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Commit f4e2298e authored by Yonghong Song's avatar Yonghong Song Committed by Daniel Borkmann
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bpf/tracing: fix kernel/events/core.c compilation error 



Commit f371b304 ("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: f371b304 ("bpf/tracing: allow user space to query prog array on the same tp")
Reported-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 553a8f2f

include/linux/bpf.h

+0 −1
Original line number Diff line number Diff line
@@ -254,7 +254,6 @@ typedef unsigned long (*bpf_ctx_copy_t)(void *dst, const void *src, 


u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,

		     void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy);

int bpf_event_query_prog_array(struct perf_event *event, void __user *info);



int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,

			  union bpf_attr __user *uattr);

include/linux/trace_events.h

+6 −0
Original line number Diff line number Diff line
@@ -467,6 +467,7 @@ trace_trigger_soft_disabled(struct trace_event_file *file) 
unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx);

int perf_event_attach_bpf_prog(struct perf_event *event, struct bpf_prog *prog);

void perf_event_detach_bpf_prog(struct perf_event *event);

int perf_event_query_prog_array(struct perf_event *event, void __user *info);

#else

static inline unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx)

{
@@ -481,6 +482,11 @@ perf_event_attach_bpf_prog(struct perf_event *event, struct bpf_prog *prog) 


static inline void perf_event_detach_bpf_prog(struct perf_event *event) { }



static inline int

perf_event_query_prog_array(struct perf_event *event, void __user *info)

{

	return -EOPNOTSUPP;

}

#endif



enum {

kernel/events/core.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

	}

kernel/trace/bpf_trace.c

+1 −1
Original line number Diff line number Diff line
@@ -856,7 +856,7 @@ void perf_event_detach_bpf_prog(struct perf_event *event) 
	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 = {};