[commit] Add OpenBSD/vax sigtramp unwinder

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

Committed,

Mark

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

	* vaxobsd-tdep.c: New file.
	* config/vax/obsd.mt (TDEPFILES): Add vaxobsd-tdep.o.
	* Makefile.in (vaxobsd-tdep.o): New dependency.

Index: vaxobsd-tdep.c
===================================================================
RCS file: vaxobsd-tdep.c
diff -N vaxobsd-tdep.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ vaxobsd-tdep.c 21 Aug 2005 15:50:11 -0000
@@ -0,0 +1,190 @@
+/* Target-dependent code for OpenBSD/vax.
+
+   Copyright 2005 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., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include "defs.h"
+#include "arch-utils.h"
+#include "frame.h"
+#include "frame-unwind.h"
+#include "osabi.h"
+#include "symtab.h"
+#include "trad-frame.h"
+
+#include "vax-tdep.h"
+
+#include "gdb_string.h"
+
+/* Signal trampolines.  */
+
+/* Since OpenBSD 3.2, the sigtramp routine is mapped at a random page
+   in virtual memory.  The randomness makes it somewhat tricky to
+   detect it, but fortunately we can rely on the fact that the start
+   of the sigtramp routine is page-aligned.  We recognize the
+   trampoline by looking for the code that invokes the sigreturn
+   system call.  The offset where we can find that code varies from
+   release to release.
+
+   By the way, the mapping mentioned above is read-only, so you cannot
+   place a breakpoint in the signal trampoline.  */
+
+/* Default page size.  */
+static const int vaxobsd_page_size = 4096;
+
+/* Offset for sigreturn(2).  */
+static const int vaxobsd_sigreturn_offset = 0x11;
+
+/* Instruction sequence for sigreturn(2).  VAX doesn't have
+   fixed-length instructions so we include the ensuing exit(2) to
+   reduce the chance of spurious matches.  */
+static const gdb_byte vaxobsd_sigreturn[] = {
+  0xbc, 0x8f, 0x67, 0x00,	/* chmk $SYS_sigreturn */
+  0xbc, 0x01			/* chmk $SYS_exit */
+};
+
+static int
+vaxobsd_sigtramp_p (struct frame_info *next_frame)
+{
+  CORE_ADDR pc = frame_pc_unwind (next_frame);
+  CORE_ADDR start_pc = (pc & ~(vaxobsd_page_size - 1));
+  CORE_ADDR sigreturn_addr = start_pc + vaxobsd_sigreturn_offset;
+  gdb_byte *buf;
+  char *name;
+
+  find_pc_partial_function (pc, &name, NULL, NULL);
+  if (name)
+    return 0;
+
+  buf = alloca(sizeof vaxobsd_sigreturn);
+  if (!safe_frame_unwind_memory (next_frame, sigreturn_addr,
+				 buf, sizeof vaxobsd_sigreturn))
+    return 0;
+
+  if (memcmp(buf, vaxobsd_sigreturn, sizeof vaxobsd_sigreturn) == 0)
+    return 1;
+
+  return 0;
+}
+
+static struct trad_frame_cache *
+vaxobsd_sigtramp_frame_cache (struct frame_info *next_frame, void **this_cache)
+{
+  struct trad_frame_cache *cache;
+  CORE_ADDR addr, base, func;
+
+  if (*this_cache)
+    return *this_cache;
+
+  cache = trad_frame_cache_zalloc (next_frame);
+  *this_cache = cache;
+
+  func = frame_pc_unwind (next_frame);
+  func &= ~(vaxobsd_page_size - 1);
+
+  base = frame_unwind_register_unsigned (next_frame, VAX_SP_REGNUM);
+  addr = get_frame_memory_unsigned (next_frame, base - 4, 4);
+
+  trad_frame_set_reg_addr (cache, VAX_SP_REGNUM, addr + 8);
+  trad_frame_set_reg_addr (cache, VAX_FP_REGNUM, addr + 12);
+  trad_frame_set_reg_addr (cache, VAX_AP_REGNUM, addr + 16);
+  trad_frame_set_reg_addr (cache, VAX_PC_REGNUM, addr + 20);
+  trad_frame_set_reg_addr (cache, VAX_PS_REGNUM, addr + 24);
