Process Events: Fix biarch compatibility issue. use __u64 timestamp

Chandra Seetharaman
2006-07-14T16:45:20Z

Linus, Andrew,

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>
---
Index: linux-2.6.18-rc1/include/linux/cn_proc.h
===================================================================
--- linux-2.6.18-rc1.orig/include/linux/cn_proc.h 2006-07-13 15:14:25.000000000 -0700
+++ linux-2.6.18-rc1/include/linux/cn_proc.h 2006-07-13 15:14:38.000000000 -0700
@@ -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;
Index: linux-2.6.18-rc1/drivers/connector/cn_proc.c
===================================================================
--- linux-2.6.18-rc1.orig/drivers/connector/cn_proc.c 2006-07-13 15:14:25.000000000 -0700
+++ linux-2.6.18-rc1/drivers/connector/cn_proc.c 2006-07-13 15:16:36.000000000 -0700
@@ -51,6 +51,7 @@ void proc_fork_connector(struct task_str
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_str
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_str
{
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_str
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_struc
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_struc
} 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_str
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_str
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 rcv
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 rcv
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;

--

----------------------------------------------------------------------
Chandra Seetharaman | Be careful what you choose....
- sekharan@us.ibm.com | .......you may get it.
----------------------------------------------------------------------