samples, bpf: Refactor kprobe tracing user progs with libbpf

Currently, the kprobe BPF program attachment method for bpf_load is
quite old. The implementation of bpf_load "directly" controls and
manages(create, delete) the kprobe events of DEBUGFS. On the other hand,
using using the libbpf automatically manages the kprobe event.
(under bpf_link interface)

By calling bpf_program__attach(_kprobe) in libbpf, the corresponding
kprobe is created and the BPF program will be attached to this kprobe.
To remove this, by simply invoking bpf_link__destroy will clean up the
event.

This commit refactors kprobe tracing programs (tracex{1~7}_user.c) with
libbpf using bpf_link interface and bpf_program__attach.

tracex2_kern.c, which tracks system calls (sys_*), has been modified to
append prefix depending on architecture.

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200516040608.1377876-3-danieltimlee@gmail.com

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 424f6fe..4c91e59 100644 (file)
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -64,13 +64,13 @@ fds_example-objs := fds_example.o
 sockex1-objs := sockex1_user.o
 sockex2-objs := sockex2_user.o
 sockex3-objs := bpf_load.o sockex3_user.o
-tracex1-objs := bpf_load.o tracex1_user.o $(TRACE_HELPERS)
-tracex2-objs := bpf_load.o tracex2_user.o
-tracex3-objs := bpf_load.o tracex3_user.o
-tracex4-objs := bpf_load.o tracex4_user.o
+tracex1-objs := tracex1_user.o $(TRACE_HELPERS)
+tracex2-objs := tracex2_user.o
+tracex3-objs := tracex3_user.o
+tracex4-objs := tracex4_user.o
 tracex5-objs := bpf_load.o tracex5_user.o $(TRACE_HELPERS)
-tracex6-objs := bpf_load.o tracex6_user.o
-tracex7-objs := bpf_load.o tracex7_user.o
+tracex6-objs := tracex6_user.o
+tracex7-objs := tracex7_user.o
 test_probe_write_user-objs := bpf_load.o test_probe_write_user_user.o
 trace_output-objs := bpf_load.o trace_output_user.o $(TRACE_HELPERS)
 lathist-objs := bpf_load.o lathist_user.o

diff --git a/samples/bpf/trace_common.h b/samples/bpf/trace_common.h
new file mode 100644 (file)
index 0000000..8cb5400
--- /dev/null
+++ b/samples/bpf/trace_common.h
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef __TRACE_COMMON_H
+#define __TRACE_COMMON_H
+
+#ifdef __x86_64__
+#define SYSCALL(SYS) "__x64_" __stringify(SYS)
+#elif defined(__s390x__)
+#define SYSCALL(SYS) "__s390x_" __stringify(SYS)
+#else
+#define SYSCALL(SYS)  __stringify(SYS)
+#endif
+
+#endif

diff --git a/samples/bpf/tracex1_user.c b/samples/bpf/tracex1_user.c
index 55fddbd..9d4adb7 100644 (file)
--- a/samples/bpf/tracex1_user.c
+++ b/samples/bpf/tracex1_user.c
@@ -1,21 +1,41 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <stdio.h>
-#include <linux/bpf.h>
 #include <unistd.h>
-#include <bpf/bpf.h>
-#include "bpf_load.h"
+#include <bpf/libbpf.h>
 #include "trace_helpers.h"
 
 int main(int ac, char **argv)
 {
-       FILE *f;
+       struct bpf_link *link = NULL;
+       struct bpf_program *prog;
+       struct bpf_object *obj;
        char filename[256];
+       FILE *f;
 
        snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+       obj = bpf_object__open_file(filename, NULL);
+       if (libbpf_get_error(obj)) {
+               fprintf(stderr, "ERROR: opening BPF object file failed\n");
+               return 0;
+       }
+
+       prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
+       if (!prog) {
+               fprintf(stderr, "ERROR: finding a prog in obj file failed\n");
+               goto cleanup;
+       }
+
+       /* load BPF program */
+       if (bpf_object__load(obj)) {
+               fprintf(stderr, "ERROR: loading BPF object file failed\n");
+               goto cleanup;
+       }
 
