Commit 456d5355 authored by Daniel T. Lee's avatar Daniel T. Lee Committed by Alexei Starovoitov
Browse files

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: default avatarDaniel T. Lee <danieltimlee@gmail.com>
Link: https://lore.kernel.org/r/20230818090119.477441-10-danieltimlee@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 8dc80551

samples/bpf/spintest.bpf.c

+3 −14
Original line number Diff line number Diff line
@@ -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)

samples/bpf/spintest_user.c

+7 −15
Original line number Diff line number Diff line
@@ -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()) {
@@ -44,12 +43,6 @@ 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");
@@ -58,7 +51,6 @@ int main(int ac, char **argv) 
		}

		j++;

	}

	}



	for (i = 0; i < 5; i++) {

		key = 0;