Re: [PATCH] ARM: efi: Simplify arch_efi_call_virt() macro by using typeof()

[Sudeep Holla <sudeep.holla@arm.com>]

On Tue, Jun 28, 2022 at 03:57:38PM +0200, Ard Biesheuvel wrote:
> On Tue, 28 Jun 2022 at 15:47, Sudeep Holla <sudeep.holla@arm.com> wrote:
> >
> > On Tue, Jun 28, 2022 at 03:16:26PM +0200, Ard Biesheuvel wrote:
> > > On Tue, 28 Jun 2022 at 14:59, Sudeep Holla <sudeep.holla@arm.com> wrote:
> > > >
> > > > Currently, the arch_efi_call_virt() assumes all users of it will have
> > > > defined a type 'efi_##f##_t' to make use of it. It is unnecessarily
> > > > forcing the users to create a new typedef when __efi_rt_asm_wrapper()
> > > > actually expects void pointer.
> > > >
> > > > Simplify the arch_efi_call_virt() macro by using typeof(p->f) which must
> > > > be a pointer as required by __efi_rt_asm_wrapper() and eliminate the
> > > > explicit need for efi_##f##_t type for every user of this macro.
> > > >
> > > > This change is done to align with implementations on other similar
> > > > architectures.
> > > >
> > > > Cc: Ard Biesheuvel <ardb@kernel.org>
> > > > Cc: Russell King <linux@armlinux.org.uk>
> > > > Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> > > > ---
> > > >  arch/arm/include/asm/efi.h | 3 +--
> > > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > > >
> > > > Hi,
> > > >
> > > > Reference for this change [1] and in particular[2]
> > > >
> > > > Regards,
> > > > Sudeep
> > > >
> > > > [1] https://lore.kernel.org/r/20220628125346.693304-1-sudeep.holla@arm.com
> > > > [2] https://lore.kernel.org/r/20220628125346.693304-3-sudeep.holla@arm.com/
> > > >
> > > > diff --git a/arch/arm/include/asm/efi.h b/arch/arm/include/asm/efi.h
> > > > index 27218eabbf9a..d4a405c9b4b6 100644
> > > > --- a/arch/arm/include/asm/efi.h
> > > > +++ b/arch/arm/include/asm/efi.h
> > > > @@ -26,8 +26,7 @@ int efi_set_mapping_permissions(struct mm_struct *mm, efi_memory_desc_t *md);
> > > >
> > > >  #define arch_efi_call_virt(p, f, args...)                              \
> > > >  ({                                                                     \
> > > > -       efi_##f##_t *__f;                                               \
> > > > -       __f = p->f;                                                     \
> > > > +       typeof(p->f) __f = p->f;                                        \
> > > >         __f(args);                                                      \
> > > >  })
> > > >
> > >
> > > I think this could simply be
> > >
> > > #define arch_efi_call_virt(p, f, args...) ((p)->f(args))
> > >
> > > no?
> >
> > Yes, I came to similar conclusion just after sending this out as I started to
> > look if we can have one generic definition for arm/arm64/riscv/loongarch.
> >
> 
> Not really - arm64 has the asm wrapper, and loongarch is only halfway
> merged so I'm not sure yet if this is the final form.
>

Aargh! arm64 was typo, indeed arm64 has wrapper. I meant to refer other 3 archs.

> > I am yet to figure out how asm/efi.h and linux/efi.h are included so that
> > we can have generic definition in linux/efi.h and x86 can undefine that
> > and redefine its own version.
> >
> > Does that make sense ?
> >
> 
> I appreciate the effort, but for now, let's just fix the ones we need
> to fix (and the ARM one too while we're at it). PRM can only be
> enabled on x86 and arm64 anyway.

True. OK then I will just update ARM version and leave loongarch as is.

--
Regards,
Sudeep

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