Re: [PATCH 8/8] membarrier: Rewrite sync_core_before_usermode() and improve documentation

[Christophe Leroy]

Le 16/06/2021 à 20:52, Andy Lutomirski a écrit :
> On 6/15/21 9:45 PM, Nicholas Piggin wrote:
> > Excerpts from Andy Lutomirski's message of June 16, 2021 1:21 pm:
> > > The old sync_core_before_usermode() comments suggested that a non-icache-syncing
> > > return-to-usermode instruction is x86-specific and that all other
> > > architectures automatically notice cross-modified code on return to
> > > userspace.
>
> > > +/*
> > > + * XXX: can a powerpc person put an appropriate comment here?
> > > + */
> > > +static inline void membarrier_sync_core_before_usermode(void)
> > > +{
> > > +}
> > > +
> > > +#endif /* _ASM_POWERPC_SYNC_CORE_H */
> >
> > powerpc's can just go in asm/membarrier.h
>
> $ ls arch/powerpc/include/asm/membarrier.h
> ls: cannot access 'arch/powerpc/include/asm/membarrier.h': No such file
> or directory

https://github.com/torvalds/linux/blob/master/arch/powerpc/include/asm/membarrier.h


Was added by https://github.com/torvalds/linux/commit/3ccfebedd8cf54e291c809c838d8ad5cc00f5688

> > /*
> >   * The RFI family of instructions are context synchronising, and
> >   * that is how we return to userspace, so nothing is required here.
> >   */
>
> Thanks!