Re: [PATCH bpf-next v8] selftests/bpf: trace_helpers.c: optimize kallsyms cache

[Jiri Olsa]

On Sat, Aug 26, 2023 at 10:46:19PM +0800, Rong Tao wrote:

SNIP

> diff --git a/samples/bpf/sampleip_user.c b/samples/bpf/sampleip_user.c
> index 9283f47844fb..aec3d557aa6b 100644
> --- a/samples/bpf/sampleip_user.c
> +++ b/samples/bpf/sampleip_user.c
> @@ -25,6 +25,7 @@
>  static int map_fd;
>  static int nr_cpus;
>  static long _text_addr;
> +struct ksyms *ksyms;
>  
>  static void usage(void)
>  {
> @@ -109,7 +110,7 @@ static void print_ip_map(int fd)
>  	qsort(counts, max, sizeof(struct ipcount), count_cmp);
>  	for (i = 0; i < max; i++) {
>  		if (counts[i].ip > _text_addr) {
> -			sym = ksym_search(counts[i].ip);
> +			sym = ksym_search(ksyms, counts[i].ip);
>  			if (!sym) {
>  				printf("ksym not found. Is kallsyms loaded?\n");
>  				continue;
> @@ -164,13 +165,14 @@ int main(int argc, char **argv)
>  	}
>  
>  	/* initialize kernel symbol translation */
> -	if (load_kallsyms()) {
> +	ksyms = load_kallsyms();

if we keep the load_kallsyms/ksym_search/ksym_get_addr functions as described
in [1] the samples/bpf would stay untouched apart from the Makefile change

jirka

[1] https://lore.kernel.org/lkml/ZOjUpt16gcTSGkdl@krava/

> +	if (!ksyms) {
>  		fprintf(stderr, "ERROR: loading /proc/kallsyms\n");
>  		return 2;
>  	}
>  
>  	/* used to determine whether the address is kernel space */
> -	_text_addr = ksym_get_addr("_text");
> +	_text_addr = ksym_get_addr(ksyms, "_text");
>  	if (!_text_addr) {
>  		fprintf(stderr, "ERROR: no '_text' in /proc/kallsyms\n");
>  		return 3;
> @@ -230,5 +232,6 @@ int main(int argc, char **argv)
>  
>  	free(links);
>  	bpf_object__close(obj);
> +	free_kallsyms(ksyms);
>  	return error;
>  }
> diff --git a/samples/bpf/spintest_user.c b/samples/bpf/spintest_user.c
> index 55971edb1088..db6a3c6d5329 100644
> --- a/samples/bpf/spintest_user.c
> +++ b/samples/bpf/spintest_user.c
> @@ -16,8 +16,10 @@ int main(int ac, char **argv)
>  	int map_fd, i, j = 0;
>  	char filename[256];
>  	struct ksym *sym;
> +	struct ksyms *ksyms;
>  
> -	if (load_kallsyms()) {
> +	ksyms = load_kallsyms();
> +	if (!ksyms) {
>  		printf("failed to process /proc/kallsyms\n");
>  		return 2;
>  	}
> @@ -58,7 +60,7 @@ int main(int ac, char **argv)
>  		while (bpf_map_get_next_key(map_fd, &key, &next_key) == 0) {
>  			bpf_map_lookup_elem(map_fd, &next_key, &value);
>  			assert(next_key == value);
> -			sym = ksym_search(value);
> +			sym = ksym_search(ksyms, value);
>  			key = next_key;
>  			if (!sym) {
>  				printf("ksym not found. Is kallsyms loaded?\n");
> @@ -80,5 +82,6 @@ int main(int ac, char **argv)
>  		bpf_link__destroy(links[j]);
>  
>  	bpf_object__close(obj);
> +	free_kallsyms(ksyms);
>  	return 0;
>  }
> diff --git a/samples/bpf/task_fd_query_user.c b/samples/bpf/task_fd_query_user.c
> index 1e61f2180470..6e7710a4a96f 100644
> --- a/samples/bpf/task_fd_query_user.c
> +++ b/samples/bpf/task_fd_query_user.c
> @@ -315,8 +315,10 @@ int main(int argc, char **argv)
>  	struct bpf_program *prog;
>  	struct bpf_object *obj;
>  	int i = 0, err = -1;
> +	struct ksyms *ksyms;
>  
> -	if (load_kallsyms()) {
> +	ksyms = load_kallsyms();
> +	if (!ksyms) {
>  		printf("failed to process /proc/kallsyms\n");
>  		return err;
>  	}
