On 07/02/2020 12:39, Thomas Gleixner wrote:
> From: Christophe Leroy <christophe.leroy@c-s.fr>
> 
> On powerpc, __arch_get_vdso_data() clobbers the link register, requiring
> the caller to save it.
> 
> As the parent function already has to set a stack frame and saves the link
> register before calling the C vdso function, retrieving the vdso data
> pointer there is less overhead.
> 
> Split out the functional code from the __cvdso.*() interfaces into new
> static functions which can either be called from the existing interfaces
> with the vdso data pointer supplied via __arch_get_vdso_data() or directly
> from ASM code.
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Link: https://lore.kernel.org/r/abf97996602ef07223fec30c005df78e5ed41b2e.1580399657.git.christophe.leroy@c-s.fr
> 
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>

[...]

-- 
Regards,
Vincenzo