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-rw-r--r--tools/bpf/bpftool/cfg.c514
1 files changed, 514 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/cfg.c b/tools/bpf/bpftool/cfg.c
new file mode 100644
index 000000000000..f30b3a4a840b
--- /dev/null
+++ b/tools/bpf/bpftool/cfg.c
@@ -0,0 +1,514 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/*
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#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 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 (BPF_CLASS(cur->code) == BPF_JMP) {
+ 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 (BPF_CLASS(insn->code) != BPF_JMP ||
+ 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);
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.