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/* The clone3 syscall wrapper. Linux/mips version.
Copyright (C) 2023-2025 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
<https://www.gnu.org/licenses/>. */
#include <sys/asm.h>
#include <sysdep.h>
#define _ERRNO_H 1
#include <bits/errno.h>
/* The userland implementation is:
int clone3 (struct clone_args *cl_args, size_t size,
int (*func)(void *arg), void *arg);
the kernel entry is:
int clone3 (struct clone_args *cl_args, size_t size);
The parameters are passed in registers from userland:
a0/$4: cl_args
a1/$5: size
a2/$6: func
a3/$7: arg */
.text
.set nomips16
#define FRAMESZ ((NARGSAVE*SZREG)+ALSZ)&ALMASK
GPOFF= FRAMESZ-(1*SZREG)
NESTED(__clone3, SZREG, sp)
#ifdef __PIC__
SETUP_GP
#endif
#if FRAMESZ
PTR_SUBU sp, FRAMESZ
cfi_adjust_cfa_offset (FRAMESZ)
#endif
SETUP_GP64_STACK (GPOFF, __clone3)
#ifdef __PIC__
SAVE_GP (GPOFF)
#endif
#ifdef PROF
.set noat
move $1,ra
jal _mcount
.set at
#endif
/* Sanity check args. */
li v0, EINVAL
beqz a0, L(error) /* No NULL cl_args pointer. */
beqz a2, L(error) /* No NULL function pointer. */
#if _MIPS_SIM == _ABIO32
/* Both stack and stack_size on clone_args are defined as uint64_t, and
there is no need to handle values larger than to 32 bits for o32. */
# if __BYTE_ORDER == __BIG_ENDIAN
# define CL_STACKPOINTER_OFFSET 44
# define CL_STACKSIZE_OFFSET 52
# else
# define CL_STACKPOINTER_OFFSET 40
# define CL_STACKSIZE_OFFSET 48
# endif
/* For o32 we need to setup a minimal stack frame to allow cprestore
on __thread_start_clone3. Also there is no guarantee by kABI that
$8 will be preserved after syscall execution (so we need to save it
on the provided stack). */
lw t0, CL_STACKPOINTER_OFFSET(a0) /* Load the stack pointer. */
lw t1, CL_STACKSIZE_OFFSET(a0) /* Load the stack_size. */
addiu t1, -32 /* Update the stack size. */
addu t2, t1, t0 /* Calculate the thread stack. */
sw a3, 0(t2) /* Save argument pointer. */
sw t1, CL_STACKSIZE_OFFSET(a0) /* Save the new stack size. */
#else
move $8, a3 /* a3 is set to 0/1 for syscall success/error
while a4/$8 is returned unmodified. */
#endif
/* Do the system call, the kernel expects:
v0: system call number
a0: cl_args
a1: size */
li v0, __NR_clone3
cfi_endproc
syscall
bnez a3, L(error)
beqz v0, L(thread_start_clone3)
/* Successful return from the parent */
cfi_startproc
#if FRAMESZ
cfi_adjust_cfa_offset (FRAMESZ)
#endif
SETUP_GP64_STACK_CFI (GPOFF)
cfi_remember_state
RESTORE_GP64_STACK
#if FRAMESZ
PTR_ADDU sp, FRAMESZ
cfi_adjust_cfa_offset (-FRAMESZ)
#endif
ret
L(error):
cfi_restore_state
#ifdef __PIC__
PTR_LA t9, __syscall_error
RESTORE_GP64_STACK
PTR_ADDU sp, FRAMESZ
cfi_adjust_cfa_offset (-FRAMESZ)
jr t9
#else
RESTORE_GP64_STACK
PTR_ADDU sp, FRAMESZ
cfi_adjust_cfa_offset (-FRAMESZ)
j __syscall_error
#endif
END (__clone3)
/* 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. */
ENTRY(__thread_start_clone3)
L(thread_start_clone3):
cfi_undefined ($31)
/* cp is already loaded. */
SAVE_GP (GPOFF)
/* The stackframe has been created on entry of clone3. */
/* Restore the arg for user's function. */
move t9, a2 /* Function pointer. */
#if _MIPS_SIM == _ABIO32
PTR_L a0, 0(sp)
#else
move a0, $8 /* Argument pointer. */
#endif
/* Call the user's function. */
jal t9
move a0, v0
li v0, __NR_exit
syscall
END(__thread_start_clone3)
libc_hidden_def (__clone3)
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