1
2/*--------------------------------------------------------------------*/
3/*--- Support for doing system calls.      syscall-mips32-linux.S  ---*/
4/*--------------------------------------------------------------------*/
5
6/*
7   This file is part of Valgrind, a dynamic binary instrumentation
8   framework.
9
10   Copyright (C) 2010-2015 RT-RK
11      mips-valgrind@rt-rk.com
12
13   This program is free software; you can redistribute it and/or
14   modify it under the terms of the GNU General Public License as
15   published by the Free Software Foundation; either version 2 of the
16   License, or (at your option) any later version.
17
18   This program is distributed in the hope that it will be useful, but
19   WITHOUT ANY WARRANTY; without even the implied warranty of
20   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
21   General Public License for more details.
22
23   You should have received a copy of the GNU General Public License
24   along with this program; if not, write to the Free Software
25   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
26   02111-1307, USA.
27
28   The GNU General Public License is contained in the file COPYING.
29*/
30
31#include "pub_core_basics_asm.h"
32
33#if defined(VGP_mips32_linux)
34
35#include "pub_core_vkiscnums_asm.h"
36#include "libvex_guest_offsets.h"
37
38
39/*----------------------------------------------------------------*/
40/*
41        Perform a syscall for the client.  This will run a syscall
42        with the client's specific per-thread signal mask.
43
44        The structure of this function is such that, if the syscall is
45        interrupted by a signal, we can determine exactly what
46        execution state we were in with respect to the execution of
47        the syscall by examining the value of IP in the signal
48        handler.  This means that we can always do the appropriate
49        thing to precisely emulate the kernel's signal/syscall
50        interactions.
51
52        The syscall number is taken from the argument, even though it
53        should also be in regs->v0.  The syscall result is written
54        back to regs->v0 on completion.
55
56        Returns 0 if the syscall was successfully called (even if the
57        syscall itself failed), or a nonzero error code in the lowest
58        8 bits if one of the sigprocmasks failed (there's no way to
59        determine which one failed).  And there's no obvious way to
60        recover from that either, but nevertheless we want to know.
61
62        VG_(fixup_guest_state_after_syscall_interrupted) does the
63        thread state fixup in the case where we were interrupted by a
64        signal.
65
66        Prototype:
67
68   UWord ML_(do_syscall_for_client_WRK)(
69              Int syscallno,                 // $4 - a0
70              void* guest_state,             // $5 - a1
71              const vki_sigset_t *sysmask,   // $6 - a2
72              const vki_sigset_t *postmask,  // $7 - a3
73              Int nsigwords)                 // stack
74*/
75/* from vki_arch.h */
76#define VKI_SIG_SETMASK 3
77
78.globl ML_(do_syscall_for_client_WRK)
79ML_(do_syscall_for_client_WRK):
80
81    subu $29, $29, 56  #set up the steck frame,
82    sw $4, 52($29)
83    sw $5, 48($29)
84    sw $6, 44($29)
85    sw $7, 40($29)
86    sw $31, 36($29)
87    sw $30, 32($29)
88    sw $16, 28($29)
89    sw $17, 24($29)
90    sw $18, 20($29)
91    sw $19, 16($29)
92    sw $20, 12($29)
93    sw $21, 8($29)
94    sw $22, 4($29)
95    sw $23, 0($29)
96    addu $30, $29, 56
97
98
99    /* Set the signal mask which should be current during the syscall. */
100
1011:  li $2, __NR_rt_sigprocmask
102    li $4, VKI_SIG_SETMASK
103    move $5, $6 /* sysmask */
104    move $6, $7 /* postmask */
105    lw $7, 72($29) /* nsigwords */
106    syscall
107    nop
108
109# TODO: this should remain, keep it just for now
110    bnez $7, 7f
111    nop
112
113    lw $8, 48($29)    /* t0 == ThreadState */
114
115    lw $2, 52($29) /* v0 == syscallno */
116    lw $4, OFFSET_mips32_r4($8)
117    lw $5, OFFSET_mips32_r5($8)
118    lw $6, OFFSET_mips32_r6($8)
119    lw $7, OFFSET_mips32_r7($8)
120    subu $29, $29, 24  #set up the steck frame,
121    lw $9, OFFSET_mips32_r29($8)
122    lw $10, 16($9)
123    sw $10, 16($29)
124    lw $10, 20($9)
125    sw $10, 20($29)
126
1272:  syscall
128
1293:  addu $29, $29, 24  #set up the steck frame,
130
131    lw $8, 48($29) /* t0 == ThreadState */
132    sw $2, OFFSET_mips32_r2($8)
133    sw $3, OFFSET_mips32_r3($8)
134    sw $7, OFFSET_mips32_r7($8)
135
1364:  li $2, __NR_rt_sigprocmask
137    li $4, VKI_SIG_SETMASK
138    lw $5, 40($29)
139    li $6, 0
140    lw $7, 72($29) /* nsigwords */
141    syscall
142    nop
143
144    bnez $7, 7f
145    nop
146
147    /* Success */
148    li $2, 0
149
1505:  lw $4, 52($29)
151    lw $5, 48($29)
152    lw $6, 44($29)
153    lw $7, 40($29)
154    lw $31, 36($29)
155    lw $30, 32($29)
156    lw $16, 28($29)
157    lw $17, 24($29)
158    lw $18, 20($29)
159    lw $19, 16($29)
160    lw $20, 12($29)
161    lw $21, 8($29)
162    lw $22, 4($29)
163    lw $23, 0($29)
164    addu $29, $29, 56 #release the stack frame.
165
166    jr $31
167    nop
168
1697:  /* Failure: return 0x8000 | error code */
170    li $2, 0x8000
171
172    lw $4, 52($29)
173    lw $5, 48($29)
174    lw $6, 44($29)
175    lw $7, 40($29)
176    lw $31, 36($29)
177    lw $30, 32($29)
178    lw $16, 28($29)
179    lw $17, 24($29)
180    lw $18, 20($29)
181    lw $19, 16($29)
182    lw $20, 12($29)
183    lw $21, 8($29)
184    lw $22, 4($29)
185    lw $23, 0($29)
186    addu $29, $29, 56 #release the stack frame.
187
188    jr $31
189    nop
190
191.section .rodata
192/* export the ranges so that
193   VG_(fixup_guest_state_after_syscall_interrupted) can do the
194   right thing */
195
196.globl ML_(blksys_setup)
197.globl ML_(blksys_restart)
198.globl ML_(blksys_complete)
199.globl ML_(blksys_committed)
200.globl ML_(blksys_finished)
201ML_(blksys_setup):      .long 1b
202ML_(blksys_restart):    .long 2b
203ML_(blksys_complete):   .long 3b
204ML_(blksys_committed):  .long 4b
205ML_(blksys_finished):   .long 5b
206
207#endif // defined(VGP_mips32_linux)
208
209/* Let the linker know we don't need an executable stack */
210MARK_STACK_NO_EXEC
211
212/*--------------------------------------------------------------------*/
213/*--- end                                                          ---*/
214/*--------------------------------------------------------------------*/
215