bpf: Introduce BPF_TRACE_x helper for the tracing tests

For BPF_PROG_TYPE_TRACING, the bpf_prog's ctx is an array of u64.
This patch borrows the idea from BPF_CALL_x in filter.h to
convert a u64 to the arg type of the traced function.

The new BPF_TRACE_x has an arg to specify the return type of a bpf_prog.
It will be used in the future TCP-ops bpf_prog that may return "void".

The new macros are defined in the new header file "bpf_trace_helpers.h".
It is under selftests/bpf/ for now.  It could be moved to libbpf later
after seeing more upcoming non-tracing use cases.

The tests are changed to use these new macros also.  Hence,
the k[s]u8/16/32/64 are no longer needed and they are removed
from the bpf_helpers.h.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191123202504.1502696-1-kafai@fb.com

1 files changed, 6 insertions, 10 deletions

diff --git a/tools/testing/selftests/bpf/progs/test_overhead.c b/tools/testing/selftests/bpf/progs/test_overhead.c
index ef06b2693f96..96c0124a04ba 100644
--- a/tools/testing/selftests/bpf/progs/test_overhead.c
+++ b/tools/testing/selftests/bpf/progs/test_overhead.c
@@ -3,6 +3,7 @@
 #include <linux/bpf.h>
 #include "bpf_helpers.h"
 #include "bpf_tracing.h"
+#include "bpf_trace_helpers.h"
 
 SEC("kprobe/__set_task_comm")
 int prog1(struct pt_regs *ctx)
@@ -22,20 +23,15 @@ int prog3(struct bpf_raw_tracepoint_args *ctx)
 	return 0;
 }
 
-struct __set_task_comm_args {
-	struct task_struct *tsk;
-	const char *buf;
-	ku8 exec;
-};
-
-SEC("fentry/__set_task_comm")
-int prog4(struct __set_task_comm_args *ctx)
+struct task_struct;
+BPF_TRACE_3("fentry/__set_task_comm", prog4,
+	    struct task_struct *, tsk, const char *, buf, __u8, exec)
 {
 	return 0;
 }
 
-SEC("fexit/__set_task_comm")
-int prog5(struct __set_task_comm_args *ctx)
+BPF_TRACE_3("fexit/__set_task_comm", prog5,
+	    struct task_struct *, tsk, const char *, buf, __u8, exec)
 {
 	return 0;
 }