diff --git a/include/tdep-x86_64/libunwind_i.h b/include/tdep-x86_64/libunwind_i.h
index ad4987b8..a949a4cb 100644
--- a/include/tdep-x86_64/libunwind_i.h
+++ b/include/tdep-x86_64/libunwind_i.h
@@ -51,7 +51,6 @@ struct unw_addr_space
     unw_word_t dyn_info_list_addr;	/* (cached) dyn_info_list_addr */
     struct dwarf_rs_cache global_cache;
     struct unw_debug_frame_list *debug_frames;
-    int validate;
    };
 
 struct cursor
@@ -67,8 +66,17 @@ struct cursor
       }
     sigcontext_format;
     unw_word_t sigcontext_addr;
+    int validate;
+    ucontext_t *uc;
   };
 
+static inline ucontext_t *
+dwarf_get_uc(const struct dwarf_cursor *cursor)
+{
+  const struct cursor *c = (struct cursor *) cursor->as_arg;
+  return c->uc;
+}
+
 #define DWARF_GET_LOC(l)	((l).val)
 
 #ifdef UNW_LOCAL_ONLY
@@ -77,10 +85,10 @@ struct cursor
 # define DWARF_LOC(r, t)	((dwarf_loc_t) { .val = (r) })
 # define DWARF_IS_REG_LOC(l)	0
 # define DWARF_REG_LOC(c,r)	(DWARF_LOC((unw_word_t)			     \
-				 tdep_uc_addr((c)->as_arg, (r)), 0))
+				 tdep_uc_addr(dwarf_get_uc(c), (r)), 0))
 # define DWARF_MEM_LOC(c,m)	DWARF_LOC ((m), 0)
 # define DWARF_FPREG_LOC(c,r)	(DWARF_LOC((unw_word_t)			     \
-				 tdep_uc_addr((c)->as_arg, (r)), 0))
+				 tdep_uc_addr(dwarf_get_uc(c), (r)), 0))
 #else /* !UNW_LOCAL_ONLY */
 
 # define DWARF_LOC_TYPE_FP	(1 << 0)
diff --git a/src/x86_64/Ginit.c b/src/x86_64/Ginit.c
index 026e8d25..031deaa2 100644
--- a/src/x86_64/Ginit.c
+++ b/src/x86_64/Ginit.c
@@ -158,7 +158,8 @@ access_mem (unw_addr_space_t as, unw_word_t addr, unw_word_t *val, int write,
   else
     {
       /* validate address */
-      if (as->validate && validate_mem(addr))
+      const struct cursor *c = (const struct cursor *)arg;
+      if (c && c->validate && validate_mem(addr))
         return -1;
       *val = *(unw_word_t *) addr;
       Debug (16, "mem[%016lx] -> %lx\n", addr, *val);
@@ -171,7 +172,7 @@ access_reg (unw_addr_space_t as, unw_regnum_t reg, unw_word_t *val, int write,
 	    void *arg)
 {
   unw_word_t *addr;
-  ucontext_t *uc = arg;
+  ucontext_t *uc = ((struct cursor *)arg)->uc;
 
   if (unw_is_fpreg (reg))
     goto badreg;
@@ -200,7 +201,7 @@ static int
 access_fpreg (unw_addr_space_t as, unw_regnum_t reg, unw_fpreg_t *val,
 	      int write, void *arg)
 {
-  ucontext_t *uc = arg;
+  ucontext_t *uc = ((struct cursor *)arg)->uc;
   unw_fpreg_t *addr;
 
   if (!unw_is_fpreg (reg))
@@ -252,7 +253,6 @@ x86_64_local_addr_space_init (void)
   local_addr_space.acc.get_proc_name = get_static_proc_name;
   unw_flush_cache (&local_addr_space, 0, 0);
 
-  local_addr_space.validate = 0;
   memset (last_good_addr, 0, sizeof (unw_word_t) * NLGA);
   lga_victim = 0;
 }
diff --git a/src/x86_64/Ginit_local.c b/src/x86_64/Ginit_local.c
index 9bb25137..1e80cb85 100644
--- a/src/x86_64/Ginit_local.c
+++ b/src/x86_64/Ginit_local.c
@@ -49,7 +49,9 @@ unw_init_local (unw_cursor_t *cursor, ucontext_t *uc)
   Debug (1, "(cursor=%p)\n", c);
 
   c->dwarf.as = unw_local_addr_space;
-  c->dwarf.as_arg = uc;
+  c->dwarf.as_arg = c;
+  c->uc = uc;
+  c->validate = 0;
   return common_init (c);
 }
 
diff --git a/src/x86_64/Ginit_remote.c b/src/x86_64/Ginit_remote.c
index 9b2fd233..8aa644d3 100644
--- a/src/x86_64/Ginit_remote.c
+++ b/src/x86_64/Ginit_remote.c
@@ -42,7 +42,16 @@ unw_init_remote (unw_cursor_t *cursor, unw_addr_space_t as, void *as_arg)
   Debug (1, "(cursor=%p)\n", c);
 
   c->dwarf.as = as;
-  c->dwarf.as_arg = as_arg;
+  if (as == unw_local_addr_space)
+    {
+      c->dwarf.as_arg = c;
+      c->uc = as_arg;
+    }
+  else
+    {
+      c->dwarf.as_arg = as_arg;
+      c->uc = 0;
+    }
   return common_init (c);
 #endif /* !UNW_LOCAL_ONLY */
 }
diff --git a/src/x86_64/Gis_signal_frame.c b/src/x86_64/Gis_signal_frame.c
index b795827c..72edf46e 100644
--- a/src/x86_64/Gis_signal_frame.c
+++ b/src/x86_64/Gis_signal_frame.c
@@ -40,7 +40,6 @@ unw_is_signal_frame (unw_cursor_t *cursor)
 
   as = c->dwarf.as;
   a = unw_get_accessors (as);
-  as->validate = 1;	/* Don't trust the ip */
   arg = c->dwarf.as_arg;
 
   /* Check if RIP points at sigreturn sequence.
diff --git a/src/x86_64/Gresume.c b/src/x86_64/Gresume.c
index 4edc4da6..b4000401 100644
--- a/src/x86_64/Gresume.c
+++ b/src/x86_64/Gresume.c
@@ -51,7 +51,7 @@ x86_64_local_resume (unw_addr_space_t as, unw_cursor_t *cursor, void *arg)
 {
 #if defined(__linux)
   struct cursor *c = (struct cursor *) cursor;
-  ucontext_t *uc = c->dwarf.as_arg;
+  ucontext_t *uc = c->uc;
 
   /* Ensure c->pi is up-to-date.  On x86-64, it's relatively common to
      be missing DWARF unwind info.  We don't want to fail in that
diff --git a/src/x86_64/Gstep.c b/src/x86_64/Gstep.c
index 75f796f5..2da1c25d 100644
--- a/src/x86_64/Gstep.c
+++ b/src/x86_64/Gstep.c
@@ -71,6 +71,10 @@ unw_step (unw_cursor_t *cursor)
       unw_word_t prev_ip = c->dwarf.ip, prev_cfa = c->dwarf.cfa;
       struct dwarf_loc rbp_loc, rsp_loc, rip_loc;
 
+      /* We could get here because of missing/bad unwind information.
+         Validate all addresses before dereferencing. */
+      c->validate = 1;
+
       Debug (13, "dwarf_step() failed (ret=%d), trying frame-chain\n", ret);
 
       if (unw_is_signal_frame (cursor))