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[2001:14ba:14f7:3c00:8461:5bff:fed3:30ca]) by smtp.gmail.com with ESMTPSA id y5sm1603918lfs.265.2021.06.14.15.27.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Jun 2021 15:27:29 -0700 (PDT) From: jarmo.tiitto@gmail.com To: Jarmo Tiitto , Kees Cook Cc: Sami Tolvanen , Bill Wendling , Nathan Chancellor , Nick Desaulniers , clang-built-linux@googlegroups.com, linux-kernel@vger.kernel.org, morbo@google.com Subject: Re: [RFC PATCH 0/5] pgo: Add PGO support for module profile data Date: Tue, 15 Jun 2021 01:27:28 +0300 Message-ID: <2164227.uJ0V1KJIEf@hyperiorarchmachine> In-Reply-To: <202106141455.45C7B198D7@keescook> References: <20210612032425.11425-1-jarmo.tiitto@gmail.com> <202106140904.484E2337C@keescook> <202106141455.45C7B198D7@keescook> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Kees Cook wrote tiistaina 15. kes=C3=A4kuuta 2021 0.57.46 EEST: > On Sat, Jun 12, 2021 at 06:24:21AM +0300, Jarmo Tiitto wrote: > > [...] > > The patches itself are based on Kees/for-next/clang/features tree > > where I have two of my bug fix patches already in. :-) >=20 > BTW, due to the (soon to be addressed) requirements of noinstr[1], > I've removed PGO from my -next tree, and moved it into its own tree in > "for-next/clang/pgo". >=20 > -Kees >=20 > [1] https://lore.kernel.org/lkml/202106140921.5E591BD@keescook/ >=20 > -- > Kees Cook Yeah, I noticed that. Actually, I think we really should wait for that noin= str=20 stuff since: > There is an lockup that only occurs during bare metal run after +15min, s= o I=20 > haven't been able to catch it in VM. > I suspect this is caused by the RCU locking I added such that it results = in=20 > recursive calls into __llvm_profile_instrument_target() That basically means LLVM is instrumenting code that I call from __llvm_profile_instrument_target() resulting in nice cycle of doom. Sigh... I wrote fix for this but it would be nice to be sure the compiler doesn't pull the rug under my toes. :-) =2D- Jarmo