1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
/* POSIX.1 `sigaction' call for Linux/x86-64.
Copyright (C) 2001, 2002, 2003, 2005, 2006 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <sysdep.h>
#include <errno.h>
#include <stddef.h>
#include <signal.h>
#include <string.h>
#include <sysdep.h>
#include <sys/syscall.h>
#include <kernel-features.h>
/* The difference here is that the sigaction structure used in the
kernel is not the same as we use in the libc. Therefore we must
translate it here. */
#include <kernel_sigaction.h>
#include "ucontext_i.h"
/* We do not globally define the SA_RESTORER flag so do it here. */
#define SA_RESTORER 0x04000000
/* Using the hidden attribute here does not change the code but it
helps to avoid warnings. */
extern void restore_rt (void) asm ("__restore_rt") attribute_hidden;
/* If ACT is not NULL, change the action for SIG to *ACT.
If OACT is not NULL, put the old action for SIG in *OACT. */
int
__libc_sigaction (int sig, const struct sigaction *act, struct sigaction *oact)
{
int result;
struct kernel_sigaction kact, koact;
if (act)
{
kact.k_sa_handler = act->sa_handler;
memcpy (&kact.sa_mask, &act->sa_mask, sizeof (sigset_t));
kact.sa_flags = act->sa_flags | SA_RESTORER;
kact.sa_restorer = &restore_rt;
}
/* XXX The size argument hopefully will have to be changed to the
real size of the user-level sigset_t. */
result = INLINE_SYSCALL (rt_sigaction, 4,
sig, act ? __ptrvalue (&kact) : NULL,
oact ? __ptrvalue (&koact) : NULL, _NSIG / 8);
if (oact && result >= 0)
{
oact->sa_handler = koact.k_sa_handler;
memcpy (&oact->sa_mask, &koact.sa_mask, sizeof (sigset_t));
oact->sa_flags = koact.sa_flags;
oact->sa_restorer = koact.sa_restorer;
}
return result;
}
libc_hidden_def (__libc_sigaction)
#ifdef WRAPPER_INCLUDE
# include WRAPPER_INCLUDE
#endif
#ifndef LIBC_SIGACTION
weak_alias (__libc_sigaction, __sigaction)
libc_hidden_weak (__sigaction)
weak_alias (__libc_sigaction, sigaction)
#endif
/* NOTE: Please think twice before making any changes to the bits of
code below. GDB needs some intimate knowledge about it to
recognize them as signal trampolines, and make backtraces through
signal handlers work right. Important are both the names
(__restore_rt) and the exact instruction sequence.
If you ever feel the need to make any changes, please notify the
appropriate GDB maintainer.
The unwind information starts a byte before __restore_rt, so that
it is found when unwinding, to get an address the unwinder assumes
will be in the middle of a call instruction. See the Linux kernel
(the i386 vsyscall, in particular) for an explanation of the complex
unwind information used here in order to get the traditional CFA.
We do not restore cs - it's only stored as two bytes here so that's
a bit tricky. We don't use the gas cfi directives, so that we can
reliably add .cfi_signal_frame. */
#define do_cfa_expr \
" .byte 0x0f\n" /* DW_CFA_def_cfa_expression */ \
" .uleb128 2f-1f\n" /* length */ \
"1: .byte 0x77\n" /* DW_OP_breg7 */ \
" .sleb128 " CFI_STRINGIFY (oRSP) "\n" \
" .byte 0x06\n" /* DW_OP_deref */ \
"2:"
#define do_expr(regno, offset) \
" .byte 0x10\n" /* DW_CFA_expression */ \
" .uleb128 " CFI_STRINGIFY (regno) "\n" \
" .uleb128 2f-1f\n" /* length */ \
"1: .byte 0x77\n" /* DW_OP_breg7 */ \
" .sleb128 " CFI_STRINGIFY (offset) "\n" \
"2:"
#define RESTORE(name, syscall) RESTORE2 (name, syscall)
# define RESTORE2(name, syscall) \
asm \
( \
/* `nop' for debuggers assuming `call' should not disalign the code. */ \
" nop\n" \
".align 16\n" \
".LSTART_" #name ":\n" \
" .type __" #name ",@function\n" \
"__" #name ":\n" \
" movq $" #syscall ", %rax\n" \
" syscall\n" \
".LEND_" #name ":\n" \
".section .eh_frame,\"a\",@progbits\n" \
".LSTARTFRAME_" #name ":\n" \
" .long .LENDCIE_" #name "-.LSTARTCIE_" #name "\n" \
".LSTARTCIE_" #name ":\n" \
" .long 0\n" /* CIE ID */ \
" .byte 1\n" /* Version number */ \
" .string \"zRS\"\n" /* NUL-terminated augmentation string */ \
" .uleb128 1\n" /* Code alignment factor */ \
" .sleb128 -8\n" /* Data alignment factor */ \
" .uleb128 16\n" /* Return address register column (rip) */ \
/* Augmentation value length */ \
" .uleb128 .LENDAUGMNT_" #name "-.LSTARTAUGMNT_" #name "\n" \
".LSTARTAUGMNT_" #name ":\n" \
" .byte 0x1b\n" /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */ \
".LENDAUGMNT_" #name ":\n" \
" .align 8\n" \
".LENDCIE_" #name ":\n" \
" .long .LENDFDE_" #name "-.LSTARTFDE_" #name "\n" /* FDE len */ \
".LSTARTFDE_" #name ":\n" \
" .long .LSTARTFDE_" #name "-.LSTARTFRAME_" #name "\n" /* CIE */ \
/* `LSTART_' is subtracted 1 as debuggers assume a `call' here. */ \
" .long (.LSTART_" #name "-1)-.\n" /* PC-relative start addr. */ \
" .long .LEND_" #name "-(.LSTART_" #name "-1)\n" \
" .uleb128 0\n" /* FDE augmentation length */ \
do_cfa_expr \
do_expr (8 /* r8 */, oR8) \
do_expr (9 /* r9 */, oR9) \
do_expr (10 /* r10 */, oR10) \
do_expr (11 /* r11 */, oR11) \
do_expr (12 /* r12 */, oR12) \
do_expr (13 /* r13 */, oR13) \
do_expr (14 /* r14 */, oR14) \
do_expr (15 /* r15 */, oR15) \
do_expr (5 /* rdi */, oRDI) \
do_expr (4 /* rsi */, oRSI) \
do_expr (6 /* rbp */, oRBP) \
do_expr (3 /* rbx */, oRBX) \
do_expr (1 /* rdx */, oRDX) \
do_expr (0 /* rax */, oRAX) \
do_expr (2 /* rcx */, oRCX) \
do_expr (7 /* rsp */, oRSP) \
do_expr (16 /* rip */, oRIP) \
do_expr (49 /* rflags */, oEFL) \
/* `cs'/`ds'/`fs' are unaligned and a different size. */ \
/* gas: Error: register save offset not a multiple of 8 */ \
" .align 8\n" \
".LENDFDE_" #name ":\n" \
" .previous\n" \
);
/* The return code for realtime-signals. */
RESTORE (restore_rt, __NR_rt_sigreturn)
|
