1/* The internal wrapper of clone and clone3.
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 <sysdep.h>
20#include <stddef.h>
21#include <errno.h>
22#include <sched.h>
23#include <clone_internal.h>
24#include <libc-pointer-arith.h> /* For cast_to_pointer. */
25#include <stackinfo.h> /* For _STACK_GROWS_{UP,DOWN}. */
26
27#define CLONE_ARGS_SIZE_VER0 64 /* sizeof first published struct */
28#define CLONE_ARGS_SIZE_VER1 80 /* sizeof second published struct */
29#define CLONE_ARGS_SIZE_VER2 88 /* sizeof third published struct */
30
31#define sizeof_field(TYPE, MEMBER) sizeof ((((TYPE *)0)->MEMBER))
32#define offsetofend(TYPE, MEMBER) \
33 (offsetof (TYPE, MEMBER) + sizeof_field (TYPE, MEMBER))
34
35_Static_assert (__alignof (struct clone_args) == 8,
36 "__alignof (struct clone_args) != 8");
37_Static_assert (offsetofend (struct clone_args, tls) == CLONE_ARGS_SIZE_VER0,
38 "offsetofend (struct clone_args, tls) != CLONE_ARGS_SIZE_VER0");
39_Static_assert (offsetofend (struct clone_args, set_tid_size) == CLONE_ARGS_SIZE_VER1,
40 "offsetofend (struct clone_args, set_tid_size) != CLONE_ARGS_SIZE_VER1");
41_Static_assert (offsetofend (struct clone_args, cgroup) == CLONE_ARGS_SIZE_VER2,
42 "offsetofend (struct clone_args, cgroup) != CLONE_ARGS_SIZE_VER2");
43_Static_assert (sizeof (struct clone_args) == CLONE_ARGS_SIZE_VER2,
44 "sizeof (struct clone_args) != CLONE_ARGS_SIZE_VER2");
45
46int
47__clone_internal (struct clone_args *cl_args,
48 int (*func) (void *arg), void *arg)
49{
50 int ret;
51#ifdef HAVE_CLONE3_WRAPPER
52 /* Try clone3 first. */
53 int saved_errno = errno;
54 ret = __clone3 (cl_args, sizeof (*cl_args), func, arg);
55 if (ret != -1 || errno != ENOSYS)
56 return ret;
57
58 /* NB: Restore errno since errno may be checked against non-zero
59 return value. */
60 __set_errno (saved_errno);
61#endif
62
63 /* Map clone3 arguments to clone arguments. NB: No need to check
64 invalid clone3 specific bits in flags nor exit_signal since this
65 is an internal function. */
66 int flags = cl_args->flags | cl_args->exit_signal;
67 void *stack = cast_to_pointer (cl_args->stack);
68
69#ifdef __ia64__
70 ret = __clone2 (func, stack, cl_args->stack_size,
71 flags, arg,
72 cast_to_pointer (cl_args->parent_tid),
73 cast_to_pointer (cl_args->tls),
74 cast_to_pointer (cl_args->child_tid));
75#else
76# if !_STACK_GROWS_DOWN && !_STACK_GROWS_UP
77# error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
78# endif
79
80# if _STACK_GROWS_DOWN
81 stack += cl_args->stack_size;
82# endif
83 ret = __clone (func, stack, flags, arg,
84 cast_to_pointer (cl_args->parent_tid),
85 cast_to_pointer (cl_args->tls),
86 cast_to_pointer (cl_args->child_tid));
87#endif
88 return ret;
89}
90
91libc_hidden_def (__clone_internal)
92