Messages in this thread | | | Subject | Re: [linus:master] BUILD REGRESSION a2e5790d841658485d642196dbb0927303d6c22f | From | Randy Dunlap <> | Date | Wed, 7 Feb 2018 10:38:41 -0800 |
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On 02/07/2018 10:13 AM, Linus Torvalds wrote: > Adding more people for this funky warning from the kbuild robot. > > Something is confused. UD0 is 0f ff, the bytes after that shouldn't > matter. But I guess they can be interpreted as modrm bytes, and > somebody started doing that. > > That said, intel only _documents_ UD2 (0f 0b).
Intel Order Number: 325383-064US, October 2017, documents UD0, UD1, and UD2. Section A.2.5, Table A-1, says:
Use the 0F0B opcode (UD2 instruction), the 0FB9H opcode (UD1 instruction), or the 0FFFH opcode (UD0 instruction) when deliberately trying to generate an invalid opcode exception (#UD).
Could this regression be a result of:
commit f5b5fab1780c98b74526dbac527574bd02dc16f8 Author: Randy Dunlap <rdunlap@infradead.org> Date: Mon Dec 11 10:38:36 2017 -0800
x86/decoder: Fix and update the opcodes map
Update x86-opcode-map.txt based on the October 2017 Intel SDM publication. Fix INVPID to INVVPID. Add UD0 and UD1 instruction opcodes.
> Maybe we should avoid using UD0/UD1 entirely. > > Linus > > On Wed, Feb 7, 2018 at 3:44 AM, kbuild test robot > <fengguang.wu@intel.com> wrote: >> tree/branch: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master >> branch HEAD: a2e5790d841658485d642196dbb0927303d6c22f Merge branch 'akpm' (patches from Andrew) >> >> Regressions in current branch: >> >> arch/x86/tools/insn_decoder_test: warning: ffffffff810010d7: 0f ff eb ud0 %ebx,%ebp >> arch/x86/tools/insn_decoder_test: warning: ffffffff81001152: 0f ff bf 09 00 00 00 ud0 0x9(%rdi),%edi >> arch/x86/tools/insn_decoder_test: warning: ffffffff81001275: 0f ff eb ud0 %ebx,%ebp >> arch/x86/tools/insn_decoder_test: warning: ffffffff810013fd: 0f ff bf 09 00 00 00 ud0 0x9(%rdi),%edi >> arch/x86/tools/insn_decoder_test: warning: ffffffff81001499: 0f ff bf 09 00 00 00 ud0 0x9(%rdi),%edi >> arch/x86/tools/insn_decoder_test: warning: ffffffff812296eb: 0f ff e8 ud0 %eax,%ebp
-- ~Randy
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