linux-kernel - Re: [PATCH v3 02/35] compiler-capability-analysis: Add infrastructure for Clang's capability analysis

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: <1ca90ba0-7bdc-43d1-af12-bba73dd3234a@acm.org>
Date: Thu, 18 Sep 2025 09:03:17 -0700
From: Bart Van Assche <bvanassche@....org>
To: Ian Rogers <irogers@...gle.com>, Marco Elver <elver@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Boqun Feng <boqun.feng@...il.com>,
 Ingo Molnar <mingo@...nel.org>, Will Deacon <will@...nel.org>,
 "David S. Miller" <davem@...emloft.net>,
 Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
 "Paul E. McKenney" <paulmck@...nel.org>,
 Alexander Potapenko <glider@...gle.com>, Arnd Bergmann <arnd@...db.de>,
 Bill Wendling <morbo@...gle.com>, Christoph Hellwig <hch@....de>,
 Dmitry Vyukov <dvyukov@...gle.com>, Eric Dumazet <edumazet@...gle.com>,
 Frederic Weisbecker <frederic@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Herbert Xu <herbert@...dor.apana.org.au>, Jann Horn <jannh@...gle.com>,
 Joel Fernandes <joelagnelf@...dia.com>, Jonathan Corbet <corbet@....net>,
 Josh Triplett <josh@...htriplett.org>, Justin Stitt
 <justinstitt@...gle.com>, Kees Cook <kees@...nel.org>,
 Kentaro Takeda <takedakn@...data.co.jp>,
 Lukas Bulwahn <lukas.bulwahn@...il.com>, Mark Rutland
 <mark.rutland@....com>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Miguel Ojeda <ojeda@...nel.org>, Nathan Chancellor <nathan@...nel.org>,
 Neeraj Upadhyay <neeraj.upadhyay@...nel.org>,
 Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
 Steven Rostedt <rostedt@...dmis.org>,
 Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
 Thomas Gleixner <tglx@...utronix.de>, Thomas Graf <tgraf@...g.ch>,
 Uladzislau Rezki <urezki@...il.com>, Waiman Long <longman@...hat.com>,
 kasan-dev@...glegroups.com, linux-crypto@...r.kernel.org,
 linux-doc@...r.kernel.org, linux-kbuild@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 linux-security-module@...r.kernel.org, linux-sparse@...r.kernel.org,
 llvm@...ts.linux.dev, rcu@...r.kernel.org,
 Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH v3 02/35] compiler-capability-analysis: Add infrastructure
 for Clang's capability analysis

On 9/18/25 8:58 AM, Ian Rogers wrote:
> On Thu, Sep 18, 2025 at 7:05 AM Marco Elver <elver@...gle.com> wrote:
>> +config WARN_CAPABILITY_ANALYSIS
>> +       bool "Compiler capability-analysis warnings"
>> +       depends on CC_IS_CLANG && CLANG_VERSION >= 220000
>> +       # Branch profiling re-defines "if", which messes with the compiler's
>> +       # ability to analyze __cond_acquires(..), resulting in false positives.
>> +       depends on !TRACE_BRANCH_PROFILING
> 
> Err, wow! What and huh, and why? Crikes. I'm amazed you found such an
> option exists. I must be very naive to have never heard of it and now
> I wonder if it is needed and load bearing?

(+Steven)

This is an old option. I think this commit introduced it:

commit 52f232cb720a7babb752849cbc2cab2d24021209
Author: Steven Rostedt <rostedt@...dmis.org>
Date:   Wed Nov 12 00:14:40 2008 -0500

     tracing: likely/unlikely branch annotation tracer

Bart.