samples/bpf: fix kprobe attachment issue on x64

Commit d5a0052 ("syscalls/core, syscalls/x86: Rename
struct pt_regs-based sys_*() to __x64_sys_*()") renamed a lot
of syscall function sys_*() to __x64_sys_*().
This caused several kprobe based samples/bpf tests failing.

This patch fixed the problem in bpf_load.c.
For x86_64 architecture, function name __x64_sys_*() will be
first used for kprobe event creation. If the creation is successful,
it will be used. Otherwise, function name sys_*() will be used
for kprobe event creation.

Fixes: d5a0052 ("syscalls/core, syscalls/x86: Rename struct pt_regs-based sys_*() to __x64_sys_*()")
Signed-off-by: Yonghong Song <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>

samples/bpf/bpf_load.c

@@ -145,6 +145,9 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
  }
 
  if (is_kprobe || is_kretprobe) {
+ bool need_normal_check = true;
+ const char *event_prefix = "";
+
  if (is_kprobe)
  event += 7;
  else
@@ -158,18 +161,33 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
  if (isdigit(*event))
  return populate_prog_array(event, fd);
 
- snprintf(buf, sizeof(buf),
- "echo '%c:%s %s' >> /sys/kernel/debug/tracing/kprobe_events",
- is_kprobe ? 'p' : 'r', event, event);
- err = system(buf);
- if (err < 0) {
- printf("failed to create kprobe '%s' error '%s'\n",
- event, strerror(errno));
- return -1;
+#ifdef __x86_64__
+ if (strncmp(event, "sys_", 4) == 0) {
+ snprintf(buf, sizeof(buf),
+ "echo '%c:__x64_%s __x64_%s' >> /sys/kernel/debug/tracing/kprobe_events",
+ is_kprobe ? 'p' : 'r', event, event);
+ err = system(buf);
+ if (err >= 0) {
+ need_normal_check = false;
+ event_prefix = "__x64_";
+ }
+ }
+#endif
+ if (need_normal_check) {
+ snprintf(buf, sizeof(buf),
+ "echo '%c:%s %s' >> /sys/kernel/debug/tracing/kprobe_events",
+ is_kprobe ? 'p' : 'r', event, event);
+ err = system(buf);
+ if (err < 0) {
+ printf("failed to create kprobe '%s' error '%s'\n",
+ event, strerror(errno));
+ return -1;
+ }
  }
 
  strcpy(buf, DEBUGFS);
  strcat(buf, "events/kprobes/");
+ strcat(buf, event_prefix);
  strcat(buf, event);
  strcat(buf, "/id");
  } else if (is_tracepoint) {