+
+  /* Construct the frame ID using the function start.  */
+  trad_frame_set_id (cache, frame_id_build (base, func));
+
+  return cache;
+}
+
+static void
+vaxobsd_sigtramp_frame_this_id (struct frame_info *next_frame,
+				void **this_cache, struct frame_id *this_id)
+{
+  struct trad_frame_cache *cache =
+    vaxobsd_sigtramp_frame_cache (next_frame, this_cache);
+
+  trad_frame_get_id (cache, this_id);
+}
+
+static void
+vaxobsd_sigtramp_frame_prev_register (struct frame_info *next_frame,
+				      void **this_cache, int regnum,
+				      int *optimizedp, enum lval_type *lvalp,
+				      CORE_ADDR *addrp, int *realnump,
+				      gdb_byte *valuep)
+{
+  struct trad_frame_cache *cache =
+    vaxobsd_sigtramp_frame_cache (next_frame, this_cache);
+
+  trad_frame_get_register (cache, next_frame, regnum,
+			   optimizedp, lvalp, addrp, realnump, valuep);
+}
+
+static const struct frame_unwind vaxobsd_sigtramp_frame_unwind = {
+  SIGTRAMP_FRAME,
+  vaxobsd_sigtramp_frame_this_id,
+  vaxobsd_sigtramp_frame_prev_register
+};
+
+static const struct frame_unwind *
+vaxobsd_sigtramp_frame_sniffer (struct frame_info *next_frame)
+{
+  if (vaxobsd_sigtramp_p (next_frame))
+    return &vaxobsd_sigtramp_frame_unwind;
+
+  return NULL;
+}
+
+
+/* OpenBSD a.out.  */
+
+static void
+vaxobsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+  frame_unwind_append_sniffer (gdbarch, vaxobsd_sigtramp_frame_sniffer);
+}
+
+/* FIXME: kettenis/20050821: Since OpenBSD/vax binaries are
+   indistingushable from NetBSD/vax a.out binaries, building a GDB
+   that should support both these targets will probably not work as
+   expected.  */
+#define GDB_OSABI_OPENBSD_AOUT GDB_OSABI_NETBSD_AOUT
+
+static enum gdb_osabi
+vaxobsd_aout_osabi_sniffer (bfd *abfd)
+{
+  if (strcmp (bfd_get_target (abfd), "a.out-vax-netbsd") == 0)
+    return GDB_OSABI_OPENBSD_AOUT;
+
+  return GDB_OSABI_UNKNOWN;
+}
+
+
+/* Provide a prototype to silence -Wmissing-prototypes.  */
+void _initialize_vaxobsd_tdep (void);
+
+void
+_initialize_vaxobsd_tdep (void)
+{
+  gdbarch_register_osabi_sniffer (bfd_arch_vax, bfd_target_aout_flavour,
+				  vaxobsd_aout_osabi_sniffer);
+
+  gdbarch_register_osabi (bfd_arch_vax, 0, GDB_OSABI_OPENBSD_AOUT,
+			  vaxobsd_init_abi);
+}
Index: Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.746
diff -u -p -r1.746 Makefile.in
--- Makefile.in 21 Aug 2005 10:47:48 -0000 1.746
+++ Makefile.in 21 Aug 2005 15:50:13 -0000
@@ -2732,6 +2732,9 @@ vax-nat.o: vax-nat.c $(defs_h) $(inferio
 	$(inf_ptrace_h)
 vaxnbsd-tdep.o: vaxnbsd-tdep.c $(defs_h) $(arch_utils_h) $(osabi_h) \
 	$(vax_tdep_h) $(solib_svr4_h) $(gdb_string_h)
+vaxobsd-tdep.o: vaxobsd-tdep.c  $(defs_h) $(arch_utils_h) $(frame_h) \
+	$(frame_unwind_h) $(osabi_h) $(symtab_h) $(trad_frame_h) \
+	$(vax_tdep_h) $(gdb_string_h)
 vax-tdep.o: vax-tdep.c $(defs_h) $(arch_utils_h) $(dis_asm_h) $(frame_h) \
 	$(frame_base_h) $(frame_unwind_h) $(gdbcore_h) $(gdbtypes_h) \
 	$(osabi_h) $(regcache_h) $(regset_h) $(trad_frame_h) $(value_h) \
Index: config/vax/obsd.mt
===================================================================
RCS file: /cvs/src/src/gdb/config/vax/obsd.mt,v
retrieving revision 1.1
diff -u -p -r1.1 obsd.mt
--- config/vax/obsd.mt 14 May 2005 20:21:03 -0000 1.1
+++ config/vax/obsd.mt 21 Aug 2005 15:50:13 -0000
@@ -1,2 +1,2 @@
 # Target: OpenBSD/vax
-TDEPFILES= vax-tdep.o corelow.o
+TDEPFILES= vax-tdep.o vaxobsd-tdep.o corelow.o