#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_CALL ||
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, struct dump_data *dd,
bool opcodes, bool linum)
{
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;
printf("{\\\n");
start_idx = bb->head - func->start;
dump_xlated_for_graph(dd, bb->head, bb->tail, start_idx,
opcodes, linum);
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 dump_data *dd,
bool opcodes, bool linum)
{
struct bb_node *bb;
list_for_each_entry(bb, &func->bbs, l) {
draw_bb_node(func, bb, dd, opcodes, linum);
}
}
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);
}
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 dump_data *dd, bool opcodes, bool linum)
{
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, dd, opcodes, linum);
func_output_edges(func);
printf("}\n");
}
printf("}\n");
}
void dump_xlated_cfg(struct dump_data *dd, void *buf, unsigned int len,
bool opcodes, bool linum)
{
struct bpf_insn *insn = buf;
struct cfg cfg;
memset(&cfg, 0, sizeof(cfg));
if (cfg_build(&cfg, insn, len))
return;
cfg_dump(&cfg, dd, opcodes, linum);
cfg_destroy(&cfg);
}