> @@ -368,22 +370,22 @@ int main(int argc, char **argv)
>  					     BPF_FD_TYPE_KRETPROBE,
>  					     buf, sizeof(buf)));
>  	CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
> -					     ksym_get_addr("bpf_check"), false,
> +					     ksym_get_addr(ksyms, "bpf_check"), false,
>  					     BPF_FD_TYPE_KPROBE,
>  					     BPF_FD_TYPE_KRETPROBE,
>  					     buf, sizeof(buf)));
>  	CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
> -					     ksym_get_addr("bpf_check"), false,
> +					     ksym_get_addr(ksyms, "bpf_check"), false,
>  					     BPF_FD_TYPE_KPROBE,
>  					     BPF_FD_TYPE_KRETPROBE,
>  					     NULL, 0));
>  	CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
> -					     ksym_get_addr("bpf_check"), true,
> +					     ksym_get_addr(ksyms, "bpf_check"), true,
>  					     BPF_FD_TYPE_KPROBE,
>  					     BPF_FD_TYPE_KRETPROBE,
>  					     buf, sizeof(buf)));
>  	CHECK_AND_RET(test_nondebug_fs_probe("kprobe", NULL, 0x0,
> -					     ksym_get_addr("bpf_check"), true,
> +					     ksym_get_addr(ksyms, "bpf_check"), true,
>  					     BPF_FD_TYPE_KPROBE,
>  					     BPF_FD_TYPE_KRETPROBE,
>  					     0, 0));
> @@ -419,5 +421,6 @@ int main(int argc, char **argv)
>  		bpf_link__destroy(links[i]);
>  
>  	bpf_object__close(obj);
> +	free_kallsyms(ksyms);
>  	return err;
>  }
> diff --git a/samples/bpf/trace_event_user.c b/samples/bpf/trace_event_user.c
> index 9664749bf618..b4822166182f 100644
> --- a/samples/bpf/trace_event_user.c
> +++ b/samples/bpf/trace_event_user.c
> @@ -23,6 +23,7 @@ static int pid;
>  static int map_fd[2];
>  struct bpf_program *prog;
>  static bool sys_read_seen, sys_write_seen;
> +struct ksyms *ksyms;
>  
>  static void print_ksym(__u64 addr)
>  {
> @@ -30,7 +31,7 @@ static void print_ksym(__u64 addr)
>  
>  	if (!addr)
>  		return;
> -	sym = ksym_search(addr);
> +	sym = ksym_search(ksyms, addr);
>  	if (!sym) {
>  		printf("ksym not found. Is kallsyms loaded?\n");
>  		return;
> @@ -303,7 +304,8 @@ int main(int argc, char **argv)
>  	signal(SIGINT, err_exit);
>  	signal(SIGTERM, err_exit);
>  
> -	if (load_kallsyms()) {
> +	ksyms = load_kallsyms();
> +	if (!ksyms) {
>  		printf("failed to process /proc/kallsyms\n");
>  		goto cleanup;
>  	}
> @@ -348,5 +350,6 @@ int main(int argc, char **argv)
>  
>  cleanup:
>  	bpf_object__close(obj);
> +	free_kallsyms(ksyms);
>  	err_exit(error);
>  }
> diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c b/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c
> index 1454cebc262b..26bf1f33b8d5 100644
> --- a/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c
> +++ b/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c
> @@ -104,8 +104,10 @@ static void kprobe_multi_link_api_subtest(void)
>  	LIBBPF_OPTS(bpf_link_create_opts, opts);
>  	unsigned long long addrs[8];
>  	__u64 cookies[8];
> +	struct ksyms *ksyms;
>  
> -	if (!ASSERT_OK(load_kallsyms(), "load_kallsyms"))
> +	ksyms = load_kallsyms();
> +	if (!ASSERT_OK(ksyms != NULL, "load_kallsyms"))
>  		goto cleanup;
>  
>  	skel = kprobe_multi__open_and_load();
> @@ -116,7 +118,7 @@ static void kprobe_multi_link_api_subtest(void)
>  	skel->bss->test_cookie = true;
>  
>  #define GET_ADDR(__sym, __addr) ({				\
> -	__addr = ksym_get_addr(__sym);				\
> +	__addr = ksym_get_addr(ksyms, __sym);				\
