Thread (20 messages) 20 messages, 3 authors, 2020-11-30

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

From: Will Deacon <will@kernel.org>
Date: 2020-11-30 11:23:57

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:
[...]
quoted hunk ↗ jump to hunk
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

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