bpf: Remove struct bpf_verifier_env argument from print_bpf_insn

We use print_bpf_insn in user space (bpftool and soon perf),
so it'd be nice to keep it generic and strip it off the kernel
struct bpf_verifier_env argument.

This argument can be safely removed, because its users can
use the struct bpf_insn_cbs::private_data to pass it.

By changing the argument type  we can no longer have clean
'verbose' alias to 'bpf_verifier_log_write' in verifier.c.
Instead  we're adding the  'verbose' cb_print callback and
removing the alias.

This way we have new cb_print callback in place, and all
the 'verbose(env, ...) calls in verifier.c will cleanly
cast to 'verbose(void *, ...)' so no other change is
needed.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

kernel/bpf/disasm.c

@@ -113,16 +113,16 @@ static const char *const bpf_jmp_string[16] = {
 };
 
 static void print_bpf_end_insn(bpf_insn_print_t verbose,
-			       struct bpf_verifier_env *env,
+			       void *private_data,
 			       const struct bpf_insn *insn)
 {
-	verbose(env, "(%02x) r%d = %s%d r%d\n", insn->code, insn->dst_reg,
+	verbose(private_data, "(%02x) r%d = %s%d r%d\n",
+		insn->code, insn->dst_reg,
 		BPF_SRC(insn->code) == BPF_TO_BE ? "be" : "le",
 		insn->imm, insn->dst_reg);
 }
 
 void print_bpf_insn(const struct bpf_insn_cbs *cbs,
-		    struct bpf_verifier_env *env,
 		    const struct bpf_insn *insn,
 		    bool allow_ptr_leaks)
 {
@@ -132,23 +132,23 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs,
 	if (class == BPF_ALU || class == BPF_ALU64) {
 		if (BPF_OP(insn->code) == BPF_END) {
 			if (class == BPF_ALU64)
-				verbose(env, "BUG_alu64_%02x\n", insn->code);
+				verbose(cbs->private_data, "BUG_alu64_%02x\n", insn->code);
 			else
-				print_bpf_end_insn(verbose, env, insn);
+				print_bpf_end_insn(verbose, cbs->private_data, insn);
 		} else if (BPF_OP(insn->code) == BPF_NEG) {
-			verbose(env, "(%02x) r%d = %s-r%d\n",
+			verbose(cbs->private_data, "(%02x) r%d = %s-r%d\n",
 				insn->code, insn->dst_reg,
 				class == BPF_ALU ? "(u32) " : "",
 				insn->dst_reg);
 		} else if (BPF_SRC(insn->code) == BPF_X) {
-			verbose(env, "(%02x) %sr%d %s %sr%d\n",
+			verbose(cbs->private_data, "(%02x) %sr%d %s %sr%d\n",
 				insn->code, class == BPF_ALU ? "(u32) " : "",
 				insn->dst_reg,
 				bpf_alu_string[BPF_OP(insn->code) >> 4],
 				class == BPF_ALU ? "(u32) " : "",
 				insn->src_reg);
 		} else {
-			verbose(env, "(%02x) %sr%d %s %s%d\n",
+			verbose(cbs->private_data, "(%02x) %sr%d %s %s%d\n",
 				insn->code, class == BPF_ALU ? "(u32) " : "",
 				insn->dst_reg,
 				bpf_alu_string[BPF_OP(insn->code) >> 4],
@@ -157,46 +157,46 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs,
 		}
 	} else if (class == BPF_STX) {
 		if (BPF_MODE(insn->code) == BPF_MEM)
-			verbose(env, "(%02x) *(%s *)(r%d %+d) = r%d\n",
+			verbose(cbs->private_data, "(%02x) *(%s *)(r%d %+d) = r%d\n",
 				insn->code,
 				bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
 				insn->dst_reg,
 				insn->off, insn->src_reg);
 		else if (BPF_MODE(insn->code) == BPF_XADD)
-			verbose(env, "(%02x) lock *(%s *)(r%d %+d) += r%d\n",
+			verbose(cbs->private_data, "(%02x) lock *(%s *)(r%d %+d) += r%d\n",
 				insn->code,
 				bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
 				insn->dst_reg, insn->off,
 				insn->src_reg);
 		else
-			verbose(env, "BUG_%02x\n", insn->code);
+			verbose(cbs->private_data, "BUG_%02x\n", insn->code);
 	} else if (class == BPF_ST) {
 		if (BPF_MODE(insn->code) != BPF_MEM) {
-			verbose(env, "BUG_st_%02x\n", insn->code);
+			verbose(cbs->private_data, "BUG_st_%02x\n", insn->code);
 			return;
 		}
-		verbose(env, "(%02x) *(%s *)(r%d %+d) = %d\n",
+		verbose(cbs->private_data, "(%02x) *(%s *)(r%d %+d) = %d\n",
 			insn->code,
 			bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
 			insn->dst_reg,
 			insn->off, insn->imm);
 	} else if (class == BPF_LDX) {
 		if (BPF_MODE(insn->code) != BPF_MEM) {
-			verbose(env, "BUG_ldx_%02x\n", insn->code);
+			verbose(cbs->private_data, "BUG_ldx_%02x\n", insn->code);
 			return;
 		}
-		verbose(env, "(%02x) r%d = *(%s *)(r%d %+d)\n",
+		verbose(cbs->private_data, "(%02x) r%d = *(%s *)(r%d %+d)\n",
 			insn->code, insn->dst_reg,
 			bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
 			insn->src_reg, insn->off);
 	} else if (class == BPF_LD) {
 		if (BPF_MODE(insn->code) == BPF_ABS) {
-			verbose(env, "(%02x) r0 = *(%s *)skb[%d]\n",
+			verbose(cbs->private_data, "(%02x) r0 = *(%s *)skb[%d]\n",
 				insn->code,
 				bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
 				insn->imm);
 		} else if (BPF_MODE(insn->code) == BPF_IND) {
-			verbose(env, "(%02x) r0 = *(%s *)skb[r%d + %d]\n",
+			verbose(cbs->private_data, "(%02x) r0 = *(%s *)skb[r%d + %d]\n",
 				insn->code,
 				bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
 				insn->src_reg, insn->imm);
@@ -212,12 +212,12 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs,
 			if (map_ptr && !allow_ptr_leaks)
 				imm = 0;
 
