Re: [PATCH v4 5/6] aarch64: Add the clone3 wrapper

[Carlos O'Donell <carlos@redhat.com>]

On 1/12/23 08:58, Adhemerval Zanella wrote:
> It follow the internal signature:
> 
>   extern int clone3 (struct clone_args *__cl_args, size_t __size,
>  int (*__func) (void *__arg), void *__arg);
> 
> Checked on aarch64-linux-gnu.

OK for 2.28.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

> ---
>  sysdeps/unix/sysv/linux/aarch64/clone3.S | 85 ++++++++++++++++++++++++
>  sysdeps/unix/sysv/linux/aarch64/sysdep.h |  2 +
>  2 files changed, 87 insertions(+)
>  create mode 100644 sysdeps/unix/sysv/linux/aarch64/clone3.S
> 
> diff --git a/sysdeps/unix/sysv/linux/aarch64/clone3.S b/sysdeps/unix/sysv/linux/aarch64/clone3.S
> new file mode 100644
> index 0000000000..88a1fa1e89
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/aarch64/clone3.S
> @@ -0,0 +1,85 @@
> +/* The clone3 syscall wrapper.  Linux/aarch64 version.
> +   Copyright (C) 2023 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 <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:
> +   x0: cl_args
> +   x1: size
> +   x2: func
> +   x3: arg  */
> +
> +        .text
> +ENTRY(__clone3)
> +	PTR_ARG (0)
> +	PTR_ARG (1)
> +	PTR_ARG (3)
> +	PTR_ARG (4)
> +	/* Save args for the child.  */
> +	mov	x10, x0		/* cl_args  */
> +	mov	x11, x2		/* func	 */
> +	mov	x12, x3		/* args  */
> +
> +	/* Sanity check args.  */
> +	mov	x0, #-EINVAL
> +	cbz	x10, .Lsyscall_error	/* No NULL cl_args pointer.  */
> +	cbz	x2, .Lsyscall_error	/* No NULL function pointer.  */
> +
> +	/* Do the system call, the kernel expects:
> +	   x8: system call number
> +	   x0: cl_args
> +	   x1: size  */
> +	mov	x0, x10
> +	mov	x8, #SYS_ify(clone3)
> +	svc	0x0
> +
> +	cmp	x0, #0
> +	beq	thread_start
> +	blt	.Lsyscall_error
> +	RET
> +PSEUDO_END (__clone3)
> +
> +	.align 4
> +	.type thread_start, %function
> +thread_start:
> +	cfi_startproc
> +	cfi_undefined (x30)
> +	mov	x29, 0
> +
> +	/* Pick the function arg and execute.  */
> +	mov	x0, x12
> +	blr	x11
> +
> +	/* We are done, pass the return value through x0.  */
> +	mov	x8, #SYS_ify(exit)
> +	svc	0x0
> +	cfi_endproc
> +	.size thread_start, .-thread_start

OK.

> +
> +libc_hidden_def (__clone3)
> +weak_alias (__clone3, clone3)
> diff --git a/sysdeps/unix/sysv/linux/aarch64/sysdep.h b/sysdeps/unix/sysv/linux/aarch64/sysdep.h
> index 6520fa15da..e94d1703ad 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/aarch64/sysdep.h
> @@ -165,6 +165,8 @@
>  # define HAVE_CLOCK_GETTIME64_VSYSCALL	"__kernel_clock_gettime"
>  # define HAVE_GETTIMEOFDAY_VSYSCALL	"__kernel_gettimeofday"
>  
> +# define HAVE_CLONE3_WRAPPER		1

OK. Enables the optimizations where possible.

> +
>  # undef INTERNAL_SYSCALL_RAW
>  # define INTERNAL_SYSCALL_RAW(name, nr, args...)		\
>    ({ long _sys_result;						\

-- 
Cheers,
Carlos.