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) 2008-2017 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#include "pub_core_basics_asm.h"
31
32#if defined(VGP_arm_linux)
33
34#include "pub_core_vkiscnums_asm.h"
35#include "libvex_guest_offsets.h"
36
37
38/*----------------------------------------------------------------*/
39/*
40        Perform a syscall for the client.  This will run a syscall
41        with the client's specific per-thread signal mask.
42
43        The structure of this function is such that, if the syscall is
44        interrupted by a signal, we can determine exactly what
45        execution state we were in with respect to the execution of
46        the syscall by examining the value of IP in the signal
47        handler.  This means that we can always do the appropriate
48        thing to precisely emulate the kernel's signal/syscall
49        interactions.
50
51        The syscall number is taken from the argument, even though it
52        should also be in regs->m_R7.  The syscall result is written
53        back to regs->m_R0 on completion.
54
55        Returns 0 if the syscall was successfully called (even if the
56        syscall itself failed), or a nonzero error code in the lowest
57        8 bits if one of the sigprocmasks failed (there's no way to
58        determine which one failed).  And there's no obvious way to
59        recover from that either, but nevertheless we want to know.
60
61        VG_(fixup_guest_state_after_syscall_interrupted) does the
62        thread state fixup in the case where we were interrupted by a
63        signal.
64
65        Prototype:
66
67   UWord ML_(do_syscall_for_client_WRK)(
68              Int syscallno,                 // r0
69              void* guest_state,             // r1
70              const vki_sigset_t *sysmask,   // r2
71              const vki_sigset_t *postmask,  // r3
72              Int nsigwords)                 // [sp, #0]
73*/
74/* from vki_arch.h */
75#define VKI_SIG_SETMASK 2
76
77.globl ML_(do_syscall_for_client_WRK)
78ML_(do_syscall_for_client_WRK):
79
80   /* Stash callee-saves and our args on the stack */
81   push {r0, r1, r3, r4, r5, r7, fp, lr}
82
831:
84
85   mov r7, #__NR_rt_sigprocmask
86   mov r0, #VKI_SIG_SETMASK
87   mov r1, r2 /* sysmask */
88   mov r2, r3 /* postmask */
89   ldr r3, [sp, #32] /* nsigwords */
90   svc 0x00000000
91
92
93   ldr r5, [sp, #4] /* guest_state */
94
95   ldr r7, [sp, #0] /* syscall# */
96   ldr r0, [r5, #OFFSET_arm_R0]
97   ldr r1, [r5, #OFFSET_arm_R1]
98   ldr r2, [r5, #OFFSET_arm_R2]
99   ldr r3, [r5, #OFFSET_arm_R3]
100   ldr r4, [r5, #OFFSET_arm_R4]
101   ldr r5, [r5, #OFFSET_arm_R5]
102
1032: svc 0x00000000
1043:
105   ldr r5, [sp, #4] /* guest_state */
106   str r0, [r5, #OFFSET_arm_R0]
107
1084:
109   mov r7, #__NR_rt_sigprocmask
110   mov r0, #VKI_SIG_SETMASK
111   ldr r1, [sp, #8] /* postmask */
112   mov r2, #0
113   ldr r3, [sp, #32] /* nsigwords */
114   svc 0x00000000
115
116   cmp r0, #0
117   blt 7f
118   add sp, sp, #4 /* r0 contains return value */
119
1205: /* Success */
121   mov r0, #0
122   pop {r1, r3, r4, r5, r7, fp, pc}
123
1247: /* Failure: return 0x8000 | error code */
125   orr r0, r0, #0x8000
126   pop {r1, r3, r4, r5, r7, fp, pc}
127
128
129.section .rodata
130/* export the ranges so that
131   VG_(fixup_guest_state_after_syscall_interrupted) can do the
132   right thing */
133
134.globl ML_(blksys_setup)
135.globl ML_(blksys_restart)
136.globl ML_(blksys_complete)
137.globl ML_(blksys_committed)
138.globl ML_(blksys_finished)
139ML_(blksys_setup):      .long 1b
140ML_(blksys_restart):    .long 2b
141ML_(blksys_complete):   .long 3b
142ML_(blksys_committed):  .long 4b
143ML_(blksys_finished):   .long 5b
144
145#endif // defined(VGP_arm_linux)
146
147/* Let the linker know we don't need an executable stack */
148MARK_STACK_NO_EXEC
149
150/*--------------------------------------------------------------------*/
151/*--- end                                                          ---*/
152/*--------------------------------------------------------------------*/
153