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

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