linux-kernel - Re: [PATCH v5 08/13] coresight: Interpret perf config with ATTR_CFG_GET

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20251119143751.GD8204@e132581.arm.com>
Date: Wed, 19 Nov 2025 14:37:51 +0000
From: Leo Yan <leo.yan@....com>
To: James Clark <james.clark@...aro.org>
Cc: Mike Leach <mike.leach@...aro.org>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jonathan Corbet <corbet@....net>,
	Randy Dunlap <rdunlap@...radead.org>, coresight@...ts.linaro.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org
Subject: Re: [PATCH v5 08/13] coresight: Interpret perf config with
 ATTR_CFG_GET_FLD()

On Wed, Nov 19, 2025 at 01:55:15PM +0000, James Clark wrote:

[...]

> >    static ssize_t format_attr_contextid_show(struct device *dev,
> >                                              struct device_attribute *attr,
> >                                              char *page)
> >    {
> >    #if IS_ENABLED(CONFIG_ARM64)
> >         if (is_kernel_in_hyp_mode())
> >                 return contextid2_show(dev, attr, page);
> >    #endif
> > 
> >         return contextid1_show(dev, attr, page);
> 
> Not having an #else implies that the contextid1_show() part is valid when
> !CONFIG_ARM64, but that isn't right. That's why I had the WARN_ON because
> it's dead code.

Based on ETMv3/v4 spec, would contextid1 always be valid ?  (Though we do
not support context ID for ETMv3 yet).

> Personally I would drop the is_visible(). It makes sense for dynamically
> hidden things, but these are all compile time. IMO it's cleaner to just not
> include them to begin with, rather than include and then hide them. Then the
> extra condition in format_attr_contextid_show() isn't needed because the
> function doesn't exist:

This is fine for me, though in general I think the dynamic approach is
readable and extendable than the compile-time approach.

Thanks,
Leo