linux-kernel - Re: [PATCH 1/3] Convert efi_call_virt to efi_call_virt

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Date:	Thu, 2 Jun 2016 16:41:14 +0100
From:	Matt Fleming <matt@...eblueprint.co.uk>
To:	Alex Thorlton <athorlton@....com>
Cc:	linux-kernel@...r.kernel.org, Borislav Petkov <bp@...e.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Mike Travis <travis@....com>,
	Russ Anderson <rja@....com>,
	Dimitri Sivanich <sivanich@....com>, x86@...nel.org,
	linux-efi@...r.kernel.org, Mark Rutland <mark.rutland@....com>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: Re: [PATCH 1/3] Convert efi_call_virt to efi_call_virt_generic

On Wed, 18 May, at 02:11:39PM, Alex Thorlton wrote:
> This commit makes a few slight modifications to the efi_call_virt macro
> to get it to work with function pointers that are stored in locations
> other than efi.systab->runtime, and renames the macro to
> efi_call_virt_generic.  The majority of the changes here are to pull
> these macros up into header files so that they can be accessed from
> outside of drivers/firmware/efi/runtime-wrappers.c.
> 
> The most significant change not directly related to the code move is to
> add an extra "p" argument into the appropriate efi_call macros, and use
> that new argument in place of the, formerly hard-coded,
> efi.systab->runtime pointer.
> 
> The last piece of the puzzle was to add an efi_call_virt macro back into
> drivers/firmware/efi/runtime-wrappers.c to wrap around the new
> efi_call_virt_generic macro - this was mainly to keep the code from
> looking too cluttered by adding a bunch of extra references to
> efi.systab->runtime everywhere.
> 
> Note that I also broke up the code in the efi_call_virt_generic macro a
> bit in the process of moving it.
> 
> Signed-off-by: Alex Thorlton <athorlton@....com>
> Cc: Matt Fleming <matt@...eblueprint.co.uk>
> Cc: Borislav Petkov <bp@...e.de>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: Mike Travis <travis@....com>
> Cc: Russ Anderson <rja@....com>
> Cc: Dimitri Sivanich <sivanich@....com>
> Cc: x86@...nel.org
> Cc: linux-efi@...r.kernel.org
> ---
>  arch/x86/include/asm/efi.h              |  4 +--
>  drivers/firmware/efi/runtime-wrappers.c | 53 +++++++--------------------------
>  include/linux/efi.h                     | 51 +++++++++++++++++++++++++++++++
>  3 files changed, 63 insertions(+), 45 deletions(-)
> 
> diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
> index 78d1e74..f310f0b 100644
> --- a/arch/x86/include/asm/efi.h
> +++ b/arch/x86/include/asm/efi.h
> @@ -81,8 +81,8 @@ struct efi_scratch {
>  	}								\
>  })
>  
> -#define arch_efi_call_virt(f, args...)					\
> -	efi_call((void *)efi.systab->runtime->f, args)			\
> +#define arch_efi_call_virt(p, f, args...)					\
> +	efi_call((void *)p->f, args)			\
>  
>  #define arch_efi_call_virt_teardown()					\
>  ({									\

Oops, you're missing updates to the 32-bit version and ARM/arm64,
which results in this,

drivers/firmware/efi/runtime-wrappers.c: In function ‘virt_efi_get_time’:
arch/x86/include/asm/efi.h:46:4: error: ‘efi_efi’ undeclared (first use in this function)
  ((efi_##f##_t __attribute__((regparm(0)))*)   \
    ^

but that's easily fixed up.

> diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
> index 23bef6b..e8bc493 100644
> --- a/drivers/firmware/efi/runtime-wrappers.c
> +++ b/drivers/firmware/efi/runtime-wrappers.c
> @@ -22,7 +22,16 @@
>  #include <linux/stringify.h>
>  #include <asm/efi.h>
>  
> -static void efi_call_virt_check_flags(unsigned long flags, const char *call)
> +/*
> + * Wrap around the new efi_call_virt_generic macros so that the
> + * code doesn't get too cluttered
> + */
> +#define efi_call_virt(f, args...)   \
> +	efi_call_virt_generic(efi.systab->runtime, f, args)
> +#define __efi_call_virt(f, args...) \
> +	__efi_call_virt_generic(efi.systab->runtime, f, args)
> +
> +void efi_call_virt_check_flags(unsigned long flags, const char *call)
>  {
>  	unsigned long cur_flags, mismatch;
>  

I'm not crazy about using "generic" in the name. How about
efi_call_virt_function() or efi_call_virt_pointer()?