1 | /* POSIX.1 `sigaction' call for Linux/x86-64. |
2 | Copyright (C) 2001-2016 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <sysdep.h> |
20 | #include <errno.h> |
21 | #include <stddef.h> |
22 | #include <signal.h> |
23 | #include <string.h> |
24 | |
25 | #include <sysdep.h> |
26 | #include <sys/syscall.h> |
27 | |
28 | /* The difference here is that the sigaction structure used in the |
29 | kernel is not the same as we use in the libc. Therefore we must |
30 | translate it here. */ |
31 | #include <kernel_sigaction.h> |
32 | |
33 | #include "ucontext_i.h" |
34 | |
35 | /* We do not globally define the SA_RESTORER flag so do it here. */ |
36 | #define SA_RESTORER 0x04000000 |
37 | |
38 | /* Using the hidden attribute here does not change the code but it |
39 | helps to avoid warnings. */ |
40 | extern void restore_rt (void) asm ("__restore_rt" ) attribute_hidden; |
41 | |
42 | |
43 | /* If ACT is not NULL, change the action for SIG to *ACT. |
44 | If OACT is not NULL, put the old action for SIG in *OACT. */ |
45 | int |
46 | __libc_sigaction (int sig, const struct sigaction *act, struct sigaction *oact) |
47 | { |
48 | int result; |
49 | struct kernel_sigaction kact, koact; |
50 | |
51 | if (act) |
52 | { |
53 | kact.k_sa_handler = act->sa_handler; |
54 | memcpy (&kact.sa_mask, &act->sa_mask, sizeof (sigset_t)); |
55 | kact.sa_flags = act->sa_flags | SA_RESTORER; |
56 | |
57 | kact.sa_restorer = &restore_rt; |
58 | } |
59 | |
60 | /* XXX The size argument hopefully will have to be changed to the |
61 | real size of the user-level sigset_t. */ |
62 | result = INLINE_SYSCALL (rt_sigaction, 4, |
63 | sig, act ? &kact : NULL, |
64 | oact ? &koact : NULL, _NSIG / 8); |
65 | if (oact && result >= 0) |
66 | { |
67 | oact->sa_handler = koact.k_sa_handler; |
68 | memcpy (&oact->sa_mask, &koact.sa_mask, sizeof (sigset_t)); |
69 | oact->sa_flags = koact.sa_flags; |
70 | oact->sa_restorer = koact.sa_restorer; |
71 | } |
72 | return result; |
73 | } |
74 | libc_hidden_def (__libc_sigaction) |
75 | |
76 | #include <nptl/sigaction.c> |
77 | |
78 | |
79 | /* NOTE: Please think twice before making any changes to the bits of |
80 | code below. GDB needs some intimate knowledge about it to |
81 | recognize them as signal trampolines, and make backtraces through |
82 | signal handlers work right. Important are both the names |
83 | (__restore_rt) and the exact instruction sequence. |
84 | If you ever feel the need to make any changes, please notify the |
85 | appropriate GDB maintainer. |
86 | |
87 | The unwind information starts a byte before __restore_rt, so that |
88 | it is found when unwinding, to get an address the unwinder assumes |
89 | will be in the middle of a call instruction. See the Linux kernel |
90 | (the i386 vsyscall, in particular) for an explanation of the complex |
91 | unwind information used here in order to get the traditional CFA. |
92 | We do not restore cs - it's only stored as two bytes here so that's |
93 | a bit tricky. We don't use the gas cfi directives, so that we can |
94 | reliably add .cfi_signal_frame. */ |
95 | |
96 | #define do_cfa_expr \ |
97 | " .byte 0x0f\n" /* DW_CFA_def_cfa_expression */ \ |
98 | " .uleb128 2f-1f\n" /* length */ \ |
99 | "1: .byte 0x77\n" /* DW_OP_breg7 */ \ |