-       if (load_bpf_file(filename)) {
-               printf("%s", bpf_log_buf);
-               return 1;
+       link = bpf_program__attach(prog);
+       if (libbpf_get_error(link)) {
+               fprintf(stderr, "ERROR: bpf_program__attach failed\n");
+               link = NULL;
+               goto cleanup;
        }
 
        f = popen("taskset 1 ping -c5 localhost", "r");
@@ -23,5 +43,8 @@ int main(int ac, char **argv)
 
        read_trace_pipe();
 
+cleanup:
+       bpf_link__destroy(link);
+       bpf_object__close(obj);
        return 0;
 }

diff --git a/samples/bpf/tracex2_kern.c b/samples/bpf/tracex2_kern.c
index d865bb3..cc5f94c 100644 (file)
--- a/samples/bpf/tracex2_kern.c
+++ b/samples/bpf/tracex2_kern.c
@@ -10,6 +10,7 @@
 #include <uapi/linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
+#include "trace_common.h"
 
 struct bpf_map_def SEC("maps") my_map = {
        .type = BPF_MAP_TYPE_HASH,
@@ -77,7 +78,7 @@ struct bpf_map_def SEC("maps") my_hist_map = {
        .max_entries = 1024,
 };
 
-SEC("kprobe/sys_write")
+SEC("kprobe/" SYSCALL(sys_write))
 int bpf_prog3(struct pt_regs *ctx)
 {
        long write_size = PT_REGS_PARM3(ctx);

diff --git a/samples/bpf/tracex2_user.c b/samples/bpf/tracex2_user.c
index c9544a4..3e36b3e 100644 (file)
--- a/samples/bpf/tracex2_user.c
+++ b/samples/bpf/tracex2_user.c
@@ -3,17 +3,19 @@
 #include <unistd.h>
 #include <stdlib.h>
 #include <signal.h>
-#include <linux/bpf.h>
 #include <string.h>
 #include <sys/resource.h>
 
 #include <bpf/bpf.h>
-#include "bpf_load.h"
+#include <bpf/libbpf.h>
 #include "bpf_util.h"
 
 #define MAX_INDEX      64
 #define MAX_STARS      38
 
+/* my_map, my_hist_map */
+static int map_fd[2];
+
 static void stars(char *str, long val, long max, int width)
 {
        int i;
@@ -115,18 +117,39 @@ static void int_exit(int sig)
 int main(int ac, char **argv)
 {
        struct rlimit r = {1024*1024, RLIM_INFINITY};
-       char filename[256];
        long key, next_key, value;
+       struct bpf_link *links[2];
+       struct bpf_program *prog;
+       struct bpf_object *obj;
+       char filename[256];
+       int i, j = 0;
        FILE *f;
-       int i;
-
-       snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 
        if (setrlimit(RLIMIT_MEMLOCK, &r)) {
                perror("setrlimit(RLIMIT_MEMLOCK)");
                return 1;
        }
 
+       snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+       obj = bpf_object__open_file(filename, NULL);
+       if (libbpf_get_error(obj)) {
+               fprintf(stderr, "ERROR: opening BPF object file failed\n");
+               return 0;
+       }
+
+       /* load BPF program */
+       if (bpf_object__load(obj)) {
+               fprintf(stderr, "ERROR: loading BPF object file failed\n");
+               goto cleanup;
+       }
+
+       map_fd[0] = bpf_object__find_map_fd_by_name(obj, "my_map");
+       map_fd[1] = bpf_object__find_map_fd_by_name(obj, "my_hist_map");
+       if (map_fd[0] < 0 || map_fd[1] < 0) {
+               fprintf(stderr, "ERROR: finding a map in obj file failed\n");
+               goto cleanup;
+       }
+
        signal(SIGINT, int_exit);
        signal(SIGTERM, int_exit);
 
@@ -138,9 +161,14 @@ int main(int ac, char **argv)
        f = popen("dd if=/dev/zero of=/dev/null count=5000000", "r");
        (void) f;
 
