selftests/resctrl: Make benchmark parameter passing robust

The benchmark used during the CMT, MBM, and MBA tests can be provided by
the user via (-b) parameter, if not provided the default "fill_buf"
benchmark is used. The user is additionally able to override
any of the "fill_buf" default parameters when running the tests with
"-b fill_buf <fill_buf parameters>".

The "fill_buf" parameters are managed as an array of strings. Using an
array of strings is complex because it requires transformations to/from
strings at every producer and consumer. This is made worse for the
individual tests where the default benchmark parameters values may not
be appropriate and additional data wrangling is required. For example,
the CMT test duplicates the entire array of strings in order to replace
one of the parameters.

More issues appear when combining the usage of an array of strings with
the use case of user overriding default parameters by specifying
"-b fill_buf <parameters>". This use case is fragile with opportunities
to trigger a SIGSEGV because of opportunities for NULL pointers to exist
in the array of strings. For example, by running below (thus by specifying
"fill_buf" should be used but all parameters are NULL):
	$ sudo resctrl_tests -t mbm -b fill_buf

Replace the "array of strings" parameters used for "fill_buf" with
new struct fill_buf_param that contains the "fill_buf" parameters that
can be used directly without transformations to/from strings. Two
instances of struct fill_buf_param may exist at any point in time:
	* If the user provides new parameters to "fill_buf", the
	  user parameter structure (struct user_params) will point to a
	  fully initialized and immutable struct fill_buf_param
	  containing the user provided parameters.
	* If "fill_buf" is the benchmark that should be used by a test,
	  then the test parameter structure (struct resctrl_val_param)
	  will point to a fully initialized struct fill_buf_param. The
	  latter may contain (a) the user provided parameters verbatim,
	  (b) user provided parameters adjusted to be appropriate for
	  the test, or (c) the default parameters for "fill_buf" that
	  is appropriate for the test if the user did not provide
	  "fill_buf" parameters nor an alternate benchmark.

The existing behavior of CMT test is to use test defined value for the
buffer size even if the user provides another value via command line.
This behavior is maintained since the test requires that the buffer size
matches the size of the cache allocated, and the amount of cache
allocated can instead be changed by the user with the "-n" command line
parameter.

Signed-off-by: Reinette Chatre <[email protected]>
Reviewed-by: Ilpo Järvinen <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

Author: rchatre

tools/testing/selftests/resctrl/cmt_test.c

@@ -116,15 +116,13 @@ static void cmt_test_cleanup(void)
 
 static int cmt_run_test(const struct resctrl_test *test, const struct user_params *uparams)
 {
-	const char * const *cmd = uparams->benchmark_cmd;
-	const char *new_cmd[BENCHMARK_ARGS];
+	struct fill_buf_param fill_buf = {};
 	unsigned long cache_total_size = 0;
 	int n = uparams->bits ? : 5;
 	unsigned long long_mask;
-	char *span_str = NULL;
 	int count_of_bits;
 	size_t span;
-	int ret, i;
+	int ret;
 
 	ret = get_full_cbm("L3", &long_mask);
 	if (ret)
@@ -155,32 +153,26 @@ static int cmt_run_test(const struct resctrl_test *test, const struct user_param
 
 	span = cache_portion_size(cache_total_size, param.mask, long_mask);
 
-	if (strcmp(cmd[0], "fill_buf") == 0) {
-		/* Duplicate the command to be able to replace span in it */
-		for (i = 0; uparams->benchmark_cmd[i]; i++)
-			new_cmd[i] = uparams->benchmark_cmd[i];
-		new_cmd[i] = NULL;
-
-		ret = asprintf(&span_str, "%zu", span);
-		if (ret < 0)
-			return -1;
-		new_cmd[1] = span_str;
-		cmd = new_cmd;
+	if (uparams->fill_buf) {
+		fill_buf.buf_size = span;
+		fill_buf.memflush = uparams->fill_buf->memflush;
+		param.fill_buf = &fill_buf;
+	} else if (!uparams->benchmark_cmd[0]) {
+		fill_buf.buf_size = span;
+		fill_buf.memflush = true;
+		param.fill_buf = &fill_buf;
 	}
 
 	remove(RESULT_FILE_NAME);
 
-	ret = resctrl_val(test, uparams, cmd, &param);
+	ret = resctrl_val(test, uparams, &param);
 	if (ret)
-		goto out;
+		return ret;
 
 	ret = check_results(&param, span, n);
 	if (ret && (get_vendor() == ARCH_INTEL))
 		ksft_print_msg("Intel CMT may be inaccurate when Sub-NUMA Clustering is enabled. Check BIOS configuration.\n");
 
