* alpha-linux-tdep.c (alpha_linux_sigtramp_offset_1): New.

	(alpha_linux_sigtramp_offset): Use it.  Make static.
	(alpha_linux_sigcontext_addr): Handle __NR_rt_sigreturn;
	update for new frame model.
	* alpha-mdebug-tdep.c: New file.
	* alpha-osf1-tdep.c (alpha_call_dummy_address): Move from alpha-tdep.c.
	(alpha_osf1_init_abi): Install it.
	* alpha-tdep.c (PROC_*): Move to alpha-mdebug-tdep.c.
	(linked_proc_desc_table): Remove.
	(alpha_frame_past_sigtramp_frame): Remove.
	(alpha_dynamic_sigtramp_offset): Remove.
	(ALPHA_PROC_SIGTRAMP_MAGIC): Remove.
	(alpha_proc_desc_is_dyn_sigtramp): Remove.
	(alpha_set_proc_desc_is_dyn_sigtramp): Remove.
	(push_sigtramp_desc): Remove.
	(alpha_cannot_fetch_register): Use ALPHA_FP_REGNUM.
	(alpha_cannot_store_register): Likewise.
	(alpha_sigcontext_addr): Remove.
	(alpha_find_saved_regs): Remove.
	(alpha_frame_init_saved_regs): Remove.
	(alpha_init_frame_pc_first): Remove.
	(read_next_frame_reg): Remove.
	(alpha_frame_saved_pc): Remove.
	(alpha_saved_pc_after_call): Remove.
	(temp_proc_desc, temp_saved_regs): Remove.
	(alpha_about_to_return): Remove.
	(cached_proc_desc): Remove.
	(alpha_frame_chain): Remove.
	(alpha_print_extra_frame_info): Remove.
	(alpha_init_extra_frame_info): Remove.
	(alpha_frame_locals_address): Remove.
	(alpha_frame_args_address): Remove.
	(alpha_push_arguments): Use ALPHA_REGISTER_BYTES not sizeof CORE_ADDR.
	(alpha_push_dummy_frame): Remove.
	(alpha_pop_frame): Remove.
	(alpha_after_prologue): Rename from after_prologue; remove mdebug bits.
	(alpha_read_insn): New.
	(alpha_skip_prologue): Merge alpha_skip_prologue_internal; adjust
	for different insn encodings.
	(alpha_in_lenient_prologue): Remove.
	(struct alpha_sigtramp_unwind_cache): New.
	(alpha_sigtramp_frame_unwind_cache): New.
	(alpha_sigtramp_register_address): New.
	(alpha_sigtramp_frame_this_id): New.
	(alpha_sigtramp_frame_prev_register): New.
	(alpha_sigtramp_frame_unwind): New.
	(alpha_sigtramp_frame_p): New.
	(struct alpha_heuristic_unwind_cache): New.
	(alpha_heuristic_proc_start): Rename from heuristic_proc_start;
	don't count nop insns that occur between functions.
	(alpha_heuristic_frame_unwind_cache): New; incorporate much of
	heuristic_proc_desc, but without the mdebug wrapping.
	(alpha_heuristic_frame_this_id): New.
	(alpha_heuristic_frame_prev_register): New.
	(alpha_heuristic_frame_unwind): New.
	(alpha_heuristic_frame_p): New.
	(alpha_heuristic_frame_base_address): New.
	(alpha_heuristic_frame_base): New.
	(alpha_unwind_dummy_id): New.
	(alpha_unwind_pc): New.
	(alpha_gdbarch_init): Don't set skip_sigtramp_frame.  Kill use of
	frame related deprecated initializations; install replacements.
	(alpha_dump_tdep): Remove.
	* alpha-tdep.h (struct gdbarch_tdep): Remove skip_sigtramp_frame.
	(alpha_read_insn, alpha_after_prologue,
	alpha_heuristic_frame_unwind_cache, alpha_heuristic_frame_this_id,
	alpha_heuristic_frame_prev_register,
	alpha_heuristic_frame_base_address, alpha_mdebug_init_abi): Declare.
	* config/alpha/alpha-linux.mt (TDEPFILES): Add alpha-mdebug-tdep.o.
	* config/alpha/tm-alpha.h (PRINT_EXTRA_FRAME_INFO): Remove.
	* config/alpha/tm-alphalinux.h (SIGTRAMP_START, SIGTRAMP_END): Remove.

1 files changed, 81 insertions, 53 deletions

diff --git a/gdb/alpha-linux-tdep.c b/gdb/alpha-linux-tdep.c
index c5d7481fbf9..e89a0fa5fe1 100644
--- a/gdb/alpha-linux-tdep.c
+++ b/gdb/alpha-linux-tdep.c
@@ -23,93 +23,121 @@
 #include "gdbcore.h"
 #include "value.h"
 #include "osabi.h"
+#include "gdb_assert.h"
 
 #include "alpha-tdep.h"
 
