Re: [PATCH v6 1/3] arch: vDSO: Add a __vdso_getrandom prototype for all architectures

["Jason A. Donenfeld" <Jason@zx2c4.com>]

On Sun, Sep 01, 2024 at 02:13:10PM +0800, Xi Ruoyao wrote:
> Without a prototype, we'll have to add a prototype for each architecture
> implementing vDSO getrandom.  As most architectures will likely have the
> vDSO getrandom implemented in a near future, and we'd like to keep the
> declarations compatible everywhere (to ease the Glibc work), we should
> really just have one copy of the prototype.
> 
> Suggested-by: Huacai Chen <chenhuacai@kernel.org>
> Signed-off-by: Xi Ruoyao <xry111@xry111.site>
> ---
>  arch/x86/entry/vdso/vgetrandom.c | 2 --
>  include/vdso/getrandom.h         | 5 +++++
>  2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/entry/vdso/vgetrandom.c b/arch/x86/entry/vdso/vgetrandom.c
> index 52d3c7faae2e..430862b8977c 100644
> --- a/arch/x86/entry/vdso/vgetrandom.c
> +++ b/arch/x86/entry/vdso/vgetrandom.c
> @@ -6,8 +6,6 @@
>  
>  #include "../../../../lib/vdso/getrandom.c"
>  
> -ssize_t __vdso_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state, size_t opaque_len);
> -
>  ssize_t __vdso_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state, size_t opaque_len)
>  {
>  	return __cvdso_getrandom(buffer, len, flags, opaque_state, opaque_len);
> diff --git a/include/vdso/getrandom.h b/include/vdso/getrandom.h
> index 4cf02e678f5e..08b47b002bf7 100644
> --- a/include/vdso/getrandom.h
> +++ b/include/vdso/getrandom.h
> @@ -56,4 +56,9 @@ struct vgetrandom_state {
>   */
>  extern void __arch_chacha20_blocks_nostack(u8 *dst_bytes, const u32 *key, u32 *counter, size_t nblocks);
>  
> +/**
> + * __vdso_getrandom: Prototype of vDSO getrandom.
> + */
> +extern ssize_t __vdso_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state, size_t opaque_len);
> +

My inclination was that this isn't correct because arm64 uses __kernel_*
symbols instead, but it seems like arm handles that on their own, and
include/vdso/gettime.h follows this same format. So I'll queue this up,
possibly fixing up the comment.