This is a note to let you know that I've just added the patch titled

x86/decoder: Add new TEST instruction pattern

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: x86-decoder-add-new-test-instruction-pattern.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 12a78d43de767eaf8fb272facb7a7b6f2dc6a9df Mon Sep 17 00:00:00 2001

From: Masami Hiramatsu mhiramat@kernel.org Date: Fri, 24 Nov 2017 13:56:30 +0900 Subject: x86/decoder: Add new TEST instruction pattern

From: Masami Hiramatsu mhiramat@kernel.org

commit 12a78d43de767eaf8fb272facb7a7b6f2dc6a9df upstream.

The kbuild test robot reported this build warning:

Warning: arch/x86/tools/test_get_len found difference at <jump_table>:ffffffff8103dd2c

Warning: ffffffff8103dd82: f6 09 d8 testb $0xd8,(%rcx) Warning: objdump says 3 bytes, but insn_get_length() says 2 Warning: decoded and checked 1569014 instructions with 1 warnings

This sequence seems to be a new instruction not in the opcode map in the Intel SDM.

The instruction sequence is "F6 09 d8", means Group3(F6), MOD(00)REG(001)RM(001), and 0xd8. Intel SDM vol2 A.4 Table A-6 said the table index in the group is "Encoding of Bits 5,4,3 of the ModR/M Byte (bits 2,1,0 in parenthesis)"

In that table, opcodes listed by the index REG bits as:

000 001 010 011 100 101 110 111 TEST Ib/Iz,(undefined),NOT,NEG,MUL AL/rAX,IMUL AL/rAX,DIV AL/rAX,IDIV AL/rAX

So, it seems TEST Ib is assigned to 001.

Add the new pattern.

Reported-by: kbuild test robot fengguang.wu@intel.com Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: H. Peter Anvin hpa@zytor.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/x86/lib/x86-opcode-map.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/lib/x86-opcode-map.txt +++ b/arch/x86/lib/x86-opcode-map.txt @@ -833,7 +833,7 @@ EndTable

GrpTable: Grp3_1 0: TEST Eb,Ib -1: +1: TEST Eb,Ib 2: NOT Eb 3: NEG Eb 4: MUL AL,Eb

Patches currently in stable-queue which might be from mhiramat@kernel.org are

queue-4.4/x86-decoder-add-new-test-instruction-pattern.patch