From mboxrd@z Thu Jan  1 00:00:00 1970
From: arnd@arndb.de (Arnd Bergmann)
Date: Tue, 10 Nov 2015 13:39:44 +0100
Subject: [PATCH v2 7/7] xen/arm: set the system time in Xen via the
 XENPF_settime64 hypercall
In-Reply-To: <1447156675-7418-7-git-send-email-stefano.stabellini@eu.citrix.com>
References: <alpine.DEB.2.02.1511101131350.5676@kaball.uk.xensource.com>
 <1447156675-7418-7-git-send-email-stefano.stabellini@eu.citrix.com>
Message-ID: <4039287.QS1nrAMb0E@wuerfel>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Tuesday 10 November 2015 11:57:55 Stefano Stabellini wrote:
> +       op.u.settime64.nsecs = now.tv_nsec;
> +       op.u.settime64.system_time = arch_timer_read_counter() * (u64)NSEC_PER_SEC;
> +       do_div(op.u.settime64.system_time, arch_timer_get_rate());

NSEC_PER_SEC is a large number, doesn't that multiplication overflow the
64-bit system_time variable?

> +       printk("GTOD: Setting to %llu.%u at %llu\n",

				   %llu.%09u

so you get the leading zeroes.

> +              op.u.settime64.secs,
> +              op.u.settime64.nsecs,
> +              op.u.settime64.system_time);
> +       (void)HYPERVISOR_platform_op(&op);

	Arnd