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[103.168.172.200]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7b18d331a28sm368853085a.75.2024.10.28.17.04.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Oct 2024 17:04:41 -0700 (PDT) Received: from phl-compute-03.internal (phl-compute-03.phl.internal [10.202.2.43]) by mailfauth.phl.internal (Postfix) with ESMTP id 81FF0120006C; Mon, 28 Oct 2024 20:04:40 -0400 (EDT) Received: from phl-mailfrontend-01 ([10.202.2.162]) by phl-compute-03.internal (MEProxy); Mon, 28 Oct 2024 20:04:40 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeeftddrvdektddgudejucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdggtfgfnhhsuhgsshgtrhhisggvpdfu rfetoffkrfgpnffqhgenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnh htshculddquddttddmnecujfgurhepfffhvfevuffkfhggtggujgesthdtredttddtvden ucfhrhhomhepuehoqhhunhcuhfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrihhlrd gtohhmqeenucggtffrrghtthgvrhhnpefftdeihfeigedtvdeuueffieetvedtgeejuefh hffgudfgfeeggfeftdeigeehvdenucffohhmrghinhepghhithhhuhgsrdgtohhmnecuve hluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepsghoqhhunhdo mhgvshhmthhprghuthhhphgvrhhsohhnrghlihhthidqieelvdeghedtieegqddujeejke ehheehvddqsghoqhhunhdrfhgvnhhgpeepghhmrghilhdrtghomhesfhhigihmvgdrnhgr mhgvpdhnsggprhgtphhtthhopedvtddpmhhouggvpehsmhhtphhouhhtpdhrtghpthhtoh epjhhonhgrshdrohgsvghrhhgruhhsvghrsehhuhgrfigvihgtlhhouhgurdgtohhmpdhr tghpthhtohepphgruhhlmhgtkheskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepshhtvg hrnhesrhhofihlrghnugdrhhgrrhhvrghrugdrvgguuhdprhgtphhtthhopehprghrrhhi rdgrnhgurhgvrgesghhmrghilhdrtghomhdprhgtphhtthhopeifihhllheskhgvrhhnvg hlrdhorhhgpdhrtghpthhtohepphgvthgvrhiisehinhhfrhgruggvrggurdhorhhgpdhr tghpthhtohepnhhpihhgghhinhesghhmrghilhdrtghomhdprhgtphhtthhopeguhhhofi gvlhhlshesrhgvughhrghtrdgtohhmpdhrtghpthhtohepjhdrrghlghhlrghvvgesuhgt lhdrrggtrdhukh X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Mon, 28 Oct 2024 20:04:39 -0400 (EDT) Date: Mon, 28 Oct 2024 17:04:38 -0700 From: Boqun Feng To: Jonas Oberhauser Cc: paulmck@kernel.org, stern@rowland.harvard.edu, parri.andrea@gmail.com, will@kernel.org, peterz@infradead.org, npiggin@gmail.com, dhowells@redhat.com, j.alglave@ucl.ac.uk, luc.maranget@inria.fr, akiyks@gmail.com, dlustig@nvidia.com, joel@joelfernandes.org, urezki@gmail.com, quic_neeraju@quicinc.com, frederic@kernel.org, linux-kernel@vger.kernel.org, lkmm@lists.linux.dev, hernan.poncedeleon@huaweicloud.com Subject: Re: [PATCH v4 4/5] tools/memory-model: Switch to softcoded herd7 tags Message-ID: References: <20240930105710.383284-1-jonas.oberhauser@huaweicloud.com> <20240930105710.383284-5-jonas.oberhauser@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240930105710.383284-5-jonas.oberhauser@huaweicloud.com> On Mon, Sep 30, 2024 at 12:57:09PM +0200, Jonas Oberhauser wrote: > A new version of herd7 provides a -lkmmv2 switch which overrides the old herd7 > behavior of simply ignoring any softcoded tags in the .def and .bell files. We > port LKMM to this version of herd7 by providing the switch in linux-kernel.cfg > and reporting an error if the LKMM is used without this switch. > > To preserve the semantics of LKMM, we also softcode the Noreturn tag on atomic > RMW which do not return a value and define atomic_add_unless with an Mb tag in > linux-kernel.def. > > We update the herd-representation.txt accordingly and clarify some of the > resulting combinations. > > (To