parisc: implement irq stacks

Default kernel stack size on parisc is 16k.  During tests we found that the
kernel stack can easily grow beyond 13k, which leaves 3k left for irq
processing.

This patch adds the possibility to activate an additional stack of 16k per CPU
which is being used during irq processing.  This implementation does not yet
uses this irq stack for the irq bh handler.

The assembler code for call_on_stack was heavily cleaned up by John
David Anglin.

CC: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index fe4afb0f152f..cad060f288cf 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -243,6 +243,14 @@ config SMP
 
           If you don't know what to do here, say N.
 
+config IRQSTACKS
+        bool "Use separate kernel stacks when processing interrupts"
+        default n
+        help
+          If you say Y here the kernel will use separate kernel stacks
+          for handling hard and soft interrupts.  This can help avoid
+          overflowing the process kernel stacks.
+
 config HOTPLUG_CPU
         bool
         default y if SMP