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Date: Wed, 9 Sep 2015 14:31:01 +0100
From: David Vrabel <david.vrabel@citrix.com>
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To: Josh Poimboeuf <jpoimboe@redhat.com>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
        <x86@kernel.org>
CC: <linux-kernel@vger.kernel.org>, <live-patching@vger.kernel.org>,
        "Michal Marek" <mmarek@suse.cz>, Peter Zijlstra <peterz@infradead.org>,
        "Andy Lutomirski" <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andi Kleen <andi@firstfloor.org>, "Pedro Alves" <palves@redhat.com>,
        Namhyung Kim <namhyung@gmail.com>,
        "Bernd Petrovitsch" <bernd@petrovitsch.priv.at>,
        Chris J Arges <chris.j.arges@canonical.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH v12 12/21] x86/xen: Add xen_cpuid() and xen_setup_gdt()
 to stacktool whitelists
References: <cover.1441749989.git.jpoimboe@redhat.com>
 <89e3e4ceb81088e26fbc850fcb6650a0fe3553ab.1441749989.git.jpoimboe@redhat.com>
In-Reply-To: <89e3e4ceb81088e26fbc850fcb6650a0fe3553ab.1441749989.git.jpoimboe@redhat.com>
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On 09/09/15 14:21, Josh Poimboeuf wrote:
> stacktool reports the following false positive warnings:
> 
>   stacktool: arch/x86/xen/enlighten.o: xen_cpuid()+0x41: can't find jump dest instruction at .text+0x108
>   stacktool: arch/x86/xen/enlighten.o: xen_setup_gdt.constprop.23()+0x2e: kernel entry/exit from callable instruction
> 
> The first warning is due to xen_cpuid()'s use of XEN_EMULATE_PREFIX to
> insert some fake instructions which stacktool doesn't know how to
> decode.
> 
> The second warning is due to xen_setup_gdt()'s use of an lret
> instruction, which stacktool normally doesn't allow in callable
> functions.  But this seems to be a valid use of the instruction.
> 
> Add both functions to the stacktool whitelist.

Reviewed-by: David Vrabel <david.vrabel@citrix.com>

David