2004-03-22 Andrew Cagney <cagney@redhat.com>

	* s390-tdep.c (struct s390_stub_unwind_cache): Rename
	s390_pltstub_unwind_cache.
	(s390_stub_frame_unwind_cache): Rename
	s390_pltstub_frame_unwind_cache.
	(s390_stub_frame_this_id): Rename s390_pltstub_frame_this_id.
	(s390_stub_frame_prev_register): Rename
	s390_pltstub_frame_prev_register.
	(s390_stub_frame_unwind): Rename s390_pltstub_frame_unwind.
	(s390_stub_frame_sniffer): Rename s390_stub_frame_sniffer.

	From Ulrich Weigand:
	* s390-tdep.c (s390_pltstub_frame_sniffer): Handle invalid function
	pointer calls like PLT calls.

1 files changed, 38 insertions, 30 deletions

diff --git a/gdb/s390-tdep.c b/gdb/s390-tdep.c
index 7e3463e1fb2..0f8f65d2f76 100644
--- a/gdb/s390-tdep.c
+++ b/gdb/s390-tdep.c
@@ -2037,27 +2037,29 @@ s390_frame_sniffer (struct frame_info *next_frame)
 }
 
 
-/* PLT stub stack frames.  */
-
-struct s390_pltstub_unwind_cache {
+/* Code stubs and their stack frames.  For things like PLTs and NULL
+   function calls (where there is no true frame and the return address
+   is in the RETADDR register).  */
 
+struct s390_stub_unwind_cache
+{
   CORE_ADDR frame_base;
   struct trad_frame_saved_reg *saved_regs;
 };
 
-static struct s390_pltstub_unwind_cache *
-s390_pltstub_frame_unwind_cache (struct frame_info *next_frame,
-				 void **this_prologue_cache)
+static struct s390_stub_unwind_cache *
+s390_stub_frame_unwind_cache (struct frame_info *next_frame,
+			      void **this_prologue_cache)
 {
   struct gdbarch *gdbarch = get_frame_arch (next_frame);
   int word_size = gdbarch_ptr_bit (gdbarch) / 8;
-  struct s390_pltstub_unwind_cache *info;
+  struct s390_stub_unwind_cache *info;
   ULONGEST reg;
 
   if (*this_prologue_cache)
     return *this_prologue_cache;
 
-  info = FRAME_OBSTACK_ZALLOC (struct s390_pltstub_unwind_cache);
+  info = FRAME_OBSTACK_ZALLOC (struct s390_stub_unwind_cache);
   *this_prologue_cache = info;
   info->saved_regs = trad_frame_alloc_saved_regs (next_frame);
 
@@ -2072,41 +2074,47 @@ s390_pltstub_frame_unwind_cache (struct frame_info *next_frame,
 }
 
 static void
-s390_pltstub_frame_this_id (struct frame_info *next_frame,
-			    void **this_prologue_cache,
-			    struct frame_id *this_id)
+s390_stub_frame_this_id (struct frame_info *next_frame,
+			 void **this_prologue_cache,
+			 struct frame_id *this_id)
 {
-  struct s390_pltstub_unwind_cache *info
-    = s390_pltstub_frame_unwind_cache (next_frame, this_prologue_cache);
+  struct s390_stub_unwind_cache *info
+    = s390_stub_frame_unwind_cache (next_frame, this_prologue_cache);
   *this_id = frame_id_build (info->frame_base, frame_pc_unwind (next_frame));
 }
 
 static void
-s390_pltstub_frame_prev_register (struct frame_info *next_frame,
-				  void **this_prologue_cache,
-				  int regnum, int *optimizedp,
-				  enum lval_type *lvalp, CORE_ADDR *addrp,
-				  int *realnump, void *bufferp)
-{
-  struct s390_pltstub_unwind_cache *info
-    = s390_pltstub_frame_unwind_cache (next_frame, this_prologue_cache);
+s390_stub_frame_prev_register (struct frame_info *next_frame,
+			       void **this_prologue_cache,
+			       int regnum, int *optimizedp,
+			       enum lval_type *lvalp, CORE_ADDR *addrp,
+			       int *realnump, void *bufferp)
+{
+  struct s390_stub_unwind_cache *info
+    = s390_stub_frame_unwind_cache (next_frame, this_prologue_cache);
   trad_frame_prev_register (next_frame, info->saved_regs, regnum,
                             optimizedp, lvalp, addrp, realnump, bufferp);
 }
 
-static const struct frame_unwind s390_pltstub_frame_unwind = {
+static const struct frame_unwind s390_stub_frame_unwind = {
   NORMAL_FRAME,
-  s390_pltstub_frame_this_id,
-  s390_pltstub_frame_prev_register
+  s390_stub_frame_this_id,
+  s390_stub_frame_prev_register
 };
 
 static const struct frame_unwind *
-s390_pltstub_frame_sniffer (struct frame_info *next_frame)
+s390_stub_frame_sniffer (struct frame_info *next_frame)
 {
-  if (!in_plt_section (frame_pc_unwind (next_frame), NULL))
-    return NULL;
-
-  return &s390_pltstub_frame_unwind;
+  CORE_ADDR pc = frame_pc_unwind (next_frame);
+  bfd_byte insn[S390_MAX_INSTR_SIZE];
+
+  /* If the current PC points to non-readable memory, we assume we
+     have trapped due to an invalid function pointer call.  We handle
+     the non-existing current function like a PLT stub.  */
+  if (in_plt_section (pc, NULL)
+      || s390_readinstruction (insn, pc) < 0)
+    return &s390_stub_frame_unwind;
+  return NULL;
 }
 
 
@@ -3028,7 +3036,7 @@ s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   dwarf2_frame_set_init_reg (gdbarch, s390_dwarf2_frame_init_reg);
   frame_unwind_append_sniffer (gdbarch, dwarf2_frame_sniffer);
   frame_base_append_sniffer (gdbarch, dwarf2_frame_base_sniffer);
-  frame_unwind_append_sniffer (gdbarch, s390_pltstub_frame_sniffer);
+  frame_unwind_append_sniffer (gdbarch, s390_stub_frame_sniffer);
   frame_unwind_append_sniffer (gdbarch, s390_sigtramp_frame_sniffer);
   frame_unwind_append_sniffer (gdbarch, s390_frame_sniffer);
   frame_base_set_default (gdbarch, &s390_frame_base);