>  	if (!ASSERT_NEQ(__addr, 0, "ksym_get_addr " #__sym))	\
>  		goto cleanup;					\
>  })
> @@ -171,6 +173,7 @@ static void kprobe_multi_link_api_subtest(void)
>  cleanup:
>  	close(link1_fd);
>  	close(link2_fd);
> +	free_kallsyms(ksyms);
>  	kprobe_multi__destroy(skel);
>  }
>  
> diff --git a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
> index 9d768e083714..a134eda17446 100644
> --- a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
> +++ b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
> @@ -302,16 +302,18 @@ void test_fill_link_info(void)
>  {
>  	struct test_fill_link_info *skel;
>  	int i;
> +	struct ksyms *ksyms;
>  
>  	skel = test_fill_link_info__open_and_load();
>  	if (!ASSERT_OK_PTR(skel, "skel_open"))
>  		return;
>  
>  	/* load kallsyms to compare the addr */
> -	if (!ASSERT_OK(load_kallsyms_refresh(), "load_kallsyms_refresh"))
> +	ksyms = load_kallsyms_refresh(NULL);
> +	if (!ASSERT_OK(ksyms != NULL, "load_kallsyms_refresh"))
>  		goto cleanup;
>  
> -	kprobe_addr = ksym_get_addr(KPROBE_FUNC);
> +	kprobe_addr = ksym_get_addr(ksyms, KPROBE_FUNC);
>  	if (test__start_subtest("kprobe_link_info"))
>  		test_kprobe_fill_link_info(skel, BPF_PERF_EVENT_KPROBE, false);
>  	if (test__start_subtest("kretprobe_link_info"))
> @@ -329,7 +331,7 @@ void test_fill_link_info(void)
>  
>  	qsort(kmulti_syms, KMULTI_CNT, sizeof(kmulti_syms[0]), symbols_cmp_r);
>  	for (i = 0; i < KMULTI_CNT; i++)
> -		kmulti_addrs[i] = ksym_get_addr(kmulti_syms[i]);
> +		kmulti_addrs[i] = ksym_get_addr(ksyms, kmulti_syms[i]);
>  	if (test__start_subtest("kprobe_multi_link_info"))
>  		test_kprobe_multi_fill_link_info(skel, false, false);
>  	if (test__start_subtest("kretprobe_multi_link_info"))
> @@ -339,4 +341,5 @@ void test_fill_link_info(void)
>  
>  cleanup:
>  	test_fill_link_info__destroy(skel);
> +	free_kallsyms(ksyms);
>  }
> diff --git a/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c b/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c
> index 858e0575f502..7a5e7741da14 100644
> --- a/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c
> +++ b/tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c
> @@ -9,6 +9,7 @@
>  #define MAX_STACK_RAWTP	100
>  
>  static int duration = 0;
> +static struct ksyms *ksyms;
>  
>  struct get_stack_trace_t {
>  	int pid;
> @@ -48,7 +49,7 @@ static void get_stack_print_output(void *ctx, int cpu, void *data, __u32 size)
>  			found = num_stack > 0;
>  		} else {
>  			for (i = 0; i < num_stack; i++) {
> -				ks = ksym_search(raw_data[i]);
> +				ks = ksym_search(ksyms, raw_data[i]);
>  				if (ks && (strcmp(ks->name, nonjit_func) == 0)) {
>  					found = true;
>  					break;
> @@ -65,7 +66,7 @@ static void get_stack_print_output(void *ctx, int cpu, void *data, __u32 size)
>  			good_kern_stack = num_stack > 0;
>  		} else {
>  			for (i = 0; i < num_stack; i++) {
> -				ks = ksym_search(e.kern_stack[i]);
> +				ks = ksym_search(ksyms, e.kern_stack[i]);
>  				if (ks && (strcmp(ks->name, nonjit_func) == 0)) {
>  					good_kern_stack = true;
>  					break;
> @@ -112,8 +113,8 @@ void test_get_stack_raw_tp(void)
>  	if (CHECK(!map, "bpf_find_map", "not found\n"))
>  		goto close_prog;
>  
> -	err = load_kallsyms();
> -	if (CHECK(err < 0, "load_kallsyms", "err %d errno %d\n", err, errno))
> +	ksyms = load_kallsyms();
