selftests/bpf: Add a test for a large global function

test results:
pyperf50 with always_inlined the same function five times: processed 46378 insns
pyperf50 with global function: processed 6102 insns

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200110064124.1760511-5-ast@kernel.org

tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c

@@ -48,6 +48,8 @@ void test_bpf_verif_scale(void)
 		{ "test_verif_scale2.o", BPF_PROG_TYPE_SCHED_CLS },
 		{ "test_verif_scale3.o", BPF_PROG_TYPE_SCHED_CLS },
 
+		{ "pyperf_global.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
+
 		/* full unroll by llvm */
 		{ "pyperf50.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
 		{ "pyperf100.o", BPF_PROG_TYPE_RAW_TRACEPOINT },

tools/testing/selftests/bpf/progs/pyperf.h

@@ -154,7 +154,12 @@ struct {
 	__uint(value_size, sizeof(long long) * 127);
 } stackmap SEC(".maps");
 
-static __always_inline int __on_event(struct pt_regs *ctx)
+#ifdef GLOBAL_FUNC
+__attribute__((noinline))
+#else
+static __always_inline
+#endif
+int __on_event(struct bpf_raw_tracepoint_args *ctx)
 {
 	uint64_t pid_tgid = bpf_get_current_pid_tgid();
 	pid_t pid = (pid_t)(pid_tgid >> 32);
@@ -254,7 +259,7 @@ static __always_inline int __on_event(struct pt_regs *ctx)
 }
 
 SEC("raw_tracepoint/kfree_skb")
-int on_event(struct pt_regs* ctx)
+int on_event(struct bpf_raw_tracepoint_args* ctx)
 {
 	int i, ret = 0;
 	ret |= __on_event(ctx);

tools/testing/selftests/bpf/progs/pyperf_global.c

@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#define STACK_MAX_LEN 50
+#define GLOBAL_FUNC
+#include "pyperf.h"