-out:
-	free(span_str);
-
 	return ret;
 }
 

tools/testing/selftests/resctrl/fill_buf.c

@@ -102,7 +102,7 @@ void fill_cache_read(unsigned char *buf, size_t buf_size, bool once)
 	*value_sink = ret;
 }
 
-unsigned char *alloc_buffer(size_t buf_size, int memflush)
+unsigned char *alloc_buffer(size_t buf_size, bool memflush)
 {
 	void *buf = NULL;
 	uint64_t *p64;
@@ -130,7 +130,7 @@ unsigned char *alloc_buffer(size_t buf_size, int memflush)
 	return buf;
 }
 
-int run_fill_buf(size_t buf_size, int memflush)
+int run_fill_buf(size_t buf_size, bool memflush)
 {
 	unsigned char *buf;
 

tools/testing/selftests/resctrl/mba_test.c

@@ -172,11 +172,22 @@ static int mba_run_test(const struct resctrl_test *test, const struct user_param
 		.setup		= mba_setup,
 		.measure	= mba_measure,
 	};
+	struct fill_buf_param fill_buf = {};
 	int ret;
 
 	remove(RESULT_FILE_NAME);
 
-	ret = resctrl_val(test, uparams, uparams->benchmark_cmd, &param);
+	if (uparams->fill_buf) {
+		fill_buf.buf_size = uparams->fill_buf->buf_size;
+		fill_buf.memflush = uparams->fill_buf->memflush;
+		param.fill_buf = &fill_buf;
+	} else if (!uparams->benchmark_cmd[0]) {
+		fill_buf.buf_size = DEFAULT_SPAN;
+		fill_buf.memflush = true;
+		param.fill_buf = &fill_buf;
+	}
+
+	ret = resctrl_val(test, uparams, &param);
 	if (ret)
 		return ret;
 

tools/testing/selftests/resctrl/mbm_test.c

@@ -139,26 +139,26 @@ static int mbm_run_test(const struct resctrl_test *test, const struct user_param
 		.setup		= mbm_setup,
 		.measure	= mbm_measure,
 	};
-	char *endptr = NULL;
-	size_t span = 0;
+	struct fill_buf_param fill_buf = {};
 	int ret;
 
 	remove(RESULT_FILE_NAME);
 
-	if (uparams->benchmark_cmd[0] && strcmp(uparams->benchmark_cmd[0], "fill_buf") == 0) {
-		if (uparams->benchmark_cmd[1] && *uparams->benchmark_cmd[1] != '\0') {
-			errno = 0;
-			span = strtoul(uparams->benchmark_cmd[1], &endptr, 10);
-			if (errno || *endptr != '\0')
-				return -EINVAL;
-		}
+	if (uparams->fill_buf) {
+		fill_buf.buf_size = uparams->fill_buf->buf_size;
+		fill_buf.memflush = uparams->fill_buf->memflush;
+		param.fill_buf = &fill_buf;
+	} else if (!uparams->benchmark_cmd[0]) {
+		fill_buf.buf_size = DEFAULT_SPAN;
+		fill_buf.memflush = true;
+		param.fill_buf = &fill_buf;
 	}
 
-	ret = resctrl_val(test, uparams, uparams->benchmark_cmd, &param);
+	ret = resctrl_val(test, uparams, &param);
 	if (ret)
 		return ret;
 
-	ret = check_results(span);
+	ret = check_results(param.fill_buf ? param.fill_buf->buf_size : 0);
 	if (ret && (get_vendor() == ARCH_INTEL))
 		ksft_print_msg("Intel MBM may be inaccurate when Sub-NUMA Clustering is enabled. Check BIOS configuration.\n");
 

tools/testing/selftests/resctrl/resctrl.h

@@ -43,16 +43,36 @@
 
 #define DEFAULT_SPAN		(250 * MB)
 
+/*
+ * fill_buf_param:	"fill_buf" benchmark parameters
+ * @buf_size:		Size (in bytes) of buffer used in benchmark.
+ *			"fill_buf" allocates and initializes buffer of
+ *			@buf_size. User can change value via command line.
+ * @memflush:		If false the buffer will not be flushed after
+ *			allocation and initialization, otherwise the
+ *			buffer will be flushed. User can change value via
+ *			command line (via integers with 0 interpreted as
+ *			false and anything else as true).
+ */
+struct fill_buf_param {
+	size_t		buf_size;
+	bool		memflush;
+};
+
 /*
  * user_params:		User supplied parameters
  * @cpu:		CPU number to which the benchmark will be bound to
  * @bits:		Number of bits used for cache allocation size
  * @benchmark_cmd:	Benchmark command to run during (some of the) tests
+ * @fill_buf:		Pointer to user provided parameters for "fill_buf",
+ *			NULL if user did not provide parameters and test
+ *			specific defaults should be used.
  */
 struct user_params {
 	int cpu;
 	int bits;
 	const char *benchmark_cmd[BENCHMARK_ARGS];
+	const struct fill_buf_param *fill_buf;
 };
 