-       if (load_bpf_file(filename)) {
-               printf("%s", bpf_log_buf);
-               return 1;
+       bpf_object__for_each_program(prog, obj) {
+               links[j] = bpf_program__attach(prog);
+               if (libbpf_get_error(links[j])) {
+                       fprintf(stderr, "ERROR: bpf_program__attach failed\n");
+                       links[j] = NULL;
+                       goto cleanup;
+               }
+               j++;
        }
 
        for (i = 0; i < 5; i++) {
@@ -156,5 +184,10 @@ int main(int ac, char **argv)
        }
        print_hist(map_fd[1]);
 
+cleanup:
+       for (j--; j >= 0; j--)
+               bpf_link__destroy(links[j]);
+
+       bpf_object__close(obj);
        return 0;
 }

diff --git a/samples/bpf/tracex3_user.c b/samples/bpf/tracex3_user.c
index cf8fedc..70e9877 100644 (file)
--- a/samples/bpf/tracex3_user.c
+++ b/samples/bpf/tracex3_user.c
@@ -7,11 +7,10 @@
 #include <unistd.h>
 #include <stdbool.h>
 #include <string.h>
-#include <linux/bpf.h>
 #include <sys/resource.h>
 
 #include <bpf/bpf.h>
-#include "bpf_load.h"
+#include <bpf/libbpf.h>
 #include "bpf_util.h"
 
 #define SLOTS 100
@@ -109,20 +108,11 @@ static void print_hist(int fd)
 int main(int ac, char **argv)
 {
        struct rlimit r = {1024*1024, RLIM_INFINITY};
+       struct bpf_link *links[2];
+       struct bpf_program *prog;
+       struct bpf_object *obj;
        char filename[256];
-       int i;
-
-       snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
-
-       if (setrlimit(RLIMIT_MEMLOCK, &r)) {
-               perror("setrlimit(RLIMIT_MEMLOCK)");
-               return 1;
-       }
-
-       if (load_bpf_file(filename)) {
-               printf("%s", bpf_log_buf);
-               return 1;
-       }
+       int map_fd, i, j = 0;
 
        for (i = 1; i < ac; i++) {
                if (strcmp(argv[i], "-a") == 0) {
@@ -137,6 +127,40 @@ int main(int ac, char **argv)
                }
        }
 
+       if (setrlimit(RLIMIT_MEMLOCK, &r)) {
+               perror("setrlimit(RLIMIT_MEMLOCK)");
+               return 1;
+       }
+
+       snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+       obj = bpf_object__open_file(filename, NULL);
+       if (libbpf_get_error(obj)) {
+               fprintf(stderr, "ERROR: opening BPF object file failed\n");
+               return 0;
+       }
+
+       /* load BPF program */
+       if (bpf_object__load(obj)) {
+               fprintf(stderr, "ERROR: loading BPF object file failed\n");
+               goto cleanup;
+       }
+
+       map_fd = bpf_object__find_map_fd_by_name(obj, "lat_map");
+       if (map_fd < 0) {
+               fprintf(stderr, "ERROR: finding a map in obj file failed\n");
+               goto cleanup;
+       }
+
+       bpf_object__for_each_program(prog, obj) {
+               links[j] = bpf_program__attach(prog);
+               if (libbpf_get_error(links[j])) {
+                       fprintf(stderr, "ERROR: bpf_program__attach failed\n");
+                       links[j] = NULL;
+                       goto cleanup;
+               }
+               j++;
+       }
+
        printf("  heatmap of IO latency\n");
        if (text_only)
                printf("  %s", sym[num_colors - 1]);
@@ -153,9 +177,14 @@ int main(int ac, char **argv)
        for (i = 0; ; i++) {
                if (i % 20 == 0)
                        print_banner();
-               print_hist(map_fd[1]);
+               print_hist(map_fd);
                sleep(2);
        }
 
