Subject: [Intel PMC TGPIO Driver 1/5] drivers/ptp: Add Enhanced handling of reserve fields

From: [email-masked]
Date: Wed, 11 Dec 2019 13:48:48 -0800

From: Christopher Hall <[email-masked]>

Add functions that parameterize checking and zeroing of reserve fields in
ioctl arguments. Eliminates need to change this code when repurposing
reserve fields.

Signed-off-by: Christopher Hall <[email-masked]>
---
 drivers/ptp/ptp_chardev.c | 60 +++++++++++++++++++++------------------
 1 file changed, 33 insertions(+), 27 deletions(-)

diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 9d72ab593f13..f9ad6df57fa5 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -12,6 +12,7 @@
 #include <linux/timekeeping.h>
 
 #include <linux/nospec.h>
+#include <linux/string.h>
 
 #include "ptp_private.h"
 
@@ -106,6 +107,28 @@ int ptp_open(struct posix_clock *pc, fmode_t fmode)
 	return 0;
 }
 
+/* Returns -1 if any reserved fields are non-zero */
+static inline int _check_rsv_field(unsigned int *field, size_t size)
+{
+	unsigned int *iter;
+	int ret = 0;
+
+	for (iter = field; iter < field+size && ret == 0; ++iter)
+		ret = *iter == 0 ? 0 : -1;
+
+	return ret;
+}
+#define check_rsv_field(field) _check_rsv_field(field, ARRAY_SIZE(field))
+
+static inline void _zero_rsv_field(unsigned int *field, size_t size)
+{
+	unsigned int *iter;
+
+	for (iter = field; iter < field+size; ++iter)
+		*iter = 0;
+}
+#define zero_rsv_field(field) _zero_rsv_field(field, ARRAY_SIZE(field))
+
 long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
 {
 	struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
@@ -154,7 +177,7 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
 			req.extts.flags |= PTP_STRICT_FLAGS;
 			/* Make sure no reserved bit is set. */
 			if ((req.extts.flags & ~PTP_EXTTS_VALID_FLAGS) ||
-			    req.extts.rsv[0] || req.extts.rsv[1]) {
+			    check_rsv_field(req.extts.rsv)) {
 				err = -EINVAL;
 				break;
 			}
@@ -166,8 +189,7 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
 			}
 		} else if (cmd == PTP_EXTTS_REQUEST) {
 			req.extts.flags &= PTP_EXTTS_V1_VALID_FLAGS;
-			req.extts.rsv[0] = 0;
-			req.extts.rsv[1] = 0;
+			zero_rsv_field(req.extts.rsv);
 		}
 		if (req.extts.index >= ops->n_ext_ts) {
 			err = -EINVAL;
@@ -188,17 +210,13 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
 			break;
 		}
 		if (((req.perout.flags & ~PTP_PEROUT_VALID_FLAGS) ||
-			req.perout.rsv[0] || req.perout.rsv[1] ||
-			req.perout.rsv[2] || req.perout.rsv[3]) &&
-			cmd == PTP_PEROUT_REQUEST2) {
+		     check_rsv_field(req.perout.rsv)) &&
+		    cmd == PTP_PEROUT_REQUEST2) {
 			err = -EINVAL;
 			break;
 		} else if (cmd == PTP_PEROUT_REQUEST) {
 			req.perout.flags &= PTP_PEROUT_V1_VALID_FLAGS;
-			req.perout.rsv[0] = 0;
-			req.perout.rsv[1] = 0;
-			req.perout.rsv[2] = 0;
-			req.perout.rsv[3] = 0;
+			zero_rsv_field(req.perout.rsv);
 		}
 		if (req.perout.index >= ops->n_per_out) {
 			err = -EINVAL;
@@ -258,7 +276,7 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
 			break;
 		}
 		if (extoff->n_samples > PTP_MAX_SAMPLES
-		    || extoff->rsv[0] || extoff->rsv[1] || extoff->rsv[2]) {
+		    || check_rsv_field(extoff->rsv)) {
 			err = -EINVAL;
 			break;
 		}
@@ -318,17 +336,11 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
 			err = -EFAULT;
 			break;
 		}
-		if ((pd.rsv[0] || pd.rsv[1] || pd.rsv[2]
-				|| pd.rsv[3] || pd.rsv[4])
-			&& cmd == PTP_PIN_GETFUNC2) {
+		if (check_rsv_field(pd.rsv) && cmd == PTP_PIN_GETFUNC2) {
 			err = -EINVAL;
 			break;
 		} else if (cmd == PTP_PIN_GETFUNC) {
-			pd.rsv[0] = 0;
-			pd.rsv[1] = 0;
-			pd.rsv[2] = 0;
-			pd.rsv[3] = 0;
-			pd.rsv[4] = 0;
+			zero_rsv_field(pd.rsv);
 		}
 		pin_index = pd.index;
 		if (pin_index >= ops->n_pins) {
@@ -350,17 +362,11 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
 			err = -EFAULT;
 			break;
 		}
-		if ((pd.rsv[0] || pd.rsv[1] || pd.rsv[2]
-				|| pd.rsv[3] || pd.rsv[4])
-			&& cmd == PTP_PIN_SETFUNC2) {
+		if (check_rsv_field(pd.rsv) && cmd == PTP_PIN_SETFUNC2) {
 			err = -EINVAL;
 			break;
 		} else if (cmd == PTP_PIN_SETFUNC) {
-			pd.rsv[0] = 0;
-			pd.rsv[1] = 0;
-			pd.rsv[2] = 0;
-			pd.rsv[3] = 0;
-			pd.rsv[4] = 0;
+			zero_rsv_field(pd.rsv);
 		}
 		pin_index = pd.index;
 		if (pin_index >= ops->n_pins) {
-- 
2.21.0