Messages in this thread |  | | From | Andy Lutomirski <> | Date | Sun, 22 Nov 2020 13:44:53 -0800 | Subject | Re: [PATCH v2 05/12] x86: rework arch_local_irq_restore() to not use popf |
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On Sat, Nov 21, 2020 at 10:55 PM Jürgen Groß <jgross@suse.com> wrote: > > On 20.11.20 12:59, Peter Zijlstra wrote: > > On Fri, Nov 20, 2020 at 12:46:23PM +0100, Juergen Gross wrote: > >> +static __always_inline void arch_local_irq_restore(unsigned long flags) > >> +{ > >> + if (!arch_irqs_disabled_flags(flags)) > >> + arch_local_irq_enable(); > >> +} > > > > If someone were to write horrible code like: > > > > local_irq_disable(); > > local_irq_save(flags); > > local_irq_enable(); > > local_irq_restore(flags); > > > > we'd be up some creek without a paddle... now I don't _think_ we have > > genius code like that, but I'd feel saver if we can haz an assertion in > > there somewhere... > > > > Maybe something like: > > > > #ifdef CONFIG_DEBUG_ENTRY // for lack of something saner > > WARN_ON_ONCE((arch_local_save_flags() ^ flags) & X86_EFLAGS_IF); > > #endif > > > > At the end? > > I'd like to, but using WARN_ON_ONCE() in include/asm/irqflags.h sounds > like a perfect receipt for include dependency hell. > > We could use a plain asm("ud2") instead.
How about out-of-lining it:
#ifdef CONFIG_DEBUG_ENTRY extern void warn_bogus_irqrestore(); #endif
static __always_inline void arch_local_irq_restore(unsigned long flags) { if (!arch_irqs_disabled_flags(flags)) { arch_local_irq_enable(); } else { #ifdef CONFIG_DEBUG_ENTRY if (unlikely(arch_local_irq_save() & X86_EFLAGS_IF)) warn_bogus_irqrestore(); #endif }
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