1
2/*--------------------------------------------------------------------*/
3/*--- Support for doing system calls.        syscall-arm-linux.S ---*/
4/*--------------------------------------------------------------------*/
5
6/*
7  This file is part of Valgrind, a dynamic binary instrumentation
8  framework.
9
10  Copyright (C) 2008-2013 Evan Geller (gaze@bea.ms)
11
12  This program is free software; you can redistribute it and/or
13  modify it under the terms of the GNU General Public License as
14  published by the Free Software Foundation; either version 2 of the
15  License, or (at your option) any later version.
16
17  This program is distributed in the hope that it will be useful, but
18  WITHOUT ANY WARRANTY; without even the implied warranty of
19  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
20  General Public License for more details.
21
22  You should have received a copy of the GNU General Public License
23  along with this program; if not, write to the Free Software
24  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
25  02111-1307, USA.
26
27  The GNU General Public License is contained in the file COPYING.
28*/
29
30#if defined(VGP_arm_linux)
31
32#include "pub_core_basics_asm.h"
33#include "pub_core_vkiscnums_asm.h"
34#include "libvex_guest_offsets.h"
35
36
37/*----------------------------------------------------------------*/
38/*
39        Perform a syscall for the client.  This will run a syscall
40        with the client's specific per-thread signal mask.
41
42        The structure of this function is such that, if the syscall is
43        interrupted by a signal, we can determine exactly what
44        execution state we were in with respect to the execution of
45        the syscall by examining the value of IP in the signal
46        handler.  This means that we can always do the appropriate
47        thing to precisely emulate the kernel's signal/syscall
48        interactions.
49
50        The syscall number is taken from the argument, even though it
51        should also be in regs->m_R7.  The syscall result is written
52        back to regs->m_R0 on completion.
53
54        Returns 0 if the syscall was successfully called (even if the
55        syscall itself failed), or a nonzero error code in the lowest
56        8 bits if one of the sigprocmasks failed (there's no way to
57        determine which one failed).  And there's no obvious way to
58        recover from that either, but nevertheless we want to know.
59
60        VG_(fixup_guest_state_after_syscall_interrupted) does the
61        thread state fixup in the case where we were interrupted by a
62        signal.
63
64        Prototype:
65
66   UWord ML_(do_syscall_for_client_WRK)(
67              Int syscallno,                 // r0
68              void* guest_state,             // r1
69              const vki_sigset_t *sysmask,   // r2
70              const vki_sigset_t *postmask,  // r3
71              Int nsigwords)                 // [sp, #0]
72*/
73/* from vki_arch.h */
74#define VKI_SIG_SETMASK 2
75
76.globl ML_(do_syscall_for_client_WRK)
77ML_(do_syscall_for_client_WRK):
78
79   /* Stash callee-saves and our args on the stack */
80   push {r0, r1, r3, r4, r5, r7, fp, lr}
81
821:
83
84   mov r7, #__NR_rt_sigprocmask
85   mov r0, #VKI_SIG_SETMASK
86   mov r1, r2 /* sysmask */
87   mov r2, r3 /* postmask */
88   ldr r3, [sp, #32] /* nsigwords */
89   svc 0x00000000
90
91
92   ldr r5, [sp, #4] /* guest_state */
93
94   ldr r7, [sp, #0] /* syscall# */
95   ldr r0, [r5, #OFFSET_arm_R0]
96   ldr r1, [r5, #OFFSET_arm_R1]
97   ldr r2, [r5, #OFFSET_arm_R2]
98   ldr r3, [r5, #OFFSET_arm_R3]
99   ldr r4, [r5, #OFFSET_arm_R4]
100   ldr r5, [r5, #OFFSET_arm_R5]
101
1022: svc 0x00000000
1033:
104   ldr r5, [sp, #4] /* guest_state */
105   str r0, [r5, #OFFSET_arm_R0]
106
1074:
108   mov r7, #__NR_rt_sigprocmask
109   mov r0, #VKI_SIG_SETMASK
110   ldr r1, [sp, #8] /* postmask */
111   mov r2, #0
112   ldr r3, [sp, #32] /* nsigwords */
113   svc 0x00000000
114
115   cmp r0, #0
116   blt 7f
117   add sp, sp, #4 /* r0 contains return value */
118
1195: /* Success */
120   mov r0, #0
121   pop {r1, r3, r4, r5, r7, fp, pc}
122
1237: /* Failure: return 0x8000 | error code */
124   orr r0, r0, #0x8000
125   pop {r1, r3, r4, r5, r7, fp, pc}
126
127
128.section .rodata
129/* export the ranges so that
130   VG_(fixup_guest_state_after_syscall_interrupted) can do the
131   right thing */
132
133.globl ML_(blksys_setup)
134.globl ML_(blksys_restart)
135.globl ML_(blksys_complete)
136.globl ML_(blksys_committed)
137.globl ML_(blksys_finished)
138ML_(blksys_setup):      .long 1b
139ML_(blksys_restart):    .long 2b
140ML_(blksys_complete):   .long 3b
141ML_(blksys_committed):  .long 4b
142ML_(blksys_finished):   .long 5b
143
144/* Let the linker know we don't need an executable stack */
145.section .note.GNU-stack,"",%progbits
146
147.previous
148
149#endif // defined(VGP_arm_linux)
150
151/*--------------------------------------------------------------------*/
152/*--- end                                                          ---*/
153/*--------------------------------------------------------------------*/
154