be) Signed-off-by: Hernan Ponce de Leon > Signed-off-by: Jonas Oberhauser Reviewed-by: Boqun Feng One bit below: > --- > .../Documentation/herd-representation.txt | 27 ++++++++++--------- > tools/memory-model/README | 2 +- > tools/memory-model/linux-kernel.bell | 3 +++ > tools/memory-model/linux-kernel.cfg | 1 + > tools/memory-model/linux-kernel.def | 18 +++++++------ > 5 files changed, 30 insertions(+), 21 deletions(-) > > diff --git a/tools/memory-model/Documentation/herd-representation.txt b/tools/memory-model/Documentation/herd-representation.txt > index ed988906f2b7..7ae1ff3d3769 100644 > --- a/tools/memory-model/Documentation/herd-representation.txt > +++ b/tools/memory-model/Documentation/herd-representation.txt > @@ -18,6 +18,11 @@ > # > # By convention, a blank line in a cell means "same as the preceding line". > # > +# Note that the syntactic representation does not always match the sets and > +# relations in linux-kernel.cat, due to redefinitions in linux-kernel.bell and > +# lock.cat. For example, the po link between LKR and LKW is upgraded to an rmw > +# link, and W[acquire] are not included in the Acquire set. > +# > # Disclaimer. The table includes representations of "add" and "and" operations; > # corresponding/identical representations of "sub", "inc", "dec" and "or", "xor", > # "andnot" operations are omitted. > @@ -60,14 +65,13 @@ > ------------------------------------------------------------------------------ > | RMW ops w/o return value | | > ------------------------------------------------------------------------------ > - | atomic_add | R*[noreturn] ->rmw W*[once] | > + | atomic_add | R*[noreturn] ->rmw W*[noreturn] | Not in this patch, but don't you need to update this again to all cap to match your changes in patch #5? ;-) Regards, Boqun > | atomic_and | | > | spin_lock | LKR ->po LKW | > ------------------------------------------------------------------------------ > | RMW ops w/ return value | | > ------------------------------------------------------------------------------ > - | atomic_add_return | F[mb] ->po R*[once] | > - | | ->rmw W*[once] ->po F[mb] | > + | atomic_add_return | R*[mb] ->rmw W*[mb] | > | atomic_fetch_add | | > | atomic_fetch_and | | > | atomic_xchg | | > @@ -79,13 +83,13 @@ > | atomic_xchg_relaxed | | > | xchg_relaxed | | > | atomic_add_negative_relaxed | | > - | atomic_add_return_acquire | R*[acquire] ->rmw W*[once] | > + | atomic_add_return_acquire | R*[acquire] ->rmw W*[acquire] | > | atomic_fetch_add_acquire | | > | atomic_fetch_and_acquire | | > | atomic_xchg_acquire | | > | xchg_acquire | | > | atomic_add_negative_acquire | | > - | atomic_add_return_release | R*[once] ->rmw W*[release] | > + | atomic_add_return_release | R*[release] ->rmw W*[release] | > | atomic_fetch_add_release | | > | atomic_fetch_and_release | | > | atomic_xchg_release | | > @@ -94,17 +98,16 @@ > ------------------------------------------------------------------------------ > | Conditional RMW ops | | > ------------------------------------------------------------------------------ > - | atomic_cmpxchg | On success: F[mb] ->po R*[once] | > - | | ->rmw W*[once] ->po F[mb] | > - | | On failure: R*[once] | > + | atomic_cmpxchg | On success: R*[mb] ->rmw W*[mb] | > + | | On failure: R*[mb] | > | cmpxchg | | > | atomic_add_unless | | > | atomic_cmpxchg_relaxed | On success: R*[once] ->rmw W*[once] | > | | On failure: R*[once] | > - | atomic_cmpxchg_acquire | On success: R*[acquire] ->rmw