From: Masami Hiramatsu <mhiramat@kernel•org>
To: Randy Dunlap <rdunlap@infradead•org>
Cc: Stephen Rothwell <sfr@canb•auug.org.au>,
Linux Next Mailing List <linux-next@vger•kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger•kernel.org>,
Josh Poimboeuf <jpoimboe@redhat•com>,
Masami Hiramatsu <mhiramat@redhat•com>, X86 ML <x86@kernel•org>,
Ingo Molnar <mingo@redhat•com>,
Thomas Gleixner <tglx@linutronix•de>
Subject: Re: linux-next: Tree for Oct 14 (insn_decoder_test)
Date: Wed, 22 Jan 2020 12:11:49 +0900 [thread overview]
Message-ID: <20200122121149.5f0090760c8c51651eca88de@kernel.org> (raw)
In-Reply-To: <aab93029-158a-5554-9976-b20aa48fef1d@infradead.org>
On Tue, 21 Jan 2020 07:43:16 -0800
Randy Dunlap <rdunlap@infradead•org> wrote:
> [adding x86 people]
>
> I am still seeing this insn_decoder warning in linux-next.
>
> Can we get this patch applied, please?
>
> Masami, you might need to resend it...
OK, I'll resend it.
Thank you for pinging!
>
> thanks.
>
>
> On 11/27/19 4:04 PM, Randy Dunlap wrote:
> > On 10/22/19 10:49 PM, Masami Hiramatsu wrote:
> >> Hi,
> >>
> >> On Mon, 14 Oct 2019 08:30:02 -0700
> >> Randy Dunlap <rdunlap@infradead•org> wrote:
> >>
> >>> On 10/13/19 11:47 PM, Stephen Rothwell wrote:
> >>>> Hi all,
> >>>>
> >>>> Changes since 20191011:
> >>>>
> >>>
> >>> on x86_64:
> >>>
> >>> HOSTCC arch/x86/tools/insn_decoder_test
> >>> HOSTCC arch/x86/tools/insn_sanity
> >>> TEST posttest
> >>> arch/x86/tools/insn_decoder_test: warning: Found an x86 instruction decoder bug, please report this.
> >>> arch/x86/tools/insn_decoder_test: warning: ffffffff81000bf1: f7 0b 00 01 08 00 testl $0x80100,(%rbx)
> >>> arch/x86/tools/insn_decoder_test: warning: objdump says 6 bytes, but insn_get_length() says 2
> >>> arch/x86/tools/insn_decoder_test: warning: Decoded and checked 11913894 instructions with 1 failures
> >>> TEST posttest
> >>> arch/x86/tools/insn_sanity: Success: decoded and checked 1000000 random instructions with 0 errors (seed:0x871ce29c)
> >>
> >> Hmm, curious.
> >>
> >> x86-opcode-map.txt said,
> >> f7: Grp3_2 Ev (1A)
> >>
> >> and "0x0b" is 00001011b, Group encoding bits are 5,4,3 (reg field),
> >> so group index is 001.
> >>
> >> GrpTable: Grp3_2
> >> 0: TEST Ev,Iz
> >> 1:
> >>
> >> Hmm, "f7 0b" is not assigned to any instruction... (testl should be f7 03)
> >>
> >> I've checked Intel SDM May 2019 version(*), but the Opcode Map (Table A-6. Opecode
> >> Extensions for One- and Two-byte Opecodes by Group Number) showed the group index
> >> 001 is still blank. I've also checked that Table B-13 (General Purpose Instruction
> >> Formats and Encodings for Non-64-Bit Modes (Note that this has no REX prefix)) but
> >> I couldn't find "f7 0b".
> >>
> >> At last, I found that on AMD64 Architecture Programmer's Manual Volume 3, Appendix A.2
> >> Table A-6. ModRM.reg Extensions for the Primary Opcode Map(**), which shows that both
> >> f7 + reg=000 and f7 + reg=001 are same. So only on AMD64, it is officially available
> >> instruction.
> >>
> >> (*) https://software.intel.com/sites/default/files/managed/a4/60/325383-sdm-vol-2abcd.pdf
> >> (**) https://www.amd.com/system/files/TechDocs/24594.pdf
> >>
> >> OK, so this should be fixed with below patch.
> >>
> >> ------
> >> >From b3f45b86df25be59fcf417730ab4c69c6310eaad Mon Sep 17 00:00:00 2001
> >> From: Masami Hiramatsu <mhiramat@kernel•org>
> >> Date: Wed, 23 Oct 2019 14:45:35 +0900
> >> Subject: [PATCH] x86/decoder: Add TEST opcode to Group3-2
> >>
> >> Add TEST opcode to Group3-2 reg=001b as same as Group3-1 does.
