[bpf-next,3/8] tools: bpftool: detect sub-programs from the eBPF sequence

diff --git a/tools/bpf/bpftool/cfg.c b/tools/bpf/bpftool/cfg.c
new file mode 100644
index 000000000000..42a0d4c4271c
--- /dev/null
+++ b/tools/bpf/bpftool/cfg.c
@@ -0,0 +1,143 @@ 
+/*
+ * Copyright (C) 2018 Netronome Systems, Inc.
+ *
+ * This software is dual licensed under the GNU General License Version 2,
+ * June 1991 as shown in the file COPYING in the top-level directory of this
+ * source tree or the BSD 2-Clause License provided below.  You have the
+ * option to license this software under the complete terms of either license.
+ *
+ * The BSD 2-Clause License:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      1. Redistributions of source code must retain the above
+ *         copyright notice, this list of conditions and the following
+ *         disclaimer.
+ *
+ *      2. Redistributions in binary form must reproduce the above
+ *         copyright notice, this list of conditions and the following
+ *         disclaimer in the documentation and/or other materials
+ *         provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <linux/list.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "cfg.h"
+#include "main.h"
+
+struct cfg {
+	struct list_head funcs;
+	int func_num;
+};
+
+struct func_node {
+	struct list_head l;
+	struct bpf_insn *start;
+	struct bpf_insn *end;
+	int idx;
+};
+
+#define func_prev(func)		list_prev_entry(func, l)
+#define func_next(func)		list_next_entry(func, l)
+#define cfg_first_func(cfg)	\
+	list_first_entry(&cfg->funcs, struct func_node, l)
+#define cfg_last_func(cfg)	\
+	list_last_entry(&cfg->funcs, struct func_node, l)
+
+static struct func_node *cfg_append_func(struct cfg *cfg, struct bpf_insn *insn)
+{
+	struct func_node *new_func, *func;
+
+	list_for_each_entry(func, &cfg->funcs, l) {
+		if (func->start == insn)
+			return func;
+		else if (func->start > insn)
+			break;
+	}
+
+	func = func_prev(func);
+	new_func = calloc(1, sizeof(*new_func));
+	if (!new_func) {
+		p_err("OOM when allocating FUNC node");
+		return NULL;
+	}
+	new_func->start = insn;
+	new_func->idx = cfg->func_num;
+	list_add(&new_func->l, &func->l);
+	cfg->func_num++;
+
+	return new_func;
+}
+
+static bool cfg_partition_funcs(struct cfg *cfg, struct bpf_insn *cur,
+				struct bpf_insn *end)
+{
+	struct func_node *func, *last_func;
+
+	func = cfg_append_func(cfg, cur);
+	if (!func)
+		return true;
+
+	for (; cur < end; cur++) {
+		if (cur->code != (BPF_JMP | BPF_CALL))
+			continue;
+		if (cur->src_reg != BPF_PSEUDO_CALL)
+			continue;
+		func = cfg_append_func(cfg, cur + cur->off + 1);
+		if (!func)
+			return true;
+	}
+
+	last_func = cfg_last_func(cfg);
+	last_func->end = end - 1;
+	func = cfg_first_func(cfg);
+	list_for_each_entry_from(func, &last_func->l, l) {
+		func->end = func_next(func)->start - 1;
+	}
+
+	return false;
+}
+
+static bool cfg_build(struct cfg *cfg, struct bpf_insn *insn, unsigned int len)
+{
+	int cnt = len / sizeof(*insn);
+
+	INIT_LIST_HEAD(&cfg->funcs);
+
+	return cfg_partition_funcs(cfg, insn, insn + cnt);
+}
+
+static void cfg_destroy(struct cfg *cfg)
+{
+	struct func_node *func, *func2;
+
+	list_for_each_entry_safe(func, func2, &cfg->funcs, l) {
+		list_del(&func->l);
+		free(func);
+	}
+}
+
+void dump_xlated_cfg(void *buf, unsigned int len)
+{
+	struct bpf_insn *insn = buf;
+	struct cfg cfg;
+
+	memset(&cfg, 0, sizeof(cfg));
+	if (cfg_build(&cfg, insn, len))
+		return;
+
+	cfg_destroy(&cfg);
+}
diff --git a/tools/bpf/bpftool/cfg.h b/tools/bpf/bpftool/cfg.h
new file mode 100644
index 000000000000..74160f429cbc
--- /dev/null
+++ b/tools/bpf/bpftool/cfg.h
@@ -0,0 +1,39 @@ 
+/*
+ * Copyright (C) 2018 Netronome Systems, Inc.
+ *
+ * This software is dual licensed under the GNU General License Version 2,
+ * June 1991 as shown in the file COPYING in the top-level directory of this
+ * source tree or the BSD 2-Clause License provided below.  You have the
+ * option to license this software under the complete terms of either license.
+ *
+ * The BSD 2-Clause License:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      1. Redistributions of source code must retain the above
+ *         copyright notice, this list of conditions and the following
+ *         disclaimer.
+ *
+ *      2. Redistributions in binary form must reproduce the above
+ *         copyright notice, this list of conditions and the following
+ *         disclaimer in the documentation and/or other materials
+ *         provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef __BPF_TOOL_CFG_H
+#define __BPF_TOOL_CFG_H
+
+void dump_xlated_cfg(void *buf, unsigned int len);
+
+#endif /* __BPF_TOOL_CFG_H */