# Re: \[PATCH v2 16/17\] selftests: vdso: Make VDSO function call more generic

- From: Jason A. Donenfeld \<Jason@zx2c4.com\>
- Date: 2024-08-26 07:38:09 
- List: linux-trace-kernel
- Page: https://ratatoskr.run/linux-trace-kernel/2024/08/290075
- Thread: https://ratatoskr.run/linuxppc-dev/2024/08/289625/t.md

```text
On Thu, Aug 22, 2024 at 09:13:24AM +0200, Christophe Leroy wrote:
> On powerpc, a call to a VDSO function is not a standard C function
> call. Unlike x86 that returns a negated error code in case of an
> error, powerpc sets CR[SO] and returns the error code as a
> positive value.
> 
> So use a macro called VDSO_CALL() which takes a pointer to the
> function to call, the number of arguments and the arguments.
 
You'll probably want to move to VDSO_CALL() for the whole test suite,
not just the getrandom one, right?
```