-/* Under GNU/Linux, signal handler invocations can be identified by the
-   designated code sequence that is used to return from a signal
+/* Under GNU/Linux, signal handler invocations can be identified by
+   the designated code sequence that is used to return from a signal
    handler.  In particular, the return address of a signal handler
-   points to the following sequence (the first instruction is quadword
-   aligned):
-  
-   bis $30,$30,$16
-   addq $31,0x67,$0
-   call_pal callsys 
-      
-   Each instruction has a unique encoding, so we simply attempt to
-   match the instruction the pc is pointing to with any of the above
-   instructions.  If there is a hit, we know the offset to the start
-   of the designated sequence and can then check whether we really are
-   executing in a designated sequence.  If not, -1 is returned,
-   otherwise the offset from the start of the desingated sequence is
-   returned.
-   
-   There is a slight chance of false hits: code could jump into the
-   middle of the designated sequence, in which case there is no
-   guarantee that we are in the middle of a sigreturn syscall.  Don't
-   think this will be a problem in praxis, though.  */
-LONGEST
-alpha_linux_sigtramp_offset (CORE_ADDR pc)
+   points to a sequence that copies $sp to $16, loads $0 with the
+   appropriate syscall number, and finally enters the kernel.
+
+   This is somewhat complicated in that:
+     (1) the expansion of the "mov" assembler macro has changed over
+         time, from "bis src,src,dst" to "bis zero,src,dst",
+     (2) the kernel has changed from using "addq" to "lda" to load the
+         syscall number,
+     (3) there is a "normal" sigreturn and an "rt" sigreturn which
+         has a different stack layout.
+*/
+
+static long
+alpha_linux_sigtramp_offset_1 (CORE_ADDR pc)
 {
-  unsigned int i[3], w;
-  long off;
+  switch (alpha_read_insn (pc))
+    {
+    case 0x47de0410:		/* bis $30,$30,$16 */
+    case 0x47fe0410:		/* bis $31,$30,$16 */
+      return 0;
 
-  if (read_memory_nobpt (pc, (char *) &w, 4) != 0)
-    return -1;
+    case 0x43ecf400:		/* addq $31,103,$0 */
+    case 0x201f0067:		/* lda $0,103($31) */
+    case 0x201f015f:		/* lda $0,351($31) */
+      return 4;
+
+    case 0x00000083:		/* call_pal callsys */
+      return 8;
 
-  off = -1;
-  switch (w)
-    {
-    case 0x47de0410:
-      off = 0;
-      break;			/* bis $30,$30,$16 */
-    case 0x43ecf400:
-      off = 4;
-      break;			/* addq $31,0x67,$0 */
-    case 0x00000083:
-      off = 8;
-      break;			/* call_pal callsys */
     default:
       return -1;
     }
+}
+
+static LONGEST
+alpha_linux_sigtramp_offset (CORE_ADDR pc)
+{
+  long i, off;
+
+  if (pc & 3)
+    return -1;
+
+  /* Guess where we might be in the sequence.  */
+  off = alpha_linux_sigtramp_offset_1 (pc);
+  if (off < 0)
+    return -1;
+
+  /* Verify that the other two insns of the sequence are as we expect.  */
   pc -= off;
-  if (pc & 0x7)
+  for (i = 0; i < 12; i += 4)
     {
-      /* designated sequence is not quadword aligned */
-      return -1;
+      if (i == off)
+	continue;
+      if (alpha_linux_sigtramp_offset_1 (pc + i) != i)
+	return -1;
     }
-  if (read_memory_nobpt (pc, (char *) i, sizeof (i)) != 0)
-    return -1;
-
-  if (i[0] == 0x47de0410 && i[1] == 0x43ecf400 && i[2] == 0x00000083)
-    return off;
 
-  return -1;
+  return off;
 }
 
 static int
 alpha_linux_pc_in_sigtramp (CORE_ADDR pc, char *func_name)
 {
-  return (alpha_linux_sigtramp_offset (pc) >= 0);
+  return alpha_linux_sigtramp_offset (pc) >= 0;
 }
 
 static CORE_ADDR
-alpha_linux_sigcontext_addr (struct frame_info *frame)
+alpha_linux_sigcontext_addr (struct frame_info *next_frame)
 {
-  return (get_frame_base (frame) - 0x298); /* sizeof(struct sigcontext) */
+  CORE_ADDR pc;
+  ULONGEST sp;
+  long off;
+
+  pc = frame_pc_unwind (next_frame);
+  frame_unwind_unsigned_register (next_frame, ALPHA_SP_REGNUM, &sp);
+
+  off = alpha_linux_sigtramp_offset (pc);
+  gdb_assert (off >= 0);
+
+  /* __NR_rt_sigreturn has a couple of structures on the stack.  This is:
+
+	struct rt_sigframe {
+	  struct siginfo info;
+	  struct ucontext uc;
+        };
+
+	offsetof (struct rt_sigframe, uc.uc_mcontext);
+  */
+  if (alpha_read_insn (pc - off + 4) == 0x201f015f)
+    return sp + 176;
+
+  /* __NR_sigreturn has the sigcontext structure at the top of the stack.  */
+  return sp;
 }
 
 static void
 alpha_linux_init_abi (struct gdbarch_info info,
                       struct gdbarch *gdbarch)
 {
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  struct gdbarch_tdep *tdep;
+
+  alpha_mdebug_init_abi (info, gdbarch);
 
   set_gdbarch_pc_in_sigtramp (gdbarch, alpha_linux_pc_in_sigtramp);
 
+  tdep = gdbarch_tdep (gdbarch);
   tdep->dynamic_sigtramp_offset = alpha_linux_sigtramp_offset;
   tdep->sigcontext_addr = alpha_linux_sigcontext_addr;
-
   tdep->jb_pc = 2;
   tdep->jb_elt_size = 8;
 }