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glibc/sysdeps/unix/sysv/linux/aarch64/clone.S
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/* Copyright (C) 1996-2016 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
The GNU C Library is free software; you can redistribute it and/or | |
modify it under the terms of the GNU Lesser General Public | |
License as published by the Free Software Foundation; either | |
version 2.1 of the License, or (at your option) any later version. | |
The GNU C Library is distributed in the hope that it will be useful, | |
but WITHOUT ANY WARRANTY; without even the implied warranty of | |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
Lesser General Public License for more details. | |
You should have received a copy of the GNU Lesser General Public | |
License along with the GNU C Library; if not, see | |
<http://www.gnu.org/licenses/>. */ | |
/* clone() is even more special than fork() as it mucks with stacks | |
and invokes a function in the right context after its all over. */ | |
#include <sysdep.h> | |
#define _ERRNO_H 1 | |
#include <bits/errno.h> | |
#define CLONE_VM_BIT 8 | |
#define CLONE_VM (1 << CLONE_VM_BIT) | |
#define CLONE_THREAD_BIT 16 | |
#define CLONE_THREAD (1 << CLONE_THREAD_BIT) | |
/* int clone(int (*fn)(void *arg), x0 | |
void *child_stack, x1 | |
int flags, x2 | |
void *arg, x3 | |
pid_t *ptid, x4 | |
struct user_desc *tls, x5 | |
pid_t *ctid); x6 | |
*/ | |
.text | |
ENTRY(__clone) | |
/* Save args for the child. */ | |
mov x10, x0 | |
mov x11, x2 | |
mov x12, x3 | |
/* Sanity check args. */ | |
mov x0, #-EINVAL | |
cbz x10, .Lsyscall_error | |
cbz x1, .Lsyscall_error | |
/* Do the system call. */ | |
/* X0:flags, x1:newsp, x2:parenttidptr, x3:newtls, x4:childtid. */ | |
mov x0, x2 /* flags */ | |
/* New sp is already in x1. */ | |
mov x2, x4 /* ptid */ | |
mov x3, x5 /* tls */ | |
mov x4, x6 /* ctid */ | |
mov x8, #SYS_ify(clone) | |
svc 0x0 | |
cmp x0, #0 | |
beq thread_start | |
blt .Lsyscall_error | |
RET | |
PSEUDO_END (__clone) | |
.align 4 | |
.type thread_start, %function | |
thread_start: | |
cfi_startproc | |
cfi_undefined (x30) | |
mov x29, 0 | |
tbnz x11, #CLONE_THREAD_BIT, 3f | |
mov x0, #-1 | |
tbnz x11, #CLONE_VM_BIT, 2f | |
mov x8, #SYS_ify(getpid) | |
svc 0x0 | |
2: | |
mrs x1, tpidr_el0 | |
sub x1, x1, #PTHREAD_SIZEOF | |
str w0, [x1, #PTHREAD_PID_OFFSET] | |
str w0, [x1, #PTHREAD_TID_OFFSET] | |
3: | |
/* Pick the function arg and execute. */ | |
mov x0, x12 | |
blr x10 | |
/* We are done, pass the return value through x0. */ | |
b HIDDEN_JUMPTARGET(_exit) | |
cfi_endproc | |
.size thread_start, .-thread_start | |
libc_hidden_def (__clone) | |
weak_alias (__clone, clone) |