linux-kernel - Re: [PATCH 1/4] x86, efi, kasan: #undef memset/memcpy/memmove per arch.

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Date:	Fri, 28 Aug 2015 09:39:41 +0100
From:	Leif Lindholm <leif.lindholm@...aro.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	Will Deacon <will.deacon@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	linux-arm-kernel@...ts.infradead.org,
	Matt Fleming <matt.fleming@...el.com>,
	linux-efi@...r.kernel.org,
	Linus Walleij <linus.walleij@...aro.org>,
	Alexander Potapenko <glider@...gle.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>
Subject: Re: [PATCH 1/4] x86, efi, kasan: #undef memset/memcpy/memmove per
 arch.

On Fri, Aug 28, 2015 at 08:27:45AM +0200, Ingo Molnar wrote:
> 
> * Andrey Ryabinin <ryabinin.a.a@...il.com> wrote:
> 
> > In not-instrumented code KASAN replaces instrumented
> > memset/memcpy/memmove with not-instrumented analogues
> > __memset/__memcpy/__memove.
> > However, on x86 EFI stub is not linked with kernel.
> 
> s/with the kernel
> 
> > It uses not-instrumented mem*() functions from
> > arch/x86/boot/compressed/string.c
> > So we don't replace them with __mem*() variants in EFI stub.
> > 
> > In ARM64 EFI stub is linked with the kernel, so we should
> 
> s/In ARM64 EFI stub/On ARM64 the EFI stub/.
> 
> > replace mem*() functions with __mem*(), because EFI stub
> 
> s/the EFI stub
> 
> > runs before KASAN setup early shadow.
> 
> s/before KASAN sets up the early shadow
> 
> ?
> 
> > So let's move these #undef mem* into arch's asm/efi.h which is
> 
> s/lets

No, that one is actually correct. Abbreviation of let us.
 
> > also included by EFI stub.
> 
> s/by the EFI stub
> 
> > 
> > Signed-off-by: Andrey Ryabinin <ryabinin.a.a@...il.com>
> > ---
> >  arch/x86/include/asm/efi.h             | 8 ++++++++
> >  drivers/firmware/efi/libstub/efistub.h | 4 ----
> >  2 files changed, 8 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
> > index 155162e..d821ce2 100644
> > --- a/arch/x86/include/asm/efi.h
> > +++ b/arch/x86/include/asm/efi.h
> > @@ -25,6 +25,14 @@
> >  #define EFI32_LOADER_SIGNATURE	"EL32"
> >  #define EFI64_LOADER_SIGNATURE	"EL64"
> >  
> > +/*
> > + * Use memcpy/memset from arch/x86/boot/compressed/string.c
> > + * for EFI stub.
> > + */
> > +#undef memcpy
> > +#undef memset
> > +#undef memmove
> 
> This comment should also mention why it's done, not what is done.
> 
> Also:
> 
>     s/for EFI stub/for the EFI stub
> 
> Thanks,
> 
> 	Ingo
> --
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