> +	if (CHECK(!ksyms, "load_kallsyms", "err %d errno %d\n", err, errno))
>  		goto close_prog;
>  
>  	CPU_ZERO(&cpu_set);
> @@ -146,4 +147,5 @@ void test_get_stack_raw_tp(void)
>  	bpf_link__destroy(link);
>  	perf_buffer__free(pb);
>  	bpf_object__close(obj);
> +	free_kallsyms(ksyms);
>  }
> diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> index 179fe300534f..e902ea50de57 100644
> --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> @@ -6,6 +6,8 @@
>  #include "bpf/libbpf_internal.h"
>  #include "bpf/hashmap.h"
>  
> +static struct ksyms *ksyms;
> +
>  static void kprobe_multi_test_run(struct kprobe_multi *skel, bool test_return)
>  {
>  	LIBBPF_OPTS(bpf_test_run_opts, topts);
> @@ -89,7 +91,7 @@ static void test_link_api(struct bpf_link_create_opts *opts)
>  }
>  
>  #define GET_ADDR(__sym, __addr) ({					\
> -	__addr = ksym_get_addr(__sym);					\
> +	__addr = ksym_get_addr(ksyms, __sym);					\
>  	if (!ASSERT_NEQ(__addr, 0, "kallsyms load failed for " #__sym))	\
>  		return;							\
>  })
> @@ -222,8 +224,8 @@ static void test_attach_api_fails(void)
>  	};
>  	__u64 cookies[2];
>  
> -	addrs[0] = ksym_get_addr("bpf_fentry_test1");
> -	addrs[1] = ksym_get_addr("bpf_fentry_test2");
> +	addrs[0] = ksym_get_addr(ksyms, "bpf_fentry_test1");
> +	addrs[1] = ksym_get_addr(ksyms, "bpf_fentry_test2");
>  
>  	if (!ASSERT_FALSE(!addrs[0] || !addrs[1], "ksym_get_addr"))
>  		goto cleanup;
> @@ -463,7 +465,8 @@ void serial_test_kprobe_multi_bench_attach(void)
>  
>  void test_kprobe_multi_test(void)
>  {
> -	if (!ASSERT_OK(load_kallsyms(), "load_kallsyms"))
> +	ksyms = load_kallsyms();
> +	if (!ASSERT_OK(ksyms != NULL, "load_kallsyms"))
>  		return;
>  
>  	if (test__start_subtest("skel_api"))
> @@ -480,4 +483,6 @@ void test_kprobe_multi_test(void)
>  		test_attach_api_syms();
>  	if (test__start_subtest("attach_api_fails"))
>  		test_attach_api_fails();
> +
> +	free_kallsyms(ksyms);
>  }
> diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_testmod_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_testmod_test.c
> index 1fbe7e4ac00a..69de53db63fd 100644
> --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_testmod_test.c
> +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_testmod_test.c
> @@ -4,6 +4,8 @@
>  #include "trace_helpers.h"
>  #include "bpf/libbpf_internal.h"
>  
> +static struct ksyms *ksyms;
> +
>  static void kprobe_multi_testmod_check(struct kprobe_multi *skel)
>  {
>  	ASSERT_EQ(skel->bss->kprobe_testmod_test1_result, 1, "kprobe_test1_result");
> @@ -50,11 +52,11 @@ static void test_testmod_attach_api_addrs(void)
>  	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
>  	unsigned long long addrs[3];
>  
> -	addrs[0] = ksym_get_addr("bpf_testmod_fentry_test1");
> +	addrs[0] = ksym_get_addr(ksyms, "bpf_testmod_fentry_test1");
>  	ASSERT_NEQ(addrs[0], 0, "ksym_get_addr");
> -	addrs[1] = ksym_get_addr("bpf_testmod_fentry_test2");
> +	addrs[1] = ksym_get_addr(ksyms, "bpf_testmod_fentry_test2");
>  	ASSERT_NEQ(addrs[1], 0, "ksym_get_addr");
> -	addrs[2] = ksym_get_addr("bpf_testmod_fentry_test3");
> +	addrs[2] = ksym_get_addr(ksyms, "bpf_testmod_fentry_test3");
>  	ASSERT_NEQ(addrs[2], 0, "ksym_get_addr");
>  
>  	opts.addrs = (const unsigned long *) addrs;
> @@ -79,11 +81,14 @@ static void test_testmod_attach_api_syms(void)
>  
