1 files changed, 485 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/cfg.c b/tools/bpf/bpftool/cfg.c
new file mode 100644
index 000000000..1951219a9
--- /dev/null
+++ b/tools/bpf/bpftool/cfg.c
@@ -0,0 +1,485 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/* Copyright (C) 2018 Netronome Systems, Inc. */
+
+#include <linux/list.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "cfg.h"
+#include "main.h"
+#include "xlated_dumper.h"
+
+struct cfg {
+	struct list_head funcs;
+	int func_num;
+};
+
+struct func_node {
+	struct list_head l;
+	struct list_head bbs;
+	struct bpf_insn *start;
+	struct bpf_insn *end;
+	int idx;
+	int bb_num;
+};
+
+struct bb_node {
+	struct list_head l;
+	struct list_head e_prevs;
+	struct list_head e_succs;
+	struct bpf_insn *head;
+	struct bpf_insn *tail;
+	int idx;
+};
+
+#define EDGE_FLAG_EMPTY		0x0
+#define EDGE_FLAG_FALLTHROUGH	0x1
+#define EDGE_FLAG_JUMP		0x2
+struct edge_node {
+	struct list_head l;
+	struct bb_node *src;
+	struct bb_node *dst;
+	int flags;
+};
+
+#define ENTRY_BLOCK_INDEX	0
+#define EXIT_BLOCK_INDEX	1
+#define NUM_FIXED_BLOCKS	2
+#define func_prev(func)		list_prev_entry(func, l)
+#define func_next(func)		list_next_entry(func, l)
+#define bb_prev(bb)		list_prev_entry(bb, l)
+#define bb_next(bb)		list_next_entry(bb, l)
+#define entry_bb(func)		func_first_bb(func)
+#define exit_bb(func)		func_last_bb(func)
+#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)
+#define func_first_bb(func)	\
+	list_first_entry(&func->bbs, struct bb_node, l)
+#define func_last_bb(func)	\
+	list_last_entry(&func->bbs, struct bb_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 struct bb_node *func_append_bb(struct func_node *func,
+				      struct bpf_insn *insn)
+{
+	struct bb_node *new_bb, *bb;
+
+	list_for_each_entry(bb, &func->bbs, l) {
+		if (bb->head == insn)
+			return bb;
+		else if (bb->head > insn)
+			break;
+	}
+
+	bb = bb_prev(bb);
+	new_bb = calloc(1, sizeof(*new_bb));
+	if (!new_bb) {
+		p_err("OOM when allocating BB node");
+		return NULL;
+	}
+	new_bb->head = insn;
+	INIT_LIST_HEAD(&new_bb->e_prevs);
+	INIT_LIST_HEAD(&new_bb->e_succs);
+	list_add(&new_bb->l, &bb->l);
+
+	return new_bb;
+}
+
+static struct bb_node *func_insert_dummy_bb(struct list_head *after)
+{
+	struct bb_node *bb;
+
+	bb = calloc(1, sizeof(*bb));
+	if (!bb) {
+		p_err("OOM when allocating BB node");
+		return NULL;
+	}
+
+	INIT_LIST_HEAD(&bb->e_prevs);
+	INIT_LIST_HEAD(&bb->e_succs);
+	list_add(&bb->l, after);
+
+	return bb;
+}
+
+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 is_jmp_insn(__u8 code)
+{
+	return BPF_CLASS(code) == BPF_JMP || BPF_CLASS(code) == BPF_JMP32;
+}
+
+static bool func_partition_bb_head(struct func_node *func)
+{
+	struct bpf_insn *cur, *end;
+	struct bb_node *bb;
+
+	cur = func->start;
+	end = func->end;
+	INIT_LIST_HEAD(&func->bbs);
+	bb = func_append_bb(func, cur);
+	if (!bb)
+		return true;
+
+	for (; cur <= end; cur++) {
+		if (is_jmp_insn(cur->code)) {
+			__u8 opcode = BPF_OP(cur->code);
+
+			if (opcode == BPF_EXIT || opcode == BPF_CALL)
+				continue;
+
+			bb = func_append_bb(func, cur + cur->off + 1);
+			if (!bb)
