[RFC PATCH v7 25/37] perf tests: Add LLVM test for eBPF on-the-fly compiling

[Wang Nan <wangnan0@huawei.com>]

Previous patch introduces llvm__compile_bpf() to compile source file to
eBPF object. This patch adds testcase to test it. It also test libbpf
by opening generated object.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
 tools/perf/tests/Build          |  1 +
 tools/perf/tests/builtin-test.c |  4 ++
 tools/perf/tests/llvm.c         | 85 +++++++++++++++++++++++++++++++++++++++++
 tools/perf/tests/tests.h        |  1 +
 4 files changed, 91 insertions(+)
 create mode 100644 tools/perf/tests/llvm.c

diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
index ee41e70..5d74604 100644
--- a/tools/perf/tests/Build
+++ b/tools/perf/tests/Build
@@ -31,6 +31,7 @@ perf-y += code-reading.o
 perf-y += sample-parsing.o
 perf-y += parse-no-sample-id-all.o
 perf-y += kmod-path.o
+perf-y += llvm.o
 
 perf-$(CONFIG_X86) += perf-time-to-tsc.o
 
diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index 87b9961..4d28fd9 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -171,6 +171,10 @@ static struct test {
 		.func = test__kmod_path__parse,
 	},
 	{
+		.desc = "Test LLVM searching and compiling",
+		.func = test__llvm,
+	},
+	{
 		.func = NULL,
 	},
 };
diff --git a/tools/perf/tests/llvm.c b/tools/perf/tests/llvm.c
new file mode 100644
index 0000000..272be1b
--- /dev/null
+++ b/tools/perf/tests/llvm.c
@@ -0,0 +1,85 @@
+#include <stdio.h>
+#include <bpf/libbpf.h>
+#include <util/llvm-utils.h>
+#include <util/cache.h>
+#include "tests.h"
+#include "debug.h"
+
+static int perf_config_cb(const char *var, const char *val,
+			  void *arg __maybe_unused)
+{
+	return perf_default_config(var, val, arg);
+}
+
+/*
+ * Randomly give it a "version" section since we don't really load it
+ * into kernel
+ */
+static const char test_bpf_prog[] =
+	"__attribute__((section(\"do_fork\"), used)) "
+	"int fork(void *ctx) {return 0;} "
+	"char _license[] __attribute__((section(\"license\"), used)) = \"GPL\";"
+	"int _version __attribute__((section(\"version\"), used)) = 0x40100;";
+
+#ifdef HAVE_LIBBPF_SUPPORT
+static int test__bpf_parsing(void *obj_buf, size_t obj_buf_sz)
+{
+	struct bpf_object *obj;
+
+	obj = bpf_object__open_buffer(obj_buf, obj_buf_sz);
+	if (!obj)
+		return -1;
+	bpf_object__close(obj);
+	return 0;
+}
+#else
+static int test__bpf_parsing(void *obj_buf __maybe_unused,
+			     size_t obj_buf_sz __maybe_unused)
+{
+	fprintf(stderr, " (skip bpf parsing)");
+	return 0;
+}
+#endif
+
+#define new_string(n, fmt, ...) \
+do { 					\
+	n##_sz = snprintf(NULL, 0, fmt, __VA_ARGS__);\
+	if (n##_sz == 0)			\
+		return -1;		\
+	n##_new = malloc(n##_sz + 1);	\
+	if (!n##_new)			\
+		return -1;		\
+	snprintf(n##_new, n##_sz + 1, fmt, __VA_ARGS__);\
+	n##_new[n##_sz] = '\0';		\
+} while(0)
+
+int test__llvm(void)
+{
+	char *tmpl_new, *clang_opt_new;
+	size_t tmpl_sz, clang_opt_sz;
+	void *obj_buf;
+	size_t obj_buf_sz;
+	int err;
+
+	perf_config(perf_config_cb, NULL);
+
+	if (!llvm_param.clang_bpf_cmd_template)
+		return -1;
+
+	if (!llvm_param.clang_opt)
+		llvm_param.clang_opt = strdup("");
+
+	new_string(tmpl, "echo '%s' | %s", test_bpf_prog,
+		   llvm_param.clang_bpf_cmd_template);
+	new_string(clang_opt, "-xc %s", llvm_param.clang_opt);
+
+	llvm_param.clang_bpf_cmd_template = tmpl_new;
+	llvm_param.clang_opt = clang_opt_new;
+	err = llvm__compile_bpf("-", &obj_buf, &obj_buf_sz);
+	if (err)
+		return -1;
+
+	err = test__bpf_parsing(obj_buf, obj_buf_sz);
+	free(obj_buf);
+	return err;
+}
diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
index 8e5038b..5b29796 100644
--- a/tools/perf/tests/tests.h
+++ b/tools/perf/tests/tests.h
@@ -61,6 +61,7 @@ int test__switch_tracking(void);
 int test__fdarray__filter(void);
 int test__fdarray__add(void);
 int test__kmod_path__parse(void);
+int test__llvm(void);
 
 #if defined(__x86_64__) || defined(__i386__) || defined(__arm__) || defined(__aarch64__)
 #ifdef HAVE_DWARF_UNWIND_SUPPORT
-- 
1.8.3.4