linux-kernel - Re: [PATCH v3 1/6] x86/mm/KASLR: Improve code comments about struct kaslr_memory

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Message-ID: <20190312005534.GK21116@MiWiFi-R3L-srv>
Date:   Tue, 12 Mar 2019 08:55:34 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>, X86 ML <x86@...nel.org>,
        Mike Travis <travis@....com>,
        Thomas Garnier <thgarnie@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>
Subject: Re: [PATCH v3 1/6] x86/mm/KASLR: Improve code comments about struct
 kaslr_memory_region

On 02/17/19 at 09:07am, Kees Cook wrote:
> > + * E.g the physical memory region, we limit the starting address to be
> > + * taken from the 1st 1/3 part of the whole available virtual address
> > + * space which is from 0xffff880000000000 to 0xfffffe0000000000, namely
> > + * the original starting address of the physical memory mapping region
> > + * to the starting address of cpu_entry_area mapping region. Once a random
> > + * address is chosen for the physical memory mapping, we jump over the
> > + * region and add 1G to begin the next region handling with the remaining
> > + * available space.
> 
> Should the "operation" comments (rather than the struct field
> comments) be moved to the start of the kernel_randomize_memory()
> function instead?

Rethink about this, I think you are right. This paragraph better be
moved to above kernel_randomize_memory(), to explain its behaviour.
Will update and repost. Thanks.

Thanks
Baoquan

> 
> >   */
> > +
> >  static __initdata struct kaslr_memory_region {
> >         unsigned long *base;
> >         unsigned long size_tb;
> > --
> > 2.17.2
> >
> 
> 
> -- 
> Kees Cook