linux-kernel - Re: [PATCH 17/29] x86/ibt: Annotate text references

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20220219052216.7b5fx6qileqrdjbw@treble>
Date:   Fri, 18 Feb 2022 21:22:16 -0800
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, joao@...rdrivepizza.com, hjl.tools@...il.com,
        andrew.cooper3@...rix.com, linux-kernel@...r.kernel.org,
        ndesaulniers@...gle.com, keescook@...omium.org,
        samitolvanen@...gle.com, mark.rutland@....com,
        alyssa.milburn@...el.com
Subject: Re: [PATCH 17/29] x86/ibt: Annotate text references

On Fri, Feb 18, 2022 at 05:49:19PM +0100, Peter Zijlstra wrote:
> Annotate away some of the generic code references. This is things
> where we take the address of a symbol for exception handling or return
> addresses (eg. context switch).
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

The vast majority of these annotations can go away if objtool only
requires ENDBR for referenced *STT_FUNC* symbols.

Anything still needing ANNOTATE_NOENDBR after that, might arguably not
belong as STT_FUNC anyway and it might make sense to convert it to
non-function code (e.g. SYM_CODE{START,END}.

> @@ -564,12 +565,16 @@ SYM_CODE_END(\asmsym)
>  	.align 16
>  	.globl __irqentry_text_start
>  __irqentry_text_start:
> +	ANNOTATE_NOENDBR // unwinders
> +	ud2;
>  
>  #include <asm/idtentry.h>
>  
>  	.align 16
>  	.globl __irqentry_text_end
>  __irqentry_text_end:
> +	ANNOTATE_NOENDBR
> +	ud2;

Why ud2?  If no ud2 then the annotation shouldn't be needed since the
first idt entry has ENDBR.

-- 
Josh