+				return true;
+
+			if (opcode != BPF_JA) {
+				bb = func_append_bb(func, cur + 1);
+				if (!bb)
+					return true;
+			}
+		}
+	}
+
+	return false;
+}
+
+static void func_partition_bb_tail(struct func_node *func)
+{
+	unsigned int bb_idx = NUM_FIXED_BLOCKS;
+	struct bb_node *bb, *last;
+
+	last = func_last_bb(func);
+	last->tail = func->end;
+	bb = func_first_bb(func);
+	list_for_each_entry_from(bb, &last->l, l) {
+		bb->tail = bb_next(bb)->head - 1;
+		bb->idx = bb_idx++;
+	}
+
+	last->idx = bb_idx++;
+	func->bb_num = bb_idx;
+}
+
+static bool func_add_special_bb(struct func_node *func)
+{
+	struct bb_node *bb;
+
+	bb = func_insert_dummy_bb(&func->bbs);
+	if (!bb)
+		return true;
+	bb->idx = ENTRY_BLOCK_INDEX;
+
+	bb = func_insert_dummy_bb(&func_last_bb(func)->l);
+	if (!bb)
+		return true;
+	bb->idx = EXIT_BLOCK_INDEX;
+
+	return false;
+}
+
+static bool func_partition_bb(struct func_node *func)
+{
+	if (func_partition_bb_head(func))
+		return true;
+
+	func_partition_bb_tail(func);
+
+	return false;
+}
+
+static struct bb_node *func_search_bb_with_head(struct func_node *func,
+						struct bpf_insn *insn)
+{
+	struct bb_node *bb;
+
+	list_for_each_entry(bb, &func->bbs, l) {
+		if (bb->head == insn)
+			return bb;
+	}
+
+	return NULL;
+}
+
+static struct edge_node *new_edge(struct bb_node *src, struct bb_node *dst,
+				  int flags)
+{
+	struct edge_node *e;
+
+	e = calloc(1, sizeof(*e));
+	if (!e) {
+		p_err("OOM when allocating edge node");
+		return NULL;
+	}
+
+	if (src)
+		e->src = src;
+	if (dst)
+		e->dst = dst;
+
+	e->flags |= flags;
+
+	return e;
+}
+
+static bool func_add_bb_edges(struct func_node *func)
+{
+	struct bpf_insn *insn;
+	struct edge_node *e;
+	struct bb_node *bb;
+
+	bb = entry_bb(func);
+	e = new_edge(bb, bb_next(bb), EDGE_FLAG_FALLTHROUGH);
+	if (!e)
+		return true;
+	list_add_tail(&e->l, &bb->e_succs);
+
+	bb = exit_bb(func);
+	e = new_edge(bb_prev(bb), bb, EDGE_FLAG_FALLTHROUGH);
+	if (!e)
+		return true;
+	list_add_tail(&e->l, &bb->e_prevs);
+
+	bb = entry_bb(func);
+	bb = bb_next(bb);
+	list_for_each_entry_from(bb, &exit_bb(func)->l, l) {
+		e = new_edge(bb, NULL, EDGE_FLAG_EMPTY);
+		if (!e)
+			return true;
+		e->src = bb;
+
+		insn = bb->tail;
+		if (!is_jmp_insn(insn->code) ||
+		    BPF_OP(insn->code) == BPF_EXIT) {
+			e->dst = bb_next(bb);
+			e->flags |= EDGE_FLAG_FALLTHROUGH;
+			list_add_tail(&e->l, &bb->e_succs);
+			continue;
+		} else if (BPF_OP(insn->code) == BPF_JA) {
+			e->dst = func_search_bb_with_head(func,
+							  insn + insn->off + 1);
+			e->flags |= EDGE_FLAG_JUMP;
+			list_add_tail(&e->l, &bb->e_succs);
+			continue;
+		}
+
+		e->dst = bb_next(bb);
+		e->flags |= EDGE_FLAG_FALLTHROUGH;
+		list_add_tail(&e->l, &bb->e_succs);
+
+		e = new_edge(bb, NULL, EDGE_FLAG_JUMP);
+		if (!e)
+			return true;
+		e->src = bb;
+		e->dst = func_search_bb_with_head(func, insn + insn->off + 1);
+		list_add_tail(&e->l, &bb->e_succs);
+	}
+
+	return false;
+}
+
+static bool cfg_build(struct cfg *cfg, struct bpf_insn *insn, unsigned int len)
+{
+	int cnt = len / sizeof(*insn);
+	struct func_node *func;
+
+	INIT_LIST_HEAD(&cfg->funcs);
+
