Messages in this thread | | | Subject | Re: [patch 4/8] x86/entry: Move irq tracing on syscall entry to C-code | From | Andy Lutomirski <> | Date | Tue, 25 Feb 2020 21:43:46 -0800 |
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On 2/25/20 2:08 PM, Thomas Gleixner wrote: > Now that the C entry points are safe, move the irq flags tracing code into > the entry helper.
I'm so confused.
> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > --- > arch/x86/entry/common.c | 5 +++++ > arch/x86/entry/entry_32.S | 12 ------------ > arch/x86/entry/entry_64.S | 2 -- > arch/x86/entry/entry_64_compat.S | 18 ------------------ > 4 files changed, 5 insertions(+), 32 deletions(-) > > --- a/arch/x86/entry/common.c > +++ b/arch/x86/entry/common.c > @@ -57,6 +57,11 @@ static inline void enter_from_user_mode( > */ > static __always_inline void syscall_entry_fixups(void) > { > + /* > + * Usermode is traced as interrupts enabled, but the syscall entry > + * mechanisms disable interrupts. Tell the tracer. > + */ > + trace_hardirqs_off();
Your earlier patches suggest quite strongly that tracing isn't safe until enter_from_user_mode(). But trace_hardirqs_off() calls trace_irq_disable_rcuidle(), which looks [0] like a tracepoint.
Did you perhaps mean to do this *after* enter_from_user_mode()?
(My tracepoint-fu is pretty bad, and I can't actually find where it's defined as a tracepoint. But then it does nothing at all, so it must be a tracepoint, right?)
> enter_from_user_mode(); > local_irq_enable(); > }
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