W*[once] | > - | | On failure: R*[once] | > - | atomic_cmpxchg_release | On success: R*[once] ->rmw W*[release] | > - | | On failure: R*[once] | > + | atomic_cmpxchg_acquire | On success: R*[acquire] ->rmw W*[acquire] | > + | | On failure: R*[acquire] | > + | atomic_cmpxchg_release | On success: R*[release] ->rmw W*[release] | > + | | On failure: R*[release] | > | spin_trylock | On success: LKR ->po LKW | > | | On failure: LF | > ------------------------------------------------------------------------------ > diff --git a/tools/memory-model/README b/tools/memory-model/README > index dab38904206a..59bc15edeb8a 100644 > --- a/tools/memory-model/README > +++ b/tools/memory-model/README > @@ -20,7 +20,7 @@ that litmus test to be exercised within the Linux kernel. > REQUIREMENTS > ============ > > -Version 7.52 or higher of the "herd7" and "klitmus7" tools must be > +Version 7.58 or higher of the "herd7" and "klitmus7" tools must be > downloaded separately: > > https://github.com/herd/herdtools7 > diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell > index 7c9ae48b9437..8ae47545df97 100644 > --- a/tools/memory-model/linux-kernel.bell > +++ b/tools/memory-model/linux-kernel.bell > @@ -94,3 +94,6 @@ let carry-dep = (data ; [~ Srcu-unlock] ; rfi)* > let addr = carry-dep ; addr > let ctrl = carry-dep ; ctrl > let data = carry-dep ; data > + > +flag ~empty (if "lkmmv2" then 0 else _) > + as this-model-requires-variant-higher-than-lkmmv1 > diff --git a/tools/memory-model/linux-kernel.cfg b/tools/memory-model/linux-kernel.cfg > index 3c8098e99f41..69b04f3aad73 100644 > --- a/tools/memory-model/linux-kernel.cfg > +++ b/tools/memory-model/linux-kernel.cfg > @@ -1,6 +1,7 @@ > macros linux-kernel.def > bell linux-kernel.bell > model linux-kernel.cat > +variant lkmmv2 > graph columns > squished true > showevents noregs > diff --git a/tools/memory-model/linux-kernel.def b/tools/memory-model/linux-kernel.def > index a12b96c547b7..d7279a357cba 100644 > --- a/tools/memory-model/linux-kernel.def > +++ b/tools/memory-model/linux-kernel.def > @@ -63,14 +63,14 @@ atomic_set(X,V) { WRITE_ONCE(*X,V); } > atomic_read_acquire(X) smp_load_acquire(X) > atomic_set_release(X,V) { smp_store_release(X,V); } > > -atomic_add(V,X) { __atomic_op(X,+,V); } > -atomic_sub(V,X) { __atomic_op(X,-,V); } > -atomic_and(V,X) { __atomic_op(X,&,V); } > -atomic_or(V,X) { __atomic_op(X,|,V); } > -atomic_xor(V,X) { __atomic_op(X,^,V); } > -atomic_inc(X) { __atomic_op(X,+,1); } > -atomic_dec(X) { __atomic_op(X,-,1); } > -atomic_andnot(V,X) { __atomic_op(X,&~,V); } > +atomic_add(V,X) { __atomic_op{noreturn}(X,+,V); } > +atomic_sub(V,X) { __atomic_op{noreturn}(X,-,V); } > +atomic_and(V,X) { __atomic_op{noreturn}(X,&,V); } > +atomic_or(V,X) { __atomic_op{noreturn}(X,|,V); } > +atomic_xor(V,X) { __atomic_op{noreturn}(X,^,V); } > +atomic_inc(X) { __atomic_op{noreturn}(X,+,1); } > +atomic_dec(X) { __atomic_op{noreturn}(X,-,1); } > +atomic_andnot(V,X) { __atomic_op{noreturn}(X,&~,V); } > > atomic_add_return(V,X) __atomic_op_return{mb}(X,+,V) > atomic_add_return_relaxed(V,X) __atomic_op_return{once}(X,+,V) > @@ -144,3 +144,5 @@ atomic_fetch_andnot(V,X) __atomic_fetch_op{mb}(X,&~,V) > atomic_fetch_andnot_acquire(V,X) __atomic_fetch_op{acquire}(X,&~,V) > atomic_fetch_andnot_release(V,X) __atomic_fetch_op{release}(X,&~,V) > atomic_fetch_andnot_relaxed(V,X) __atomic_fetch_op{once}(X,&~,V) > + > +atomic_add_unless(X,V,W) __atomic_add_unless{mb}(X,V,W) > -- > 2.34.1 > >