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, 58 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/bpf_trace_helpers.h b/tools/testing/selftests/bpf/bpf_trace_helpers.h
new file mode 100644
index 000000000000..c76a214a53b0
--- /dev/null
+++ b/tools/testing/selftests/bpf/bpf_trace_helpers.h
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __BPF_TRACE_HELPERS_H
+#define __BPF_TRACE_HELPERS_H
+
+#include "bpf_helpers.h"
+
+#define __BPF_MAP_0(i, m, v, ...) v
+#define __BPF_MAP_1(i, m, v, t, a, ...) m(t, a, ctx[i])
+#define __BPF_MAP_2(i, m, v, t, a, ...) m(t, a, ctx[i]), __BPF_MAP_1(i+1, m, v, __VA_ARGS__)
+#define __BPF_MAP_3(i, m, v, t, a, ...) m(t, a, ctx[i]), __BPF_MAP_2(i+1, m, v, __VA_ARGS__)
+#define __BPF_MAP_4(i, m, v, t, a, ...) m(t, a, ctx[i]), __BPF_MAP_3(i+1, m, v, __VA_ARGS__)
+#define __BPF_MAP_5(i, m, v, t, a, ...) m(t, a, ctx[i]), __BPF_MAP_4(i+1, m, v, __VA_ARGS__)
+#define __BPF_MAP_6(i, m, v, t, a, ...) m(t, a, ctx[i]), __BPF_MAP_5(i+1, m, v, __VA_ARGS__)
+#define __BPF_MAP_7(i, m, v, t, a, ...) m(t, a, ctx[i]), __BPF_MAP_6(i+1, m, v, __VA_ARGS__)
+#define __BPF_MAP_8(i, m, v, t, a, ...) m(t, a, ctx[i]), __BPF_MAP_7(i+1, m, v, __VA_ARGS__)
+#define __BPF_MAP_9(i, m, v, t, a, ...) m(t, a, ctx[i]), __BPF_MAP_8(i+1, m, v, __VA_ARGS__)
+#define __BPF_MAP_10(i, m, v, t, a, ...) m(t, a, ctx[i]), __BPF_MAP_9(i+1, m, v, __VA_ARGS__)
+#define __BPF_MAP_11(i, m, v, t, a, ...) m(t, a, ctx[i]), __BPF_MAP_10(i+1, m, v, __VA_ARGS__)
+#define __BPF_MAP_12(i, m, v, t, a, ...) m(t, a, ctx[i]), __BPF_MAP_11(i+1, m, v, __VA_ARGS__)
+#define __BPF_MAP(n, ...) __BPF_MAP_##n(0, __VA_ARGS__)
+
+/* BPF sizeof(void *) is always 8, so no need to cast to long first
+ * for ptr to avoid compiler warning.
+ */
+#define __BPF_CAST(t, a, ctx) (t) ctx
+#define __BPF_V void
+#define __BPF_N
+
+#define __BPF_DECL_ARGS(t, a, ctx) t a
+
+#define BPF_TRACE_x(x, sec_name, fname, ret_type, ...)			\
+static __always_inline ret_type						\
+____##fname(__BPF_MAP(x, __BPF_DECL_ARGS, __BPF_V, __VA_ARGS__));	\
+									\
+SEC(sec_name)								\
+ret_type fname(__u64 *ctx)						\
+{									\
+	return ____##fname(__BPF_MAP(x, __BPF_CAST, __BPF_N, __VA_ARGS__));\
+}									\
+									\
+static __always_inline							\
+ret_type ____##fname(__BPF_MAP(x, __BPF_DECL_ARGS, __BPF_V, __VA_ARGS__))
+
+#define BPF_TRACE_0(sec, fname, ...)  BPF_TRACE_x(0, sec, fname, int, __VA_ARGS__)
+#define BPF_TRACE_1(sec, fname, ...)  BPF_TRACE_x(1, sec, fname, int, __VA_ARGS__)
+#define BPF_TRACE_2(sec, fname, ...)  BPF_TRACE_x(2, sec, fname, int, __VA_ARGS__)
+#define BPF_TRACE_3(sec, fname, ...)  BPF_TRACE_x(3, sec, fname, int, __VA_ARGS__)
+#define BPF_TRACE_4(sec, fname, ...)  BPF_TRACE_x(4, sec, fname, int, __VA_ARGS__)
+#define BPF_TRACE_5(sec, fname, ...)  BPF_TRACE_x(5, sec, fname, int, __VA_ARGS__)
+#define BPF_TRACE_6(sec, fname, ...)  BPF_TRACE_x(6, sec, fname, int, __VA_ARGS__)
+#define BPF_TRACE_7(sec, fname, ...)  BPF_TRACE_x(7, sec, fname, int, __VA_ARGS__)
+#define BPF_TRACE_8(sec, fname, ...)  BPF_TRACE_x(8, sec, fname, int, __VA_ARGS__)
+#define BPF_TRACE_9(sec, fname, ...)  BPF_TRACE_x(9, sec, fname, int, __VA_ARGS__)
+#define BPF_TRACE_10(sec, fname, ...)  BPF_TRACE_x(10, sec, fname, int, __VA_ARGS__)
+#define BPF_TRACE_11(sec, fname, ...)  BPF_TRACE_x(11, sec, fname, int, __VA_ARGS__)
+#define BPF_TRACE_12(sec, fname, ...)  BPF_TRACE_x(12, sec, fname, int, __VA_ARGS__)
+
+#endif