mirror/xdp-project-bpf-examples
1
0
Fork 0
mirror of https://github.com/xdp-project/bpf-examples.git synced 2024-05-06 15:54:53 +00:00
Code Issues Projects Releases Wiki Activity

ktrace-CO-RE: Add trivial BPF-prog

Browse Source 
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
This commit is contained in:
Jesper Dangaard Brouer
2021-05-31 18:57:50 +02:00
parent d2c3b9d8bc
commit f11ff90d61
2 changed files with 104 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

80
ktrace-CO-RE/ktrace01.c Normal file
View File

@@ -0,0 +1,80 @@
// SPDX-License-Identifier: GPL-2.0+
// static const char *__doc__ = " Trivial ktrace example";
#include <bpf/libbpf.h>
#include <stdlib.h>
#include <errno.h>
#include <stdio.h>
#define pr_err(fmt, ...) \
fprintf(stderr, "%s:%d - " fmt, __FILE__, __LINE__, ##__VA_ARGS__)
int main(int argc, char **argv)
{
struct bpf_object *obj = NULL;
struct bpf_link *link = NULL;
struct bpf_program *prog;
char filename[256];
//char pin_file[256];
// char *pin_file;
char buf[100];
int err;
int c;
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
obj = bpf_object__open_file(filename, NULL);
err = libbpf_get_error(obj);
if (err) {
libbpf_strerror(err, buf, sizeof(buf));
pr_err("Error(%d) opening file: %s\n", err, buf);
goto out;
}
err = bpf_object__load(obj);
if (err) {
libbpf_strerror(err, buf, sizeof(buf));
pr_err("Error(%d) loading: %s\n", err, buf);
goto out;
}
prog = bpf_program__next(NULL, obj);
if (!prog) {
pr_err("No program!\n");
err = -ENOENT;
goto out;
}
link = bpf_program__attach(prog);
err = libbpf_get_error(link);
if (err) {
libbpf_strerror(err, buf, sizeof(buf));
pr_err("Error(%d) attaching: %s\n", err, buf);
goto out;
}
printf("Loaded BPF file %s\n", filename);
printf( "Press any key + enter to unload program again [Y/y]:");
c = getchar();
putchar(c);
// snprintf(pin_file, sizeof(pin_file), "/sys/fs/bpf/%s", argv[0]);
/*
pin_file = "/sys/fs/bpf/ktrace01";
err = bpf_link__pin(link, pin_file);
printf("pin_file %s\n", pin_file);
if (err) {
libbpf_strerror(err, buf, sizeof(buf));
pr_err("Error(%d) pinning: %s\n", err, buf);
goto out;
}
printf("Loaded BPF file %s (pinned at %s)\n", filename, pin_file);
*/
out:
bpf_link__destroy(link);
bpf_object__close(obj);
if (err)
return EXIT_FAILURE;
return EXIT_SUCCESS;
}

24
ktrace-CO-RE/ktrace01_kern.c Normal file
View File

@@ -0,0 +1,24 @@
/* SPDX-License-Identifier: GPL-2.0+ */
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
char _license[] SEC("license") = "GPL";
struct my_struct {
int v;
__u64 m2;
};
SEC("kprobe/open_ctree")
int bpf_prog1(struct pt_regs *ctx)
{
unsigned long rc = 0;
struct my_struct a;
//a.v = 42;
// bpf_override_return(ctx, rc);
if (a.v == 43)
return 0;
return a.v;
}