Re: [PATCH] LoongArch: Add syscall.c for getting correct return value

[Xi Ruoyao <xry111@xry111.site>]

On Wed, 2022-11-23 at 09:57 +0800, Xing Li wrote:
> The __SYS_mmap syscall should return 47bits value. If we use
> the common syscall interface which defined in
> sysdeps/unix/sysv/linux/syscall.c, the syscall return value
> is 32bits with sign extend, which lead to mmap failure.

Could we just change

int r = INTERNAL_SYSCALL_NCS_CALL (number, a0, a1, a2, a3, a4, a5);

in sysdeps/unix/sysv/linux/syscall.c to "long r = ..." instead?

> 
> Testcase:
> 
>  #include <sys/syscall.h>
>  #include <sys/mman.h>
>  #include <stdio.h>
> 
> void main()
> {
>         long int ret;
>         ret = syscall(SYS_mmap, NULL, 0x801000, PROT_READ |
> PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
>         printf("map address is %lx\n",ret);
> }
> 
> Result:
> [lixing@Sunhaiyong test]$ ./mmap
> map address is fffffffff008c000
> 
>        * sysdeps/unix/sysv/linux/loongarch/syscall.c: New file
> ---
>  sysdeps/unix/sysv/linux/loongarch/syscall.c | 34
> +++++++++++++++++++++
>  1 file changed, 34 insertions(+)
>  create mode 100644 sysdeps/unix/sysv/linux/loongarch/syscall.c
> 
> diff --git a/sysdeps/unix/sysv/linux/loongarch/syscall.c
> b/sysdeps/unix/sysv/linux/loongarch/syscall.c
> new file mode 100644
> index 0000000000..fe9672a403
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/loongarch/syscall.c
> @@ -0,0 +1,34 @@
> +/* system call interface.  Linux/LoongArch version.
> +   Copyright (C) 2001-2022 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>
> +
> +long int
> +syscall (long int syscall_number, long int arg1, long int arg2, long
> int arg3,
> +        long int arg4, long int arg5, long int arg6, long int arg7)
> +{
> +  long int ret;
> +
> +  ret = INTERNAL_SYSCALL_NCS_CALL (syscall_number, arg1, arg2, arg3,
> arg4,
> +                                  arg5, arg6, arg7);
> +
> +  if (INTERNAL_SYSCALL_ERROR_P (ret))
> +    return __syscall_error (ret);
> +
> +  return ret;
> +}

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University