Thread (62 messages) 62 messages, 6 authors, 2018-12-10

Re: [PATCH v6 06/24] arm64: ptrace: Provide definitions for PMR values

From: Mark Rutland <mark.rutland@arm.com>
Date: 2018-11-29 16:40:20
Also in: lkml

On Mon, Nov 12, 2018 at 11:56:57AM +0000, Julien Thierry wrote:
Introduce fixed values for PMR that are going to be used to mask and
unmask interrupts by priority. These values are chosent in such a way
Nit: s/chosent/chosen/
that a single bit (GIC_PMR_UNMASKED_BIT) encodes the information whether
interrupts are masked or not.
There's no GIC_PMR_UNMASKED_BIT in this patch. Should that be
GIC_PRIO_STATUS_BIT?
quoted hunk ↗ jump to hunk
Signed-off-by: Julien Thierry <redacted>
Suggested-by: Daniel Thompson <redacted>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <redacted>
---
 arch/arm64/include/asm/ptrace.h | 6 ++++++
 1 file changed, 6 insertions(+)
diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index fce22c4..ce6998c 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -25,6 +25,12 @@
 #define CurrentEL_EL1		(1 << 2)
 #define CurrentEL_EL2		(2 << 2)
 
+/* PMR values used to mask/unmask interrupts */
+#define GIC_PRIO_IRQON		0xf0
+#define GIC_PRIO_STATUS_SHIFT	6
+#define GIC_PRIO_STATUS_BIT	(1 << GIC_PRIO_STATUS_SHIFT)
+#define GIC_PRIO_IRQOFF		(GIC_PRIO_IRQON ^ GIC_PRIO_STATUS_BIT)
Could you elaborate on the GIC priority logic a bit?

Are lower numbers higher priority?

Are there restrictions on valid PMR values?

IIUC GIC_PRIO_IRQOFF is 0xb0 (aka 0b10110000), which seems a little
surprising. I'd have expected that we'd use the most signficant bit.


Thanks,
Mark.

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