perf tests: Add LLVM test for eBPF on-the-fly compiling

Previous patches introduce llvm__compile_bpf() to compile source file to
eBPF object. This patch adds testcase to test it. It also tests libbpf
by opening generated object after applying next patch which introduces
HAVE_LIBBPF_SUPPORT option.

Since llvm__compile_bpf() prints long messages which users who don't
explicitly test llvm doesn't care, this patch set verbose to -1 to
suppress all debug, warning and error message, and hint user use 'perf
test -v' to see the full output.

For the same reason, if clang is not found in PATH and there's no [llvm]
section in .perfconfig, skip this test.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/n/1436445342-1402-17-git-send-email-wangnan0@huawei.com
[ Add tools/lib/bpf/ to tools/perf/MANIFEST, so that the tarball targets build ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/MANIFEST

@@ -18,6 +18,7 @@ tools/arch/x86/include/asm/atomic.h
 tools/arch/x86/include/asm/rmwcc.h
 tools/lib/traceevent
 tools/lib/api
+tools/lib/bpf
 tools/lib/hweight.c
 tools/lib/rbtree.c
 tools/lib/symbol/kallsyms.c

tools/perf/tests/Build

@@ -32,6 +32,7 @@ perf-y += sample-parsing.o
 perf-y += parse-no-sample-id-all.o
 perf-y += kmod-path.o
 perf-y += thread-map.o
+perf-y += llvm.o
 
 perf-$(CONFIG_X86) += perf-time-to-tsc.o
 

tools/perf/tests/builtin-test.c

@@ -174,6 +174,10 @@ static struct test {
 		.desc = "Test thread map",
 		.func = test__thread_map,
 	},
+	{
+		.desc = "Test LLVM searching and compiling",
+		.func = test__llvm,
+	},
 	{
 		.func = NULL,
 	},

tools/perf/tests/llvm.c

+#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
+
+int test__llvm(void)
+{
+	char *tmpl_new, *clang_opt_new;
+	void *obj_buf;
+	size_t obj_buf_sz;
+	int err, old_verbose;
+
+	perf_config(perf_config_cb, NULL);
+
+	/*
+	 * Skip this test if user's .perfconfig doesn't set [llvm] section
+	 * and clang is not found in $PATH, and this is not perf test -v
+	 */
+	if (verbose == 0 && !llvm_param.user_set_param && llvm__search_clang()) {
+		fprintf(stderr, " (no clang, try 'perf test -v LLVM')");
+		return TEST_SKIP;
+	}
+
+	old_verbose = verbose;
+	/*
+	 * llvm is verbosity when error. Suppress all error output if
+	 * not 'perf test -v'.
+	 */
+	if (verbose == 0)
+		verbose = -1;
+
+	if (!llvm_param.clang_bpf_cmd_template)
+		return -1;
+
+	if (!llvm_param.clang_opt)
+		llvm_param.clang_opt = strdup("");
+
+	err = asprintf(&tmpl_new, "echo '%s' | %s", test_bpf_prog,
+		       llvm_param.clang_bpf_cmd_template);
+	if (err < 0)
+		return -1;
+	err = asprintf(&clang_opt_new, "-xc %s", llvm_param.clang_opt);
+	if (err < 0)
+		return -1;
+
+	llvm_param.clang_bpf_cmd_template = tmpl_new;
+	llvm_param.clang_opt = clang_opt_new;
+	err = llvm__compile_bpf("-", &obj_buf, &obj_buf_sz);
+
+	verbose = old_verbose;
+	if (err) {
+		if (!verbose)
+			fprintf(stderr, " (use -v to see error message)");
+		return -1;
+	}
+
+	err = test__bpf_parsing(obj_buf, obj_buf_sz);
+	free(obj_buf);
+	return err;
+}

tools/perf/tests/tests.h

@@ -62,6 +62,7 @@ int test__fdarray__filter(void);
 int test__fdarray__add(void);
 int test__kmod_path__parse(void);
 int test__thread_map(void);
+int test__llvm(void);
 
 #if defined(__x86_64__) || defined(__i386__) || defined(__arm__) || defined(__aarch64__)
 #ifdef HAVE_DWARF_UNWIND_SUPPORT

tools/perf/util/llvm-utils.c

@@ -22,6 +22,7 @@ struct llvm_param llvm_param = {
 	.clang_opt = NULL,
 	.kbuild_dir = NULL,
 	.kbuild_opts = NULL,
+	.user_set_param = false,
 };
 
 int perf_llvm_config(const char *var, const char *value)
@@ -42,6 +43,7 @@ int perf_llvm_config(const char *var, const char *value)
 		llvm_param.kbuild_opts = strdup(value);
 	else
 		return -1;
+	llvm_param.user_set_param = true;
 	return 0;
 }
 
@@ -397,3 +399,10 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
 		*p_obj_buf_sz = 0;
 	return err;
 }
+
+int llvm__search_clang(void)
+{
+	char clang_path[PATH_MAX];
+
+	return search_program(llvm_param.clang_path, "clang", clang_path);
+}

tools/perf/util/llvm-utils.h

@@ -29,6 +29,13 @@ struct llvm_param {
 	 * compiling. Should not be used for dynamic compiling.
 	 */
 	const char *kbuild_opts;
+	/*
+	 * Default is false. If one of the above fields is set by user
+	 * explicitly then user_set_llvm is set to true. This is used
+	 * for perf test. If user doesn't set anything in .perfconfig
+	 * and clang is not found, don't trigger llvm test.
+	 */
+	bool user_set_param;
 };
 
 extern struct llvm_param llvm_param;
@@ -36,4 +43,7 @@ extern int perf_llvm_config(const char *var, const char *value);
 
 extern int llvm__compile_bpf(const char *path, void **p_obj_buf,
 			     size_t *p_obj_buf_sz);
+
+/* This function is for test__llvm() use only */
+extern int llvm__search_clang(void);
 #endif