linux-kernel - Re: [PATCH v1 06/19] perf/x86/intel/ds: Check insn_get

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Message-ID: <20210119104007.GE27433@zn.tnic>
Date:   Tue, 19 Jan 2021 11:40:07 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Andy Lutomirski <luto@...capital.net>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 06/19] perf/x86/intel/ds: Check insn_get_length()
 retval

On Mon, Jan 04, 2021 at 02:19:19PM +0100, Peter Zijlstra wrote:
> Do we really still need the !insn.length? That is, it *should* be
> impossible to not fail insn_get_length() and still have a 0 length,
> seeing how x86 doesn't have 0 length instructions.

I was responding to the "doubly important" thing in the comment scarying
me about an infinite loop and thus left the length check in, in case
the insn decoder would have a bug and return success but still have
insn.length 0.

With the length check the endless loop won't happen but let's be
brave here ... :-)

So removed.

-- 
Regards/Gruss,
    Boris.

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