Commit 8bad31ed authored by Menglong Dong's avatar Menglong Dong Committed by Alexei Starovoitov
Browse files

selftests/bpf: move get_ksyms and get_addrs to trace_helpers.c 



We need to get all the kernel function that can be traced sometimes, so we
move the get_syms() and get_addrs() in kprobe_multi_test.c to
trace_helpers.c and rename it to bpf_get_ksyms() and bpf_get_addrs().

Signed-off-by: default avatarMenglong Dong <dongml2@chinatelecom.cn>
Link: https://lore.kernel.org/r/20250904021011.14069-2-dongml2@chinatelecom.cn


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent c9110e6f

tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c

+3 −217
Original line number Diff line number Diff line
@@ -422,220 +422,6 @@ static void test_unique_match(void) 
	kprobe_multi__destroy(skel);

}



static size_t symbol_hash(long key, void *ctx __maybe_unused)

{

	return str_hash((const char *) key);

}



static bool symbol_equal(long key1, long key2, void *ctx __maybe_unused)

{

	return strcmp((const char *) key1, (const char *) key2) == 0;

}



static bool is_invalid_entry(char *buf, bool kernel)

{

	if (kernel && strchr(buf, '['))

		return true;

	if (!kernel && !strchr(buf, '['))

		return true;

	return false;

}



static bool skip_entry(char *name)

{

	/*

	 * We attach to almost all kernel functions and some of them

	 * will cause 'suspicious RCU usage' when fprobe is attached

	 * to them. Filter out the current culprits - arch_cpu_idle

	 * default_idle and rcu_* functions.

	 */

	if (!strcmp(name, "arch_cpu_idle"))

		return true;

	if (!strcmp(name, "default_idle"))

		return true;

	if (!strncmp(name, "rcu_", 4))

		return true;

	if (!strcmp(name, "bpf_dispatcher_xdp_func"))

		return true;

	if (!strncmp(name, "__ftrace_invalid_address__",

		     sizeof("__ftrace_invalid_address__") - 1))

		return true;

	return false;

}



/* Do comparison by ignoring '.llvm.<hash>' suffixes. */

static int compare_name(const char *name1, const char *name2)

{

	const char *res1, *res2;

	int len1, len2;



	res1 = strstr(name1, ".llvm.");

	res2 = strstr(name2, ".llvm.");

	len1 = res1 ? res1 - name1 : strlen(name1);

	len2 = res2 ? res2 - name2 : strlen(name2);



	if (len1 == len2)

		return strncmp(name1, name2, len1);

	if (len1 < len2)

		return strncmp(name1, name2, len1) <= 0 ? -1 : 1;

	return strncmp(name1, name2, len2) >= 0 ? 1 : -1;

}



static int load_kallsyms_compare(const void *p1, const void *p2)

{

	return compare_name(((const struct ksym *)p1)->name, ((const struct ksym *)p2)->name);

}



static int search_kallsyms_compare(const void *p1, const struct ksym *p2)

{

	return compare_name(p1, p2->name);

}



static int get_syms(char ***symsp, size_t *cntp, bool kernel)

{

	size_t cap = 0, cnt = 0;

	char *name = NULL, *ksym_name, **syms = NULL;

	struct hashmap *map;

	struct ksyms *ksyms;

	struct ksym *ks;

	char buf[256];

	FILE *f;

	int err = 0;



	ksyms = load_kallsyms_custom_local(load_kallsyms_compare);

	if (!ASSERT_OK_PTR(ksyms, "load_kallsyms_custom_local"))

		return -EINVAL;



	/*

	 * The available_filter_functions contains many duplicates,

	 * but other than that all symbols are usable in kprobe multi

	 * interface.

	 * Filtering out duplicates by using hashmap__add, which won't

	 * add existing entry.

	 */



	if (access("/sys/kernel/tracing/trace", F_OK) == 0)

		f = fopen("/sys/kernel/tracing/available_filter_functions", "r");

	else

		f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");



	if (!f)

		return -EINVAL;



	map = hashmap__new(symbol_hash, symbol_equal, NULL);

	if (IS_ERR(map)) {

		err = libbpf_get_error(map);

		goto error;

	}



	while (fgets(buf, sizeof(buf), f)) {

		if (is_invalid_entry(buf, kernel))

			continue;



		free(name);

		if (sscanf(buf, "%ms$*[^\n]\n", &name) != 1)

			continue;

		if (skip_entry(name))

			continue;



		ks = search_kallsyms_custom_local(ksyms, name, search_kallsyms_compare);

		if (!ks) {

			err = -EINVAL;

			goto error;

		}



		ksym_name = ks->name;

		err = hashmap__add(map, ksym_name, 0);

		if (err == -EEXIST) {

			err = 0;

			continue;

		}

		if (err)

			goto error;



		err = libbpf_ensure_mem((void **) &syms, &cap,

					sizeof(*syms), cnt + 1);

		if (err)

			goto error;



		syms[cnt++] = ksym_name;

	}



	*symsp = syms;

