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x86/delay: Avoid preemptible context checks in delay_mwaitx()
We do use this_cpu_ptr(&cpu_tss) as a cacheline-aligned, seldomly accessed per-cpu var as the MONITORX target in delay_mwaitx(). However, when called in preemptible context, this_cpu_ptr -> smp_processor_id() -> debug_smp_processor_id() fires: BUG: using smp_processor_id() in preemptible [00000000] code: udevd/312 caller is delay_mwaitx+0x40/0xa0 But we don't care about that check - we only need cpu_tss as a MONITORX target and it doesn't really matter which CPU's var we're touching as we're going idle anyway. Fix that. Suggested-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Huang Rui <ray.huang@amd.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: spg_linux_kernel@amd.com Link: http://lkml.kernel.org/r/20160309205622.GG6564@pd.tnic Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -102,7 +102,7 @@ static void delay_mwaitx(unsigned long __loops)
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* Use cpu_tss as a cacheline-aligned, seldomly
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* accessed per-cpu variable as the monitor target.
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*/
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__monitorx(this_cpu_ptr(&cpu_tss), 0, 0);
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__monitorx(raw_cpu_ptr(&cpu_tss), 0, 0);
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/*
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* AMD, like Intel, supports the EAX hint and EAX=0xf
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