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Commit 6e9eb7e3 authored by Jiong Wang's avatar Jiong Wang Committed by Alexei Starovoitov
Browse files

tools: bpftool: add out edges for each basic-block 



This patch adds out edges for each basic-block. We will need these out
edges to finish the .dot graph drawing.

Signed-off-by: default avatarJiong Wang <jiong.wang@netronome.com>
Acked-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 0824611f

tools/bpf/bpftool/cfg.c

+160 −2
Original line number Diff line number Diff line
@@ -58,15 +58,32 @@ struct func_node { 


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)	\
@@ -120,11 +137,30 @@ static struct bb_node *func_append_bb(struct func_node *func, 
		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)

{
@@ -190,8 +226,8 @@ static bool func_partition_bb_head(struct func_node *func) 


static void func_partition_bb_tail(struct func_node *func)

{

	unsigned int bb_idx = NUM_FIXED_BLOCKS;

	struct bb_node *bb, *last;

	unsigned int bb_idx = 0;



	last = func_last_bb(func);

	last->tail = func->end;
@@ -205,6 +241,23 @@ static void func_partition_bb_tail(struct func_node *func) 
	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))
@@ -215,6 +268,96 @@ static bool func_partition_bb(struct func_node *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);
@@ -226,7 +369,10 @@ static bool cfg_build(struct cfg *cfg, struct bpf_insn *insn, unsigned int len) 
		return true;



	list_for_each_entry(func, &cfg->funcs, l) {

		if (func_partition_bb(func))

		if (func_partition_bb(func) || func_add_special_bb(func))

			return true;



		if (func_add_bb_edges(func))

			return true;

	}
@@ -241,6 +387,18 @@ static void cfg_destroy(struct cfg *cfg) 
		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);

		}