linux-kernel - Re: [PATCH 9/9] x86/nmi: Improve NMI duration console print

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]

Message-ID: <fdd8a59820d4e6764e77f61ebeaa85cb69c9fef5.camel@intel.com>
Date: Tue, 1 Apr 2025 00:42:28 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "Mehta, Sohil" <sohil.mehta@...el.com>, "tglx@...utronix.de"
	<tglx@...utronix.de>, "mingo@...hat.com" <mingo@...hat.com>, "x86@...nel.org"
	<x86@...nel.org>
CC: "Nikula, Jani" <jani.nikula@...el.com>, "bp@...en8.de" <bp@...en8.de>,
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
	"peterz@...radead.org" <peterz@...radead.org>, "hpa@...or.com"
	<hpa@...or.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "kirill.shutemov@...ux.intel.com"
	<kirill.shutemov@...ux.intel.com>, "rppt@...nel.org" <rppt@...nel.org>,
	"bigeasy@...utronix.de" <bigeasy@...utronix.de>, "jpoimboe@...nel.org"
	<jpoimboe@...nel.org>, "pmladek@...e.com" <pmladek@...e.com>, "xin@...or.com"
	<xin@...or.com>, "Luck, Tony" <tony.luck@...el.com>
Subject: Re: [PATCH 9/9] x86/nmi: Improve NMI duration console print

On Thu, 2025-03-27 at 23:46 +0000, Mehta, Sohil wrote:
> Convert the last remaining printk() in nmi.c to pr_info(). Along with
> it, use timespec macros to calculate the NMI handler duration.
> 
> Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>

I eventually figured out the reasons to use NSEC_PER_MSEC and NSEC_PER_USEC:

Reviewed-by: Kai Huang <kai.huang@...el.com>

> ---
>  arch/x86/kernel/nmi.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
> index 59ed74ec010e..be93ec7255bf 100644
> --- a/arch/x86/kernel/nmi.c
> +++ b/arch/x86/kernel/nmi.c
> @@ -119,12 +119,12 @@ static void nmi_check_duration(struct nmiaction *action, u64 duration)
>  
>  	action->max_duration = duration;
>  
> -	remainder_ns = do_div(duration, (1000 * 1000));
> -	decimal_msecs = remainder_ns / 1000;
> +	/* Convert duration from nsec to msec */
> +	remainder_ns = do_div(duration, NSEC_PER_MSEC);
> +	decimal_msecs = remainder_ns / NSEC_PER_USEC;
>  
> -	printk_ratelimited(KERN_INFO
> -		"INFO: NMI handler (%ps) took too long to run: %lld.%03d msecs\n",
> -		action->handler, duration, decimal_msecs);
> +	pr_info_ratelimited("INFO: NMI handler (%ps) took too long to run: %lld.%03d msecs\n",
> +			    action->handler, duration, decimal_msecs);
>  }
>  
>  static int nmi_handle(unsigned int type, struct pt_regs *regs)