linux-kernel - Re: kexec, x86/purgatory: Cleanup the unholy mess

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Message-ID: <1489153665.4410.4.camel@gmx.de>
Date:   Fri, 10 Mar 2017 14:47:45 +0100
From:   Mike Galbraith <efault@....de>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>
Cc:     "Tobin C. Harding" <me@...in.cc>,
        LKML <linux-kernel@...r.kernel.org>,
        Nicholas Mc Guire <der.herr@...r.at>,
        Vivek Goyal <vgoyal@...hat.com>, x86@...nel.org
Subject: Re: kexec, x86/purgatory: Cleanup the unholy mess

On Fri, 2017-03-10 at 13:17 +0100, Thomas Gleixner wrote:
> The purgatory code defines global variables which are referenced via a
> symbol lookup in the kexec code (core and arch).
> 
> A recent commit addressing sparse warning made these static and thereby
> broke kexec file.
> 
> Why did this happen? Simply because the whole machinery is undocumented and
> lacks any form of forward declarations. The variable names are unspecific
> and lack a prefix, so adding forward declarations creates shadow variables
> in the core code. Aside of that the code relies on magic constants and
> duplicate struct definitions with no way to ensure that these things stay
> in sync.
> 
> Unbreak kexec and cleanup the mess by:
> 
>  - Adding proper forward declarations and document the usage
>  - Use the proper common defines instead of magic constants
>  - Add a purgatory_ prefix to have a proper name space
>  - Use ARRAY_SIZE() instead of a homebrewn reimplementation
> 
> Fixes: 72042a8c7b01 ("x86/purgatory: Make functions and variables static")

Well, almost fixes.

[   15.118820] kexec: symbol 'purgatory_sha_regions' in common section
[   15.119187] kexec-bzImage64: Loading purgatory failed

	-Mike