1
2/*--------------------------------------------------------------------*/
3/*--- Support for doing system calls.        syscall-ppc32-linux.S ---*/
4/*--------------------------------------------------------------------*/
5
6/*
7  This file is part of Valgrind, a dynamic binary instrumentation
8  framework.
9
10  Copyright (C) 2005-2015 Paul Mackerras (paulus@samba.org)
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_ppc32_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 NIP 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_gpr[0].  The syscall result is written
53        back to regs->m_gpr[3]/m_xer/m_result 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,		// r3
69				  void* guest_state,		// r4
70				  const vki_sigset_t *sysmask,	// r5
71				  const vki_sigset_t *postmask,	// r6
72				  Int sigsetSzB)		// r7
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        /* make a stack frame */
80        stwu    1,-32(1)
81        stw     31,28(1)
82        stw     30,24(1)
83        stw     29,20(1)
84        stw     28,16(1)
85        mr      31,3            /* syscall number */
86        mr      30,4            /* guest_state */
87        mr      29,6            /* postmask */
88        mr      28,7            /* sigsetSzB */
89
90        /* set the signal mask for doing the system call */
91        /* set up for sigprocmask(SIG_SETMASK, sysmask, postmask) */
921:      li      0,__NR_rt_sigprocmask
93        li      3,VKI_SIG_SETMASK
94        mr      4,5
95        mr      5,6
96	mr	6,7
97        sc                      /* set the mask */
98        bso     7f              /* if the sigprocmask fails */
99
100        /* load up syscall args from the threadstate */
101        lwz     3,OFFSET_ppc32_GPR3(30)
102        lwz     4,OFFSET_ppc32_GPR4(30)
103        lwz     5,OFFSET_ppc32_GPR5(30)
104        lwz     6,OFFSET_ppc32_GPR6(30)
105        lwz     7,OFFSET_ppc32_GPR7(30)
106        lwz     8,OFFSET_ppc32_GPR8(30)
107        mr      0,31            /* syscall number */
1082:      sc                      /* do the syscall */
109
110        /* put the result back in the threadstate  */
1113:	stw     3,OFFSET_ppc32_GPR3(30)     /* gst->GPR3 = sc result */
112	/* copy cr0.so back to simulated state */
113	mfcr    5                           /* r5 = CR               */
114	rlwinm	5,5,4,31,31                 /* r5 = (CR >> 28) & 1   */
115        stb     5,OFFSET_ppc32_CR0_0(30)    /* gst->CR0.SO = cr0.so  */
116
117        /* block signals again */
118	/* set up for sigprocmask(SIG_SETMASK, postmask, NULL) */
1194:      li      0,__NR_rt_sigprocmask
120        li      3,VKI_SIG_SETMASK
121        mr      4,29
122        li      5,0
123        mr      6,28
124        sc                      /* set the mask */
125        bso     7f              /* if the sigprocmask fails */
126        /* now safe from signals */
127	li	3,0		/* SUCCESS */
128
129        /* pop off stack frame */
1305:      lwz     28,16(1)
131        lwz     29,20(1)
132        lwz     30,24(1)
133        lwz     31,28(1)
134        addi    1,1,32
135        blr
136
137	/* failure: return 0x8000 | error code */
1387:      ori	3,3,0x8000	/* FAILURE -- ensure return value is nonzero */
139        b       5b
140
141.section .rodata
142/* export the ranges so that
143   VG_(fixup_guest_state_after_syscall_interrupted) can do the
144   right thing */
145
146.globl ML_(blksys_setup)
147.globl ML_(blksys_restart)
148.globl ML_(blksys_complete)
149.globl ML_(blksys_committed)
150.globl ML_(blksys_finished)
151ML_(blksys_setup):     .long 1b
152ML_(blksys_restart):   .long 2b
153ML_(blksys_complete):  .long 3b
154ML_(blksys_committed): .long 4b
155ML_(blksys_finished):  .long 5b
156
157#endif // defined(VGP_ppc32_linux)
158
159/* Let the linker know we don't need an executable stack */
160MARK_STACK_NO_EXEC
161
162/*--------------------------------------------------------------------*/
163/*--- end                                                          ---*/
164/*--------------------------------------------------------------------*/
165