall
88
89 sll t0, v0, 2
90 la t1, sys_call_table
91 addu t1, t0
92 lw t2, (t1) # syscall routine
93
94 beqz t2, illegal_syscall
95
96 jalr t2 # Do The Real Thing (TM)
97
98 li t0, -EMAXERRNO - 1 # error?
99 sltu t0, t0, v0
100 sw t0, PT_R7(sp) # set error flag
101 beqz t0, 1f
102
103 lw t1, PT_R2(sp) # syscall number
104 negu v0 # error
105 sw t1, PT_R0(sp) # save it for syscall restarting
1061: sw v0, PT_R2(sp) # result
107
108o32_syscall_exit:
109 j syscall_exit_partial
110
111/* ------------------------------------------------------------------------ */
112
113syscall_trace_entry:
114 SAVE_STATIC
115 move a0, sp
116
117 /*
118 * syscall number is in v0 unless we called syscall(__NR_###)
119 * where the real syscall number is in a0
120 */
121 move a1, v0
122 subu t2, v0, __NR_O32_Linux
123 bnez t2, 1f /* __NR_syscall at offset 0 */
124 lw a1, PT_R4(sp)
125
1261: jal syscall_trace_enter
127
128 bltz v0, 1f # seccomp failed? Skip syscall
129
130 RESTORE_STATIC
131 lw v0, PT_R2(sp) # Restore syscall (maybe modified)
132 lw a0, PT_R4(sp) # Restore argument registers
133 lw a1, PT_R5(sp)
134 lw a2, PT_R6(sp)
135 lw a3, PT_R7(sp)
136 j syscall_common
137
1381: j syscall_exit
139
140/* ------------------------------------------------------------------------ */
141
142 /*
143 * Our open-coded access area sanity test for the stack pointer
144 * failed. We probably should handle this case a bit more drastic.
145 */
146bad_stack:
147 li v0, EFAULT
148 sw v0, PT_R2(sp)
149 li t0, 1 # set error flag
150 sw t0, PT_R7(sp)
151 j o32_syscall_exit
152
153bad_stack_a4:
154 li t5, 0
155 b load_a5
156
157bad_stack_a5:
158 li t6, 0
159 b load_a6
160
161bad_stack_a6:
162 li t7, 0
163 b load_a7
164
165bad_stack_a7:
166 li t8, 0
167 b loads_done
168
169 /*
170 * The system call does not exist in this kernel
171 */
172illegal_syscall:
173 li v0, ENOSYS # error
174 sw v0, PT_R2(sp)
175 li t0, 1 # set error flag
176 sw t0, PT_R7(sp)
177 j o32_syscall_exit
178 END(handle_sys)
179
180 LEAF(sys_syscall)
181 subu t0, a0, __NR_O32_Linux # check syscall number
182 sltiu v0, t0, __NR_O32_Linux_syscalls
183 beqz t0, einval # do not recurse
184 sll t1, t0, 2
185 beqz v0, einval
186 lw t2, sys_call_table(t1) # syscall routine
187
188 move a0, a1 # shift argument registers
189 move a1, a2
190 move a2, a3
191 lw a3, 16(sp)
192 lw t4, 20(sp)
193 lw t5, 24(sp)
194 lw t6, 28(sp)
195 sw t4, 16(sp)
196 sw t5, 20(sp)
197 sw t6, 24(sp)
198 jr t2
199 /* Unreached */
200
201einval: li v0, -ENOSYS
202 jr ra
203 END(sys_syscall)
204
205#ifdef CONFIG_MIPS_MT_FPAFF
206 /*
207 * For FPU affinity scheduling on MIPS MT processors, we need to
208 * intercept sys_sched_xxxaffinity() calls until we get a proper hook
209 * in kernel/sched/core.c. Considered only temporary we only support
210 * these hooks for the 32-bit kernel - there is no MIPS64 MT processor
211 * atm.
212 */
213#define sys_sched_setaffinity mipsmt_sys_sched_setaffinity
214#define sys_sched_getaffinity mipsmt_sys_sched_getaffinity
215#endif /* CONFIG_MIPS_MT_FPAFF */
216
217#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native)
218#define __SYSCALL(nr, entry) PTR_WD entry
219 .align 2
220 .type sys_call_table, @object
221EXPORT(sys_call_table)
222#include <asm/syscall_table_o32.h>
223

source code of linux/arch/mips/kernel/scall32-o32.S