ARM: 8488/1: Make IPI_CPU_BACKTRACE a "non-secure" SGI

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.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index d50a77d638d3bf566e4fadd265ced7c70ef50a21..37312f6749f3dd641f48803b67c8f26a4623a8a2 100644 (file)
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -72,7 +72,12 @@ enum ipi_msg_type {
        IPI_CPU_STOP,
        IPI_IRQ_WORK,
        IPI_COMPLETION,
-       IPI_CPU_BACKTRACE = 15,
+       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);