Re: [PATCH 07/11] arm64: entry: fix non-NMI user<->kernel transitions

Will Deacon
2020-11-30T11:23:57Z

On Thu, Nov 26, 2020 at 12:35:58PM +0000, Mark Rutland wrote:
> When built with PROVE_LOCKING, NO_HZ_FULL, and CONTEXT_TRACKING_FORCE
> will WARN() at boot time that interrupts are enabled when we call
> context_tracking_user_enter(), despite the DAIF flags indicating that
> IRQs are masked.
>
> The problem is that we're not tracking IRQ flag changes accurately, and
> so lockdep believes interrupts are enabled when they are not (and
> vice-versa). We can shuffle things so to make this more accurate. For
> kernel->user transitions there are a number of constraints we need to
> consider:

[...]

> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 53e30750fc28..d17a68c24608 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -30,18 +30,18 @@
> #include <asm/unistd.h>
>
> /*
> - * Context tracking subsystem. Used to instrument transitions
> - * between user and kernel mode.
> + * Context tracking and irqflag tracing need to inrstrument transitions between

Typo: "inrstrument".

Will