Hi, [adding Lorenzo] On Mon, Aug 08, 2016 at 12:03:38PM -0400, Chris Metcalf wrote: > When doing an nmi backtrace of many cores, most of which are idle, > the output is a little overwhelming and very uninformative. Suppress > messages for cpus that are idling when they are interrupted and just > emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN". > > We do this by grouping all the cpuidle code together into a new > .cpuidle.text section, and then checking the address of the > interrupted PC to see if it lies within that section. > > This commit suitably tags x86, arm64, and tile idle routines, > and only adds in the minimal framework for other architectures. > diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S > index 659963d40bb4..fe7f93b7b11b 100644 > --- a/arch/arm64/kernel/vmlinux.lds.S > +++ b/arch/arm64/kernel/vmlinux.lds.S > @@ -122,6 +122,7 @@ SECTIONS > ENTRY_TEXT > TEXT_TEXT > SCHED_TEXT > + CPUIDLE_TEXT > LOCK_TEXT > KPROBES_TEXT > HYPERVISOR_TEXT > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S > index 5bb61de23201..64f088ca3192 100644 > --- a/arch/arm64/mm/proc.S > +++ b/arch/arm64/mm/proc.S > @@ -48,11 +48,13 @@ > * > * Idle the processor (wait for interrupt). > */ > + .pushsection ".cpuidle.text","ax" > ENTRY(cpu_do_idle) > dsb sy // WFI may enter a low-power mode > wfi > ret > ENDPROC(cpu_do_idle) > + .popsection >From a quick scan it looks like we only call this with interrupts disabled, and we have no NMI. So shouldn't we be annotating arch_cpu_idle(), which calls this and subsequently enables interrupts? I'm also not sure what you need to do for PSCI, which is the preferred (FW-backed) idle mechanism for arm64. The infrastrucure for that is spread over a few files: arch/arm64/kernel/sleep.S arch/arm64/kernel/smccc-call.S arch/arm64/kernel/suspend.c drivers/cpuidle/cpuidle-arm.c drivers/firmware/psci.c I'm not sure where we'd be an an interruptible state, and therefore I'm not immediately sure what we should annotate. Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
