samples: bpf: Refactor ibumad program with libbpf

This commit refactors the existing ibumad program with libbpf bpf
loader. Attach/detach of Tracepoint bpf programs has been managed
with the generic bpf_program__attach() and bpf_link__destroy() from
the libbpf.

Also, instead of using the previous BPF MAP definition, this commit
refactors ibumad MAP definition with the new BTF-defined MAP format.

To verify that this bpf program works without an infiniband device,
try loading ib_umad kernel module and test the program as follows:

    # modprobe ib_umad
    # ./ibumad

Moreover, TRACE_HELPERS has been removed from the Makefile since it is
not used on this program.

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201124090310.24374-5-danieltimlee@gmail.com

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 3bffd42..09a2494 100644 (file)
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -109,7 +109,7 @@ xsk_fwd-objs := xsk_fwd.o
 xdp_fwd-objs := xdp_fwd_user.o
 task_fd_query-objs := task_fd_query_user.o $(TRACE_HELPERS)
 xdp_sample_pkts-objs := xdp_sample_pkts_user.o $(TRACE_HELPERS)
-ibumad-objs := bpf_load.o ibumad_user.o $(TRACE_HELPERS)
+ibumad-objs := ibumad_user.o
 hbm-objs := hbm.o $(CGROUP_HELPERS)
 
 # Tell kbuild to always build the programs

diff --git a/samples/bpf/ibumad_kern.c b/samples/bpf/ibumad_kern.c
index 3a91b4c..26dcd4d 100644 (file)
--- a/samples/bpf/ibumad_kern.c
+++ b/samples/bpf/ibumad_kern.c
@@ -16,19 +16,19 @@
 #include <bpf/bpf_helpers.h>
 
 
-struct bpf_map_def SEC("maps") read_count = {
-       .type        = BPF_MAP_TYPE_ARRAY,
-       .key_size    = sizeof(u32), /* class; u32 required */
-       .value_size  = sizeof(u64), /* count of mads read */
-       .max_entries = 256, /* Room for all Classes */
-};
-
-struct bpf_map_def SEC("maps") write_count = {
-       .type        = BPF_MAP_TYPE_ARRAY,
-       .key_size    = sizeof(u32), /* class; u32 required */
-       .value_size  = sizeof(u64), /* count of mads written */
-       .max_entries = 256, /* Room for all Classes */
-};
+struct {
+       __uint(type, BPF_MAP_TYPE_ARRAY);
+       __type(key, u32); /* class; u32 required */
+       __type(value, u64); /* count of mads read */
+       __uint(max_entries, 256); /* Room for all Classes */
+} read_count SEC(".maps");
+
+struct {
+       __uint(type, BPF_MAP_TYPE_ARRAY);
+       __type(key, u32); /* class; u32 required */
+       __type(value, u64); /* count of mads written */
+       __uint(max_entries, 256); /* Room for all Classes */
+} write_count SEC(".maps");
 
 #undef DEBUG
 #ifndef DEBUG

diff --git a/samples/bpf/ibumad_user.c b/samples/bpf/ibumad_user.c
index fa06eef..d83d810 100644 (file)
--- a/samples/bpf/ibumad_user.c
+++ b/samples/bpf/ibumad_user.c
@@ -23,10 +23,15 @@
 #include <getopt.h>
 #include <net/if.h>
 
-#include "bpf_load.h"
+#include <bpf/bpf.h>
 #include "bpf_util.h"
 #include <bpf/libbpf.h>
 
+static struct bpf_link *tp_links[3];
+static struct bpf_object *obj;
+static int map_fd[2];
+static int tp_cnt;
+
 static void dump_counts(int fd)
 {
        __u32 key;
@@ -53,6 +58,11 @@ static void dump_all_counts(void)
 static void dump_exit(int sig)
 {
        dump_all_counts();
+       /* Detach tracepoints */
+       while (tp_cnt)
+               bpf_link__destroy(tp_links[--tp_cnt]);
+
+       bpf_object__close(obj);
        exit(0);
 }
 
@@ -73,19 +83,11 @@ static void usage(char *cmd)
 
 int main(int argc, char **argv)
 {
+       struct bpf_program *prog;
        unsigned long delay = 5;
+       char filename[256];
        int longindex = 0;
-       int opt;
-       char bpf_file[256];
-
-       /* Create the eBPF kernel code path name.
-        * This follows the pattern of all of the other bpf samples
-        */
-       snprintf(bpf_file, sizeof(bpf_file), "%s_kern.o", argv[0]);
-
-       /* Do one final dump when exiting */
-       signal(SIGINT, dump_exit);
-       signal(SIGTERM, dump_exit);
+       int opt, err = -1;
 
        while ((opt = getopt_long(argc, argv, "hd:rSw",
                                  long_options, &longindex)) != -1) {
@@ -107,16 +109,51 @@ int main(int argc, char **argv)
                }
        }
 
-       if (load_bpf_file(bpf_file)) {
-               fprintf(stderr, "ERROR: failed to load eBPF from file : %s\n",
-                       bpf_file);
-               return 1;
+       /* Do one final dump when exiting */
+       signal(SIGINT, dump_exit);
+       signal(SIGTERM, dump_exit);
+
+       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 err;
+       }
+
+       /* 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, "read_count");
+       map_fd[1] = bpf_object__find_map_fd_by_name(obj, "write_count");
+       if (map_fd[0] < 0 || map_fd[1] < 0) {
+               fprintf(stderr, "ERROR: finding a map in obj file failed\n");
+               goto cleanup;
+       }
+
+       bpf_object__for_each_program(prog, obj) {
+               tp_links[tp_cnt] = bpf_program__attach(prog);
+               if (libbpf_get_error(tp_links[tp_cnt])) {
+                       fprintf(stderr, "ERROR: bpf_program__attach failed\n");
+                       tp_links[tp_cnt] = NULL;
+                       goto cleanup;
+               }
+               tp_cnt++;
        }
 
        while (1) {
                sleep(delay);
                dump_all_counts();
        }
+       err = 0;
+
+cleanup:
+       /* Detach tracepoints */
+       while (tp_cnt)
+               bpf_link__destroy(tp_links[--tp_cnt]);
 
-       return 0;
+       bpf_object__close(obj);
+       return err;
 }