	*cntp = cnt;



error:

	free(name);

	fclose(f);

	hashmap__free(map);

	if (err)

		free(syms);

	return err;

}



static int get_addrs(unsigned long **addrsp, size_t *cntp, bool kernel)

{

	unsigned long *addr, *addrs, *tmp_addrs;

	int err = 0, max_cnt, inc_cnt;

	char *name = NULL;

	size_t cnt = 0;

	char buf[256];

	FILE *f;



	if (access("/sys/kernel/tracing/trace", F_OK) == 0)

		f = fopen("/sys/kernel/tracing/available_filter_functions_addrs", "r");

	else

		f = fopen("/sys/kernel/debug/tracing/available_filter_functions_addrs", "r");



	if (!f)

		return -ENOENT;



	/* In my local setup, the number of entries is 50k+ so Let us initially

	 * allocate space to hold 64k entries. If 64k is not enough, incrementally

	 * increase 1k each time.

	 */

	max_cnt = 65536;

	inc_cnt = 1024;

	addrs = malloc(max_cnt * sizeof(long));

	if (addrs == NULL) {

		err = -ENOMEM;

		goto error;

	}



	while (fgets(buf, sizeof(buf), f)) {

		if (is_invalid_entry(buf, kernel))

			continue;



		free(name);

		if (sscanf(buf, "%p %ms$*[^\n]\n", &addr, &name) != 2)

			continue;

		if (skip_entry(name))

			continue;



		if (cnt == max_cnt) {

			max_cnt += inc_cnt;

			tmp_addrs = realloc(addrs, max_cnt);

			if (!tmp_addrs) {

				err = -ENOMEM;

				goto error;

			}

			addrs = tmp_addrs;

		}



		addrs[cnt++] = (unsigned long)addr;

	}



	*addrsp = addrs;

	*cntp = cnt;



error:

	free(name);

	fclose(f);

	if (err)

		free(addrs);

	return err;

}



static void do_bench_test(struct kprobe_multi_empty *skel, struct bpf_kprobe_multi_opts *opts)

{

	long attach_start_ns, attach_end_ns;
@@ -670,7 +456,7 @@ static void test_kprobe_multi_bench_attach(bool kernel) 
	char **syms = NULL;

	size_t cnt = 0;



	if (!ASSERT_OK(get_syms(&syms, &cnt, kernel), "get_syms"))

	if (!ASSERT_OK(bpf_get_ksyms(&syms, &cnt, kernel), "bpf_get_ksyms"))

		return;



	skel = kprobe_multi_empty__open_and_load();
@@ -696,13 +482,13 @@ static void test_kprobe_multi_bench_attach_addr(bool kernel) 
	size_t cnt = 0;

	int err;



	err = get_addrs(&addrs, &cnt, kernel);

	err = bpf_get_addrs(&addrs, &cnt, kernel);

	if (err == -ENOENT) {

		test__skip();

		return;

	}



	if (!ASSERT_OK(err, "get_addrs"))

	if (!ASSERT_OK(err, "bpf_get_addrs"))

		return;



	skel = kprobe_multi_empty__open_and_load();

tools/testing/selftests/bpf/trace_helpers.c

+214 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/limits.h>

#include <libelf.h>

#include <gelf.h>

#include "bpf/hashmap.h"

#include "bpf/libbpf_internal.h"



#define TRACEFS_PIPE	"/sys/kernel/tracing/trace_pipe"
@@ -519,3 +520,216 @@ void read_trace_pipe(void) 
{

	read_trace_pipe_iter(trace_pipe_cb, NULL, 0);

}



static size_t symbol_hash(long key, void *ctx __maybe_unused)

{

	return str_hash((const char *) key);

}



static bool symbol_equal(long key1, long key2, void *ctx __maybe_unused)

{

	return strcmp((const char *) key1, (const char *) key2) == 0;

}



static bool is_invalid_entry(char *buf, bool kernel)

{

	if (kernel && strchr(buf, '['))

		return true;

	if (!kernel && !strchr(buf, '['))

		return true;

	return false;

}



static bool skip_entry(char *name)

{

	/*

	 * We attach to almost all kernel functions and some of them

	 * will cause 'suspicious RCU usage' when fprobe is attached

	 * to them. Filter out the current culprits - arch_cpu_idle

	 * default_idle and rcu_* functions.

