linux-kernel - [PATCH 1/2] clocksource: timer-ti-dm: Do not restore context on every timer enable

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 24 Feb 2020 10:37:52 +0530
From:   Lokesh Vutla <lokeshvutla@...com>
To:     Tony Lindgren <tony@...mide.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>
CC:     Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <narmstrong@...libre.com>,
        Sekhar Nori <nsekhar@...com>, Tero Kristo <t-kristo@...com>,
        Lokesh Vutla <lokeshvutla@...com>
Subject: [PATCH 1/2] clocksource: timer-ti-dm: Do not restore context on every timer enable

omap_dm_timer_enable() restores the entire context(including counter)
based on 2 conditions:
- If get_context_loss_count is populated and context is lost.
- If get_context_loss_count is not populated update unconditionally.

Case2 has a side effect of updating the counter register even though
context is not lost. When timer is configured in pwm mode, this is
causing undesired behaviour in the pwm period. So restore context only
if get_context_loss_count is populated and context is actually lost.

Signed-off-by: Lokesh Vutla <lokeshvutla@...com>
---
 drivers/clocksource/timer-ti-dm.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/clocksource/timer-ti-dm.c b/drivers/clocksource/timer-ti-dm.c
index 269a994d6a99..40742715ed21 100644
--- a/drivers/clocksource/timer-ti-dm.c
+++ b/drivers/clocksource/timer-ti-dm.c
@@ -229,15 +229,12 @@ static void omap_dm_timer_enable(struct omap_dm_timer *timer)
 
 	pm_runtime_get_sync(&timer->pdev->dev);
 
-	if (!(timer->capability & OMAP_TIMER_ALWON)) {
-		if (timer->get_context_loss_count) {
-			c = timer->get_context_loss_count(&timer->pdev->dev);
-			if (c != timer->ctx_loss_count) {
-				omap_timer_restore_context(timer);
-				timer->ctx_loss_count = c;
-			}
-		} else {
+	if (!(timer->capability & OMAP_TIMER_ALWON) &&
+	    timer->get_context_loss_count) {
+		c = timer->get_context_loss_count(&timer->pdev->dev);
+		if (c != timer->ctx_loss_count) {
 			omap_timer_restore_context(timer);
+			timer->ctx_loss_count = c;
 		}
 	}
 }
-- 
2.23.0