[bpf-next,v9] selftests/bpf: trace_helpers.c: optimize kallsyms cache

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 4ccf4236031c..6c707ebcebb9 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -175,6 +175,7 @@  TPROGS_CFLAGS += -I$(srctree)/tools/testing/selftests/bpf/
 TPROGS_CFLAGS += -I$(LIBBPF_INCLUDE)
 TPROGS_CFLAGS += -I$(srctree)/tools/include
 TPROGS_CFLAGS += -I$(srctree)/tools/perf
+TPROGS_CFLAGS += -I$(srctree)/tools/lib
 TPROGS_CFLAGS += -DHAVE_ATTR_TEST=0
 
 ifdef SYSROOT
@@ -314,6 +315,9 @@  XDP_SAMPLE_CFLAGS += -Wall -O2 \
 
 $(obj)/$(XDP_SAMPLE): TPROGS_CFLAGS = $(XDP_SAMPLE_CFLAGS)
 $(obj)/$(XDP_SAMPLE): $(src)/xdp_sample_user.h $(src)/xdp_sample_shared.h
+# Override includes for trace_helpers.o because __must_check won't be defined
+# in our include path.
+$(obj)/$(TRACE_HELPERS): TPROGS_CFLAGS := $(TPROGS_CFLAGS) -D__must_check=
 
 -include $(BPF_SAMPLES_PATH)/Makefile.target
 
diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c b/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c
index 1454cebc262b..4ed47dc75669 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_local();
+	if (!ASSERT_OK(ksyms != NULL, "load_kallsyms_local"))
 		goto cleanup;
 
 	skel = kprobe_multi__open_and_load();
@@ -116,8 +118,8 @@  static void kprobe_multi_link_api_subtest(void)
 	skel->bss->test_cookie = true;
 
 #define GET_ADDR(__sym, __addr) ({				\
-	__addr = ksym_get_addr(__sym);				\
-	if (!ASSERT_NEQ(__addr, 0, "ksym_get_addr " #__sym))	\
+	__addr = ksym_get_addr_local(ksyms, __sym);		\
+	if (!ASSERT_NEQ(__addr, 0, "ksym_get_addr_local " #__sym))	\
 		goto cleanup;					\
 })
 
@@ -171,6 +173,7 @@  static void kprobe_multi_link_api_subtest(void)
 cleanup:
 	close(link1_fd);
 	close(link2_fd);
+	free_kallsyms_local(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..154aaa08761f 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_local(NULL);
+	if (!ASSERT_OK(ksyms != NULL, "load_kallsyms_refresh_local"))
 		goto cleanup;
 
-	kprobe_addr = ksym_get_addr(KPROBE_FUNC);
+	kprobe_addr = ksym_get_addr_local(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_local(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_local(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..a317a6d04458 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_local(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_local(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_local();
+	if (CHECK(!ksyms, "load_kallsyms_local", "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_local(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..8683536ce217 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_local(ksyms, __sym);			\
 	if (!ASSERT_NEQ(__addr, 0, "kallsyms load failed for " #__sym))	\
 		return;							\
 })
@@ -222,10 +224,10 @@  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_local(ksyms, "bpf_fentry_test1");
+	addrs[1] = ksym_get_addr_local(ksyms, "bpf_fentry_test2");
 
-	if (!ASSERT_FALSE(!addrs[0] || !addrs[1], "ksym_get_addr"))
+	if (!ASSERT_FALSE(!addrs[0] || !addrs[1], "ksym_get_addr_local"))
 		goto cleanup;
 
 	skel = kprobe_multi__open_and_load();
@@ -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_local();
+	if (!ASSERT_OK(ksyms != NULL, "load_kallsyms_local"))
 		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_local(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..ee3e28d76a78 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");
@@ -50,12 +52,12 @@  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");
-	ASSERT_NEQ(addrs[0], 0, "ksym_get_addr");
-	addrs[1] = ksym_get_addr("bpf_testmod_fentry_test2");
-	ASSERT_NEQ(addrs[1], 0, "ksym_get_addr");
-	addrs[2] = ksym_get_addr("bpf_testmod_fentry_test3");
-	ASSERT_NEQ(addrs[2], 0, "ksym_get_addr");
+	addrs[0] = ksym_get_addr_local(ksyms, "bpf_testmod_fentry_test1");
+	ASSERT_NEQ(addrs[0], 0, "ksym_get_addr_local");
+	addrs[1] = ksym_get_addr_local(ksyms, "bpf_testmod_fentry_test2");
+	ASSERT_NEQ(addrs[1], 0, "ksym_get_addr_local");
+	addrs[2] = ksym_get_addr_local(ksyms, "bpf_testmod_fentry_test3");
+	ASSERT_NEQ(addrs[2], 0, "ksym_get_addr_local");
 
 	opts.addrs = (const unsigned long *) addrs;
 	opts.cnt = ARRAY_SIZE(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_local(ksyms);
+	if (!ASSERT_OK(ksyms != NULL, "load_kallsyms_refresh_local"))
 		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_local(ksyms);
 }
diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index f83d9f65c65b..398c4fa5d1dc 100644
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -14,104 +14,176 @@ 
 #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 struct ksyms *ksyms;
+
+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_local(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_local(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_local(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_local(ksyms);
+	return NULL;
+}
+
+int load_kallsyms_refresh(void)
+{
+	ksyms = load_kallsyms_refresh_local(NULL);
+	return ksyms ? 0 : 1;
+}
+
+struct ksyms *load_kallsyms_local(void)
+{
+	return load_kallsyms_refresh_local(NULL);
 }
 
 int load_kallsyms(void)
 {
-	/*
-	 * This is called/used from multiplace places,
-	 * load symbols just once.
-	 */
-	if (sym_cnt)
-		return 0;
-	return load_kallsyms_refresh();
+	ksyms = load_kallsyms_local();
+	return ksyms ? 0 : 1;
 }
 
-struct ksym *ksym_search(long key)
+struct ksym *ksym_search_local(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)
+struct ksym *ksym_search(long key)
+{
+	if (!ksyms)
+		return NULL;
+	return ksym_search_local(ksyms, key);
+}
+
+long ksym_get_addr_local(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;
 }
 
+long ksym_get_addr(const char *name)
+{
+	if (!ksyms)
+		return 0;
+	return ksym_get_addr_local(ksyms, name);
+}
+
 /* open kallsyms and read symbol addresses on the fly. Without caching all symbols,
  * this is faster than load + find.
  */
diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h
index 876f3e711df6..4441a239316d 100644
--- a/tools/testing/selftests/bpf/trace_helpers.h
+++ b/tools/testing/selftests/bpf/trace_helpers.h
@@ -11,6 +11,7 @@  struct ksym {
 	long addr;
 	char *name;
 };
+struct ksyms;
 
 int load_kallsyms(void);
 int load_kallsyms_refresh(void);
@@ -18,6 +19,13 @@  int load_kallsyms_refresh(void);
 struct ksym *ksym_search(long key);
 long ksym_get_addr(const char *name);
 
+struct ksyms *load_kallsyms_local(void);
+struct ksyms *load_kallsyms_refresh_local(struct ksyms *ksyms);
+void free_kallsyms_local(struct ksyms *ksyms);
+
+struct ksym *ksym_search_local(struct ksyms *ksyms, long key);
+long ksym_get_addr_local(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);