100 | " .sleb128 " CFI_STRINGIFY (oRSP) "\n" \ |
101 | " .byte 0x06\n" /* DW_OP_deref */ \ |
102 | "2:" |
103 | |
104 | #define do_expr(regno, offset) \ |
105 | " .byte 0x10\n" /* DW_CFA_expression */ \ |
106 | " .uleb128 " CFI_STRINGIFY (regno) "\n" \ |
107 | " .uleb128 2f-1f\n" /* length */ \ |
108 | "1: .byte 0x77\n" /* DW_OP_breg7 */ \ |
109 | " .sleb128 " CFI_STRINGIFY (offset) "\n" \ |
110 | "2:" |
111 | |
112 | #define RESTORE(name, syscall) RESTORE2 (name, syscall) |
113 | # define RESTORE2(name, syscall) \ |
114 | asm \ |
115 | ( \ |
116 | /* `nop' for debuggers assuming `call' should not disalign the code. */ \ |
117 | " nop\n" \ |
118 | ".align 16\n" \ |
119 | ".LSTART_" #name ":\n" \ |
120 | " .type __" #name ",@function\n" \ |
121 | "__" #name ":\n" \ |
122 | " movq $" #syscall ", %rax\n" \ |
123 | " syscall\n" \ |
124 | ".LEND_" #name ":\n" \ |
125 | ".section .eh_frame,\"a\",@progbits\n" \ |
126 | ".LSTARTFRAME_" #name ":\n" \ |
127 | " .long .LENDCIE_" #name "-.LSTARTCIE_" #name "\n" \ |
128 | ".LSTARTCIE_" #name ":\n" \ |
129 | " .long 0\n" /* CIE ID */ \ |
130 | " .byte 1\n" /* Version number */ \ |
131 | " .string \"zRS\"\n" /* NUL-terminated augmentation string */ \ |
132 | " .uleb128 1\n" /* Code alignment factor */ \ |
133 | " .sleb128 -8\n" /* Data alignment factor */ \ |
134 | " .uleb128 16\n" /* Return address register column (rip) */ \ |
135 | /* Augmentation value length */ \ |
136 | " .uleb128 .LENDAUGMNT_" #name "-.LSTARTAUGMNT_" #name "\n" \ |
137 | ".LSTARTAUGMNT_" #name ":\n" \ |
138 | " .byte 0x1b\n" /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */ \ |
139 | ".LENDAUGMNT_" #name ":\n" \ |
140 | " .align " LP_SIZE "\n" \ |
141 | ".LENDCIE_" #name ":\n" \ |
142 | " .long .LENDFDE_" #name "-.LSTARTFDE_" #name "\n" /* FDE len */ \ |
143 | ".LSTARTFDE_" #name ":\n" \ |
144 | " .long .LSTARTFDE_" #name "-.LSTARTFRAME_" #name "\n" /* CIE */ \ |
145 | /* `LSTART_' is subtracted 1 as debuggers assume a `call' here. */ \ |
146 | " .long (.LSTART_" #name "-1)-.\n" /* PC-relative start addr. */ \ |
147 | " .long .LEND_" #name "-(.LSTART_" #name "-1)\n" \ |
148 | " .uleb128 0\n" /* FDE augmentation length */ \ |
149 | do_cfa_expr \ |
150 | do_expr (8 /* r8 */, oR8) \ |
151 | do_expr (9 /* r9 */, oR9) \ |
152 | do_expr (10 /* r10 */, oR10) \ |
153 | do_expr (11 /* r11 */, oR11) \ |
154 | do_expr (12 /* r12 */, oR12) \ |
155 | do_expr (13 /* r13 */, oR13) \ |
156 | do_expr (14 /* r14 */, oR14) \ |
157 | do_expr (15 /* r15 */, oR15) \ |
158 | do_expr (5 /* rdi */, oRDI) \ |
159 | do_expr (4 /* rsi */, oRSI) \ |
160 | do_expr (6 /* rbp */, oRBP) \ |
161 | do_expr (3 /* rbx */, oRBX) \ |
162 | do_expr (1 /* rdx */, oRDX) \ |
163 | do_expr (0 /* rax */, oRAX) \ |
164 | do_expr (2 /* rcx */, oRCX) \ |
165 | do_expr (7 /* rsp */, oRSP) \ |
166 | do_expr (16 /* rip */, oRIP) \ |
167 | /* libgcc-4.1.1 has only `DWARF_FRAME_REGISTERS == 17'. */ \ |
168 | /* do_expr (49 |* rflags *|, oEFL) */ \ |
169 | /* `cs'/`ds'/`fs' are unaligned and a different size. */ \ |
170 | /* gas: Error: register save offset not a multiple of 8 */ \ |
171 | " .align " LP_SIZE "\n" \ |
172 | ".LENDFDE_" #name ":\n" \ |
173 | " .previous\n" \ |
174 | ); |
175 | /* The return code for realtime-signals. */ |
176 | RESTORE (restore_rt, __NR_rt_sigreturn) |
177 | |