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

…estamp

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>

drivers/connector/cn_proc.c

@@ -51,14 +51,16 @@ void proc_fork_connector(struct task_struct *task)
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE];
+	struct timespec ts;
 
 	if (atomic_read(&proc_event_num_listeners) < 1)
 		return;
 
 	msg = (struct cn_msg*)buffer;
 	ev = (struct proc_event*)msg->data;
 	get_seq(&msg->seq, &ev->cpu);
-	ktime_get_ts(&ev->timestamp); /* get high res monotonic timestamp */
+	ktime_get_ts(&ts); /* get high res monotonic timestamp */
+	ev->timestamp_ns = timespec_to_ns(&ts);
 	ev->what = PROC_EVENT_FORK;
 	ev->event_data.fork.parent_pid = task->real_parent->pid;
 	ev->event_data.fork.parent_tgid = task->real_parent->tgid;
@@ -76,6 +78,7 @@ void proc_exec_connector(struct task_struct *task)
 {
 	struct cn_msg *msg;
 	struct proc_event *ev;
+	struct timespec ts;
 	__u8 buffer[CN_PROC_MSG_SIZE];
 
 	if (atomic_read(&proc_event_num_listeners) < 1)
@@ -84,7 +87,8 @@ void proc_exec_connector(struct task_struct *task)
 	msg = (struct cn_msg*)buffer;
 	ev = (struct proc_event*)msg->data;
 	get_seq(&msg->seq, &ev->cpu);
-	ktime_get_ts(&ev->timestamp);
+	ktime_get_ts(&ts); /* get high res monotonic timestamp */
+	ev->timestamp_ns = timespec_to_ns(&ts);
 	ev->what = PROC_EVENT_EXEC;
 	ev->event_data.exec.process_pid = task->pid;
 	ev->event_data.exec.process_tgid = task->tgid;
@@ -100,6 +104,7 @@ void proc_id_connector(struct task_struct *task, int which_id)
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE];
+	struct timespec ts;
 
 	if (atomic_read(&proc_event_num_listeners) < 1)
 		return;
@@ -118,7 +123,8 @@ void proc_id_connector(struct task_struct *task, int which_id)
 	} else
 	     	return;
 	get_seq(&msg->seq, &ev->cpu);
-	ktime_get_ts(&ev->timestamp);
+	ktime_get_ts(&ts); /* get high res monotonic timestamp */
+	ev->timestamp_ns = timespec_to_ns(&ts);
 
 	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 	msg->ack = 0; /* not used */
@@ -131,14 +137,16 @@ void proc_exit_connector(struct task_struct *task)
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE];
+	struct timespec ts;
 
 	if (atomic_read(&proc_event_num_listeners) < 1)
 		return;
 
 	msg = (struct cn_msg*)buffer;
 	ev = (struct proc_event*)msg->data;
 	get_seq(&msg->seq, &ev->cpu);
-	ktime_get_ts(&ev->timestamp);
+	ktime_get_ts(&ts); /* get high res monotonic timestamp */
+	ev->timestamp_ns = timespec_to_ns(&ts);
 	ev->what = PROC_EVENT_EXIT;
 	ev->event_data.exit.process_pid = task->pid;
 	ev->event_data.exit.process_tgid = task->tgid;
@@ -164,14 +172,16 @@ static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE];
+	struct timespec ts;
 
 	if (atomic_read(&proc_event_num_listeners) < 1)
 		return;
 
 	msg = (struct cn_msg*)buffer;
 	ev = (struct proc_event*)msg->data;
 	msg->seq = rcvd_seq;
-	ktime_get_ts(&ev->timestamp);
+	ktime_get_ts(&ts); /* get high res monotonic timestamp */
+	ev->timestamp_ns = timespec_to_ns(&ts);
 	ev->cpu = -1;
 	ev->what = PROC_EVENT_NONE;
 	ev->event_data.ack.err = err;

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;