samples/bpf: simplify spintest with kprobe.multi

With the introduction of kprobe.multi, it is now possible to attach
multiple kprobes to a single BPF program without the need for multiple
definitions. Additionally, this method supports wildcard-based
matching, allowing for further simplification of BPF programs. In here,
an asterisk (*) wildcard is used to map to all symbols relevant to
spin_{lock|unlock}.

Furthermore, since kprobe.multi handles symbol matching, this commit
eliminates the need for the previous logic of reading the ksym table to
verify the existence of symbols.

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Link: https://lore.kernel.org/r/20230818090119.477441-10-danieltimlee@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/samples/bpf/spintest.bpf.c b/samples/bpf/spintest.bpf.c
index 15740b16a3f7a3266fd625c8d21481a6ac11e6bf..cba5a9d507831cb17d78467707a56901f73efb3b 100644 (file)
--- a/samples/bpf/spintest.bpf.c
+++ b/samples/bpf/spintest.bpf.c
@@ -47,20 +47,9 @@ int foo(struct pt_regs *ctx) \
 }
 
 /* add kprobes to all possible *spin* functions */
-SEC("kprobe/spin_unlock")PROG(p1)
-SEC("kprobe/spin_lock")PROG(p2)
-SEC("kprobe/mutex_spin_on_owner")PROG(p3)
-SEC("kprobe/rwsem_spin_on_owner")PROG(p4)
-SEC("kprobe/spin_unlock_irqrestore")PROG(p5)
-SEC("kprobe/_raw_spin_unlock_irqrestore")PROG(p6)
-SEC("kprobe/_raw_spin_unlock_bh")PROG(p7)
-SEC("kprobe/_raw_spin_unlock")PROG(p8)
-SEC("kprobe/_raw_spin_lock_irqsave")PROG(p9)
-SEC("kprobe/_raw_spin_trylock_bh")PROG(p10)
-SEC("kprobe/_raw_spin_lock_irq")PROG(p11)
-SEC("kprobe/_raw_spin_trylock")PROG(p12)
-SEC("kprobe/_raw_spin_lock")PROG(p13)
-SEC("kprobe/_raw_spin_lock_bh")PROG(p14)
+SEC("kprobe.multi/spin_*lock*")PROG(spin_lock)
+SEC("kprobe.multi/*_spin_on_owner")PROG(spin_on_owner)
+SEC("kprobe.multi/_raw_spin_*lock*")PROG(raw_spin_lock)
 
 /* and to inner bpf helpers */
 SEC("kprobe/htab_map_update_elem")PROG(p15)

diff --git a/samples/bpf/spintest_user.c b/samples/bpf/spintest_user.c
index 8c77600776fb4206a3b328f7b977e0371a6610b6..55971edb1088977dbdf8aaff520bdbbe756f129f 100644 (file)
--- a/samples/bpf/spintest_user.c
+++ b/samples/bpf/spintest_user.c
@@ -9,13 +9,12 @@
 
 int main(int ac, char **argv)
 {
-       char filename[256], symbol[256];
        struct bpf_object *obj = NULL;
        struct bpf_link *links[20];
        long key, next_key, value;
        struct bpf_program *prog;
        int map_fd, i, j = 0;
-       const char *section;
+       char filename[256];
        struct ksym *sym;
 
        if (load_kallsyms()) {
@@ -44,20 +43,13 @@ int main(int ac, char **argv)
        }
 
        bpf_object__for_each_program(prog, obj) {
-               section = bpf_program__section_name(prog);
-               if (sscanf(section, "kprobe/%s", symbol) != 1)
-                       continue;
-
-               /* Attach prog only when symbol exists */
-               if (ksym_get_addr(symbol)) {
-                       links[j] = bpf_program__attach(prog);
-                       if (libbpf_get_error(links[j])) {
-                               fprintf(stderr, "bpf_program__attach failed\n");
-                               links[j] = NULL;
-                               goto cleanup;
-                       }
-                       j++;
+               links[j] = bpf_program__attach(prog);
+               if (libbpf_get_error(links[j])) {
+                       fprintf(stderr, "bpf_program__attach failed\n");
+                       links[j] = NULL;
+                       goto cleanup;
                }
+               j++;
        }
 
        for (i = 0; i < 5; i++) {