tools/memory-model: Switch to softcoded herd7 tags

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.

Co-developed-by: Hernan Ponce de Leon <hernan.poncedeleon@huaweicloud.com>
Signed-off-by: Hernan Ponce de Leon <hernan.poncedeleon@huaweicloud.com>
Signed-off-by: Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Tested-by: Akira Yokosawa <akiyks@gmail.com> # herdtools7.7.58

diff --git a/tools/memory-model/Documentation/herd-representation.txt b/tools/memory-model/Documentation/herd-representation.txt
index ed988906f2b71e55967b6c3a2ebaa210c9e8d70c..7ae1ff3d3769e72b2297720d22dce97f93744bb8 100644 (file)
--- 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]           |
     |                     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 dab38904206a0ba0fea7ccd10469443fec1f396c..59bc15edeb8abd029e513f28b3cdda419f891f23 100644 (file)
--- 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 7c9ae48b94377ad667615157ea67e09adf235cc8..8ae47545df978ca90b674860c88650e29dce2e2d 100644 (file)
--- 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 3c8098e99f41dfe72cb75f4c276801ab2c855f83..69b04f3aad737f34cd19914e507aaac30f78fe33 100644 (file)
--- 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 a12b96c547b7a9bd9c8b21f918fa7bf1cdecef87..d7279a357cba054e2d531b4b52c2eb4dbd239641 100644 (file)
--- 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)