diff mbox series

[1/3] arm64: efi: Simplify arch_efi_call_virt macro by not using efi_##f##_t type

Message ID 20220624152331.4009502-2-sudeep.holla@arm.com
State New
Headers show
Series ACPI: Enable Platform Runtime Mechanism(PRM) support on ARM64 | expand

Commit Message

Sudeep Holla June 24, 2022, 3:23 p.m. UTC
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 typecasting p->f to (void *)
as required by __efi_rt_asm_wrapper() and eliminate the explicit need
for efi_##f##_t type for every user of this macro.

This is needed now in preparation to enable PRMT support on ARM64.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
 arch/arm64/include/asm/efi.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

Hi Ard,

I am not sure if you prefer to add type for each users of this or this
is acceptable. I see only compile time advantage but I am not sure if
it make sense to add typedefs in ACPI PRMT driver just for this reason.

Let me know.

Regards,
Sudeep

Comments

Sudeep Holla June 25, 2022, 10:10 a.m. UTC | #1
On Fri, Jun 24, 2022 at 07:45:14PM +0200, Ard Biesheuvel wrote:
> On Fri, 24 Jun 2022 at 17:23, 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 typecasting p->f to (void *)
> > as required by __efi_rt_asm_wrapper() and eliminate the explicit need
> > for efi_##f##_t type for every user of this macro.
> >
>
> Can't we just use typeof() here?

I had tried that, but unless p->f is pointer of some type, we will get
the warning as it is passed without a cast to __efi_rt_asm_wrapper().

> __efi_rt_asm_wrapper() was intended as a temporary thing, so I'd
> prefer to avoid starting to rely on the void* type of its first
> argument.
>

Fair enough. Can we expect p->f to be some pointer then ? If yes, then
PRMT driver needs to change the handler_addr from u64 to some pointer
which sounds OK to me.

--
Regards,
Sudeep
Ard Biesheuvel June 25, 2022, 4:01 p.m. UTC | #2
On Sat, 25 Jun 2022 at 12:11, Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> On Fri, Jun 24, 2022 at 07:45:14PM +0200, Ard Biesheuvel wrote:
> > On Fri, 24 Jun 2022 at 17:23, 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 typecasting p->f to (void *)
> > > as required by __efi_rt_asm_wrapper() and eliminate the explicit need
> > > for efi_##f##_t type for every user of this macro.
> > >
> >
> > Can't we just use typeof() here?
>
> I had tried that, but unless p->f is pointer of some type, we will get
> the warning as it is passed without a cast to __efi_rt_asm_wrapper().
>
> > __efi_rt_asm_wrapper() was intended as a temporary thing, so I'd
> > prefer to avoid starting to rely on the void* type of its first
> > argument.
> >
>
> Fair enough. Can we expect p->f to be some pointer then ? If yes, then
> PRMT driver needs to change the handler_addr from u64 to some pointer
> which sounds OK to me.
>

We are dealing with function pointers here, so passing those as u64 is
just sloppy.
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index ad55079abe47..263d7fd67207 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -29,9 +29,7 @@  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;							\
-	__efi_rt_asm_wrapper(__f, #f, args);				\
+	__efi_rt_asm_wrapper((void *)p->f, #f, args);			\
 })
 
 #define arch_efi_call_virt_teardown()					\