+	if (cfg_partition_funcs(cfg, insn, insn + cnt))
+		return true;
+
+	list_for_each_entry(func, &cfg->funcs, l) {
+		if (func_partition_bb(func) || func_add_special_bb(func))
+			return true;
+
+		if (func_add_bb_edges(func))
+			return true;
+	}
+
+	return false;
+}
+
+static void cfg_destroy(struct cfg *cfg)
+{
+	struct func_node *func, *func2;
+
+	list_for_each_entry_safe(func, func2, &cfg->funcs, l) {
+		struct bb_node *bb, *bb2;
+
+		list_for_each_entry_safe(bb, bb2, &func->bbs, l) {
+			struct edge_node *e, *e2;
+
+			list_for_each_entry_safe(e, e2, &bb->e_prevs, l) {
+				list_del(&e->l);
+				free(e);
+			}
+
+			list_for_each_entry_safe(e, e2, &bb->e_succs, l) {
+				list_del(&e->l);
+				free(e);
+			}
+
+			list_del(&bb->l);
+			free(bb);
+		}
+
+		list_del(&func->l);
+		free(func);
+	}
+}
+
+static void draw_bb_node(struct func_node *func, struct bb_node *bb)
+{
+	const char *shape;
+
+	if (bb->idx == ENTRY_BLOCK_INDEX || bb->idx == EXIT_BLOCK_INDEX)
+		shape = "Mdiamond";
+	else
+		shape = "record";
+
+	printf("\tfn_%d_bb_%d [shape=%s,style=filled,label=\"",
+	       func->idx, bb->idx, shape);
+
+	if (bb->idx == ENTRY_BLOCK_INDEX) {
+		printf("ENTRY");
+	} else if (bb->idx == EXIT_BLOCK_INDEX) {
+		printf("EXIT");
+	} else {
+		unsigned int start_idx;
+		struct dump_data dd = {};
+
+		printf("{");
+		kernel_syms_load(&dd);
+		start_idx = bb->head - func->start;
+		dump_xlated_for_graph(&dd, bb->head, bb->tail, start_idx);
+		kernel_syms_destroy(&dd);
+		printf("}");
+	}
+
+	printf("\"];\n\n");
+}
+
+static void draw_bb_succ_edges(struct func_node *func, struct bb_node *bb)
+{
+	const char *style = "\"solid,bold\"";
+	const char *color = "black";
+	int func_idx = func->idx;
+	struct edge_node *e;
+	int weight = 10;
+
+	if (list_empty(&bb->e_succs))
+		return;
+
+	list_for_each_entry(e, &bb->e_succs, l) {
+		printf("\tfn_%d_bb_%d:s -> fn_%d_bb_%d:n [style=%s, color=%s, weight=%d, constraint=true",
+		       func_idx, e->src->idx, func_idx, e->dst->idx,
+		       style, color, weight);
+		printf("];\n");
+	}
+}
+
+static void func_output_bb_def(struct func_node *func)
+{
+	struct bb_node *bb;
+
+	list_for_each_entry(bb, &func->bbs, l) {
+		draw_bb_node(func, bb);
+	}
+}
+
+static void func_output_edges(struct func_node *func)
+{
+	int func_idx = func->idx;
+	struct bb_node *bb;
+
+	list_for_each_entry(bb, &func->bbs, l) {
+		draw_bb_succ_edges(func, bb);
+	}
+
+	/* Add an invisible edge from ENTRY to EXIT, this is to
+	 * improve the graph layout.
+	 */
+	printf("\tfn_%d_bb_%d:s -> fn_%d_bb_%d:n [style=\"invis\", constraint=true];\n",
+	       func_idx, ENTRY_BLOCK_INDEX, func_idx, EXIT_BLOCK_INDEX);
+}
+
+static void cfg_dump(struct cfg *cfg)
+{
+	struct func_node *func;
+
+	printf("digraph \"DOT graph for eBPF program\" {\n");
+	list_for_each_entry(func, &cfg->funcs, l) {
+		printf("subgraph \"cluster_%d\" {\n\tstyle=\"dashed\";\n\tcolor=\"black\";\n\tlabel=\"func_%d ()\";\n",
+		       func->idx, func->idx);
+		func_output_bb_def(func);
+		func_output_edges(func);
+		printf("}\n");
+	}
+	printf("}\n");
+}
+
+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_dump(&cfg);
+
+	cfg_destroy(&cfg);
+}