[commit] Improve OpenBSD/alpha support

[Mark Kettenis <mark dot kettenis at xs4all dot nl>]

This seperates out the OpenBSD-specific code from the NetBSD code and
adds proper unwinding for signal trampolines on OpenBSD.

Committed,

Mark


Index: ChangeLog
from  Mark Kettenis  <kettenis@gnu.org>

	* alphaobsd-tdep.c: New file.
	* alphanbsd-tdep.c (_initialize_alphanbsd_tdep): Do not register a
	handler for GDB_OSABI_OPENBSD_ELF.
	* Makefile.in (ALLDEPFILES): Add alphaobsd-tdep.c.
	(alphaobsd-tdep.o): New target.
	* config/alpha/obsd.mt: New file.
	* configure.tgt (alpha*-*-openbsd*): Set gdb_target to obsd.

Index: alphanbsd-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/alphanbsd-tdep.c,v
retrieving revision 1.31
diff -u -p -r1.31 alphanbsd-tdep.c
--- alphanbsd-tdep.c 9 Jul 2006 22:01:59 -0000 1.31
+++ alphanbsd-tdep.c 10 Jul 2006 19:37:01 -0000
@@ -311,6 +311,4 @@ _initialize_alphanbsd_tdep (void)
 
   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_NETBSD_ELF,
                           alphanbsd_init_abi);
-  gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_OPENBSD_ELF,
-                          alphanbsd_init_abi);
 }
Index: alphaobsd-tdep.c
===================================================================
RCS file: alphaobsd-tdep.c
diff -N alphaobsd-tdep.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ alphaobsd-tdep.c 10 Jul 2006 19:37:01 -0000
@@ -0,0 +1,135 @@
+/* Target-dependent code for OpenBSD/alpha.
+
+   Copyright (C) 2006 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor,
+   Boston, MA 02110-1301, USA.  */
+
+#include "defs.h"
+#include "frame.h"
+#include "gdbcore.h"
+#include "osabi.h"
+
+#include "alpha-tdep.h"
+#include "alphabsd-tdep.h"
+#include "solib-svr4.h"
+
+/* Signal trampolines.  */
+
+/* The OpenBSD kernel maps the signal trampoline at some random
+   location in user space, which means that the traditional BSD way of
+   detecting it won't work.
+
+   The signal trampoline will be mapped at an address that is page
+   aligned.  We recognize the signal trampoline by looking for the
+   sigreturn system call.  */
+
+static const int alphaobsd_page_size = 8192;
+
+static LONGEST
+alphaobsd_sigtramp_offset (CORE_ADDR pc)
+{
+  return (pc & (alphaobsd_page_size - 1));
+}
+
+static int
+alphaobsd_pc_in_sigtramp (CORE_ADDR pc, char *name)
+{
+  CORE_ADDR start_pc = (pc & ~(alphaobsd_page_size - 1));
+  unsigned insn;
+
+  if (name)
+    return 0;
+
+  /* Check for "".  */
+  insn = alpha_read_insn (start_pc + 5 * ALPHA_INSN_SIZE);
+  if (insn != 0x201f0067)
+    return 0;
+
+  /* Check for "".  */
+  insn = alpha_read_insn (start_pc + 6 * ALPHA_INSN_SIZE);
+  if (insn != 0x00000083)
+    return 0;
+
+  return 1;
+}
+
+static CORE_ADDR
+alphaobsd_sigcontext_addr (struct frame_info *next_frame)
+{
+  CORE_ADDR pc = frame_pc_unwind (next_frame);
+
+  if (alphaobsd_sigtramp_offset (pc) < 3 * ALPHA_INSN_SIZE)
+    {
+      /* On entry, a pointer the `struct sigcontext' is passed in %a2.  */
+      return frame_unwind_register_unsigned (next_frame, ALPHA_A0_REGNUM + 2);
+    }
+  else if (alphaobsd_sigtramp_offset (pc) < 4 * ALPHA_INSN_SIZE)
+    {
+      /* It is stored on the stack Before calling the signal handler.  */
+      CORE_ADDR sp;
+      sp = frame_unwind_register_unsigned (next_frame, ALPHA_SP_REGNUM);
+      return get_frame_memory_unsigned (next_frame, sp, 8);
+    }
+  else
+    {
+      /* It is reloaded into %a0 for the sigreturn(2) call.  */
+      return frame_unwind_register_unsigned (next_frame, ALPHA_A0_REGNUM);
+    }
+}
+
+
+static void
+alphaobsd_init_abi(struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  /* Hook into the DWARF CFI frame unwinder.  */
+  alpha_dwarf2_init_abi (info, gdbarch);
+
+  /* Hook into the MDEBUG frame unwinder.  */
+  alpha_mdebug_init_abi (info, gdbarch);
+
+  /* OpenBSD/alpha 3.0 and earlier does not provide single step
+     support via ptrace(2); use software single-stepping for now.  */
+  set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);
+
+  /* OpenBSD/alpha has SVR4-style shared libraries.  */
+  set_solib_svr4_fetch_link_map_offsets
+    (gdbarch, svr4_lp64_fetch_link_map_offsets);
+
+  tdep->dynamic_sigtramp_offset = alphaobsd_sigtramp_offset;
+  tdep->pc_in_sigtramp = alphaobsd_pc_in_sigtramp;
+  tdep->sigcontext_addr = alphaobsd_sigcontext_addr;
+
+  tdep->jb_pc = 2;
+  tdep->jb_elt_size = 8;
+
+  set_gdbarch_regset_from_core_section
+    (gdbarch, alphanbsd_regset_from_core_section);
+}
+
+
+/* Provide a prototype to silence -Wmissing-prototypes.  */
+void _initialize_alphaobsd_tdep (void);
+
+void
+_initialize_alphaobsd_tdep (void)
+{
+  gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_OPENBSD_ELF,
+                          alphaobsd_init_abi);
+}
Index: Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.824
diff -u -p -r1.824 Makefile.in
--- Makefile.in 9 Jul 2006 16:12:11 -0000 1.824
+++ Makefile.in 10 Jul 2006 19:37:04 -0000
@@ -1404,9 +1404,10 @@ MAKEOVERRIDES=
 
