On 11/21/2017 03:19 PM, Mathieu Desnoyers wrote:
> Implements two basic tests of RSEQ functionality, and one more
> exhaustive parameterizable test.
>
> The first, "basic_test" only asserts that RSEQ works moderately
> correctly. E.g. that the CPUID pointer works.
>
> "basic_percpu_ops_test" is a slightly more "realistic" variant,
> implementing a few simple per-cpu operations and testing their
> correctness.
>
> "param_test" is a parametrizable restartable sequences test. See
> the "--help" output for usage.
>
> A run_param_test.sh script runs many variants of the parametrizable
> tests.
>
> As part of those tests, a helper library "rseq" implements a user-space
> API around restartable sequences. It uses the cpu_opv system call as
> fallback when single-stepped by a debugger. It exposes the instruction
> pointer addresses where the rseq assembly blocks begin and end, as well
> as the associated abort instruction pointer, in the __rseq_table
> section. This section allows debuggers may know where to place
> breakpoints when single-stepping through assembly blocks which may be
> aborted at any point by the kernel.
>
> The rseq library expose APIs that present the fast-path operations.
> The new from userspace is, e.g. for a counter increment:
>
> cpu = rseq_cpu_start();
> ret = rseq_addv(&data->c[cpu].count, 1, cpu);
> if (likely(!ret))
> return 0; /* Success. */
> do {
> cpu = rseq_current_cpu();
> ret = cpu_op_addv(&data->c[cpu].count, 1, cpu);
> if (likely(!ret))
> return 0; /* Success. */
> } while (ret > 0 || errno == EAGAIN);
> perror("cpu_op_addv");
> return -1; /* Unexpected error. */
>
> PowerPC tests have been implemented by Boqun Feng.
>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
> CC: Russell King <linux@xxxxxxxxxxxxxxxx>
> CC: Catalin Marinas <catalin.marinas@xxxxxxx>
> CC: Will Deacon <will.deacon@xxxxxxx>
> CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> CC: Paul Turner <pjt@xxxxxxxxxx>
> CC: Andrew Hunter <ahh@xxxxxxxxxx>
> CC: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> CC: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
> CC: Andi Kleen <andi@xxxxxxxxxxxxxx>
> CC: Dave Watson <davejwatson@xxxxxx>
> CC: Chris Lameter <cl@xxxxxxxxx>
> CC: Ingo Molnar <mingo@xxxxxxxxxx>
> CC: "H. Peter Anvin" <hpa@xxxxxxxxx>
> CC: Ben Maurer <bmaurer@xxxxxx>
> CC: Steven Rostedt <rostedt@xxxxxxxxxxx>
> CC: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
> CC: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
> CC: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> CC: Boqun Feng <boqun.feng@xxxxxxxxx>
> CC: Shuah Khan <shuah@xxxxxxxxxx>
> CC: linux-kselftest@xxxxxxxxxxxxxxx
> CC: linux-api@xxxxxxxxxxxxxxx
> ---
> Changes since v1:
> - Provide abort-ip signature: The abort-ip signature is located just
> before the abort-ip target. It is currently hardcoded, but a
> user-space application could use the __rseq_table to iterate on all
> abort-ip targets and use a random value as signature if needed in the
> future.
> - Add rseq_prepare_unload(): Libraries and JIT code using rseq critical
> sections need to issue rseq_prepare_unload() on each thread at least
> once before reclaim of struct rseq_cs.
> - Use initial-exec TLS model, non-weak symbol: The initial-exec model is
> signal-safe, whereas the global-dynamic model is not. Remove the
> "weak" symbol attribute from the __rseq_abi in rseq.c. The rseq.so
> library will have ownership of that symbol, and there is not reason for
> an application or user library to try to define that symbol.
> The expected use is to link against libreq.so, which owns and provide
> that symbol.
> - Set cpu_id to -2 on register error
> - Add rseq_len syscall parameter, rseq_cs version
> - Ensure disassember-friendly signature: x86 32/64 disassembler have a
> hard time decoding the instruction stream after a bad instruction. Use
> a nopl instruction to encode the signature. Suggested by Andy Lutomirski.
> - Exercise parametrized tests variants in a shell scripts.
> - Restartable sequences selftests: Remove use of event counter.
> - Use cpu_id_start field: With the cpu_id_start field, the C
> preparation phase of the fast-path does not need to compare cpu_id < 0
> anymore.
> - Signal-safe registration and refcounting: Allow libraries using
> librseq.so to register it from signal handlers.
> - Use OVERRIDE_TARGETS in makefile.
> - Use "m" constraints for rseq_cs field.
>
> Changes since v2:
> - Update based on Thomas Gleixner's comments.
>
> Changes since v3:
> - Generate param_test_skip_fastpath and param_test_benchmark with
> -DSKIP_FASTPATH and -DBENCHMARK (respectively). Add param_test_fastpath
> to run_param_test.sh.
> ---
> MAINTAINERS | 1 +
> tools/testing/selftests/Makefile | 1 +
> tools/testing/selftests/rseq/.gitignore | 4 +
> tools/testing/selftests/rseq/Makefile | 33 +
> .../testing/selftests/rseq/basic_percpu_ops_test.c | 333 +++++
> tools/testing/selftests/rseq/basic_test.c | 55 +
> tools/testing/selftests/rseq/param_test.c | 1285 ++++++++++++++++++++
> tools/testing/selftests/rseq/rseq-arm.h | 535 ++++++++
> tools/testing/selftests/rseq/rseq-ppc.h | 567 +++++++++
> tools/testing/selftests/rseq/rseq-x86.h | 898 ++++++++++++++
> tools/testing/selftests/rseq/rseq.c | 116 ++
> tools/testing/selftests/rseq/rseq.h | 154 +++
> tools/testing/selftests/rseq/run_param_test.sh | 126 ++
> 13 files changed, 4108 insertions(+)
> create mode 100644 tools/testing/selftests/rseq/.gitignore
> create mode 100644 tools/testing/selftests/rseq/Makefile
> create mode 100644 tools/testing/selftests/rseq/basic_percpu_ops_test.c
> create mode 100644 tools/testing/selftests/rseq/basic_test.c
> create mode 100644 tools/testing/selftests/rseq/param_test.c
> create mode 100644 tools/testing/selftests/rseq/rseq-arm.h
> create mode 100644 tools/testing/selftests/rseq/rseq-ppc.h
> create mode 100644 tools/testing/selftests/rseq/rseq-x86.h
> create mode 100644 tools/testing/selftests/rseq/rseq.c
> create mode 100644 tools/testing/selftests/rseq/rseq.h
> create mode 100755 tools/testing/selftests/rseq/run_param_test.sh
>
Looks good.
Acked-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
thanks,
-- Shuah
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