Messages in this thread | | | Date | Mon, 27 Jul 2020 05:49:28 -0700 | Subject | Re: [PATCH 4/4] x86/cpu: Use SERIALIZE in sync_core() when available | From | hpa@zytor ... |
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On July 27, 2020 1:36:19 AM PDT, peterz@infradead.org wrote: >On Sun, Jul 26, 2020 at 10:55:15PM -0700, hpa@zytor.com wrote: >> For a really overenginered solution, but which might perform >> unnecessary poorly on existing hardware: >> >> asm volatile("1: .byte 0xf, 0x1, 0xe8; 2:" >> _ASM_EXTABLE(1b,2b)); > >Ha! cute, you take an #UD ? > >We could optimize the #UD exception handler for this I suppose, but >that >makes it an even worse hack. The simple alternative() seems like a much >simpler approach.
If this is in any way performance critical, then no :) Taking the #UD has the cute property that we end up IRET on the way back, so we don't even need a fix-up path.
-- Sent from my Android device with K-9 Mail. Please excuse my brevity.
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