 ALLDEPFILES = \
 	aix-thread.c \
-	alpha-nat.c alphabsd-nat.c alpha-linux-nat.c linux-fork.c \
-	alpha-tdep.c alpha-linux-tdep.c alphabsd-tdep.c alphanbsd-tdep.c \
-	alpha-osf1-tdep.c alphafbsd-tdep.c alpha-mdebug-tdep.c \
+	alpha-nat.c alphabsd-nat.c alpha-linux-nat.c \
+	alpha-tdep.c alpha-mdebug-tdep.c \
+	alpha-linux-tdep.c alpha-osf1-tdep.c \
+	alphabsd-tdep.c alphafbsd-tdep.c alphanbsd-tdep.c alphaobsd-tdep.c \
 	amd64-nat.c amd64-tdep.c \
 	amd64bsd-nat.c amd64fbsd-nat.c amd64fbsd-tdep.c \
 	amd64nbsd-nat.c amd64nbsd-tdep.c \
@@ -1440,6 +1441,7 @@ ALLDEPFILES = \
 	inf-ptrace.c inf-ttrace.c \
 	infptrace.c inftarg.c irix5-nat.c \
 	libunwind-frame.c \
+	linux-fork.c \
 	lynx-nat.c \
 	m68hc11-tdep.c \
 	m32r-tdep.c \
@@ -1711,6 +1713,8 @@ alphanbsd-tdep.o: alphanbsd-tdep.c $(def
 	$(regcache_h) $(regset_h) $(value_h) $(osabi_h) $(gdb_string_h) \
 	$(gdb_assert_h) $(alpha_tdep_h) $(alphabsd_tdep_h) $(nbsd_tdep_h) \
 	$(solib_svr4_h)
+alphaobsd-tdep.o: alphaobsd-tdep.c $(defs_h) $(frame_h) $(gdbcore_h) \
+	$(osabi_h) $(alpha_tdep_h) $(alphabsd_tdep_h) $(solib_svr4_h)
 alpha-osf1-tdep.o: alpha-osf1-tdep.c $(defs_h) $(frame_h) $(gdbcore_h) \
 	$(value_h) $(osabi_h) $(gdb_string_h) $(objfiles_h) $(alpha_tdep_h)
 alpha-tdep.o: alpha-tdep.c $(defs_h) $(doublest_h) $(frame_h) \
Index: configure.tgt
===================================================================
RCS file: /cvs/src/src/gdb/configure.tgt,v
retrieving revision 1.173
diff -u -p -r1.173 configure.tgt
--- configure.tgt 19 Jun 2006 01:23:26 -0000 1.173
+++ configure.tgt 10 Jul 2006 19:37:04 -0000
@@ -45,7 +45,7 @@ alpha*-*-osf*)		gdb_target=alpha-osf1 ;;
 alpha*-*-linux*)	gdb_target=alpha-linux ;;
 alpha*-*-netbsd* | alpha*-*-knetbsd*-gnu)
 			gdb_target=nbsd ;;
-alpha*-*-openbsd*)	gdb_target=nbsd ;;
+alpha*-*-openbsd*)	gdb_target=obsd ;;
 alpha*-*-*)		gdb_target=alpha ;;
 
 # mn10300 / am33 liunux
Index: config/alpha/obsd.mt
===================================================================
RCS file: config/alpha/obsd.mt
diff -N config/alpha/obsd.mt
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ config/alpha/obsd.mt 10 Jul 2006 19:37:04 -0000
@@ -0,0 +1,4 @@
+# Target: OpenBSD/alpha
+TDEPFILES= alpha-tdep.o alpha-mdebug-tdep.o \
+	alphabsd-tdep.o alphanbsd-tdep.o alphaobsd-tdep.o nbsd-tdep.o \
+	corelow.o solib.o solib-svr4.o