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

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Commit f371b304f1 ("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: f371b304f1 ("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>
This commit is contained in:
Yonghong Song 2017-12-13 10:35:37 -08:00 committed by Daniel Borkmann
parent 553a8f2f42
commit f4e2298e63
4 changed files with 8 additions and 3 deletions
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1
include/linux/bpf.h
View File

@ -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);

6
include/linux/trace_events.h
View File

@ -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 {

2
kernel/events/core.c
View File

@ -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;
}

2
kernel/trace/bpf_trace.c
View File

@ -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 = {};