On Mon, May 04, 2020 at 10:05:23AM +0200, Ard Biesheuvel wrote:
> On Mon, 4 May 2020 at 02:38, Arvind Sankar <nivedita@xxxxxxxxxxxx> wrote:
> >
> > Commit
> > 22090f84bc3f ("efi/libstub: unify EFI call wrappers for non-x86")
> >
> > refactored the macros that are used to provide wrappers for mixed-mode
> > calls on x86, allowing us to boot a 64-bit kernel on 32-bit firmware.
> >
> > Unfortunately, this broke mixed mode boot due to the fact that
> > efi_is_native() is not a macro on x86.
> >
> > Fix this by conditioning the generic macro definitions on
> > CONFIG_EFI_MIXED, and removing the wrapper definitions on x86 if
> > CONFIG_EFI_MIXED is not enabled.
> >
> > Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> > Signed-off-by: Arvind Sankar <nivedita@xxxxxxxxxxxx>
>
> Thanks Arvind.
>
> Currently, CONFIG_EFI_MIXED is never referenced outside of arch/x86,
> and I prefer to keep it that way.
All these macros go together though -- they should either all be defined
or none, so it makes sense to put them under a single #if. If you think
it's possible that a future architecture might need the wrappers but not
be mixed, we could maybe add an ARCH_NEEDS_EFISTUB_WRAPPERS?
>
> Also, I fail to see where the definition of efi_is_native() comes from
> after applying this patch.
The generic definition is in the same place -- I just moved it to the
top as it's a predicate rather than a wrapper, and kept all the actual
wrappers together.
> > diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
> > index 874233cf8820..37ca286a40c6 100644
> > --- a/drivers/firmware/efi/libstub/efistub.h
> > +++ b/drivers/firmware/efi/libstub/efistub.h
> > @@ -33,20 +33,14 @@ extern bool efi_novamap;
> >
> > extern const efi_system_table_t *efi_system_table;
> >
> > -#ifndef efi_bs_call
> > +#ifndef CONFIG_EFI_MIXED
> > +
> > +#define efi_is_native() (true)
> > #define efi_bs_call(func, ...) efi_system_table->boottime->func(__VA_ARGS__)
> > -#endif
> > -#ifndef efi_rt_call
> > #define efi_rt_call(func, ...) efi_system_table->runtime->func(__VA_ARGS__)
> > -#endif
> > -#ifndef efi_is_native
> > -#define efi_is_native() (true)
> > -#endif
> > -#ifndef efi_table_attr
> > #define efi_table_attr(inst, attr) (inst->attr)
> > -#endif
> > -#ifndef efi_call_proto
> > #define efi_call_proto(inst, func, ...) inst->func(inst, ##__VA_ARGS__)
> > +
> > #endif
> >
> > #define efi_info(msg) do { \
> > --
> > 2.26.2
> >
