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glibc/sysdeps/unix/sysv/linux/alpha/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 Richard Henderson <rth@tamu.edu>, 1996. | |
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 0x00000100 | |
#define CLONE_THREAD 0x00010000 | |
/* int clone(int (*fn)(void *arg), void *child_stack, int flags, | |
void *arg, pid_t *ptid, void *tls, pid_t *ctid); | |
Note that everything past ARG is technically optional, based | |
on FLAGS, and that CTID is arg 7, and thus is on the stack. | |
However, since a load from top-of-stack better be legal always, | |
we don't bother checking FLAGS. */ | |
.text | |
.align 4 | |
.globl __clone | |
.ent __clone | |
.usepv __clone, USEPV_PROF | |
cfi_startproc | |
__clone: | |
#ifdef PROF | |
ldgp gp,0(pv) | |
lda AT, _mcount | |
jsr AT, (AT), _mcount | |
#endif | |
/* Sanity check arguments. */ | |
ldiq v0, EINVAL | |
beq a0, SYSCALL_ERROR_LABEL /* no NULL function pointers */ | |
beq a1, SYSCALL_ERROR_LABEL /* no NULL stack pointers */ | |
/* Save the fn ptr and arg on the new stack. */ | |
subq a1, 32, a1 | |
stq a0, 0(a1) | |
stq a3, 8(a1) | |
stq a2, 16(a1) | |
/* The syscall is of the form clone(flags, usp, ptid, ctid, tls). | |
Shift the flags, ptid, ctid, tls arguments into place; the | |
child_stack argument is already correct. */ | |
mov a2, a0 | |
mov a4, a2 | |
ldq a3, 0(sp) | |
mov a5, a4 | |
/* Do the system call. */ | |
ldiq v0, __NR_clone | |
call_pal PAL_callsys | |
bne a3, SYSCALL_ERROR_LABEL | |
beq v0, thread_start | |
/* Successful return from the parent. */ | |
ret | |
PSEUDO_END(__clone) | |
cfi_endproc | |
/* Load up the arguments to the function. Put this block of code in | |
its own function so that we can terminate the stack trace with our | |
debug info. */ | |
.align 4 | |
.ent thread_start | |
cfi_startproc | |
thread_start: | |
mov 0, fp | |
cfi_def_cfa_register(fp) | |
cfi_undefined(ra) | |
/* Check and see if we need to reset the PID. */ | |
ldq t0, 16(sp) | |
lda t1, CLONE_THREAD | |
and t0, t1, t2 | |
beq t2, 2f | |
1: | |
/* Load up the arguments. */ | |
ldq pv, 0(sp) | |
ldq a0, 8(sp) | |
addq sp, 32, sp | |
/* Call the user's function. */ | |
jsr ra, (pv) | |
ldgp gp, 0(ra) | |
/* Call _exit rather than doing it inline for breakpoint purposes. */ | |
mov v0, a0 | |
#ifdef PIC | |
bsr ra, HIDDEN_JUMPTARGET(_exit) !samegp | |
#else | |
jsr ra, HIDDEN_JUMPTARGET(_exit) | |
#endif | |
/* Die horribly. */ | |
.align 4 | |
halt | |
.align 4 | |
2: | |
rduniq | |
lda t1, CLONE_VM | |
mov v0, s0 | |
lda v0, -1 | |
and t0, t1, t2 | |
bne t2, 3f | |
lda v0, __NR_getxpid | |
callsys | |
3: | |
stl v0, PID_OFFSET(s0) | |
stl v0, TID_OFFSET(s0) | |
br 1b | |
cfi_endproc | |
.end thread_start | |
libc_hidden_def (__clone) | |
weak_alias (__clone, clone) |