[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>

2 files changed, 17 insertions, 6 deletions

diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
index 498aa37bca22..3ece69231343 100644
--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -51,6 +51,7 @@ 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;
@@ -58,7 +59,8 @@ void proc_fork_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); /* 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 */
@@ -131,6 +137,7 @@ 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;
@@ -138,7 +145,8 @@ void proc_exit_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_EXIT;
         ev->event_data.exit.process_pid = task->pid;
         ev->event_data.exit.process_tgid = task->tgid;
@@ -164,6 +172,7 @@ 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;
@@ -171,7 +180,8 @@ static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
         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;
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;