+cleanup:
+       for (j--; j >= 0; j--)
+               bpf_link__destroy(links[j]);
+
+       bpf_object__close(obj);
        return 0;
 }

diff --git a/samples/bpf/tracex4_user.c b/samples/bpf/tracex4_user.c
index ec52203..e8faf8f 100644 (file)
--- a/samples/bpf/tracex4_user.c
+++ b/samples/bpf/tracex4_user.c
@@ -8,11 +8,10 @@
 #include <stdbool.h>
 #include <string.h>
 #include <time.h>
-#include <linux/bpf.h>
 #include <sys/resource.h>
 
 #include <bpf/bpf.h>
-#include "bpf_load.h"
+#include <bpf/libbpf.h>
 
 struct pair {
        long long val;
@@ -36,8 +35,8 @@ static void print_old_objects(int fd)
        key = write(1, "\e[1;1H\e[2J", 12); /* clear screen */
 
        key = -1;
-       while (bpf_map_get_next_key(map_fd[0], &key, &next_key) == 0) {
-               bpf_map_lookup_elem(map_fd[0], &next_key, &v);
+       while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
+               bpf_map_lookup_elem(fd, &next_key, &v);
                key = next_key;
                if (val - v.val < 1000000000ll)
                        /* object was allocated more then 1 sec ago */
@@ -50,25 +49,55 @@ static void print_old_objects(int fd)
 int main(int ac, char **argv)
 {
        struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
+       struct bpf_link *links[2];
+       struct bpf_program *prog;
+       struct bpf_object *obj;
        char filename[256];
-       int i;
-
-       snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+       int map_fd, i, j = 0;
 
        if (setrlimit(RLIMIT_MEMLOCK, &r)) {
                perror("setrlimit(RLIMIT_MEMLOCK, RLIM_INFINITY)");
                return 1;
        }
 
-       if (load_bpf_file(filename)) {
-               printf("%s", bpf_log_buf);
-               return 1;
+       snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+       obj = bpf_object__open_file(filename, NULL);
+       if (libbpf_get_error(obj)) {
+               fprintf(stderr, "ERROR: opening BPF object file failed\n");
+               return 0;
+       }
+
+       /* load BPF program */
+       if (bpf_object__load(obj)) {
+               fprintf(stderr, "ERROR: loading BPF object file failed\n");
+               goto cleanup;
+       }
+
+       map_fd = bpf_object__find_map_fd_by_name(obj, "my_map");
+       if (map_fd < 0) {
+               fprintf(stderr, "ERROR: finding a map in obj file failed\n");
+               goto cleanup;
+       }
+
+       bpf_object__for_each_program(prog, obj) {
+               links[j] = bpf_program__attach(prog);
+               if (libbpf_get_error(links[j])) {
+                       fprintf(stderr, "ERROR: bpf_program__attach failed\n");
+                       links[j] = NULL;
+                       goto cleanup;
+               }
+               j++;
        }
 
        for (i = 0; ; i++) {
-               print_old_objects(map_fd[1]);
+               print_old_objects(map_fd);
                sleep(1);
        }
 
+cleanup:
+       for (j--; j >= 0; j--)
+               bpf_link__destroy(links[j]);
+
+       bpf_object__close(obj);
        return 0;
 }

diff --git a/samples/bpf/tracex6_user.c b/samples/bpf/tracex6_user.c
index 4bb3c83..33df978 100644 (file)
--- a/samples/bpf/tracex6_user.c
+++ b/samples/bpf/tracex6_user.c
@@ -4,7 +4,6 @@
 #include <assert.h>
 #include <fcntl.h>
 #include <linux/perf_event.h>
-#include <linux/bpf.h>
 #include <sched.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -15,12 +14,15 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
-#include "bpf_load.h"
 #include <bpf/bpf.h>
+#include <bpf/libbpf.h>
 #include "perf-sys.h"
 