>  void serial_test_kprobe_multi_testmod_test(void)
>  {
> -	if (!ASSERT_OK(load_kallsyms_refresh(), "load_kallsyms_refresh"))
> +	ksyms = load_kallsyms_refresh(NULL);
> +	if (!ASSERT_OK(ksyms != NULL, "load_kallsyms_refresh"))
>  		return;
>  
>  	if (test__start_subtest("testmod_attach_api_syms"))
>  		test_testmod_attach_api_syms();
>  	if (test__start_subtest("testmod_attach_api_addrs"))
>  		test_testmod_attach_api_addrs();
> +
> +	free_kallsyms(ksyms);
>  }
> diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
> index f83d9f65c65b..048522d2ac6e 100644
> --- a/tools/testing/selftests/bpf/trace_helpers.c
> +++ b/tools/testing/selftests/bpf/trace_helpers.c
> @@ -14,99 +14,143 @@
>  #include <linux/limits.h>
>  #include <libelf.h>
>  #include <gelf.h>
> +#include "bpf/libbpf_internal.h"
>  
>  #define TRACEFS_PIPE	"/sys/kernel/tracing/trace_pipe"
>  #define DEBUGFS_PIPE	"/sys/kernel/debug/tracing/trace_pipe"
>  
> -#define MAX_SYMS 400000
> -static struct ksym syms[MAX_SYMS];
> -static int sym_cnt;
> +struct ksyms {
> +	struct ksym *syms;
> +	size_t sym_cap;
> +	size_t sym_cnt;
> +};
> +
> +static int ksyms__add_symbol(struct ksyms *ksyms, const char *name,
> +							 unsigned long addr)
> +{
> +	void *tmp;
> +
> +	tmp = strdup(name);
> +	if (!tmp)
> +		return -ENOMEM;
> +	ksyms->syms[ksyms->sym_cnt].addr = addr;
> +	ksyms->syms[ksyms->sym_cnt].name = tmp;
> +
> +	ksyms->sym_cnt++;
> +
> +	return 0;
> +}
> +
> +void free_kallsyms(struct ksyms *ksyms)
> +{
> +	unsigned int i;
> +
> +	if (!ksyms)
> +		return;
> +
> +	if (!ksyms->syms) {
> +		free(ksyms);
> +		return;
> +	}
> +
> +	for (i = 0; i < ksyms->sym_cnt; i++)
> +		free(ksyms->syms[i].name);
> +	free(ksyms->syms);
> +	free(ksyms);
> +}
>  
>  static int ksym_cmp(const void *p1, const void *p2)
>  {
>  	return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
>  }
>  
> -int load_kallsyms_refresh(void)
> +struct ksyms *load_kallsyms_refresh(struct ksyms *ksyms)
>  {
>  	FILE *f;
>  	char func[256], buf[256];
>  	char symbol;
>  	void *addr;
> -	int i = 0;
> +	int ret;
>  
> -	sym_cnt = 0;
> +	/* flush kallsyms, free the previously allocated dynamic memory */
> +	free_kallsyms(ksyms);
>  
>  	f = fopen("/proc/kallsyms", "r");
>  	if (!f)
> -		return -ENOENT;
> +		return NULL;
> +
> +	ksyms = calloc(1, sizeof(struct ksyms));
> +	if (!ksyms)
> +		return NULL;
>  
>  	while (fgets(buf, sizeof(buf), f)) {
>  		if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3)
>  			break;
>  		if (!addr)
>  			continue;
> -		if (i >= MAX_SYMS)
> -			return -EFBIG;
>  
> -		syms[i].addr = (long) addr;
> -		syms[i].name = strdup(func);
> -		i++;
> +		ret = libbpf_ensure_mem((void **) &ksyms->syms, &ksyms->sym_cap,
> +					sizeof(struct ksym), ksyms->sym_cnt + 1);
> +		if (ret)
> +			goto error;
> +		ret = ksyms__add_symbol(ksyms, func, (unsigned long)addr);
> +		if (ret)
> +			goto error;
>  	}
>  	fclose(f);
> -	sym_cnt = i;
> -	qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp);
> -	return 0;
> +	qsort(ksyms->syms, ksyms->sym_cnt, sizeof(struct ksym), ksym_cmp);
> +	return ksyms;
> +
> +error:
> +	free_kallsyms(ksyms);
> +	return NULL;
>  }
>  
> -int load_kallsyms(void)
> +struct ksyms *load_kallsyms(void)
>  {
> -	/*
> -	 * This is called/used from multiplace places,
> -	 * load symbols just once.
