[PATCH v2 1/2] wifi: iwlwifi: mvm: Fix GP2 to nanoseconds overflow on 32-bit

[Zhan Xusheng <zhanxusheng1024@gmail.com>]

scale_update_gp2 and gp2_on_air_rise are u32 GP2 timestamps in
microseconds.  NSEC_PER_USEC is 1000L, so on 32-bit the products are
computed in 32-bit arithmetic and truncated before being widened:

	u64 last_gp2_ns = mvm->ptp_data.scale_update_gp2 * NSEC_PER_USEC;

A GP2 value above (U32_MAX / 1000) us, i.e. 4.295 s, wraps.  GP2 is a
free-running counter that wraps every 2^32 us, so almost its whole range
is affected and the PTP clock jumps.

The neighbouring conversions in the same files already cast:

	gp2_ns = iwl_mvm_ptp_get_adj_time(mvm, (u64)gp2 * NSEC_PER_USEC);

Cast the remaining ones the same way.  The i386 build of
iwl_mvm_ptp_get_adj_time() changes from "imul $0x3e8,...,%ecx" to
"mull", i.e. from a 32-bit product to a 32x32->64 one.

mvm/ptp.c:219 is already u64 and needs no change.

Fixes: a2f49f7d52a9 ("wifi: iwlwifi: mvm: implement PHC clock adjustments")
Fixes: 0e49e940d1bc ("wifi: iwlwifi: mvm: add an option to use ptp clock for rx timestamp")
Signed-off-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
---
 drivers/net/wireless/intel/iwlwifi/mvm/ptp.c  | 4 ++--
 drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c | 4 +++-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/ptp.c b/drivers/net/wireless/intel/iwlwifi/mvm/ptp.c
index 49dcb1388007..5f33e2f8fb2a 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/ptp.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/ptp.c
@@ -47,7 +47,7 @@ static void iwl_mvm_ptp_update_new_read(struct iwl_mvm *mvm, u32 gp2)
 u64 iwl_mvm_ptp_get_adj_time(struct iwl_mvm *mvm, u64 base_time_ns)
 {
 	struct ptp_data *data = &mvm->ptp_data;
-	u64 last_gp2_ns = mvm->ptp_data.scale_update_gp2 * NSEC_PER_USEC;
+	u64 last_gp2_ns = (u64)mvm->ptp_data.scale_update_gp2 * NSEC_PER_USEC;
 	u64 res;
 	u64 diff;
 
@@ -259,7 +259,7 @@ static int iwl_mvm_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
 	 */
 	gp2 = iwl_mvm_get_systime(mvm);
 	data->scale_update_adj_time_ns =
-		iwl_mvm_ptp_get_adj_time(mvm, gp2 * NSEC_PER_USEC);
+		iwl_mvm_ptp_get_adj_time(mvm, (u64)gp2 * NSEC_PER_USEC);
 	data->scale_update_gp2 = gp2;
 	data->wrap_counter = 0;
 	data->delta = 0;
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c b/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
index c01c704929ba..e9146c38a81c 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
@@ -2021,7 +2021,9 @@ static void iwl_mvm_rx_fill_status(struct iwl_mvm *mvm,
 
 	if (mvm->rx_ts_ptp && mvm->monitor_on) {
 		u64 adj_time =
-			iwl_mvm_ptp_get_adj_time(mvm, phy_data->gp2_on_air_rise * NSEC_PER_USEC);
+			iwl_mvm_ptp_get_adj_time(mvm,
+						 (u64)phy_data->gp2_on_air_rise *
+						 NSEC_PER_USEC);
 
 		rx_status->mactime = div64_u64(adj_time, NSEC_PER_USEC);
 		rx_status->flag |= RX_FLAG_MACTIME_IS_RTAP_TS64;
-- 
2.43.0