linux-kernel - Re: [PATCH v3 1/7] x86/boot/compressed: Move .got.plt entries out of the .got section

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Message-ID: <20200629155011.GA900899@rani.riverdale.lan>
Date:   Mon, 29 Jun 2020 11:50:11 -0400
From:   Arvind Sankar <nivedita@...m.mit.edu>
To:     Kees Cook <keescook@...omium.org>
Cc:     Arvind Sankar <nivedita@...m.mit.edu>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Fangrui Song <maskray@...gle.com>,
        Dmitry Golovin <dima@...ovin.in>,
        clang-built-linux@...glegroups.com,
        Ard Biesheuvel <ardb@...nel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Daniel Kiper <daniel.kiper@...cle.com>,
        Sedat Dilek <sedat.dilek@...il.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        "H . J . Lu" <hjl@...rceware.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/7] x86/boot/compressed: Move .got.plt entries out of
 the .got section

On Mon, Jun 29, 2020 at 08:48:05AM -0700, Kees Cook wrote:
> On Mon, Jun 29, 2020 at 10:09:22AM -0400, Arvind Sankar wrote:
> 
> This is also being done on arm64, and the section was specified slightly
> differently (with INFO) which maybe should be done here too?

I was actually just about to email you to ask what that INFO is for :)
What does it do?

> 
>        .got.plt (INFO) : { *(.got.plt) }
>        ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0x18, ".got.plt not empty")
> 
> Otherwise, yes, looks good.
> 
> Reviewed-by: Kees Cook <keescook@...omium.org>
> 
> > +
> >  	.data :	{
> >  		_data = . ;
> >  		*(.data)
> > @@ -77,3 +80,9 @@ SECTIONS
> >  
> >  	DISCARDS
> >  }
> > +
> > +#ifdef CONFIG_X86_64
> > +ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0x18, "Unexpected GOT/PLT entries detected!")
> > +#else
> > +ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0xc, "Unexpected GOT/PLT entries detected!")
> > +#endif
> > -- 
> > 2.26.2
> > 
> 
> -- 
> Kees Cook