 /*
@@ -87,21 +107,29 @@ struct resctrl_test {
  * @init:		Callback function to initialize test environment
  * @setup:		Callback function to setup per test run environment
  * @measure:		Callback that performs the measurement (a single test)
+ * @fill_buf:		Parameters for default "fill_buf" benchmark.
+ *			Initialized with user provided parameters, possibly
+ *			adapted to be relevant to the test. If user does
+ *			not provide parameters for "fill_buf" nor a
+ *			replacement benchmark then initialized with defaults
+ *			appropriate for test. NULL if user provided
+ *			benchmark.
  */
 struct resctrl_val_param {
-	const char	*ctrlgrp;
-	const char	*mongrp;
-	char		filename[64];
-	unsigned long	mask;
-	int		num_of_runs;
-	int		(*init)(const struct resctrl_val_param *param,
-				int domain_id);
-	int		(*setup)(const struct resctrl_test *test,
-				 const struct user_params *uparams,
-				 struct resctrl_val_param *param);
-	int		(*measure)(const struct user_params *uparams,
-				   struct resctrl_val_param *param,
-				   pid_t bm_pid);
+	const char		*ctrlgrp;
+	const char		*mongrp;
+	char			filename[64];
+	unsigned long		mask;
+	int			num_of_runs;
+	int			(*init)(const struct resctrl_val_param *param,
+					int domain_id);
+	int			(*setup)(const struct resctrl_test *test,
+					 const struct user_params *uparams,
+					 struct resctrl_val_param *param);
+	int			(*measure)(const struct user_params *uparams,
+					   struct resctrl_val_param *param,
+					   pid_t bm_pid);
+	struct fill_buf_param	*fill_buf;
 };
 
 struct perf_event_read {
@@ -138,18 +166,17 @@ int write_schemata(const char *ctrlgrp, char *schemata, int cpu_no,
 int write_bm_pid_to_resctrl(pid_t bm_pid, const char *ctrlgrp, const char *mongrp);
 int perf_event_open(struct perf_event_attr *hw_event, pid_t pid, int cpu,
 		    int group_fd, unsigned long flags);
-unsigned char *alloc_buffer(size_t buf_size, int memflush);
+unsigned char *alloc_buffer(size_t buf_size, bool memflush);
 void mem_flush(unsigned char *buf, size_t buf_size);
 void fill_cache_read(unsigned char *buf, size_t buf_size, bool once);
-int run_fill_buf(size_t buf_size, int memflush);
+int run_fill_buf(size_t buf_size, bool memflush);
 int initialize_read_mem_bw_imc(void);
 int measure_read_mem_bw(const struct user_params *uparams,
 			struct resctrl_val_param *param, pid_t bm_pid);
 void initialize_mem_bw_resctrl(const struct resctrl_val_param *param,
 			       int domain_id);
 int resctrl_val(const struct resctrl_test *test,
 		const struct user_params *uparams,
-		const char * const *benchmark_cmd,
 		struct resctrl_val_param *param);
 unsigned long create_bit_mask(unsigned int start, unsigned int len);
 unsigned int count_contiguous_bits(unsigned long val, unsigned int *start);

tools/testing/selftests/resctrl/resctrl_tests.c

@@ -148,6 +148,78 @@ static void run_single_test(const struct resctrl_test *test, const struct user_p
 	test_cleanup(test);
 }
 
