bpf/tracing: fix kernel/events/core.c compilation error

Commit f371b304f12e ("bpf/tracing: allow user space to
query prog array on the same tp") introduced a perf
ioctl command to query prog array attached to the
same perf tracepoint. The commit introduced a
compilation error under certain config conditions, e.g.,
  (1). CONFIG_BPF_SYSCALL is not defined, or
  (2). CONFIG_TRACING is defined but neither CONFIG_UPROBE_EVENTS
       nor CONFIG_KPROBE_EVENTS is defined.

Error message:
  kernel/events/core.o: In function `perf_ioctl':
  core.c:(.text+0x98c4): undefined reference to `bpf_event_query_prog_array'

This patch fixed this error by guarding the real definition under
CONFIG_BPF_EVENTS and provided static inline dummy function
if CONFIG_BPF_EVENTS was not defined.
It renamed the function from bpf_event_query_prog_array to
perf_event_query_prog_array and moved the definition from linux/bpf.h
to linux/trace_events.h so the definition is in proximity to
other prog_array related functions.

Fixes: f371b304f12e ("bpf/tracing: allow user space to query prog array on the same tp")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

2 files changed, 2 insertions, 2 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 5857c500721b..34fda6aa4606 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4725,7 +4725,7 @@ static long _perf_ioctl(struct perf_event *event, unsigned int cmd, unsigned lon
 	}
 
 	case PERF_EVENT_IOC_QUERY_BPF:
-		return bpf_event_query_prog_array(event, (void __user *)arg);
+		return perf_event_query_prog_array(event, (void __user *)arg);
 	default:
 		return -ENOTTY;
 	}
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index e009b7ecf473..c5dd60cc0751 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -856,7 +856,7 @@ unlock:
 	mutex_unlock(&bpf_event_mutex);
 }
 
-int bpf_event_query_prog_array(struct perf_event *event, void __user *info)
+int perf_event_query_prog_array(struct perf_event *event, void __user *info)
 {
 	struct perf_event_query_bpf __user *uquery = info;
 	struct perf_event_query_bpf query = {};