From: Thomas Gleixner <tglx@linutronix.de>
To: Nicolas Saenz Julienne <nsaenzju@redhat.com>,
mark.rutland@arm.com, paulmck@kernel.org
Cc: rostedt@goodmis.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, rcu@vger.kernel.org,
peterz@infradead.org, mtosatti@redhat.com, frederic@kernel.org,
corbet@lwn.net, Nicolas Saenz Julienne <nsaenzju@redhat.com>
Subject: Re: [PATCH v3 1/2] Documentation: Fill the gaps about entry/noinstr constraints
Date: Fri, 17 Dec 2021 18:40:25 +0100 [thread overview]
Message-ID: <87a6gzcepi.ffs@tglx> (raw)
In-Reply-To: <20211217105753.892855-1-nsaenzju@redhat.com>
Nicolas,
On Fri, Dec 17 2021 at 11:57, Nicolas Saenz Julienne wrote:
> +Non-instrumentable code - noinstr
> +---------------------------------
> +
> +Most instrumentation facilities depend on RCU, so intrumentation is prohibited
> +for entry code before RCU starts watching and exit code after RCU stops
> +watching. In addition, many architectures must save and restore register state,
> +which means that (for example) a breakpoint in the breakpoint entry code would
> +overwrite the debug registers of the initial breakpoint.
> +
> +Such code must be marked with the 'noinstr' attribute, placing that code into a
> +special section inaccessible to instrumentation and debug facilities. Some
> +functions are partially instrumentable, which is handled by marking them nointr
s/nointr/noinstr/
Thanks for polishing this!
tglx
next prev parent reply other threads:[~2021-12-17 17:40 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-17 10:57 [PATCH v3 1/2] Documentation: Fill the gaps about entry/noinstr constraints Nicolas Saenz Julienne
2021-12-17 10:57 ` [PATCH v3 2/2] Documentation: core-api: entry: Add comments about nesting Nicolas Saenz Julienne
2021-12-17 17:56 ` Paul E. McKenney
2021-12-17 17:40 ` Thomas Gleixner [this message]
2021-12-17 17:51 ` [PATCH v3 1/2] Documentation: Fill the gaps about entry/noinstr constraints Paul E. McKenney
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