diff options
| author | Jonas Oberhauser <jonas.oberhauser@huaweicloud.com> | 2024-09-30 13:57:09 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2025-02-25 21:16:57 +0300 |
| commit | fafa180683591f5f917bfa68e95aae463afc852a (patch) | |
| tree | e8401ed5a3804c81b07416bd0241acba8a0dc2dd /tools/memory-model/Documentation | |
| parent | 29279349a566232057f52392d1a8af91772de7e1 (diff) | |
| download | linux-fafa180683591f5f917bfa68e95aae463afc852a.tar.xz | |
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
Diffstat (limited to 'tools/memory-model/Documentation')
| -rw-r--r-- | tools/memory-model/Documentation/herd-representation.txt | 27 |
1 files changed, 15 insertions, 12 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] | | 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 | ------------------------------------------------------------------------------ |