Date:   Tue, 21 Dec 2021 16:22:19 +0100
From:   Borislav Petkov <bp@suse.de>
To:     Marco Elver <elver@google.com>
Cc:     Carel Si <beibei.si@intel.com>,
        "Yin, Fengwei" <fengwei.yin@intel.com>,
        Joerg Roedel <jroedel@suse.de>,
        LKML <linux-kernel@vger.kernel.org>,
        "x86@kernel.org" <x86@kernel.org>,
        "lkp@lists.01.org" <lkp@lists.01.org>, lkp <lkp@intel.com>,
        "bfields@fieldses.org" <bfields@fieldses.org>,
        "llvm@lists.linux.dev" <llvm@lists.linux.dev>
Subject: Re: [LKP] Re: [x86/mm/64] f154f29085:
 BUG:kernel_reboot-without-warning_in_boot_stage - clang KCOV?
Message-ID: <YcHxKzB3WPurKlZ9@zn.tnic>
References: <YbjIoewxGaodXHKF@zn.tnic>
 <20211215070012.GA26582@linux.intel.com>
 <Ybm96seTxl+pWjTX@zn.tnic>
 <009391a5-468b-2a5d-1f12-44d2e3104bd6@intel.com>
 <YbsPwyLnejLQMbTb@zn.tnic>
 <20211216115838.GA23522@linux.intel.com>
 <e48b72d4-558a-ed7c-43cd-0cb70091be11@intel.com>
 <YbyIJYzqtHPKRMFt@zn.tnic>
 <20211221143153.GA4676@linux.intel.com>
 <CANpmjNO4hs1B9eDY9edGGOXY45a8smdtYfYfbDRnGWSYch4wGg@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <CANpmjNO4hs1B9eDY9edGGOXY45a8smdtYfYfbDRnGWSYch4wGg@mail.gmail.com>
Precedence: bulk

On Tue, Dec 21, 2021 at 04:10:31PM +0100, Marco Elver wrote:
> Also double-check the Makefile-based solution: the Makefiles in both
> directories already contain various KCOV_INSTRUMENT/K*SAN_SANITIZE :=
> n, so perhaps adding GCOV_PROFILE or GCOV_PROFILE_whicheverfile.o := n
> may be more appropriate should the functions that should not be
> instrumented be a moving target, and prone to breakage again in
> future.

Yeah, I asked whether we should exclude the whole ...cpu/common.c from
profiling - it has mostly init code so it probably doesn't matter
for coverage but no one said anything so I left it to the function
annotation.

And also, I'm still waiting on clang folks to chime in on the New Pass
Manager and whether there's a bug in clang there so that we won't need
the __no_profile annotation at all. I mean, gcc is fine with that config
so unless clang is doing more profiling gunk than gcc and requires that
__llvm_gcov_init constructor... see Nathan's mail upthread.

Thx.

-- 
Regards/Gruss,
    Boris.

SUSE Software Solutions Germany GmbH, GF: Ivo Totev, HRB 36809, AG Nürnberg