1/* Copyright (C) 2003-2020 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Jakub Jelinek <jakub@redhat.com>.
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 License as
7 published by the Free Software Foundation; either version 2.1 of the
8 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; see the file COPYING.LIB. If
17 not, see <https://www.gnu.org/licenses/>. */
18
19#include <dlfcn.h>
20#include <stdio.h>
21#include <unwind.h>
22#include <pthreadP.h>
23#include <sysdep.h>
24#include <gnu/lib-names.h>
25#include <unwind-resume.h>
26
27static void *libgcc_s_handle;
28void (*__libgcc_s_resume) (struct _Unwind_Exception *exc)
29 attribute_hidden __attribute__ ((noreturn));
30static _Unwind_Reason_Code (*libgcc_s_personality) PERSONALITY_PROTO;
31static _Unwind_Reason_Code (*libgcc_s_forcedunwind)
32 (struct _Unwind_Exception *, _Unwind_Stop_Fn, void *);
33static _Unwind_Word (*libgcc_s_getcfa) (struct _Unwind_Context *);
34
35void
36__attribute_noinline__
37pthread_cancel_init (void)
38{
39 void *resume;
40 void *personality;
41 void *forcedunwind;
42 void *getcfa;
43 void *handle;
44
45 if (__glibc_likely (libgcc_s_handle != NULL))
46 {
47 /* Force gcc to reload all values. */
48 asm volatile ("" ::: "memory");
49 return;
50 }
51
52 /* See include/dlfcn.h. Use of __libc_dlopen requires RTLD_NOW. */
53 handle = __libc_dlopen (LIBGCC_S_SO);
54
55 if (handle == NULL
56 || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL
57 || (personality = __libc_dlsym (handle, "__gcc_personality_v0")) == NULL
58 || (forcedunwind = __libc_dlsym (handle, "_Unwind_ForcedUnwind"))
59 == NULL
60 || (getcfa = __libc_dlsym (handle, "_Unwind_GetCFA")) == NULL
61#ifdef ARCH_CANCEL_INIT
62 || ARCH_CANCEL_INIT (handle)
63#endif
64 )
65 __libc_fatal (LIBGCC_S_SO " must be installed for pthread_cancel to work\n");
66
67 PTR_MANGLE (resume);
68 __libgcc_s_resume = resume;
69 PTR_MANGLE (personality);
70 libgcc_s_personality = personality;
71 PTR_MANGLE (forcedunwind);
72 libgcc_s_forcedunwind = forcedunwind;
73 PTR_MANGLE (getcfa);
74 libgcc_s_getcfa = getcfa;
75 /* Make sure libgcc_s_handle is written last. Otherwise,
76 pthread_cancel_init might return early even when the pointer the
77 caller is interested in is not initialized yet. */
78 atomic_write_barrier ();
79 libgcc_s_handle = handle;
80}
81
82/* Register for cleanup in libpthread.so. */
83void
84__nptl_unwind_freeres (void)
85{
86 void *handle = libgcc_s_handle;
87 if (handle != NULL)
88 {
89 libgcc_s_handle = NULL;
90 __libc_dlclose (handle);
91 }
92}
93
94#if !HAVE_ARCH_UNWIND_RESUME
95void
96_Unwind_Resume (struct _Unwind_Exception *exc)
97{
98 if (__glibc_unlikely (libgcc_s_handle == NULL))
99 pthread_cancel_init ();
100 else
101 atomic_read_barrier ();
102
103 void (*resume) (struct _Unwind_Exception *exc) = __libgcc_s_resume;
104 PTR_DEMANGLE (resume);
105 resume (exc);
106}
107#endif
108
109_Unwind_Reason_Code
110__gcc_personality_v0 PERSONALITY_PROTO
111{
112 if (__glibc_unlikely (libgcc_s_handle == NULL))
113 pthread_cancel_init ();
114 else
115 atomic_read_barrier ();
116
117 __typeof (libgcc_s_personality) personality = libgcc_s_personality;
118 PTR_DEMANGLE (personality);
119 return (*personality) PERSONALITY_ARGS;
120}
121
122_Unwind_Reason_Code
123_Unwind_ForcedUnwind (struct _Unwind_Exception *exc, _Unwind_Stop_Fn stop,
124 void *stop_argument)
125{
126 if (__glibc_unlikely (libgcc_s_handle == NULL))
127 pthread_cancel_init ();
128 else
129 atomic_read_barrier ();
130
131 _Unwind_Reason_Code (*forcedunwind)
132 (struct _Unwind_Exception *, _Unwind_Stop_Fn, void *)
133 = libgcc_s_forcedunwind;
134 PTR_DEMANGLE (forcedunwind);
135 return forcedunwind (exc, stop, stop_argument);
136}
137
138_Unwind_Word
139_Unwind_GetCFA (struct _Unwind_Context *context)
140{
141 if (__glibc_unlikely (libgcc_s_handle == NULL))
142 pthread_cancel_init ();
143 else
144 atomic_read_barrier ();
145
146 _Unwind_Word (*getcfa) (struct _Unwind_Context *) = libgcc_s_getcfa;
147 PTR_DEMANGLE (getcfa);
148 return getcfa (context);
149}
150