kernel/linux.git/tools/memory-model/litmus-tests, branch v6.12.80

tools/memory-model: Keep assembly-language litmus tests

2023-03-24T17:24:14+00:00

This commit retains the assembly-language litmus tests generated from the C-language litmus tests, appending the hardware tag to the original C-language litmus test's filename. Thus, S+poonceonces.litmus.AArch64 contains the Armv8 assembly language corresponding to the C-language S+poonceonces.litmus test. This commit also updates the .gitignore to avoid committing these automatically generated assembly-language litmus tests. Signed-off-by: Paul E. McKenney

tools/memory-model: Move from .AArch64.litmus.out to .litmus.AArch.out

2023-03-24T17:24:14+00:00

When the github scripts see ".litmus.out", they assume that there must be a corresponding C-language ".litmus" file. Won't they be disappointed when they instead see nothing, or, worse yet, the corresponding assembly-language litmus test? This commit therefore swaps the hardware tag with the "litmus" to avoid this sort of disappointment. This commit also adjusts the .gitignore file so as to avoid adding these new ".out" files to git. [ paulmck: Apply Akira Yokosawa feedback. ] Signed-off-by: Paul E. McKenney

tools: memory-model: Make plain accesses carry dependencies

2023-01-04T04:47:04+00:00

As reported by Viktor, plain accesses in LKMM are weaker than accesses to registers: the latter carry dependencies but the former do not. This is exemplified in the following snippet: int r = READ_ONCE(*x); WRITE_ONCE(*y, r); Here a data dependency links the READ_ONCE() to the WRITE_ONCE(), preserving their order, because the model treats r as a register. If r is turned into a memory location accessed by plain accesses, however, the link is broken and the order between READ_ONCE() and WRITE_ONCE() is no longer preserved. This is too conservative, since any optimizations on plain accesses that might break dependencies are also possible on registers; it also contradicts the intuitive notion of "dependency" as the data stored by the WRITE_ONCE() does depend on the data read by the READ_ONCE(), independently of whether r is a register or a memory location. This is resolved by redefining all dependencies to include dependencies carried by memory accesses; a dependency is said to be carried by memory accesses (in the model: carry-dep) from one load to another load if the initial load is followed by an arbitrarily long sequence alternating between stores and loads of the same thread, where the data of each store depends on the previous load, and is read by the next load. Any dependency linking the final load in the sequence to another access also links the initial load in the sequence to that access. More deep details can be found in this LKML discussion: https://lore.kernel.org/lkml/d86295788ad14a02874ab030ddb8a6f8@huawei.com/ Reported-by: Viktor Vafeiadis Signed-off-by: Jonas Oberhauser Reviewed-by: Alan Stern Signed-off-by: Paul E. McKenney

tools/memory-model: litmus: Add two tests for unlock(A)+lock(B) ordering

2021-12-01T01:47:08+00:00

The memory model has been updated to provide a stronger ordering guarantee for unlock(A)+lock(B) on the same CPU/thread. Therefore add two litmus tests describing this new guarantee, these tests are simple yet can clearly show the usage of the new guarantee, also they can serve as the self tests for the modification in the model. Co-developed-by: Alan Stern Signed-off-by: Alan Stern Signed-off-by: Boqun Feng Acked-by: Peter Zijlstra (Intel) Signed-off-by: Paul E. McKenney

tools/memory-model: Remove redundant initialization in litmus tests

2021-01-04T22:40:49+00:00

This is a revert of commit 1947bfcf81a9 ("tools/memory-model: Add types to litmus tests") with conflict resolutions. klitmus7 [1] is aware of default types of "int" and "int*". It accepts litmus tests for herd7 without extra type info unless non-"int" variables are referenced by an "exists", "locations", or "filter" directive. [1]: Tested with klitmus7 versions 7.49 or later. Suggested-by: Paul E. McKenney Signed-off-by: Akira Yokosawa Signed-off-by: Paul E. McKenney

tools/memory-model: Label MP tests' producers and consumers

2020-11-07T01:25:17+00:00

This commit adds comments that label the MP tests' producer and consumer processes, and also that label the "exists" clause as the bad outcome. Reported-by: Johannes Weiner Signed-off-by: Paul E. McKenney

tools/memory-model: Use "buf" and "flag" for message-passing tests

2020-11-07T01:25:16+00:00

The use of "x" and "y" for message-passing tests is fine for people familiar with memory models and litmus-test nomenclature, but is a bit obtuse for others. This commit therefore substitutes "buf" for "x" and "flag" for "y" for the MP tests. There are a few special-case MP tests that use locks and these are unchanged. There is another MP test that uses pointers, and this is changed to name the pointer "p". Reported-by: Johannes Weiner Signed-off-by: Paul E. McKenney

tools/memory-model: Add types to litmus tests

2020-11-07T01:25:16+00:00

This commit adds type information for global variables in the litmus tests in order to allow easier use with klitmus7. Signed-off-by: Paul E. McKenney

.gitignore: add SPDX License Identifier

2020-03-25T10:50:48+00:00

Add SPDX License Identifier to all .gitignore files. Signed-off-by: Masahiro Yamada Signed-off-by: Greg Kroah-Hartman

tools/memory-model: Do not use "herd" to refer to "herd7"

2019-06-19T16:32:10+00:00

Use "herd7" in each such reference. Signed-off-by: Andrea Parri Cc: Will Deacon Cc: Peter Zijlstra Cc: Boqun Feng Cc: Nicholas Piggin Cc: David Howells Cc: Jade Alglave Cc: Luc Maranget Cc: "Paul E. McKenney" Cc: Akira Yokosawa Cc: Daniel Lustig Acked-by: Alan Stern Signed-off-by: Paul E. McKenney