-			verbose(env, "(%02x) r%d = %s\n",
+			verbose(cbs->private_data, "(%02x) r%d = %s\n",
 				insn->code, insn->dst_reg,
 				__func_imm_name(cbs, insn, imm,
 						tmp, sizeof(tmp)));
 		} else {
-			verbose(env, "BUG_ld_%02x\n", insn->code);
+			verbose(cbs->private_data, "BUG_ld_%02x\n", insn->code);
 			return;
 		}
 	} else if (class == BPF_JMP) {
@@ -227,35 +227,35 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs,
 			char tmp[64];
 
 			if (insn->src_reg == BPF_PSEUDO_CALL) {
-				verbose(env, "(%02x) call pc%s\n",
+				verbose(cbs->private_data, "(%02x) call pc%s\n",
 					insn->code,
 					__func_get_name(cbs, insn,
 							tmp, sizeof(tmp)));
 			} else {
 				strcpy(tmp, "unknown");
-				verbose(env, "(%02x) call %s#%d\n", insn->code,
+				verbose(cbs->private_data, "(%02x) call %s#%d\n", insn->code,
 					__func_get_name(cbs, insn,
 							tmp, sizeof(tmp)),
 					insn->imm);
 			}
 		} else if (insn->code == (BPF_JMP | BPF_JA)) {
-			verbose(env, "(%02x) goto pc%+d\n",
+			verbose(cbs->private_data, "(%02x) goto pc%+d\n",
 				insn->code, insn->off);
 		} else if (insn->code == (BPF_JMP | BPF_EXIT)) {
-			verbose(env, "(%02x) exit\n", insn->code);
+			verbose(cbs->private_data, "(%02x) exit\n", insn->code);
 		} else if (BPF_SRC(insn->code) == BPF_X) {
-			verbose(env, "(%02x) if r%d %s r%d goto pc%+d\n",
+			verbose(cbs->private_data, "(%02x) if r%d %s r%d goto pc%+d\n",
 				insn->code, insn->dst_reg,
 				bpf_jmp_string[BPF_OP(insn->code) >> 4],
 				insn->src_reg, insn->off);
 		} else {
-			verbose(env, "(%02x) if r%d %s 0x%x goto pc%+d\n",
+			verbose(cbs->private_data, "(%02x) if r%d %s 0x%x goto pc%+d\n",
 				insn->code, insn->dst_reg,
 				bpf_jmp_string[BPF_OP(insn->code) >> 4],
 				insn->imm, insn->off);
 		}
 	} else {
-		verbose(env, "(%02x) %s\n",
+		verbose(cbs->private_data, "(%02x) %s\n",
 			insn->code, bpf_class_string[class]);
 	}
 }

