powerpc: Reduce footprint of irq_stat

PowerPC is currently using asm-generic/hardirq.h which statically allocates an
NR_CPUS irq_stat array. Switch to an arch specific implementation which uses
per cpu data:

On a kernel with NR_CPUS=1024, this saves quite a lot of memory:

   text    data     bss      dec         hex    filename
8767938 2944132 1636796 13348866         cbb002 vmlinux.baseline
8767779 2944260 1505724 13217763         c9afe3 vmlinux.irq_cpustat

A saving of around 128kB.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 9040330b0530..c6ac5583672a 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -73,6 +73,9 @@
 #define CREATE_TRACE_POINTS
 #include <asm/trace.h>
 
+DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
+EXPORT_PER_CPU_SYMBOL(irq_stat);
+
 int __irq_offset_value;
 static int ppc_spurious_interrupts;