[PATCH 2/2] pps: fix padding issue with PPS_FETCH for ioctl_compat

[Matt Ranostay <matt.ranostay@konsulko.com>]

Issue is that x86 32-bit aligns to 4-bytes instead of 8-bytes
so this patchset works around the issue and corrects the data
returned in pps_fdata_compat.

Cc: Rodolfo Giometti <giometti@enneenne.com>
Cc: Moritz Fischer <mdf@kernel.org>
Cc: George McCollister <george.mccollister@gmail.com>
Signed-off-by: Matt Ranostay <matt.ranostay@konsulko.com>
---
 drivers/pps/pps.c        | 110 ++++++++++++++++++++++++++++++++++-------------
 include/uapi/linux/pps.h |  19 ++++++++
 2 files changed, 98 insertions(+), 31 deletions(-)

diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index 452ead5a5e52..6eb0db37dd88 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -64,6 +64,43 @@ static int pps_cdev_fasync(int fd, struct file *file, int on)
 	return fasync_helper(fd, file, on, &pps->async_queue);
 }
 
+static int pps_cdev_pps_fetch(struct pps_device *pps, struct pps_fdata *fdata)
+{
+	unsigned int ev = pps->last_ev;
+	int err = 0;
+
+	/* Manage the timeout */
+	if (fdata->timeout.flags & PPS_TIME_INVALID)
+		err = wait_event_interruptible(pps->queue,
+				ev != pps->last_ev);
+	else {
+		unsigned long ticks;
+
+		dev_dbg(pps->dev, "timeout %lld.%09d\n",
+				(long long) fdata->timeout.sec,
+				fdata->timeout.nsec);
+		ticks = fdata->timeout.sec * HZ;
+		ticks += fdata->timeout.nsec / (NSEC_PER_SEC / HZ);
+
+		if (ticks != 0) {
+			err = wait_event_interruptible_timeout(
+					pps->queue,
+					ev != pps->last_ev,
+					ticks);
+			if (err == 0)
+				return -ETIMEDOUT;
+		}
+	}
+
+	/* Check for pending signals */
+	if (err == -ERESTARTSYS) {
+		dev_dbg(pps->dev, "pending signal caught\n");
+		return -EINTR;
+	}
+
+	return 0;
+}
+
 static long pps_cdev_ioctl(struct file *file,
 		unsigned int cmd, unsigned long arg)
 {
@@ -144,7 +181,6 @@ static long pps_cdev_ioctl(struct file *file,
 
 	case PPS_FETCH: {
 		struct pps_fdata fdata;
-		unsigned int ev;
 
 		dev_dbg(pps->dev, "PPS_FETCH\n");
 
@@ -152,36 +188,9 @@ static long pps_cdev_ioctl(struct file *file,
 		if (err)
 			return -EFAULT;
 
-		ev = pps->last_ev;
-
-		/* Manage the timeout */
-		if (fdata.timeout.flags & PPS_TIME_INVALID)
-			err = wait_event_interruptible(pps->queue,
-					ev != pps->last_ev);
-		else {
-			unsigned long ticks;
-
-			dev_dbg(pps->dev, "timeout %lld.%09d\n",
-					(long long) fdata.timeout.sec,
-					fdata.timeout.nsec);
-			ticks = fdata.timeout.sec * HZ;
-			ticks += fdata.timeout.nsec / (NSEC_PER_SEC / HZ);
-
-			if (ticks != 0) {
-				err = wait_event_interruptible_timeout(
-						pps->queue,
-						ev != pps->last_ev,
-						ticks);
-				if (err == 0)
-					return -ETIMEDOUT;
-			}
-		}
-
-		/* Check for pending signals */
-		if (err == -ERESTARTSYS) {
-			dev_dbg(pps->dev, "pending signal caught\n");
-			return -EINTR;
-		}
+		err = pps_cdev_pps_fetch(pps, &fdata);
+		if (err)
+			return err;
 
 		/* Return the fetched timestamp */
 		spin_lock_irq(&pps->lock);
@@ -246,8 +255,47 @@ static long pps_cdev_ioctl(struct file *file,
 static long pps_cdev_compat_ioctl(struct file *file,
 		unsigned int cmd, unsigned long arg)
 {
+	struct pps_device *pps = file->private_data;
+	void __user *uarg = (void __user *) arg;
+
 	cmd = _IOC(_IOC_DIR(cmd), _IOC_TYPE(cmd), _IOC_NR(cmd), sizeof(void *));
 
+	if (cmd == PPS_FETCH) {
+		struct pps_fdata_compat compat;
+		struct pps_fdata fdata;
+		int err;
+
+		dev_dbg(pps->dev, "PPS_FETCH\n");
+
+		err = copy_from_user(&compat, uarg, sizeof(struct pps_fdata_compat));
+		if (err)
+			return -EFAULT;
+
+		memcpy(&fdata.timeout, &compat.timeout,
+					sizeof(struct pps_ktime_compat));
+
+		err = pps_cdev_pps_fetch(pps, &fdata);
+		if (err)
+			return err;
+
+		/* Return the fetched timestamp */
+		spin_lock_irq(&pps->lock);
+
+		compat.info.assert_sequence = pps->assert_sequence;
+		compat.info.clear_sequence = pps->clear_sequence;
+		compat.info.current_mode = pps->current_mode;
+
+		memcpy(&compat.info.assert_tu, &pps->assert_tu,
+				sizeof(struct pps_ktime_compat));
+		memcpy(&compat.info.clear_tu, &pps->clear_tu,
+				sizeof(struct pps_ktime_compat));
+
+		spin_unlock_irq(&pps->lock);
+
+		return copy_to_user(uarg, &compat,
+				sizeof(struct pps_fdata_compat)) ? -EFAULT : 0;
+	}
+
 	return pps_cdev_ioctl(file, cmd, arg);
 }
 #else
diff --git a/include/uapi/linux/pps.h b/include/uapi/linux/pps.h
index a9bb1d93451a..c1cb3825a8bc 100644
--- a/include/uapi/linux/pps.h
+++ b/include/uapi/linux/pps.h
@@ -55,6 +55,12 @@ struct pps_ktime {
 	__s32 nsec;
 	__u32 flags;
 };
+
+struct pps_ktime_compat {
+	__s64 sec;
+	__s32 nsec;
+	__u32 flags;
+} __attribute__((packed, aligned(4)));
 #define PPS_TIME_INVALID	(1<<0)	/* used to specify timeout==NULL */
 
 struct pps_kinfo {
@@ -65,6 +71,14 @@ struct pps_kinfo {
 	int current_mode;		/* current mode bits */
 };
 
+struct pps_kinfo_compat {
+	__u32 assert_sequence;			/* seq. num. of assert event */
+	__u32 clear_sequence;			/* seq. num. of clear event */
+	struct pps_ktime_compat assert_tu;	/* time of assert event */
+	struct pps_ktime_compat clear_tu;	/* time of clear event */
+	int current_mode;			/* current mode bits */
+};
+
 struct pps_kparams {
 	int api_version;		/* API version # */
 	int mode;			/* mode bits */
@@ -114,6 +128,11 @@ struct pps_fdata {
 	struct pps_ktime timeout;
 };
 
+struct pps_fdata_compat {
+	struct pps_kinfo_compat info;
+	struct pps_ktime_compat timeout;
+};
+
 struct pps_bind_args {
 	int tsformat;	/* format of time stamps */
 	int edge;	/* selected event type */
-- 
2.10.2