libbpf-tools: fix readahead, support v5.10+ kernel

Signed-off-by: Wenbo Zhang <[email protected]>

libbpf-tools/readahead.bpf.c

@@ -26,8 +26,8 @@ struct {
 
 static struct hist hist;
 
-SEC("fentry/__do_page_cache_readahead")
-int BPF_PROG(do_page_cache_readahead)
+SEC("fentry/do_page_cache_ra")
+int BPF_PROG(do_page_cache_ra)
 {
  u32 pid = bpf_get_current_pid_tgid();
  u64 one = 1;
@@ -53,8 +53,8 @@ int BPF_PROG(page_cache_alloc_ret, gfp_t gfp, struct page *ret)
  return 0;
 }
 
-SEC("fexit/__do_page_cache_readahead")
-int BPF_PROG(do_page_cache_readahead_ret)
+SEC("fexit/do_page_cache_ra")
+int BPF_PROG(do_page_cache_ra_ret)
 {
  u32 pid = bpf_get_current_pid_tgid();
 

libbpf-tools/readahead.c

@@ -72,6 +72,24 @@ static void sig_handler(int sig)
  exiting = true;
 }
 
+static int readahead__set_attach_target(struct bpf_program *prog)
+{
+ int err;
+
+ err = bpf_program__set_attach_target(prog, 0, "do_page_cache_ra");
+ if (!err)
+ return 0;
+
+ err = bpf_program__set_attach_target(prog, 0,
+ "__do_page_cache_readahead");
+ if (!err)
+ return 0;
+
+ fprintf(stderr, "failed to set attach target to %s: %s\n",
+ bpf_program__section_name(prog), strerror(-err));
+ return err;
+}
+
 int main(int argc, char **argv)
 {
  static const struct argp argp = {
@@ -95,12 +113,29 @@ int main(int argc, char **argv)
  return 1;
  }
 
- obj = readahead_bpf__open_and_load();
+ obj = readahead_bpf__open();
  if (!obj) {
- fprintf(stderr, "failed to open and/or load BPF ojbect\n");
+ fprintf(stderr, "failed to open BPF object\n");
  return 1;
  }
 
+ /*
+ * Starting from v5.10-rc1 (8238287), __do_page_cache_readahead has
+ * renamed to do_page_cache_ra. So we specify the function dynamically.
+ */
+ err = readahead__set_attach_target(obj->progs.do_page_cache_ra);
+ if (err)
+ goto cleanup;
+ err = readahead__set_attach_target(obj->progs.do_page_cache_ra_ret);
+ if (err)
+ goto cleanup;
+
+ err = readahead_bpf__load(obj);
+ if (err) {
+ fprintf(stderr, "failed to load BPF object\n");
+ goto cleanup;
+ }
+
  err = readahead_bpf__attach(obj);
  if (err) {
  fprintf(stderr, "failed to attach BPF programs\n");