[POWERPC] spufs: Add marker-based tracing facility

This adds markers two important points in the spufs code and a new
module (sputrace.ko) that allows reading these out through a proc file.

Long-term I'd rather see something like lttng extended to use the spufs
instrumentation, but for now I think this is a good enough quick
solution.  We'll probably want to add various addition event in addition
to that ones I have already.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/cell/Kconfig

@@ -54,6 +54,13 @@ config SPU_FS_64K_LS
 	  uses 4K pages. This can improve performances of applications
 	  using multiple SPEs by lowering the TLB pressure on them.
 
+config SPU_TRACE
+	tristate "SPU event tracing support"
+	depends on SPU_FS && MARKERS
+	help
+	  This option allows reading a trace of spu-related events through
+	  the sputrace file in procfs.
+
 config SPU_BASE
 	bool
 	default n