linux-kernel - Re: [PATCH v9] pgo: add clang's Profile Guided Optimization infrastructure

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: <20210614153545.GA68749@worktop.programming.kicks-ass.net>
Date:   Mon, 14 Jun 2021 17:35:45 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     Marco Elver <elver@...gle.com>, Bill Wendling <morbo@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Linux Doc Mailing List <linux-doc@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Fangrui Song <maskray@...gle.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, johannes.berg@...el.com,
        oberpar@...ux.vnet.ibm.com, linux-toolchains@...r.kernel.org
Subject: Re: [PATCH v9] pgo: add clang's Profile Guided Optimization
 infrastructure

On Mon, Jun 14, 2021 at 08:26:01AM -0700, Kees Cook wrote:
> So, AFAICT, the original blocking issue ("PGO does not respect noinstr")
> is not actually an issue (noinstr contains notrace, which IS respected
> by PGO[2]), I think this is fine to move forward.

It is *NOT*: https://godbolt.org/z/9c7xdvGd9

Look at how both compilers generate instrumentation in the no_instr()
function.