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glibc/sysdeps/unix/sysv/linux/arm/clone.S
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/* Copyright (C) 1996-2016 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
Contributed by Pat Beirne <patb@corelcomputer.com> | |
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> | |
#include <tcb-offsets.h> | |
#define _ERRNO_H 1 | |
#include <bits/errno.h> | |
#define CLONE_VM 0x00000100 | |
#define CLONE_THREAD 0x00010000 | |
/* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg, | |
pid_t *ptid, struct user_desc *tls, pid_t *ctid); */ | |
.text | |
ENTRY(__clone) | |
@ sanity check args | |
cmp r0, #0 | |
ite ne | |
cmpne r1, #0 | |
moveq r0, #-EINVAL | |
beq PLTJMP(syscall_error) | |
@ insert the args onto the new stack | |
str r3, [r1, #-4]! | |
str r0, [r1, #-4]! | |
@ do the system call | |
@ get flags | |
mov r0, r2 | |
mov ip, r2 | |
@ new sp is already in r1 | |
push {r4, r7} | |
cfi_adjust_cfa_offset (8) | |
cfi_rel_offset (r4, 0) | |
cfi_rel_offset (r7, 4) | |
ldr r2, [sp, #8] | |
ldr r3, [sp, #12] | |
ldr r4, [sp, #16] | |
ldr r7, =SYS_ify(clone) | |
swi 0x0 | |
cfi_endproc | |
cmp r0, #0 | |
beq 1f | |
pop {r4, r7} | |
blt PLTJMP(C_SYMBOL_NAME(__syscall_error)) | |
RETINSTR(, lr) | |
cfi_startproc | |
PSEUDO_END (__clone) | |
1: | |
.fnstart | |
.cantunwind | |
tst ip, #CLONE_THREAD | |
bne 3f | |
GET_TLS (lr) | |
mov r1, r0 | |
tst ip, #CLONE_VM | |
ldr r7, =SYS_ify(getpid) | |
ite ne | |
movne r0, #-1 | |
swieq 0x0 | |
NEGOFF_ADJ_BASE (r1, TID_OFFSET) | |
str r0, NEGOFF_OFF1 (r1, TID_OFFSET) | |
str r0, NEGOFF_OFF2 (r1, PID_OFFSET, TID_OFFSET) | |
3: | |
@ pick the function arg and call address off the stack and execute | |
ldr r0, [sp, #4] | |
ldr ip, [sp], #8 | |
BLX (ip) | |
@ and we are done, passing the return value through r0 | |
b PLTJMP(HIDDEN_JUMPTARGET(_exit)) | |
.fnend | |
libc_hidden_def (__clone) | |
weak_alias (__clone, clone) |