linux-kernel - Re: [PATCH v5 00/15] powerpc/objtool: uaccess validation for PPC32 (v5)

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Message-ID: <92e889d2-b883-41fe-b75f-1909ac23f5e2@csgroup.eu>
Date: Thu, 16 Jan 2025 07:25:35 +0100
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Josh Poimboeuf <jpoimboe@...nel.org>,
 Peter Zijlstra <peterz@...radead.org>, Nathan Chancellor
 <nathan@...nel.org>, Nick Desaulniers <ndesaulniers@...gle.com>,
 Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>,
 Julien Thierry <jthierry@...hat.com>, Miroslav Benes <mbenes@...e.cz>,
 Raphael Gault <raphael.gault@....com>, Michael Ellerman
 <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
 Naveen N Rao <naveen@...nel.org>, Madhavan Srinivasan <maddy@...ux.ibm.com>
Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
 llvm@...ts.linux.dev
Subject: Re: [PATCH v5 00/15] powerpc/objtool: uaccess validation for PPC32
 (v5)



Le 15/01/2025 à 23:42, Christophe Leroy a écrit :
> This series adds UACCESS validation for PPC32. It includes
> a dozen of changes to objtool core.
> 
> It applies on top of series "Cleanup/Optimise KUAP (v3)"
> https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=363368&state=*

I forgot to remove that sentence. That was merged long time ago so the 
series doesn't have any dependency anymore, it applies as standalone on 
top of git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git branch 
tip/objtool/core (HEAD 41a1e976623e ("x86/mm: Convert unreachable() to 
BUG()"))

> 
> It is almost mature, performs code analysis for all PPC32.
> 
> In this version objtool switch table lookup has been enhanced to
> handle nested switch tables.
> 
> Most object files are correctly decoded, only a few
> 'unreachable instruction' warnings remain due to more complex
> fonctions which include back and forth jumps or branches. Two types
> of switch tables are missed at the time being:
> - When switch table address is temporarily saved in the stack before
> being used.
> - When there are backwards jumps in the path.
> 
> It allowed to detect some UACCESS mess in a few files. They've been
> fixed through other patches.
> 
> Changes in v5:
> - Rebased on top of https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git branch tip/objtool/core
> - Use generic annotation infrastructure to annotate uaccess begin and end instructions
>