Re: [PATCH 1/1] efi/libstub: Fix mixed mode boot issue after macro refactor

[Ard Biesheuvel <ardb@kernel.org>]

On Mon, 4 May 2020 at 02:38, Arvind Sankar <nivedita@alum.mit.edu> 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@roeck-us.net>
> Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>

Thanks Arvind.

Currently, CONFIG_EFI_MIXED is never referenced outside of arch/x86,
and I prefer to keep it that way.

Also, I fail to see where the definition of efi_is_native() comes from
after applying this patch.



> ---
>  arch/x86/include/asm/efi.h             | 17 +++++++++++++----
>  drivers/firmware/efi/libstub/efistub.h | 14 ++++----------
>  2 files changed, 17 insertions(+), 14 deletions(-)
>
> diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
> index cd0c3fbf6156..88f29f84a4d0 100644
> --- a/arch/x86/include/asm/efi.h
> +++ b/arch/x86/include/asm/efi.h
> @@ -225,13 +225,13 @@ efi_status_t efi_set_virtual_address_map(unsigned long memory_map_size,
>
>  /* arch specific definitions used by the stub code */
>
> -extern const bool efi_is64;
> +#ifdef CONFIG_EFI_MIXED
>
>  static inline bool efi_is_64bit(void)
>  {
> -       if (IS_ENABLED(CONFIG_EFI_MIXED))
> -               return efi_is64;
> -       return IS_ENABLED(CONFIG_X86_64);
> +       extern const bool efi_is64;
> +
> +       return efi_is64;
>  }
>
>  static inline bool efi_is_native(void)
> @@ -356,6 +356,15 @@ static inline u32 efi64_convert_status(efi_status_t status)
>                                                    runtime),            \
>                                     func, __VA_ARGS__))
>
> +#else /* CONFIG_EFI_MIXED */
> +
> +static inline bool efi_is_64bit(void)
> +{
> +       return IS_ENABLED(CONFIG_X86_64);
> +}
> +
> +#endif /* CONFIG_EFI_MIXED */
> +
>  extern bool efi_reboot_required(void);
>  extern bool efi_is_table_address(unsigned long phys_addr);
>
> 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
>