From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shuah Khan Subject: Re: [PATCH update for 4.15 3/3] rseq: selftests: Provide self-tests (v4) Date: Wed, 22 Nov 2017 08:23:22 -0700 Message-ID: References: <20171121221933.25959-1-mathieu.desnoyers@efficios.com> <20171121221933.25959-3-mathieu.desnoyers@efficios.com> Reply-To: shuah-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20171121221933.25959-3-mathieu.desnoyers-vg+e7yoeK/dWk0Htik3J/w@public.gmane.org> Content-Language: en-US Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mathieu Desnoyers , Peter Zijlstra , "Paul E . McKenney" , Boqun Feng , Andy Lutomirski , Dave Watson Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Paul Turner , Andrew Morton , Russell King , Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , Andrew Hunter , Andi Kleen , Chris Lameter , Ben Maurer , Steven Rostedt , Josh Triplett , Linus Torvalds , Catalin Marinas , Will Deacon , Michael Kerrisk , linux-kselftest-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Shuah Khan , Shuah Khan List-Id: linux-api@vger.kernel.org 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 > CC: Russell King > CC: Catalin Marinas > CC: Will Deacon > CC: Thomas Gleixner > CC: Paul Turner > CC: Andrew Hunter > CC: Peter Zijlstra > CC: Andy Lutomirski > CC: Andi Kleen > CC: Dave Watson > CC: Chris Lameter > CC: Ingo Molnar > CC: "H. Peter Anvin" > CC: Ben Maurer > CC: Steven Rostedt > CC: "Paul E. McKenney" > CC: Josh Triplett > CC: Linus Torvalds > CC: Andrew Morton > CC: Boqun Feng > CC: Shuah Khan > CC: linux-kselftest-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > CC: linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > --- > 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 thanks, -- Shuah