On Fri, Sep 5, 2025 at 4:24 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > On Thu, Sep 04, 2025 at 11:58:26PM +0200, Peter Zijlstra wrote: > > On Thu, Sep 04, 2025 at 11:56:17PM +0200, Peter Zijlstra wrote: > > > > > Ooh, that suggests we do something like so: > > > > N/m, I need to go sleep, that doesn't work right for the 32bit nops that > > use lea instead of nopl. I'll see if I can come up with something more > > sensible. > > Something like this. Can someone please look very critical at this fancy > insn_is_nop()? Can't truly review that low-level instruction decoding logic (and you seem to have found an issue yourself), but superficially the cases that are claimed to be handled seem like legit no-op instructions. And the overall logic of nop handling in can_optimize and emulation seems to be intact as well. Thanks for generalizing all this! To the extent that this means anything: Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > > --- > arch/x86/include/asm/insn-eval.h | 2 + > arch/x86/kernel/alternative.c | 20 +-------- > arch/x86/kernel/uprobes.c | 32 ++------------ > arch/x86/lib/insn-eval.c | 92 ++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 98 insertions(+), 48 deletions(-) > [...]
