linux-kernel - Re: [PATCH] x86: perf: insn: Tweak opcode map for Intel CET instructions

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Date:   Thu, 26 Mar 2020 11:57:26 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     "Hunter, Adrian" <adrian.hunter@...el.com>
Cc:     Arnaldo Carvalho de Melo <acme@...hat.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mingbo Zhang <whensungoes@...il.com>,
        "x86@...nel.org" <x86@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, Andi Kleen <ak@...ux.intel.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: perf: insn: Tweak opcode map for Intel CET
 instructions

Em Thu, Mar 26, 2020 at 02:19:07PM +0000, Hunter, Adrian escreveu:
> > -----Original Message-----
> > From: Arnaldo Carvalho de Melo <acme@...hat.com>
> > Sent: Thursday, March 26, 2020 3:56 PM
> > To: Hunter, Adrian <adrian.hunter@...el.com>
> > Cc: Masami Hiramatsu <mhiramat@...nel.org>; Mingbo Zhang
> > <whensungoes@...il.com>; Arnaldo Carvalho de Melo
> > <acme@...nel.org>; x86@...nel.org; Thomas Gleixner
> > <tglx@...utronix.de>; Ingo Molnar <mingo@...hat.com>; Borislav Petkov
> > <bp@...en8.de>; H. Peter Anvin <hpa@...or.com>; Andi Kleen
> > <ak@...ux.intel.com>; Josh Poimboeuf <jpoimboe@...hat.com>; linux-
> > kernel@...r.kernel.org
> > Subject: Re: [PATCH] x86: perf: insn: Tweak opcode map for Intel CET
> > instructions
> > 
> > Em Thu, Mar 26, 2020 at 07:09:45AM +0200, Adrian Hunter escreveu:
> > > On 26/03/20 3:31 am, Masami Hiramatsu wrote:
> > > > Hi,
> > > >
> > > > On Mon,  2 Mar 2020 23:50:30 -0500
> > > > Mingbo Zhang <whensungoes@...il.com> wrote:
> > > >
> > > >> Intel CET instructions are not described in the Intel SDM. When
> > > >> trying to get the instruction length, the following instructions
> > > >> get wrong (missing ModR/M byte).
> > > >>
> > > >> RDSSPD r32
> > > >> RSDDPQ r64
> > > >> ENDBR32
> > > >> ENDBR64
> > > >> WRSSD r/m32, r32
> > > >> WRSSQ r/m64, r64
> > > >>
> > > >> RDSSPD/Q and ENDBR32/64 use the same opcode (f3 0f 1e) slot, which
> > > >> is described in SDM as Reserved-NOP with no encoding characters,
> > > >> and got an empty slot in the opcode map. WRSSD/Q (0f 38 f6) also got
> > an empty slot.
> > > >>
> > > >
> > > > This looks good to me. BTW, wouldn't we need to add decode test cases
> > to perf?
> > > >
> > > > Acked-by: Masami Hiramatsu <mhiramat@...nel.org>
> > > >
> > > > Thank you,
> > > >
> > >
> > > We have correct patches that you ack'ed for CET here:
> > >
> > >
> > > https://lore.kernel.org/lkml/20200204171425.28073-1-yu-cheng.yu@intel.
> > > com/
> > >
> > > But they have not yet been applied.
> > >
> > > Sorry for the confusion.
> > 
> > I'll collect them, thanks for pointing this out.
> 
> The patches are in tip courtesy of Borislav Petkov thank you!

Ok, thanks Borislav,

- Arnaldo