linux-kernel - [tip: timers/clocksource] clocksource/drivers/timer-tegra186: Avoid 64-bit divide operation

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>] [day] [month] [year] [list]

Message-ID: <175883602648.709179.10589873692601492232.tip-bot2@tip-bot2>
Date: Thu, 25 Sep 2025 21:33:46 -0000
From: "tip-bot2 for Guenter Roeck" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Guenter Roeck <linux@...ck-us.net>,
 Daniel Lezcano <daniel.lezcano@...aro.org>, Jon Hunter <jonathanh@...dia.com>,
 Pohsun Su <pohsuns@...dia.com>, Robert Lin <robelin@...dia.com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: timers/clocksource] clocksource/drivers/timer-tegra186: Avoid
 64-bit divide operation

The following commit has been merged into the timers/clocksource branch of tip:

Commit-ID:     916aa36042db8ee230543ffe0d192f900e8b8c9f
Gitweb:        https://git.kernel.org/tip/916aa36042db8ee230543ffe0d192f900e8b8c9f
Author:        Guenter Roeck <linux@...ck-us.net>
AuthorDate:    Sat, 14 Jun 2025 10:55:55 -07:00
Committer:     Daniel Lezcano <daniel.lezcano@...aro.org>
CommitterDate: Tue, 23 Sep 2025 10:54:29 +02:00

clocksource/drivers/timer-tegra186: Avoid 64-bit divide operation

Building the driver on xtensa fails with

tensa-linux-ld: drivers/clocksource/timer-tegra186.o:
	in function `tegra186_timer_remove':
timer-tegra186.c:(.text+0x350):
	undefined reference to `__udivdi3'

Avoid the problem by rearranging the offending code to avoid the 64-bit
divide operation.

Fixes: 28c842c8b0f5 ("clocksource/drivers/timer-tegra186: Add WDIOC_GETTIMELEFT support")
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
Reviewed-by: Jon Hunter <jonathanh@...dia.com>
Cc: Pohsun Su <pohsuns@...dia.com>
Cc: Robert Lin <robelin@...dia.com>
Link: https://lore.kernel.org/r/20250614175556.922159-1-linux@roeck-us.net
---
 drivers/clocksource/timer-tegra186.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
index 56a5342..76a5481 100644
--- a/drivers/clocksource/timer-tegra186.c
+++ b/drivers/clocksource/timer-tegra186.c
@@ -267,7 +267,7 @@ static unsigned int tegra186_wdt_get_timeleft(struct watchdog_device *wdd)
 	 * counter value to the time of the counter expirations that
 	 * remain.
 	 */
-	timeleft += (((u64)wdt->base.timeout * USEC_PER_SEC) / 5) * (4 - expiration);
+	timeleft += ((u64)wdt->base.timeout * (USEC_PER_SEC / 5)) * (4 - expiration);
 
 	/*
 	 * Convert the current counter value to seconds,