perf fs: Add procfs support

Adding procfs support into fs class.

The interface function:
const char *procfs__mountpoint(void);

provides existing mountpoint path for procfs.

Signed-off-by: Jiri Olsa <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Corey Ashford <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Frederic Weisbecker <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
[ Fixup namespace ]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/fs.c

···
 	0,
 };
 
+static const char * const procfs__known_mountpoints[] = {
+	"/proc",
+	0,
+};
+
 struct fs {
 	const char		*name;
 	const char * const	*mounts;
···
 };
 
 enum {
-	FS__SYSFS = 0,
+	FS__SYSFS  = 0,
+	FS__PROCFS = 1,
 };
 
 static struct fs fs__entries[] = {
···
 		.name	= "sysfs",
 		.mounts	= sysfs__fs_known_mountpoints,
 		.magic	= SYSFS_MAGIC,
+	},
+	[FS__PROCFS] = {
+		.name	= "proc",
+		.mounts	= procfs__known_mountpoints,
+		.magic	= PROC_SUPER_MAGIC,
 	},
 };
 
···
 	return fs__mountpoint(idx);	\
 }
 
-FS__MOUNTPOINT(sysfs, FS__SYSFS);
+FS__MOUNTPOINT(sysfs,  FS__SYSFS);
+FS__MOUNTPOINT(procfs, FS__PROCFS);

tools/perf/util/fs.h

···
 #define __PERF_FS
 
 const char *sysfs__mountpoint(void);
+const char *procfs__mountpoint(void);
 
 #endif /* __PERF_FS */

tools/perf/util/include/linux/magic.h

···
 #define SYSFS_MAGIC            0x62656572
 #endif
 
+#ifndef PROC_SUPER_MAGIC
+#define PROC_SUPER_MAGIC       0x9fa0
+#endif
+
 #endif