From: marc.zyngier@arm•com (Marc Zyngier)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 2/2] ARM: Make IPI_CPU_BACKTRACE a "non-secure" SGI
Date: Fri, 18 Dec 2015 09:48:51 +0000 [thread overview]
Message-ID: <5673D683.8050002@arm.com> (raw)
In-Reply-To: <20151218093412.GN8644@n2100.arm.linux.org.uk>
On 18/12/15 09:34, Russell King - ARM Linux wrote:
> On Fri, Dec 18, 2015 at 09:16:13AM +0000, Marc Zyngier wrote:
>> Having IPI_CPU_BACKTRACE as SGI15 may not work if the kernel is
>> running in non-secure mode and that the secure firmware has
>> decided to follow ARM's recommendations that SGI8-15 should
>> be reserved for secure purpose.
>>
>> Now that we are "only" using SGI0-6, change IPI_CPU_BACKTRACE
>> to use SGI7, which makes it more likely to work.
>
> We should add a comment to the enum explaining this, so it's obvious
> for the future - best place is after the IPI_CPU_BACKTRACE entry.
> Not everyone checks the git logs for these kinds of details.
Indeed. How about something like this:
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index fe517f1..37312f6 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -73,6 +73,11 @@ enum ipi_msg_type {
IPI_IRQ_WORK,
IPI_COMPLETION,
IPI_CPU_BACKTRACE,
+ /*
+ * SGI8-15 can be reserved by secure firmware, and thus may
+ * not be usable by the kernel. Please keep the above limited
+ * to at most 8 entries.
+ */
};
static DECLARE_COMPLETION(cpu_running);
Thanks,
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2015-12-18 9:48 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-18 9:16 [PATCH 0/2] IPI numbering cleanup Marc Zyngier
2015-12-18 9:16 ` [PATCH 1/2] ARM: Remove IPI_CALL_FUNC_SINGLE Marc Zyngier
2015-12-18 9:16 ` [PATCH 2/2] ARM: Make IPI_CPU_BACKTRACE a "non-secure" SGI Marc Zyngier
2015-12-18 9:34 ` Russell King - ARM Linux
2015-12-18 9:48 ` Marc Zyngier [this message]
2015-12-18 9:52 ` Russell King - ARM Linux
2015-12-18 11:20 ` Daniel Thompson
2015-12-18 11:29 ` Marc Zyngier
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