--- a/libgcc/unwind-dw2.c	Thu Oct 25 07:37:49 2018 +0900
+++ b/libgcc/unwind-dw2.c	Thu Feb 13 11:34:05 2020 +0900
@@ -1,5 +1,5 @@
 /* DWARF2 exception handling and frame unwind runtime interface routines.
-   Copyright (C) 1997-2018 Free Software Foundation, Inc.
+   Copyright (C) 1997-2020 Free Software Foundation, Inc.
 
    This file is part of GCC.
 
@@ -136,8 +136,9 @@
 #define SIGNAL_FRAME_BIT ((~(_Unwind_Word) 0 >> 1) + 1)
   /* Context which has version/args_size/by_value fields.  */
 #define EXTENDED_CONTEXT_BIT ((~(_Unwind_Word) 0 >> 2) + 1)
-  /* Bit reserved on AArch64, return address has been signed with A key.  */
-#define RA_A_SIGNED_BIT ((~(_Unwind_Word) 0 >> 3) + 1)
+  /* Bit reserved on AArch64, return address has been signed with A or B
+     key.  */
+#define RA_SIGNED_BIT ((~(_Unwind_Word) 0 >> 3) + 1)
   _Unwind_Word flags;
   /* 0 for now, can be increased when further fields are added to
      struct _Unwind_Context.  */
@@ -225,7 +226,7 @@
   _Unwind_Context_Reg_Val val;
 
 #ifdef DWARF_ZERO_REG
-  if (index == DWARF_ZERO_REG)
+  if (regno == DWARF_ZERO_REG)
     return 0;
 #endif
 
@@ -502,6 +503,11 @@
 	  fs->signal_frame = 1;
 	  aug += 1;
 	}
+      /* aarch64 B-key pointer authentication.  */
+      else if (aug[0] == 'B')
+	{
+	  aug += 1;
+      }
 
       /* Otherwise we have an unknown augmentation string.
 	 Bail unless we saw a 'z' prefix.  */