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3677d0a131
For the problem of increasing fragmentation of the bpf loader programs,
instead of using bpf_loader.o, which is used in samples/bpf, this
commit refactors the existing kprobe tracing programs with libbbpf
bpf loader.
- For kprobe events pointing to system calls, the SYSCALL() macro in
trace_common.h was used.
- Adding a kprobe event and attaching a bpf program to it was done
through bpf_program_attach().
- Instead of using the existing BPF MAP definition, MAP definition
has been refactored with the new BTF-defined MAP format.
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200823085334.9413-3-danieltimlee@gmail.com
113 lines
2.4 KiB
C
113 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Copyright (c) 2016 Sargun Dhillon <sargun@sargun.me>
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*/
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#define _GNU_SOURCE
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#include <stdio.h>
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#include <unistd.h>
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#include <bpf/bpf.h>
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#include <bpf/libbpf.h>
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#include "cgroup_helpers.h"
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#define CGROUP_PATH "/my-cgroup"
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int main(int argc, char **argv)
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{
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pid_t remote_pid, local_pid = getpid();
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struct bpf_link *link = NULL;
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struct bpf_program *prog;
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int cg2, idx = 0, rc = 1;
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struct bpf_object *obj;
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char filename[256];
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int map_fd[2];
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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obj = bpf_object__open_file(filename, NULL);
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if (libbpf_get_error(obj)) {
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fprintf(stderr, "ERROR: opening BPF object file failed\n");
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return 0;
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}
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prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
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if (!prog) {
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printf("finding a prog in obj file failed\n");
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goto cleanup;
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}
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/* load BPF program */
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if (bpf_object__load(obj)) {
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fprintf(stderr, "ERROR: loading BPF object file failed\n");
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goto cleanup;
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}
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map_fd[0] = bpf_object__find_map_fd_by_name(obj, "cgroup_map");
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map_fd[1] = bpf_object__find_map_fd_by_name(obj, "perf_map");
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if (map_fd[0] < 0 || map_fd[1] < 0) {
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fprintf(stderr, "ERROR: finding a map in obj file failed\n");
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goto cleanup;
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}
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link = bpf_program__attach(prog);
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if (libbpf_get_error(link)) {
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fprintf(stderr, "ERROR: bpf_program__attach failed\n");
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link = NULL;
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goto cleanup;
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}
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if (setup_cgroup_environment())
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goto err;
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cg2 = create_and_get_cgroup(CGROUP_PATH);
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if (cg2 < 0)
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goto err;
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if (bpf_map_update_elem(map_fd[0], &idx, &cg2, BPF_ANY)) {
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log_err("Adding target cgroup to map");
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goto err;
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}
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if (join_cgroup(CGROUP_PATH))
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goto err;
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/*
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* The installed helper program catched the sync call, and should
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* write it to the map.
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*/
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sync();
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bpf_map_lookup_elem(map_fd[1], &idx, &remote_pid);
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if (local_pid != remote_pid) {
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fprintf(stderr,
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"BPF Helper didn't write correct PID to map, but: %d\n",
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remote_pid);
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goto err;
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}
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/* Verify the negative scenario; leave the cgroup */
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if (join_cgroup("/"))
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goto err;
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remote_pid = 0;
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bpf_map_update_elem(map_fd[1], &idx, &remote_pid, BPF_ANY);
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sync();
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bpf_map_lookup_elem(map_fd[1], &idx, &remote_pid);
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if (local_pid == remote_pid) {
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fprintf(stderr, "BPF cgroup negative test did not work\n");
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goto err;
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}
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rc = 0;
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err:
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close(cg2);
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cleanup_cgroup_environment();
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cleanup:
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bpf_link__destroy(link);
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bpf_object__close(obj);
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return rc;
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}
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