+/*
+ * Allocate and initialize a struct fill_buf_param with user provided
+ * (via "-b fill_buf <fill_buf parameters>") parameters.
+ *
+ * Use defaults (that may not be appropriate for all tests) for any
+ * fill_buf parameters omitted by the user.
+ *
+ * Historically it may have been possible for user space to provide
+ * additional parameters, "operation" ("read" vs "write") in
+ * benchmark_cmd[3] and "once" (run "once" or until terminated) in
+ * benchmark_cmd[4]. Changing these parameters have never been
+ * supported with the default of "read" operation and running until
+ * terminated built into the tests. Any unsupported values for
+ * (original) "fill_buf" parameters are treated as failure.
+ *
+ * Return: On failure, forcibly exits the test on any parsing failure,
+ *         returns NULL if no parsing needed (user did not actually provide
+ *         "-b fill_buf").
+ *         On success, returns pointer to newly allocated and fully
+ *         initialized struct fill_buf_param that caller must free.
+ */
+static struct fill_buf_param *alloc_fill_buf_param(struct user_params *uparams)
+{
+	struct fill_buf_param *fill_param = NULL;
+	char *endptr = NULL;
+
+	if (!uparams->benchmark_cmd[0] || strcmp(uparams->benchmark_cmd[0], "fill_buf"))
+		return NULL;
+
+	fill_param = malloc(sizeof(*fill_param));
+	if (!fill_param)
+		ksft_exit_skip("Unable to allocate memory for fill_buf parameters.\n");
+
+	if (uparams->benchmark_cmd[1] && *uparams->benchmark_cmd[1] != '\0') {
+		errno = 0;
+		fill_param->buf_size = strtoul(uparams->benchmark_cmd[1], &endptr, 10);
+		if (errno || *endptr != '\0') {
+			free(fill_param);
+			ksft_exit_skip("Unable to parse benchmark buffer size.\n");
+		}
+	} else {
+		fill_param->buf_size = DEFAULT_SPAN;
+	}
+
+	if (uparams->benchmark_cmd[2] && *uparams->benchmark_cmd[2] != '\0') {
+		errno = 0;
+		fill_param->memflush = strtol(uparams->benchmark_cmd[2], &endptr, 10) != 0;
+		if (errno || *endptr != '\0') {
+			free(fill_param);
+			ksft_exit_skip("Unable to parse benchmark memflush parameter.\n");
+		}
+	} else {
+		fill_param->memflush = true;
+	}
+
+	if (uparams->benchmark_cmd[3] && *uparams->benchmark_cmd[3] != '\0') {
+		if (strcmp(uparams->benchmark_cmd[3], "0")) {
+			free(fill_param);
+			ksft_exit_skip("Only read operations supported.\n");
+		}
+	}
+
+	if (uparams->benchmark_cmd[4] && *uparams->benchmark_cmd[4] != '\0') {
+		if (strcmp(uparams->benchmark_cmd[4], "false")) {
+			free(fill_param);
+			ksft_exit_skip("fill_buf is required to run until termination.\n");
+		}
+	}
+
+	return fill_param;
+}
+
 static void init_user_params(struct user_params *uparams)
 {
 	memset(uparams, 0, sizeof(*uparams));
@@ -158,11 +230,11 @@ static void init_user_params(struct user_params *uparams)
 
 int main(int argc, char **argv)
 {
+	struct fill_buf_param *fill_param = NULL;
 	int tests = ARRAY_SIZE(resctrl_tests);
 	bool test_param_seen = false;
 	struct user_params uparams;
-	char *span_str = NULL;
-	int ret, c, i;
+	int c, i;
 
 	init_user_params(&uparams);
 
@@ -239,6 +311,10 @@ int main(int argc, char **argv)
 	}
 last_arg:
 
+	fill_param = alloc_fill_buf_param(&uparams);
+	if (fill_param)
+		uparams.fill_buf = fill_param;
+
 	ksft_print_header();
 
 	/*
@@ -257,32 +333,11 @@ int main(int argc, char **argv)
 
 	filter_dmesg();
 
-	if (!uparams.benchmark_cmd[0]) {
-		/* If no benchmark is given by "-b" argument, use fill_buf. */
-		uparams.benchmark_cmd[0] = "fill_buf";
-		ret = asprintf(&span_str, "%u", DEFAULT_SPAN);
-		if (ret < 0)
-			ksft_exit_fail_msg("Out of memory!\n");
-		uparams.benchmark_cmd[1] = span_str;
-		uparams.benchmark_cmd[2] = "1";
-		/*
-		 * Third parameter was previously used for "operation"
-		 * (read/write) of which only (now default) "read"/"0"
-		 * works.
-		 * Fourth parameter was previously used to indicate
-		 * how long "fill_buf" should run for, with "false"
-		 * ("fill_buf" will keep running until terminated)
-		 * the only option that works.
-		 */
-		uparams.benchmark_cmd[3] = NULL;
-		uparams.benchmark_cmd[4] = NULL;
-	}
-
 	ksft_set_plan(tests);
 
 	for (i = 0; i < ARRAY_SIZE(resctrl_tests); i++)
 		run_single_test(resctrl_tests[i], &uparams);
 
-	free(span_str);
+	free(fill_param);
 	ksft_finished();
 }