 #define SAMPLE_PERIOD  0x7fffffffffffffffULL
 
+/* counters, values, values2 */
+static int map_fd[3];
+
 static void check_on_cpu(int cpu, struct perf_event_attr *attr)
 {
        struct bpf_perf_event_value value2;
@@ -174,16 +176,51 @@ static void test_bpf_perf_event(void)
 int main(int argc, char **argv)
 {
        struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
+       struct bpf_link *links[2];
+       struct bpf_program *prog;
+       struct bpf_object *obj;
        char filename[256];
+       int i = 0;
+
+       setrlimit(RLIMIT_MEMLOCK, &r);
 
        snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+       obj = bpf_object__open_file(filename, NULL);
+       if (libbpf_get_error(obj)) {
+               fprintf(stderr, "ERROR: opening BPF object file failed\n");
+               return 0;
+       }
 
-       setrlimit(RLIMIT_MEMLOCK, &r);
-       if (load_bpf_file(filename)) {
-               printf("%s", bpf_log_buf);
-               return 1;
+       /* load BPF program */
+       if (bpf_object__load(obj)) {
+               fprintf(stderr, "ERROR: loading BPF object file failed\n");
+               goto cleanup;
+       }
+
+       map_fd[0] = bpf_object__find_map_fd_by_name(obj, "counters");
+       map_fd[1] = bpf_object__find_map_fd_by_name(obj, "values");
+       map_fd[2] = bpf_object__find_map_fd_by_name(obj, "values2");
+       if (map_fd[0] < 0 || map_fd[1] < 0 || map_fd[2] < 0) {
+               fprintf(stderr, "ERROR: finding a map in obj file failed\n");
+               goto cleanup;
+       }
+
+       bpf_object__for_each_program(prog, obj) {
+               links[i] = bpf_program__attach(prog);
+               if (libbpf_get_error(links[i])) {
+                       fprintf(stderr, "ERROR: bpf_program__attach failed\n");
+                       links[i] = NULL;
+                       goto cleanup;
+               }
+               i++;
        }
 
        test_bpf_perf_event();
+
+cleanup:
+       for (i--; i >= 0; i--)
+               bpf_link__destroy(links[i]);
+
+       bpf_object__close(obj);
        return 0;
 }

diff --git a/samples/bpf/tracex7_user.c b/samples/bpf/tracex7_user.c
index ea6dae7..fdcd658 100644 (file)
--- a/samples/bpf/tracex7_user.c
+++ b/samples/bpf/tracex7_user.c
@@ -1,28 +1,51 @@
 #define _GNU_SOURCE
 
 #include <stdio.h>
-#include <linux/bpf.h>
 #include <unistd.h>
-#include <bpf/bpf.h>
-#include "bpf_load.h"
+#include <bpf/libbpf.h>
 
 int main(int argc, char **argv)
 {
-       FILE *f;
+       struct bpf_link *link = NULL;
+       struct bpf_program *prog;
+       struct bpf_object *obj;
        char filename[256];
        char command[256];
-       int ret;
+       int ret = 0;
+       FILE *f;
 
        snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+       obj = bpf_object__open_file(filename, NULL);
+       if (libbpf_get_error(obj)) {
+               fprintf(stderr, "ERROR: opening BPF object file failed\n");
+               return 0;
+       }
+
+       prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
+       if (!prog) {
+               fprintf(stderr, "ERROR: finding a prog in obj file failed\n");
+               goto cleanup;
+       }
+
+       /* load BPF program */
+       if (bpf_object__load(obj)) {
+               fprintf(stderr, "ERROR: loading BPF object file failed\n");
+               goto cleanup;
+       }
 
-       if (load_bpf_file(filename)) {
-               printf("%s", bpf_log_buf);
-               return 1;
+       link = bpf_program__attach(prog);
+       if (libbpf_get_error(link)) {
+               fprintf(stderr, "ERROR: bpf_program__attach failed\n");
+               link = NULL;
+               goto cleanup;
        }
 
        snprintf(command, 256, "mount %s tmpmnt/", argv[1]);
        f = popen(command, "r");
        ret = pclose(f);
 
+cleanup:
+       bpf_link__destroy(link);
+       bpf_object__close(obj);
        return ret ? 0 : 1;
 }