> >>
> >> Commit 12a78d43de76 ("x86/decoder: Add new TEST instruction pattern")
> >> added a TEST opcode assignment to f6 XX/001/XXX (Group 3-1), but not
> >> added f7 XX/001/XXX (Group 3-2). Actually these TEST opcode is not
> >> described in Intel SDM Vol2, but described in AMD64 Architecture
> >> Programmer's Manual Vol.3, Appendix A.2 Table A-6. ModRM.reg
> >> Extensions for the Primary Opcode Map.
> >>
> >> Without this fix, Randy found a warning by insn_decoder_test related
> >> to this issue as below.
> >>
> >> HOSTCC arch/x86/tools/insn_decoder_test
> >> HOSTCC arch/x86/tools/insn_sanity
> >> TEST posttest
> >> arch/x86/tools/insn_decoder_test: warning: Found an x86 instruction decoder bug, please report this.
> >> arch/x86/tools/insn_decoder_test: warning: ffffffff81000bf1: f7 0b 00 01 08 00 testl $0x80100,(%rbx)
> >> arch/x86/tools/insn_decoder_test: warning: objdump says 6 bytes, but insn_get_length() says 2
> >> arch/x86/tools/insn_decoder_test: warning: Decoded and checked 11913894 instructions with 1 failures
> >> TEST posttest
> >> arch/x86/tools/insn_sanity: Success: decoded and checked 1000000 random instructions with 0 errors (seed:0x871ce29c)
> >>
> >> To fix this error, add TEST opcode according to AMD64 APM Vol.3.
> >>
> >> Reported-by: Randy Dunlap <rdunlap@infradead•org>
> >> Signed-off-by: Masami Hiramatsu <mhiramat@kernel•org>
> >
> > Acked-by: Randy Dunlap <rdunlap@infradead•org>
> > Tested-by: Randy Dunlap <rdunlap@infradead•org>
> >
> > Thanks.
> >
> >> ---
> >> arch/x86/lib/x86-opcode-map.txt | 2 +-
> >> tools/arch/x86/lib/x86-opcode-map.txt | 2 +-
> >> 2 files changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/arch/x86/lib/x86-opcode-map.txt b/arch/x86/lib/x86-opcode-map.txt
> >> index e0b85930dd77..4635ce298d1d 100644
> >> --- a/arch/x86/lib/x86-opcode-map.txt
> >> +++ b/arch/x86/lib/x86-opcode-map.txt
> >> @@ -907,7 +907,7 @@ EndTable
> >>
> >> GrpTable: Grp3_2
> >> 0: TEST Ev,Iz
> >> -1:
> >> +1: TEST Ev,Iz
> >> 2: NOT Ev
> >> 3: NEG Ev
> >> 4: MUL rAX,Ev
> >> diff --git a/tools/arch/x86/lib/x86-opcode-map.txt b/tools/arch/x86/lib/x86-opcode-map.txt
> >> index e0b85930dd77..4635ce298d1d 100644
> >> --- a/tools/arch/x86/lib/x86-opcode-map.txt
> >> +++ b/tools/arch/x86/lib/x86-opcode-map.txt
> >> @@ -907,7 +907,7 @@ EndTable
> >>
> >> GrpTable: Grp3_2
> >> 0: TEST Ev,Iz
> >> -1:
> >> +1: TEST Ev,Iz
> >> 2: NOT Ev
> >> 3: NEG Ev
> >> 4: MUL rAX,Ev
> >>
> >
> >
>
>
> --
> ~Randy
> Reported-by: Randy Dunlap <rdunlap@infradead•org>
--
Masami Hiramatsu <mhiramat@kernel•org>
prev parent reply other threads:[~2020-01-22 3:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-14 6:47 linux-next: Tree for Oct 14 Stephen Rothwell
2019-10-14 15:05 ` linux-next: Tree for Oct 14 (sound/soc/sof/) Randy Dunlap
2019-10-14 15:30 ` linux-next: Tree for Oct 14 (insn_decoder_test) Randy Dunlap
2019-10-23 5:49 ` Masami Hiramatsu
2019-11-28 0:04 ` Randy Dunlap
2020-01-21 15:43 ` Randy Dunlap
2020-01-22 3:11 ` Masami Hiramatsu [this message]
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