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Subject[tip:x86/irq] x86, 32-bit: Align percpu area and irq stacks to THREAD_SIZE
Commit-ID:  fe8e0c25cad28e8858ecfa5863333c70685a6811
Gitweb: http://git.kernel.org/tip/fe8e0c25cad28e8858ecfa5863333c70685a6811
Author: Alexander van Heukelum <heukelum@fastmail.fm>
AuthorDate: Mon, 6 Sep 2010 20:53:42 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 7 Sep 2010 05:07:00 +0200
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>
---
arch/x86/kernel/irq_32.c | 4 ++--
arch/x86/kernel/vmlinux.lds.S | 2 +-
include/linux/percpu-defs.h | 12 ++++++++++++
3 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index 3b5609f..50fbbe6 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -60,8 +60,8 @@ union irq_ctx {
static DEFINE_PER_CPU(union irq_ctx *, hardirq_ctx);
static DEFINE_PER_CPU(union irq_ctx *, softirq_ctx);

-static DEFINE_PER_CPU_PAGE_ALIGNED(union irq_ctx, hardirq_stack);
-static DEFINE_PER_CPU_PAGE_ALIGNED(union irq_ctx, softirq_stack);
+static DEFINE_PER_CPU_MULTIPAGE_ALIGNED(union irq_ctx, hardirq_stack, THREAD_SIZE);
+static DEFINE_PER_CPU_MULTIPAGE_ALIGNED(union irq_ctx, softirq_stack, THREAD_SIZE);

static void call_on_stack(void *func, void *stack)
{
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index d0bb522..bb89947 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -273,7 +273,7 @@ SECTIONS
}

#if !defined(CONFIG_X86_64) || !defined(CONFIG_SMP)
- PERCPU(PAGE_SIZE)
+ PERCPU(THREAD_SIZE)
#endif

. = ALIGN(PAGE_SIZE);
diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index ce2dc65..ab20d11 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__.

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