perf llvm: Extract helpers in llvm-utils.c

The following commits will use builtin clang to compile BPF scripts.

llvm__get_kbuild_opts() and llvm__get_nr_cpus() are extracted to help
building '-DKERNEL_VERSION_CODE' and '-D__NR_CPUS__' macros.

Doing object dumping in bpf loader, so further builtin clang compiling
needn't consider it.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Stringer <joe@ovn.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161126070354.141764-7-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/bpf-loader.c

@@ -90,6 +90,10 @@ struct bpf_object *bpf__prepare_load(const char *filename, bool source)
 		if (err)
 			return ERR_PTR(-BPF_LOADER_ERRNO__COMPILE);
 		obj = bpf_object__open_buffer(obj_buf, obj_buf_sz, filename);
+
+		if (!IS_ERR(obj) && llvm_param.dump_obj)
+			llvm__dump_obj(filename, obj_buf, obj_buf_sz);
+
 		free(obj_buf);
 	} else
 		obj = bpf_object__open(filename);

tools/perf/util/llvm-utils.c

@@ -7,6 +7,7 @@
 #include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <linux/err.h>
 #include "debug.h"
 #include "llvm-utils.h"
 #include "config.h"
@@ -282,9 +283,10 @@ static const char *kinc_fetch_script =
 "rm -rf $TMPDIR\n"
 "exit $RET\n";
 
-static inline void
-get_kbuild_opts(char **kbuild_dir, char **kbuild_include_opts)
+void llvm__get_kbuild_opts(char **kbuild_dir, char **kbuild_include_opts)
 {
+	static char *saved_kbuild_dir;
+	static char *saved_kbuild_include_opts;
 	int err;
 
 	if (!kbuild_dir || !kbuild_include_opts)
@@ -293,10 +295,28 @@ get_kbuild_opts(char **kbuild_dir, char **kbuild_include_opts)
 	*kbuild_dir = NULL;
 	*kbuild_include_opts = NULL;
 
+	if (saved_kbuild_dir && saved_kbuild_include_opts &&
+	    !IS_ERR(saved_kbuild_dir) && !IS_ERR(saved_kbuild_include_opts)) {
+		*kbuild_dir = strdup(saved_kbuild_dir);
+		*kbuild_include_opts = strdup(saved_kbuild_include_opts);
+
+		if (*kbuild_dir && *kbuild_include_opts)
+			return;
+
+		zfree(kbuild_dir);
+		zfree(kbuild_include_opts);
+		/*
+		 * Don't fall through: it may breaks saved_kbuild_dir and
+		 * saved_kbuild_include_opts if detect them again when
+		 * memory is low.
+		 */
+		return;
+	}
+
 	if (llvm_param.kbuild_dir && !llvm_param.kbuild_dir[0]) {
 		pr_debug("[llvm.kbuild-dir] is set to \"\" deliberately.\n");
 		pr_debug("Skip kbuild options detection.\n");
-		return;
+		goto errout;
 	}
 
 	err = detect_kbuild_dir(kbuild_dir);
@@ -306,7 +326,7 @@ get_kbuild_opts(char **kbuild_dir, char **kbuild_include_opts)
 "Hint:\tSet correct kbuild directory using 'kbuild-dir' option in [llvm]\n"
 "     \tsection of ~/.perfconfig or set it to \"\" to suppress kbuild\n"
 "     \tdetection.\n\n");
-		return;
+		goto errout;
 	}
 
 	pr_debug("Kernel build dir is set to %s\n", *kbuild_dir);
@@ -325,14 +345,43 @@ get_kbuild_opts(char **kbuild_dir, char **kbuild_include_opts)
 
 		free(*kbuild_dir);
 		*kbuild_dir = NULL;
-		return;
+		goto errout;
 	}
 
 	pr_debug("include option is set to %s\n", *kbuild_include_opts);
+
+	saved_kbuild_dir = strdup(*kbuild_dir);
+	saved_kbuild_include_opts = strdup(*kbuild_include_opts);
+
+	if (!saved_kbuild_dir || !saved_kbuild_include_opts) {
+		zfree(&saved_kbuild_dir);
+		zfree(&saved_kbuild_include_opts);
+	}
+	return;
+errout:
+	saved_kbuild_dir = ERR_PTR(-EINVAL);
+	saved_kbuild_include_opts = ERR_PTR(-EINVAL);
 }
 
-static void
-dump_obj(const char *path, void *obj_buf, size_t size)
+int llvm__get_nr_cpus(void)
+{
+	static int nr_cpus_avail = 0;
+	char serr[STRERR_BUFSIZE];
+
+	if (nr_cpus_avail > 0)
+		return nr_cpus_avail;
+
+	nr_cpus_avail = sysconf(_SC_NPROCESSORS_CONF);
+	if (nr_cpus_avail <= 0) {
+		pr_err(
+"WARNING:\tunable to get available CPUs in this system: %s\n"
+"        \tUse 128 instead.\n", str_error_r(errno, serr, sizeof(serr)));
+		nr_cpus_avail = 128;
+	}
+	return nr_cpus_avail;
+}
+
+void llvm__dump_obj(const char *path, void *obj_buf, size_t size)
 {
 	char *obj_path = strdup(path);
 	FILE *fp;
@@ -406,15 +455,9 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
 	 * This is an optional work. Even it fail we can continue our
 	 * work. Needn't to check error return.
 	 */
-	get_kbuild_opts(&kbuild_dir, &kbuild_include_opts);
+	llvm__get_kbuild_opts(&kbuild_dir, &kbuild_include_opts);
 
-	nr_cpus_avail = sysconf(_SC_NPROCESSORS_CONF);
-	if (nr_cpus_avail <= 0) {
-		pr_err(
-"WARNING:\tunable to get available CPUs in this system: %s\n"
-"        \tUse 128 instead.\n", str_error_r(errno, serr, sizeof(serr)));
-		nr_cpus_avail = 128;
-	}
+	nr_cpus_avail = llvm__get_nr_cpus();
 	snprintf(nr_cpus_avail_str, sizeof(nr_cpus_avail_str), "%d",
 		 nr_cpus_avail);
 
@@ -453,9 +496,6 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
 	free(kbuild_dir);
 	free(kbuild_include_opts);
 
-	if (llvm_param.dump_obj)
-		dump_obj(path, obj_buf, obj_buf_sz);
-
 	if (!p_obj_buf)
 		free(obj_buf);
 	else

tools/perf/util/llvm-utils.h

@@ -50,4 +50,10 @@ 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 */
 int llvm__search_clang(void);
+
+/* Following functions are reused by builtin clang support */
+void llvm__get_kbuild_opts(char **kbuild_dir, char **kbuild_include_opts);
+int llvm__get_nr_cpus(void);
+
+void llvm__dump_obj(const char *path, void *obj_buf, size_t size);
 #endif