1 /* Check if clone (CLONE_THREAD) does not call exit_group (BZ #21512)
2 Copyright (C) 2021-2022 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 <https://www.gnu.org/licenses/>. */
18
19 #include <string.h>
20 #include <sched.h>
21 #include <signal.h>
22 #include <unistd.h>
23 #include <errno.h>
24 #include <sys/syscall.h>
25 #include <sys/wait.h>
26 #include <sys/types.h>
27 #include <linux/futex.h>
28 #include <support/check.h>
29 #include <stdatomic.h>
30 #include <clone_internal.h>
31
32 /* Test if clone call with CLONE_THREAD does not call exit_group. The 'f'
33 function returns '1', which will be used by clone thread to call the
34 'exit' syscall directly. If _exit is used instead, exit_group will be
35 used and thus the thread group will finish with return value of '1'
36 (where '2' from main thread is expected.). */
37
38 static int
f(void * a)39 f (void *a)
40 {
41 return 1;
42 }
43
44 /* Futex wait for TID argument, similar to pthread_join internal
45 implementation. */
46 #define wait_tid(ctid_ptr, ctid_val) \
47 do { \
48 __typeof (*(ctid_ptr)) __tid; \
49 /* We need acquire MO here so that we synchronize with the \
50 kernel's store to 0 when the clone terminates. */ \
51 while ((__tid = atomic_load_explicit (ctid_ptr, \
52 memory_order_acquire)) != 0) \
53 futex_wait (ctid_ptr, ctid_val); \
54 } while (0)
55
56 static inline int
futex_wait(int * futexp,int val)57 futex_wait (int *futexp, int val)
58 {
59 #ifdef __NR_futex
60 return syscall (__NR_futex, futexp, FUTEX_WAIT, val);
61 #else
62 return syscall (__NR_futex_time64, futexp, FUTEX_WAIT, val);
63 #endif
64 }
65
66 static int
do_test(void)67 do_test (void)
68 {
69 char st[1024] __attribute__ ((aligned));
70 int clone_flags = CLONE_THREAD;
71 /* Minimum required flags to used along with CLONE_THREAD. */
72 clone_flags |= CLONE_VM | CLONE_SIGHAND;
73 /* We will used ctid to call on futex to wait for thread exit. */
74 clone_flags |= CLONE_CHILD_CLEARTID;
75 /* Initialize with a known value. ctid is set to zero by the kernel after the
76 cloned thread has exited. */
77 #define CTID_INIT_VAL 1
78 pid_t ctid = CTID_INIT_VAL;
79 pid_t tid;
80
81 struct clone_args clone_args =
82 {
83 .flags = clone_flags & ~CSIGNAL,
84 .exit_signal = clone_flags & CSIGNAL,
85 .stack = (uintptr_t) st,
86 .stack_size = sizeof (st),
87 .child_tid = (uintptr_t) &ctid,
88 };
89 tid = __clone_internal (&clone_args, f, NULL);
90 if (tid == -1)
91 FAIL_EXIT1 ("clone failed: %m");
92
93 wait_tid (&ctid, CTID_INIT_VAL);
94
95 return 2;
96 }
97
98 #define EXPECTED_STATUS 2
99 #include <support/test-driver.c>
100