> -	 */
> -	if (sym_cnt)
> -		return 0;
> -	return load_kallsyms_refresh();
> +	return load_kallsyms_refresh(NULL);
>  }
>  
> -struct ksym *ksym_search(long key)
> +struct ksym *ksym_search(struct ksyms *ksyms, long key)
>  {
> -	int start = 0, end = sym_cnt;
> +	int start = 0, end = ksyms->sym_cnt;
>  	int result;
>  
> +	if (!ksyms)
> +		return NULL;
> +
>  	/* kallsyms not loaded. return NULL */
> -	if (sym_cnt <= 0)
> +	if (ksyms->sym_cnt <= 0)
>  		return NULL;
>  
>  	while (start < end) {
>  		size_t mid = start + (end - start) / 2;
>  
> -		result = key - syms[mid].addr;
> +		result = key - ksyms->syms[mid].addr;
>  		if (result < 0)
>  			end = mid;
>  		else if (result > 0)
>  			start = mid + 1;
>  		else
> -			return &syms[mid];
> +			return &ksyms->syms[mid];
>  	}
>  
> -	if (start >= 1 && syms[start - 1].addr < key &&
> -	    key < syms[start].addr)
> +	if (start >= 1 && ksyms->syms[start - 1].addr < key &&
> +	    key < ksyms->syms[start].addr)
>  		/* valid ksym */
> -		return &syms[start - 1];
> +		return &ksyms->syms[start - 1];
>  
>  	/* out of range. return _stext */
> -	return &syms[0];
> +	return &ksyms->syms[0];
>  }
>  
> -long ksym_get_addr(const char *name)
> +long ksym_get_addr(struct ksyms *ksyms, const char *name)
>  {
>  	int i;
>  
> -	for (i = 0; i < sym_cnt; i++) {
> -		if (strcmp(syms[i].name, name) == 0)
> -			return syms[i].addr;
> +	for (i = 0; i < ksyms->sym_cnt; i++) {
> +		if (strcmp(ksyms->syms[i].name, name) == 0)
> +			return ksyms->syms[i].addr;
>  	}
>  
>  	return 0;
> diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h
> index 876f3e711df6..6be64f44dd76 100644
> --- a/tools/testing/selftests/bpf/trace_helpers.h
> +++ b/tools/testing/selftests/bpf/trace_helpers.h
> @@ -11,12 +11,14 @@ struct ksym {
>  	long addr;
>  	char *name;
>  };
> +struct ksyms;
>  
> -int load_kallsyms(void);
> -int load_kallsyms_refresh(void);
> +struct ksyms *load_kallsyms(void);
> +struct ksyms *load_kallsyms_refresh(struct ksyms *ksyms);
> +void free_kallsyms(struct ksyms *ksyms);
>  
> -struct ksym *ksym_search(long key);
> -long ksym_get_addr(const char *name);
> +struct ksym *ksym_search(struct ksyms *ksyms, long key);
> +long ksym_get_addr(struct ksyms *ksyms, const char *name);
>  
>  /* open kallsyms and find addresses on the fly, faster than load + search. */
>  int kallsyms_find(const char *sym, unsigned long long *addr);
> -- 
> 2.41.0
>