Hi, On Mon, 14 Oct 2019 08:30:02 -0700 Randy Dunlap <rdunlap@xxxxxxxxxxxxx> 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@xxxxxxxxxx> 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@xxxxxxxxxxxxx> Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> --- 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 -- 2.20.1 -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
