1 | /* Low-level thread creation for NPTL. Linux version. |
2 | Copyright (C) 2002-2020 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | Contributed by Ulrich Drepper <drepper@redhat.com>, 2002. |
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 <sched.h> |
21 | #include <setjmp.h> |
22 | #include <signal.h> |
23 | #include <stdlib.h> |
24 | #include <atomic.h> |
25 | #include <ldsodefs.h> |
26 | #include <tls.h> |
27 | #include <stdint.h> |
28 | |
29 | #include <arch-fork.h> |
30 | |
31 | #ifdef __NR_clone2 |
32 | # define ARCH_CLONE __clone2 |
33 | #else |
34 | # define ARCH_CLONE __clone |
35 | #endif |
36 | |
37 | /* See the comments in pthread_create.c for the requirements for these |
38 | two macros and the create_thread function. */ |
39 | |
40 | #define START_THREAD_DEFN \ |
41 | static int __attribute__ ((noreturn)) start_thread (void *arg) |
42 | #define START_THREAD_SELF arg |
43 | |
44 | /* pthread_create.c defines this using START_THREAD_DEFN |
45 | We need a forward declaration here so we can take its address. */ |
46 | static int start_thread (void *arg) __attribute__ ((noreturn)); |
47 | |
48 | static int |
49 | create_thread (struct pthread *pd, const struct pthread_attr *attr, |
50 | bool *stopped_start, STACK_VARIABLES_PARMS, bool *thread_ran) |
51 | { |
52 | /* Determine whether the newly created threads has to be started |
53 | stopped since we have to set the scheduling parameters or set the |
54 | affinity. */ |
55 | if (attr != NULL |
56 | && (__glibc_unlikely (attr->cpuset != NULL) |
57 | || __glibc_unlikely ((attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0))) |
58 | *stopped_start = true; |
59 | |
60 | pd->stopped_start = *stopped_start; |
61 | if (__glibc_unlikely (*stopped_start)) |
62 | /* See CONCURRENCY NOTES in nptl/pthread_creat.c. */ |
63 | lll_lock (pd->lock, LLL_PRIVATE); |
64 | |
65 | /* We rely heavily on various flags the CLONE function understands: |
66 | |
67 | CLONE_VM, CLONE_FS, CLONE_FILES |
68 | These flags select semantics with shared address space and |
69 | file descriptors according to what POSIX requires. |
70 | |
71 | CLONE_SIGHAND, CLONE_THREAD |
72 | This flag selects the POSIX signal semantics and various |
73 | other kinds of sharing (itimers, POSIX timers, etc.). |
74 | |
75 | CLONE_SETTLS |
76 | The sixth parameter to CLONE determines the TLS area for the |
77 | new thread. |
78 | |
79 | CLONE_PARENT_SETTID |
80 | The kernels writes the thread ID of the newly created thread |
81 | into the location pointed to by the fifth parameters to CLONE. |
82 | |
83 | Note that it would be semantically equivalent to use |
84 | CLONE_CHILD_SETTID but it is be more expensive in the kernel. |
85 | |
86 | CLONE_CHILD_CLEARTID |
87 | The kernels clears the thread ID of a thread that has called |
88 | sys_exit() in the location pointed to by the seventh parameter |
89 | to CLONE. |
90 | |
91 | The termination signal is chosen to be zero which means no signal |
92 | is sent. */ |
93 | const int clone_flags = (CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SYSVSEM |
94 | | CLONE_SIGHAND | CLONE_THREAD |
95 | | CLONE_SETTLS | CLONE_PARENT_SETTID |
96 | | CLONE_CHILD_CLEARTID |
97 | | 0); |
98 | |
99 | TLS_DEFINE_INIT_TP (tp, pd); |
100 | |
101 | if (__glibc_unlikely (ARCH_CLONE (&start_thread, STACK_VARIABLES_ARGS, |
102 | clone_flags, pd, &pd->tid, tp, &pd->tid) |
103 | == -1)) |
104 | return errno; |
105 | |
106 | /* It's started now, so if we fail below, we'll have to cancel it |
107 | and let it clean itself up. */ |
108 | *thread_ran = true; |
109 | |
110 | /* Now we have the possibility to set scheduling parameters etc. */ |
111 | if (attr != NULL) |
112 | { |
113 | INTERNAL_SYSCALL_DECL (err); |
114 | int res; |
115 | |
116 | /* Set the affinity mask if necessary. */ |
117 | if (attr->cpuset != NULL) |
118 | { |
119 | assert (*stopped_start); |
120 | |
121 | res = INTERNAL_SYSCALL (sched_setaffinity, err, 3, pd->tid, |
122 | attr->cpusetsize, attr->cpuset); |
123 | |
124 | if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (res, err))) |
125 | err_out: |
126 | { |
127 | /* The operation failed. We have to kill the thread. |
128 | We let the normal cancellation mechanism do the work. */ |
129 | |
130 | pid_t pid = __getpid (); |
131 | INTERNAL_SYSCALL_DECL (err2); |
132 | (void) INTERNAL_SYSCALL_CALL (tgkill, err2, pid, pd->tid, |
133 | SIGCANCEL); |
134 | |
135 | return INTERNAL_SYSCALL_ERRNO (res, err); |
136 | } |
137 | } |
138 | |
139 | /* Set the scheduling parameters. */ |
140 | if ((attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0) |
141 | { |
142 | assert (*stopped_start); |
143 | |
144 | res = INTERNAL_SYSCALL (sched_setscheduler, err, 3, pd->tid, |
145 | pd->schedpolicy, &pd->schedparam); |
146 | |
147 | if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (res, err))) |
148 | goto err_out; |
149 | } |
150 | } |
151 | |
152 | return 0; |
153 | } |
154 | |