1/* Copyright (C) 2003-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>
4 and Richard Henderson <rth@redhat.com>, 2003.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20#include <setjmp.h>
21#include <stdio.h>
22#include <stdlib.h>
23#include <string.h>
24#include <unistd.h>
25#include "pthreadP.h"
26#include <libc-diag.h>
27#include <jmpbuf-unwind.h>
28#include <shlib-compat.h>
29
30#ifdef _STACK_GROWS_DOWN
31# define FRAME_LEFT(frame, other, adj) \
32 ((uintptr_t) frame - adj >= (uintptr_t) other - adj)
33#elif _STACK_GROWS_UP
34# define FRAME_LEFT(frame, other, adj) \
35 ((uintptr_t) frame - adj <= (uintptr_t) other - adj)
36#else
37# error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
38#endif
39
40static _Unwind_Reason_Code
41unwind_stop (int version, _Unwind_Action actions,
42 _Unwind_Exception_Class exc_class,
43 struct _Unwind_Exception *exc_obj,
44 struct _Unwind_Context *context, void *stop_parameter)
45{
46 struct pthread_unwind_buf *buf = stop_parameter;
47 struct pthread *self = THREAD_SELF;
48 struct _pthread_cleanup_buffer *curp = THREAD_GETMEM (self, cleanup);
49 int do_longjump = 0;
50
51 /* Adjust all pointers used in comparisons, so that top of thread's
52 stack is at the top of address space. Without that, things break
53 if stack is allocated above the main stack. */
54 uintptr_t adj = (uintptr_t) self->stackblock + self->stackblock_size;
55
56 /* Do longjmp if we're at "end of stack", aka "end of unwind data".
57 We assume there are only C frame without unwind data in between
58 here and the jmp_buf target. Otherwise simply note that the CFA
59 of a function is NOT within it's stack frame; it's the SP of the
60 previous frame. */
61 if ((actions & _UA_END_OF_STACK)
62 || ! _JMPBUF_CFA_UNWINDS_ADJ (buf->cancel_jmp_buf[0].jmp_buf, context,
63 adj))
64 do_longjump = 1;
65
66 if (__glibc_unlikely (curp != NULL))
67 {
68 /* Handle the compatibility stuff. Execute all handlers
69 registered with the old method which would be unwound by this
70 step. */
71 struct _pthread_cleanup_buffer *oldp = buf->priv.data.cleanup;
72 void *cfa = (void *) (_Unwind_Ptr) _Unwind_GetCFA (context);
73
74 if (curp != oldp && (do_longjump || FRAME_LEFT (cfa, curp, adj)))
75 {
76 do
77 {
78 /* Pointer to the next element. */
79 struct _pthread_cleanup_buffer *nextp = curp->__prev;
80
81 /* Call the handler. */
82 curp->__routine (curp->__arg);
83
84 /* To the next. */
85 curp = nextp;
86 }
87 while (curp != oldp
88 && (do_longjump || FRAME_LEFT (cfa, curp, adj)));
89
90 /* Mark the current element as handled. */
91 THREAD_SETMEM (self, cleanup, curp);
92 }
93 }
94
95 DIAG_PUSH_NEEDS_COMMENT;
96#if __GNUC_PREREQ (7, 0)
97 /* This call results in a -Wstringop-overflow warning because struct
98 pthread_unwind_buf is smaller than jmp_buf. setjmp and longjmp
99 do not use anything beyond the common prefix (they never access
100 the saved signal mask), so that is a false positive. */
101 DIAG_IGNORE_NEEDS_COMMENT (11, "-Wstringop-overflow=");
102#endif
103 if (do_longjump)
104 __libc_unwind_longjmp ((struct __jmp_buf_tag *) buf->cancel_jmp_buf, 1);
105 DIAG_POP_NEEDS_COMMENT;
106
107 return _URC_NO_REASON;
108}
109
110
111static void
112unwind_cleanup (_Unwind_Reason_Code reason, struct _Unwind_Exception *exc)
113{
114 /* When we get here a C++ catch block didn't rethrow the object. We
115 cannot handle this case and therefore abort. */
116 __libc_fatal ("FATAL: exception not rethrown\n");
117}
118
119
120void
121__cleanup_fct_attribute __attribute ((noreturn))
122__pthread_unwind (__pthread_unwind_buf_t *buf)
123{
124 struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
125 struct pthread *self = THREAD_SELF;
126
127 /* This is not a catchable exception, so don't provide any details about
128 the exception type. We do need to initialize the field though. */
129 THREAD_SETMEM (self, exc.exception_class, 0);
130 THREAD_SETMEM (self, exc.exception_cleanup, &unwind_cleanup);
131
132 _Unwind_ForcedUnwind (&self->exc, unwind_stop, ibuf);
133 /* NOTREACHED */
134
135 /* We better do not get here. */
136 abort ();
137}
138libc_hidden_def (__pthread_unwind)
139
140void
141__cleanup_fct_attribute __attribute ((noreturn))
142___pthread_unwind_next (__pthread_unwind_buf_t *buf)
143{
144 struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
145
146 __pthread_unwind ((__pthread_unwind_buf_t *) ibuf->priv.data.prev);
147}
148versioned_symbol (libc, ___pthread_unwind_next, __pthread_unwind_next,
149 GLIBC_2_34);
150#if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_3_3, GLIBC_2_34)
151compat_symbol (libpthread, ___pthread_unwind_next, __pthread_unwind_next,
152 GLIBC_2_3_3);
153#endif
154