Re: [PATCH v1] selftests: Enhance kselftest_harness.h to print which assert failed

[Shuah Khan <shuah@kernel.org>]

On 08/06/2017 05:23 PM, Mickaël Salaün wrote:
> When a test process is not able to write to TH_LOG_STREAM, this step
> mechanism enable to print the assert number which triggered the failure.
> This can be enabled by setting _metadata->no_print to true at the
> beginning of the test sequence.
> 
> Update the seccomp-bpf test to return 0 if a test succeeded.
> 
> This feature is needed for the Landlock tests.
> 
> Signed-off-by: Mickaël Salaün <mic@digikod.net>
> Cc: Andy Lutomirski <luto@amacapital.net>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Shuah Khan <shuah@kernel.org>
> Cc: Will Drewry <wad@chromium.org>
> Link: https://lkml.kernel.org/r/CAGXu5j+D-FP8Kt9unNOqKrQJP4DYTpmgkJxWykZyrYiVPz3Y3Q@mail.gmail.com

I am looking through my Inbox and found this one. Okay to pull
this in for 4.14-rc1?

thanks,
-- Shuah

> ---
> 
> Changes since the patch from the Landlock series:
> * add the step counter in assert/expect macros and use _metadata to
>   enable the counter (suggested by Kees Cook)
> * only count asserts
> * add documentation
> ---
>  tools/testing/selftests/kselftest_harness.h   | 39 +++++++++++++++++++++++----
>  tools/testing/selftests/seccomp/seccomp_bpf.c |  2 +-
>  2 files changed, 35 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h
> index c56f72e07cd7..e81bd28bdd89 100644
> --- a/tools/testing/selftests/kselftest_harness.h
> +++ b/tools/testing/selftests/kselftest_harness.h
> @@ -51,6 +51,9 @@
>  #define __KSELFTEST_HARNESS_H
>  
>  #define _GNU_SOURCE
> +#include <asm/types.h>
> +#include <errno.h>
> +#include <stdbool.h>
>  #include <stdint.h>
>  #include <stdio.h>
>  #include <stdlib.h>
> @@ -84,6 +87,14 @@
>   * E.g., #define TH_LOG_ENABLED 1
>   *
>   * If no definition is provided, logging is enabled by default.
> + *
> + * If there is no way to print an error message for the process running the
> + * test (e.g. not allowed to write to stderr), it is still possible to get the
> + * ASSERT_* number for which the test failed.  This behavior can be enabled by
> + * writing `_metadata->no_print = true;` before the check sequence that is
> + * unable to print.  When an error occur, instead of printing an error message
> + * and calling `abort(3)`, the test process call `_exit(2)` with the assert
> + * number as argument, which is then printed by the parent process.
>   */
>  #define TH_LOG(fmt, ...) do { \
>  	if (TH_LOG_ENABLED) \
> @@ -555,12 +566,18 @@
>   * return while still providing an optional block to the API consumer.
>   */
>  #define OPTIONAL_HANDLER(_assert) \
> -	for (; _metadata->trigger;  _metadata->trigger = __bail(_assert))
> +	for (; _metadata->trigger; _metadata->trigger = \
> +			__bail(_assert, _metadata->no_print, _metadata->step))
> +
> +#define __INC_STEP(_metadata) \
> +	if (_metadata->passed && _metadata->step < 255) \
> +		_metadata->step++;
>  
>  #define __EXPECT(_expected, _seen, _t, _assert) do { \
>  	/* Avoid multiple evaluation of the cases */ \
>  	__typeof__(_expected) __exp = (_expected); \
>  	__typeof__(_seen) __seen = (_seen); \
> +	if (_assert) __INC_STEP(_metadata); \
>  	if (!(__exp _t __seen)) { \
>  		unsigned long long __exp_print = (uintptr_t)__exp; \
>  		unsigned long long __seen_print = (uintptr_t)__seen; \
> @@ -576,6 +593,7 @@
>  #define __EXPECT_STR(_expected, _seen, _t, _assert) do { \
>  	const char *__exp = (_expected); \
>  	const char *__seen = (_seen); \
> +	if (_assert) __INC_STEP(_metadata); \
>  	if (!(strcmp(__exp, __seen) _t 0))  { \
>  		__TH_LOG("Expected '%s' %s '%s'.", __exp, #_t, __seen); \
>  		_metadata->passed = 0; \
> @@ -590,6 +608,8 @@ struct __test_metadata {
>  	int termsig;
>  	int passed;
>  	int trigger; /* extra handler after the evaluation */
> +	__u8 step;
> +	bool no_print; /* manual trigger when TH_LOG_STREAM is not available */
>  	struct __test_metadata *prev, *next;
>  };
>  
> @@ -634,10 +654,13 @@ static inline void __register_test(struct __test_metadata *t)
>  	}
>  }
>  
> -static inline int __bail(int for_realz)
> +static inline int __bail(int for_realz, bool no_print, __u8 step)
>  {
> -	if (for_realz)
> +	if (for_realz) {
> +		if (no_print)
> +			_exit(step);
>  		abort();
> +	}
>  	return 0;
>  }
>  
> @@ -655,18 +678,24 @@ void __run_test(struct __test_metadata *t)
>  		t->passed = 0;
>  	} else if (child_pid == 0) {
>  		t->fn(t);
> -		_exit(t->passed);
> +		/* return the step that failed or 0 */
> +		_exit(t->passed ? 0 : t->step);
>  	} else {
>  		/* TODO(wad) add timeout support. */
>  		waitpid(child_pid, &status, 0);
>  		if (WIFEXITED(status)) {
> -			t->passed = t->termsig == -1 ? WEXITSTATUS(status) : 0;
> +			t->passed = t->termsig == -1 ? !WEXITSTATUS(status) : 0;
>  			if (t->termsig != -1) {
>  				fprintf(TH_LOG_STREAM,
>  					"%s: Test exited normally "
>  					"instead of by signal (code: %d)\n",
>  					t->name,
>  					WEXITSTATUS(status));
> +			} else if (!t->passed) {
> +				fprintf(TH_LOG_STREAM,
> +					"%s: Test failed at step #%d\n",
> +					t->name,
> +					WEXITSTATUS(status));
>  			}
>  		} else if (WIFSIGNALED(status)) {
>  			t->passed = 0;
> diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
> index 73f5ea6778ce..4d6f92a9df6b 100644
> --- a/tools/testing/selftests/seccomp/seccomp_bpf.c
> +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
> @@ -107,7 +107,7 @@ TEST(mode_strict_support)
>  	ASSERT_EQ(0, ret) {
>  		TH_LOG("Kernel does not support CONFIG_SECCOMP");
>  	}
> -	syscall(__NR_exit, 1);
> +	syscall(__NR_exit, 0);
>  }
>  
>  TEST_SIGNAL(mode_strict_cannot_call_prctl, SIGKILL)
>