On Thu, Dec 17, 2020 at 03:36:40PM +0100, Peter Zijlstra wrote:
> On Wed, Dec 09, 2020 at 06:33:37PM +0000, Mark Rutland wrote:
> > This means that a seuence such as:
>
> +q
>
> > diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h
> > index 3ed4e8771b64..bca3c6fa8270 100644
> > --- a/include/linux/irqflags.h
> > +++ b/include/linux/irqflags.h
> > @@ -220,10 +220,26 @@ do { \
> >
> > #else /* !CONFIG_TRACE_IRQFLAGS */
> >
> > +#ifdef CONFIG_DEBUG_IRQFLAGS
> > +extern void warn_bogus_irq_restore(bool *warned);
> > +#define check_bogus_irq_restore() \
> > + do { \
> > + static bool __section(".data.once") __warned; \
> > + if (unlikely(!raw_irqs_disabled())) \
> > + warn_bogus_irq_restore(&__warned); \
> > + } while (0)
> > +#else
> > +#define check_bogus_irq_restore() do { } while (0)
> > +#endif
> > +
> > #define local_irq_enable() do { raw_local_irq_enable(); } while (0)
> > #define local_irq_disable() do { raw_local_irq_disable(); } while
> > (0)
> > #define local_irq_save(flags) do { raw_local_irq_save(flags); } while
> > (0)
> > -#define local_irq_restore(flags) do { raw_local_irq_restore(flags); }
> > while (0)
> > +#define local_irq_restore(flags) \
> > + do { \
> > + check_bogus_irq_restore(); \
> > + raw_local_irq_restore(flags); \
> > + } while (0)
>
> Shouldn't that be in raw_local_irq_restore() ?
Yup, that'd be preferable. Note that will require a refactoring here if
we want the warning to be available regardless of CONFIG_TRACE_IRQFLAGS.
I'd intended to rejig that for v2, but I didn't get the chance before
finishing work for the year, and had only done some basic rework in my
WIP (e.g. removing the per-instance bool as per Andy's comments):
https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/commit/?h=fuzzing/5.10-rc7&id=61336e25d1415a4ac3aaf8cf75105c2ec2eb95e7
I'll try to respin that in the next few days if I get the chance.
Thanks,
Mark.
>
> > #define safe_halt() do { raw_safe_halt(); } while (0)
> >
> > #endif /* CONFIG_TRACE_IRQFLAGS */
>
> --- a/include/linux/irqflags.h
> +++ b/include/linux/irqflags.h
> @@ -162,6 +162,7 @@ do { \
> #define raw_local_irq_restore(flags) \
> do { \
> typecheck(unsigned long, flags); \
> + check_bogus_irq_restore(); \
> arch_local_irq_restore(flags); \
> } while (0)
> #define raw_local_save_flags(flags) \
> @@ -235,11 +236,7 @@ extern void warn_bogus_irq_restore(bool
> #define local_irq_enable() do { raw_local_irq_enable(); } while (0)
> #define local_irq_disable() do { raw_local_irq_disable(); } while (0)
> #define local_irq_save(flags) do { raw_local_irq_save(flags); } while
> (0)
> -#define local_irq_restore(flags) \
> - do { \
> - check_bogus_irq_restore(); \
> - raw_local_irq_restore(flags); \
> - } while (0)
> +#define local_irq_restore(flags) do { raw_local_irq_restore(flags); } while
> (0)
> #define safe_halt() do { raw_safe_halt(); } while (0)
>
> #endif /* CONFIG_TRACE_IRQFLAGS */
