Fix RISC-V vfork build with Linux 5.3 kernel headers

[Alistair Francis]

On Tue, Sep 17, 2019 at 3:15 PM Joseph Myers <joseph@codesourcery.com> wrote:
>
> Building glibc for RISC-V with Linux 5.3 kernel headers fails because
> <linux/sched.h>, included in vfork.S for CLONE_* constants, contains a
> structure definition not safe for inclusion in assembly code.
>
> All other architectures already avoid use of that header in vfork.S,
> either defining the CLONE_* constants locally or embedding the
> required values directly in the relevant instruction, where they
> implement vfork using the clone syscall (see the implementations for
> aarch64, ia64, mips and nios2).  This patch makes the RISC-V version
> define the constants locally like the other architectures.
>
> Tested build for all three RISC-V configurations in
> build-many-glibcs.py with Linux 5.3 headers.

LGTM.

I was confused why I haven't seen this, but I'm using the 5.2 headers
which is why I haven't hit this.

Alistair

>
> 2019-09-17  Joseph Myers  <joseph@codesourcery.com>
>
>         * sysdeps/unix/sysv/linux/riscv/vfork.S: Do not include
>         <linux/sched.h>.
>         (CLONE_VM): New macro.
>         (CLONE_VFORK): Likewise.
>
> diff --git a/sysdeps/unix/sysv/linux/riscv/vfork.S b/sysdeps/unix/sysv/linux/riscv/vfork.S
> index e68dbc7d5d..062a562e72 100644
> --- a/sysdeps/unix/sysv/linux/riscv/vfork.S
> +++ b/sysdeps/unix/sysv/linux/riscv/vfork.S
> @@ -21,9 +21,12 @@
>  #include <sys/asm.h>
>  #include <sysdep.h>
>  #define __ASSEMBLY__
> -#include <linux/sched.h>
>  #include <asm/signal.h>
>
> +#define CLONE_VM      0x00000100 /* Set if VM shared between processes.  */
> +#define CLONE_VFORK   0x00004000 /* Set if the parent wants the child to
> +                                   wake it up on mm_release.  */
> +
>         .text
>  LEAF (__libc_vfork)
>
>
> --
> Joseph S. Myers
> joseph@codesourcery.com