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/* Copyright (C) 2011-2016 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
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 it's all over. */
#include <sysdep.h>
#define _ERRNO_H 1
#include <bits/errno.h>
#include <asm/unistd.h>
#include <arch/abi.h>
#include <tls.h>
#include <linux/sched.h>
/* What we save where in the stack frame; must include all callee-saves. */
#define FRAME_NEXT_LR (0 * REGSIZE) /* reserved by ABI; not used here */
#define FRAME_SP (1 * REGSIZE)
#define FRAME_R30 (2 * REGSIZE)
#define FRAME_R31 (3 * REGSIZE)
#define FRAME_R32 (4 * REGSIZE)
#define FRAME_SIZE (5 * REGSIZE)
/* 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)
/* Create a stack frame so we can pass callee-saves to new task. */
{
move r10, sp
ST sp, lr
ADDI_PTR sp, sp, -FRAME_SIZE
}
cfi_offset (lr, 0)
cfi_def_cfa_offset (FRAME_SIZE)
ADDI_PTR r11, sp, FRAME_SP
{
ST r11, r10
ADDI_PTR r11, sp, FRAME_R30
}
{
ST r11, r30
ADDI_PTR r11, sp, FRAME_R31
}
cfi_offset (r30, FRAME_R30 - FRAME_SIZE)
{
ST r11, r31
ADDI_PTR r11, sp, FRAME_R32
}
cfi_offset (r31, FRAME_R31 - FRAME_SIZE)
ST r11, r32
cfi_offset (r32, FRAME_R32 - FRAME_SIZE)
/* sanity check arguments */
BEQZ r0, .Linvalid
BEQZ r1, .Linvalid
/* Make sure child stack is properly aligned, and set up the
top frame so that we can call out of it immediately in the
child. Setting it up here means we fault in the parent if
it's bogus, which is probably cleaner than faulting first
thing in the child. */
ADDI_PTR r1, r1, -C_ABI_SAVE_AREA_SIZE
andi r1, r1, -C_ABI_SAVE_AREA_SIZE
ADDI_PTR r9, r1, REGSIZE /* sp of this frame on entry, i.e. zero */
ST r9, zero
/* We need to switch the argument convention around from
libc to kernel:
libc:
r0 fn
r1 child_stack
r2 flags
r3 arg
r4 ptid
r5 tls
r6 ctid
kernel:
r0 flags
r1 child_stack [same as libc]
r2 ptid
r3 ctid
r4 tls
Plus the callee-saves as described at .Lthread_start, below. */
{
move r32, r0
move r0, r2
}
{
move r31, r3
move r3, r6
}
{
move r30, r2
move r2, r4
}
{
move r4, r5
moveli TREG_SYSCALL_NR_NAME, __NR_clone
}
swint1
BEQZ r0, .Lthread_start /* If in child task. */
.Ldone:
/* Restore the callee-saved registers and return. */
ADDLI_PTR lr, sp, FRAME_SIZE
{
LD lr, lr
ADDLI_PTR r30, sp, FRAME_R30
}
{
LD r30, r30
ADDLI_PTR r31, sp, FRAME_R31
}
{
LD r31, r31
ADDLI_PTR r32, sp, FRAME_R32
}
{
LD r32, r32
ADDI_PTR sp, sp, FRAME_SIZE
}
cfi_def_cfa_offset (0)
BNEZ r1, .Lerror
jrp lr
.Lerror:
j SYSCALL_ERROR_NAME
.Linvalid:
{
movei r1, EINVAL
j .Ldone
}
/* This function expects to receive:
sp: the top of a valid stack area
r30: clone() flags
r31: the argument to pass to the user function
r32: the user function pointer */
.Lthread_start:
cfi_def_cfa_offset (FRAME_SIZE)
cfi_undefined (lr)
/* Check and see if we need to reset the PID, which we do if
CLONE_VM isn't set, i.e. it's a fork-like clone with a new
address space. In that case we update the cached values
from the true system pid (retrieved via __NR_getpid syscall). */
moveli r0, CLONE_VM
and r0, r30, r0
BNEZ r0, .Lno_reset_pid /* CLONE_VM is set */
moveli TREG_SYSCALL_NR_NAME, __NR_getpid
swint1
ADDLI_PTR r2, tp, PID_OFFSET
{
ST4 r2, r0
ADDLI_PTR r2, tp, TID_OFFSET
}
ST4 r2, r0
.Lno_reset_pid:
{
/* Invoke user function with specified argument. */
move r0, r31
jalr r32
}
{
j HIDDEN_JUMPTARGET(_exit)
info INFO_OP_CANNOT_BACKTRACE /* Notify backtracer to stop. */
}
PSEUDO_END (__clone)
libc_hidden_def (__clone)
weak_alias (__clone, clone)
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