bpf: Update logging functions to work with BTF

* Based on 430e68d10b,
  77d2e05abd
  and a2a7d57010

Change-Id: I27e2c804726078646ca9beda31cbae2a745dfd47
Signed-off-by: Cyber Knight <cyberknight755@gmail.com>

include/linux/bpf_verifier.h

@@ -136,9 +136,11 @@ struct bpf_insn_aux_data {
 
 #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
 
+#define BPF_VERIFIER_TMP_LOG_SIZE	1024
+
 struct bpf_verifier_log {
 	u32 level;
-	char *kbuf;
+	char kbuf[BPF_VERIFIER_TMP_LOG_SIZE];
 	char __user *ubuf;
 	u32 len_used;
 	u32 len_total;
@@ -149,6 +151,17 @@ static inline bool bpf_verifier_log_full(const struct bpf_verifier_log *log)
 	return log->len_used >= log->len_total - 1;
 }
 
+static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log)
+{
+	return log->level && log->ubuf && !bpf_verifier_log_full(log);
+}
+
+__printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_log *log,
+					   const char *fmt, ...);
+
+void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt,
+		       va_list args);
+
 struct bpf_verifier_env;
 struct bpf_ext_analyzer_ops {
 	int (*insn_hook)(struct bpf_verifier_env *env,

kernel/bpf/verifier.c

@@ -160,21 +160,55 @@ static struct bpf_verifier_log verifier_log;
 
 static DEFINE_MUTEX(bpf_verifier_lock);
 
-/* log_level controls verbosity level of eBPF verifier.
- * verbose() is used to dump the verification trace to the log, so the user
- * can figure out what's wrong with the program
- */
-static __printf(1, 2) void verbose(const char *fmt, ...)
+void bpf_verifier_vlog(struct bpf_verifier_log *log,
+		       const char *fmt, va_list args)
+{
+	unsigned int n;
+
+	n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args);
+
+	WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1,
+		  "verifier log line truncated - local buffer too short\n");
+
+	n = min(log->len_total - log->len_used - 1, n);
+	log->kbuf[n] = '\0';
+
+	if (!copy_to_user(log->ubuf + log->len_used, log->kbuf, n + 1))
+		log->len_used += n;
+	else
+		log->ubuf = NULL;
+}
+
+/* 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_log *log,
+						  const char *fmt, ...)
 {
-	struct bpf_verifier_log *log = &verifier_log;
 	va_list args;
 
-	if (!log->level || bpf_verifier_log_full(log))
+	if (!bpf_verifier_log_needed(log))
 		return;
 
 	va_start(args, fmt);
-	log->len_used += vscnprintf(log->kbuf + log->len_used,
-				    log->len_total - log->len_used, fmt, args);
+	bpf_verifier_vlog(log, fmt, args);
+	va_end(args);
+}
+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.
+ */
+static __printf(1, 2) void verbose(const char *fmt, ...)
+{
+	va_list args;
+
+	if (!bpf_verifier_log_needed(&verifier_log))
+		return;
+
+	va_start(args, fmt);
+	bpf_verifier_vlog(&verifier_log, fmt, args);
 	va_end(args);
 }
 
@@ -5118,9 +5152,6 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
 			goto err_unlock;
 
 		ret = -ENOMEM;
-		log->kbuf = vmalloc(log->len_total);
-		if (!log->kbuf)
-			goto err_unlock;
 	} else {
 		log->level = 0;
 	}
@@ -5167,17 +5198,12 @@ skip_full_check:
 		ret = fixup_bpf_calls(env);
 
 	if (log->level && bpf_verifier_log_full(log)) {
-		BUG_ON(log->len_used >= log->len_total);
-		/* verifier log exceeded user supplied buffer */
 		ret = -ENOSPC;
-		/* fall through to return what was recorded */
 	}
 
-	/* copy verifier log back to user space including trailing zero */
-	if (log->level && copy_to_user(log->ubuf, log->kbuf,
-				       log->len_used + 1) != 0) {
+	if (log->level && !log->ubuf) {
 		ret = -EFAULT;
-		goto free_log_buf;
+		goto err_release_maps;
 	}
 
 	if (ret == 0 && env->used_map_cnt) {
@@ -5188,7 +5214,7 @@ skip_full_check:
 
 		if (!env->prog->aux->used_maps) {
 			ret = -ENOMEM;
-			goto free_log_buf;
+			goto err_release_maps;
 		}
 
 		memcpy(env->prog->aux->used_maps, env->used_maps,
@@ -5201,9 +5227,7 @@ skip_full_check:
 		convert_pseudo_ld_imm64(env);
 	}
 
-free_log_buf:
-	if (log->level)
-		vfree(log->kbuf);
+err_release_maps:
 	if (!env->prog->aux->used_maps)
 		/* if we didn't copy map pointers into bpf_prog_info, release
 		 * them now. Otherwise free_used_maps() will release them.

scripts/module-lto.lds

@@ -0,0 +1,22 @@
+
+SECTIONS {
+ /DISCARD/ : {
+  *(.eh_frame)
+ }
+ .bss : {
+  *(.bss .bss.[0-9a-zA-Z_]*)
+  *(.bss..L*)
+ }
+ .data : {
+  *(.data .data.[0-9a-zA-Z_]*)
+  *(.data..L*)
+ }
+ .rodata : {
+  *(.rodata .rodata.[0-9a-zA-Z_]*)
+  *(.rodata..L*)
+ }
+ .text : ALIGN((1 << 12)) {
+  *(.text.__cfi_check)
+  *(.text .text.[0-9a-zA-Z_]* .text..L.cfi*)
+ }
+}