netdev - [PATCH bpf-next 1/2] bpf: remove global variables

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Date:   Fri, 19 Apr 2019 07:44:54 -0700
From:   Alexei Starovoitov <ast@...nel.org>
To:     <davem@...emloft.net>
CC:     <daniel@...earbox.net>, <netdev@...r.kernel.org>,
        <bpf@...r.kernel.org>, <kernel-team@...com>
Subject: [PATCH bpf-next 1/2] bpf: remove global variables

Move three global variables protected by bpf_verifier_lock into
'struct bpf_verifier_env' to allow parallel verification.

Signed-off-by: Alexei Starovoitov <ast@...nel.org>
---
 include/linux/bpf_verifier.h |  5 +++++
 kernel/bpf/verifier.c        | 25 +++++++++++++------------
 2 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index b3ab61fe1932..1305ccbd8fe6 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -295,6 +295,11 @@ struct bpf_verifier_env {
 	const struct bpf_line_info *prev_linfo;
 	struct bpf_verifier_log log;
 	struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 1];
+	struct {
+		int *insn_state;
+		int *insn_stack;
+		int cur_stack;
+	} cfg;
 	u32 subprog_cnt;
 	/* number of instructions analyzed by the verifier */
 	u32 insn_processed;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index db301e9b5295..5f0eb5bd5589 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5369,10 +5369,6 @@ enum {
 
 #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L)
 
-static int *insn_stack;	/* stack of insns to process */
-static int cur_stack;	/* current stack index */
-static int *insn_state;
-
 /* t, w, e - match pseudo-code above:
  * t - index of current instruction
  * w - next instruction
@@ -5380,6 +5376,9 @@ static int *insn_state;
  */
 static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
 {
+	int *insn_stack = env->cfg.insn_stack;
+	int *insn_state = env->cfg.insn_state;
+
 	if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
 		return 0;
 
@@ -5400,9 +5399,9 @@ static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
 		/* tree-edge */
 		insn_state[t] = DISCOVERED | e;
 		insn_state[w] = DISCOVERED;
-		if (cur_stack >= env->prog->len)
+		if (env->cfg.cur_stack >= env->prog->len)
 			return -E2BIG;
-		insn_stack[cur_stack++] = w;
+		insn_stack[env->cfg.cur_stack++] = w;
 		return 1;
 	} else if ((insn_state[w] & 0xF0) == DISCOVERED) {
 		verbose_linfo(env, t, "%d: ", t);
@@ -5426,14 +5425,15 @@ static int check_cfg(struct bpf_verifier_env *env)
 {
 	struct bpf_insn *insns = env->prog->insnsi;
 	int insn_cnt = env->prog->len;
+	int *insn_stack, *insn_state;
 	int ret = 0;
 	int i, t;
 
-	insn_state = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
+	insn_state = env->cfg.insn_state = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
 	if (!insn_state)
 		return -ENOMEM;
 
-	insn_stack = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
+	insn_stack = env->cfg.insn_stack = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
 	if (!insn_stack) {
 		kvfree(insn_state);
 		return -ENOMEM;
@@ -5441,12 +5441,12 @@ static int check_cfg(struct bpf_verifier_env *env)
 
 	insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
 	insn_stack[0] = 0; /* 0 is the first instruction */
-	cur_stack = 1;
+	env->cfg.cur_stack = 1;
 
 peek_stack:
-	if (cur_stack == 0)
+	if (env->cfg.cur_stack == 0)
 		goto check_state;
-	t = insn_stack[cur_stack - 1];
+	t = insn_stack[env->cfg.cur_stack - 1];
 
 	if (BPF_CLASS(insns[t].code) == BPF_JMP ||
 	    BPF_CLASS(insns[t].code) == BPF_JMP32) {
@@ -5515,7 +5515,7 @@ static int check_cfg(struct bpf_verifier_env *env)
 
 mark_explored:
 	insn_state[t] = EXPLORED;
-	if (cur_stack-- <= 0) {
+	if (env->cfg.cur_stack-- <= 0) {
 		verbose(env, "pop stack internal bug\n");
 		ret = -EFAULT;
 		goto err_free;
@@ -5535,6 +5535,7 @@ static int check_cfg(struct bpf_verifier_env *env)
 err_free:
 	kvfree(insn_state);
 	kvfree(insn_stack);
+	env->cfg.insn_state = env->cfg.insn_stack = NULL;
 	return ret;
 }
 
-- 
2.20.0