x86, 32-bit: Align percpu area and irq stacks to THREAD_SIZE

The irq stacks, located in the percpu-area, need to be
THREAD_SIZE aligned. Add the infrastucture to align percpu
variables to larger-than-pagesize amounts within the percpu
area, and use it to specify the alignment for the irq stacks.
Also align the percpu area itself to THREAD_SIZE.

This should make irq stacks work with 8K THREAD_SIZE.

Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Cc: Tejun Heo <tj@kernel.org>
Cc: hch@lst.de
LKML-Reference: <1283799222.15941.1393621887@webmail.messagingengine.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index ce2dc655cd1d..ab20d119a85d 100644
--- a/include/linux/percpu-defs.h
+++ b/include/linux/percpu-defs.h
@@ -139,6 +139,18 @@
         __aligned(PAGE_SIZE)
 
 /*
+ * Declaration/definition used for large per-CPU variables that must be
+ * aligned to something larger than the pagesize.
+ */
+#define DECLARE_PER_CPU_MULTIPAGE_ALIGNED(type, name, size)             \
+        DECLARE_PER_CPU_SECTION(type, name, "..page_aligned")           \
+        __aligned(size)
+
+#define DEFINE_PER_CPU_MULTIPAGE_ALIGNED(type, name, size)              \
+        DEFINE_PER_CPU_SECTION(type, name, "..page_aligned")            \
+        __aligned(size)
+
+/*
  * Intermodule exports for per-CPU variables.  sparse forgets about
  * address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to
  * noop if __CHECKER__.