	 */

	if (!strcmp(name, "arch_cpu_idle"))

		return true;

	if (!strcmp(name, "default_idle"))

		return true;

	if (!strncmp(name, "rcu_", 4))

		return true;

	if (!strcmp(name, "bpf_dispatcher_xdp_func"))

		return true;

	if (!strncmp(name, "__ftrace_invalid_address__",

		     sizeof("__ftrace_invalid_address__") - 1))

		return true;

	return false;

}



/* Do comparison by ignoring '.llvm.<hash>' suffixes. */

static int compare_name(const char *name1, const char *name2)

{

	const char *res1, *res2;

	int len1, len2;



	res1 = strstr(name1, ".llvm.");

	res2 = strstr(name2, ".llvm.");

	len1 = res1 ? res1 - name1 : strlen(name1);

	len2 = res2 ? res2 - name2 : strlen(name2);



	if (len1 == len2)

		return strncmp(name1, name2, len1);

	if (len1 < len2)

		return strncmp(name1, name2, len1) <= 0 ? -1 : 1;

	return strncmp(name1, name2, len2) >= 0 ? 1 : -1;

}



static int load_kallsyms_compare(const void *p1, const void *p2)

{

	return compare_name(((const struct ksym *)p1)->name, ((const struct ksym *)p2)->name);

}



static int search_kallsyms_compare(const void *p1, const struct ksym *p2)

{

	return compare_name(p1, p2->name);

}



int bpf_get_ksyms(char ***symsp, size_t *cntp, bool kernel)

{

	size_t cap = 0, cnt = 0;

	char *name = NULL, *ksym_name, **syms = NULL;

	struct hashmap *map;

	struct ksyms *ksyms;

	struct ksym *ks;

	char buf[256];

	FILE *f;

	int err = 0;



	ksyms = load_kallsyms_custom_local(load_kallsyms_compare);

	if (!ksyms)

		return -EINVAL;



	/*

	 * The available_filter_functions contains many duplicates,

	 * but other than that all symbols are usable to trace.

	 * Filtering out duplicates by using hashmap__add, which won't

	 * add existing entry.

	 */



	if (access("/sys/kernel/tracing/trace", F_OK) == 0)

		f = fopen("/sys/kernel/tracing/available_filter_functions", "r");

	else

		f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");



	if (!f)

		return -EINVAL;



	map = hashmap__new(symbol_hash, symbol_equal, NULL);

	if (IS_ERR(map)) {

		err = libbpf_get_error(map);

		goto error;

	}



	while (fgets(buf, sizeof(buf), f)) {

		if (is_invalid_entry(buf, kernel))

			continue;



		free(name);

		if (sscanf(buf, "%ms$*[^\n]\n", &name) != 1)

			continue;

		if (skip_entry(name))

			continue;



		ks = search_kallsyms_custom_local(ksyms, name, search_kallsyms_compare);

		if (!ks) {

			err = -EINVAL;

			goto error;

		}



		ksym_name = ks->name;

		err = hashmap__add(map, ksym_name, 0);

		if (err == -EEXIST) {

			err = 0;

			continue;

		}

		if (err)

			goto error;



		err = libbpf_ensure_mem((void **) &syms, &cap,

					sizeof(*syms), cnt + 1);

		if (err)

			goto error;



		syms[cnt++] = ksym_name;

	}



	*symsp = syms;

	*cntp = cnt;



error:

	free(name);

	fclose(f);

	hashmap__free(map);

	if (err)

		free(syms);

	return err;

}



int bpf_get_addrs(unsigned long **addrsp, size_t *cntp, bool kernel)

{

	unsigned long *addr, *addrs, *tmp_addrs;

	int err = 0, max_cnt, inc_cnt;

	char *name = NULL;

	size_t cnt = 0;

	char buf[256];

	FILE *f;



	if (access("/sys/kernel/tracing/trace", F_OK) == 0)

		f = fopen("/sys/kernel/tracing/available_filter_functions_addrs", "r");

	else

		f = fopen("/sys/kernel/debug/tracing/available_filter_functions_addrs", "r");



	if (!f)

		return -ENOENT;



	/* In my local setup, the number of entries is 50k+ so Let us initially

	 * allocate space to hold 64k entries. If 64k is not enough, incrementally

	 * increase 1k each time.

	 */

	max_cnt = 65536;

	inc_cnt = 1024;

	addrs = malloc(max_cnt * sizeof(long));

	if (addrs == NULL) {

		err = -ENOMEM;

		goto error;

	}



	while (fgets(buf, sizeof(buf), f)) {

		if (is_invalid_entry(buf, kernel))

			continue;



		free(name);

		if (sscanf(buf, "%p %ms$*[^\n]\n", &addr, &name) != 2)

			continue;

		if (skip_entry(name))

			continue;



		if (cnt == max_cnt) {

			max_cnt += inc_cnt;

			tmp_addrs = realloc(addrs, max_cnt);

			if (!tmp_addrs) {

				err = -ENOMEM;

				goto error;

			}

			addrs = tmp_addrs;

		}



		addrs[cnt++] = (unsigned long)addr;

	}



	*addrsp = addrs;

	*cntp = cnt;



error:

	free(name);

	fclose(f);

	if (err)

		free(addrs);

	return err;

}

tools/testing/selftests/bpf/trace_helpers.h

+3 −0
Original line number Diff line number Diff line
@@ -41,4 +41,7 @@ ssize_t get_rel_offset(uintptr_t addr); 


int read_build_id(const char *path, char *build_id, size_t size);



int bpf_get_ksyms(char ***symsp, size_t *cntp, bool kernel);

int bpf_get_addrs(unsigned long **addrsp, size_t *cntp, bool kernel);



#endif