[PATCH] Process Events: Fix biarch compatibility issue. use __u64 timestamp

Events sent by Process Events Connector from a 64-bit kernel are not binary
compatible with a 32-bit userspace program because the "timestamp" field
(struct timespec) is not arch independent.  This affects the fields that
follow "timestamp" as they will be be off by 8 bytes.

This is a problem for 32-bit userspace programs running with 64-bit kernels
on ppc64, s390, x86-64..  any "biarch" system.

Matt had submitted a different solution to lkml as an RFC earlier.  We have
since switched to a solution recommended by Evgeniy Polyakov.

This patch fixes the problem by changing the timestamp to be a __u64, which
stores the number of nanoseconds.

Tested on a x86_64 system with both 32 bit application and 64 bit
application and on a i386 system.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: Guillaume Thouvenin <guillaume.thouvenin@bull.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/cn_proc.h b/include/linux/cn_proc.h
index dbb7769009be..1c86d65bc4b9 100644
--- a/include/linux/cn_proc.h
+++ b/include/linux/cn_proc.h
@@ -57,7 +57,8 @@ struct proc_event {
 		PROC_EVENT_EXIT = 0x80000000
 	} what;
 	__u32 cpu;
-	struct timespec timestamp;
+	__u64 __attribute__((aligned(8))) timestamp_ns;
+		/* Number of nano seconds since system boot */
 	union { /* must be last field of proc_event struct */
 		struct {
 			__u32 err;