kernel/bpf/disasm.h

@@ -22,14 +22,12 @@
 #include <string.h>
 #endif
 
-struct bpf_verifier_env;
-
 extern const char *const bpf_alu_string[16];
 extern const char *const bpf_class_string[8];
 
 const char *func_id_name(int id);
 
-typedef __printf(2, 3) void (*bpf_insn_print_t)(struct bpf_verifier_env *env,
+typedef __printf(2, 3) void (*bpf_insn_print_t)(void *private_data,
 						const char *, ...);
 typedef const char *(*bpf_insn_revmap_call_t)(void *private_data,
 					      const struct bpf_insn *insn);
@@ -45,7 +43,6 @@ struct bpf_insn_cbs {
 };
 
 void print_bpf_insn(const struct bpf_insn_cbs *cbs,
-		    struct bpf_verifier_env *env,
 		    const struct bpf_insn *insn,
 		    bool allow_ptr_leaks);
 #endif

kernel/bpf/verifier.c

@@ -168,23 +168,16 @@ struct bpf_call_arg_meta {
 
 static DEFINE_MUTEX(bpf_verifier_lock);
 
-/* log_level controls verbosity level of eBPF verifier.
- * bpf_verifier_log_write() is used to dump the verification trace to the log,
- * so the user can figure out what's wrong with the program
- */
-__printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
-					   const char *fmt, ...)
+static void log_write(struct bpf_verifier_env *env, const char *fmt,
+		      va_list args)
 {
 	struct bpf_verifer_log *log = &env->log;
 	unsigned int n;
-	va_list args;
 
 	if (!log->level || !log->ubuf || bpf_verifier_log_full(log))
 		return;
 
-	va_start(args, fmt);
 	n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args);
-	va_end(args);
 
 	WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1,
 		  "verifier log line truncated - local buffer too short\n");
@@ -197,14 +190,30 @@ __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
 	else
 		log->ubuf = NULL;
 }
-EXPORT_SYMBOL_GPL(bpf_verifier_log_write);
-/* Historically bpf_verifier_log_write was called verbose, but the name was too
- * generic for symbol export. The function was renamed, but not the calls in
- * the verifier to avoid complicating backports. Hence the alias below.
+
+/* log_level controls verbosity level of eBPF verifier.
+ * bpf_verifier_log_write() is used to dump the verification trace to the log,
+ * so the user can figure out what's wrong with the program
  */
-static __printf(2, 3) void verbose(struct bpf_verifier_env *env,
-				   const char *fmt, ...)
-	__attribute__((alias("bpf_verifier_log_write")));
+__printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
+					   const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	log_write(env, fmt, args);
+	va_end(args);
+}
+EXPORT_SYMBOL_GPL(bpf_verifier_log_write);
+
+__printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	log_write(private_data, fmt, args);
+	va_end(args);
+}
 
 static bool type_is_pkt_pointer(enum bpf_reg_type type)
 {
@@ -4600,10 +4609,11 @@ static int do_check(struct bpf_verifier_env *env)
 		if (env->log.level) {
 			const struct bpf_insn_cbs cbs = {
 				.cb_print	= verbose,
+				.private_data	= env,
 			};
 
 			verbose(env, "%d: ", insn_idx);
-			print_bpf_insn(&cbs, env, insn, env->allow_ptr_leaks);
+			print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
 		}
 
 		if (bpf_prog_is_dev_bound(env->prog->aux)) {