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Message-ID: <aab93029-158a-5554-9976-b20aa48fef1d@infradead.org>
Date: Tue, 21 Jan 2020 07:43:16 -0800
From: Randy Dunlap <rdunlap@...radead.org>
To: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Stephen Rothwell <sfr@...b.auug.org.au>,
Linux Next Mailing List <linux-next@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Masami Hiramatsu <mhiramat@...hat.com>,
X86 ML <x86@...nel.org>, Ingo Molnar <mingo@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: linux-next: Tree for Oct 14 (insn_decoder_test)
[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...
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@...radead.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@...nel.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@...radead.org>
>> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
>
> Acked-by: Randy Dunlap <rdunlap@...radead.org>
> Tested-by: Randy Dunlap <rdunlap@...radead.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@...radead.org>
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