* i386obsd-nat.c: Include "gdbcore.h", "regcache.h", "target.h",

<machine/frame.h>, <machine/pcb.h>, "i386bsd-nat.h" and
"bsd-kvm.h".
(i386obsd_supply_pcb): New function.
(_initialize_i386obsd_nat): Construct and add target
vector. Enable libkvm interface.
* Makefile.in (i386obsd-nat.o): Update dependencies.
* config/i386/obsd.mh (NATDEPFILES): Remove i386nbsd-nat.c

gdb/ChangeLog

@@ -1,5 +1,14 @@
 2006-12-16  Mark Kettenis  <kettenis@gnu.org>
 
+	* i386obsd-nat.c: Include "gdbcore.h", "regcache.h", "target.h",
+	<machine/frame.h>, <machine/pcb.h>, "i386bsd-nat.h" and
+	"bsd-kvm.h".
+	(i386obsd_supply_pcb): New function.
+	(_initialize_i386obsd_nat): Construct and add target
+	vector. Enable libkvm interface.
+	* Makefile.in (i386obsd-nat.o): Update dependencies.
+	* config/i386/obsd.mh (NATDEPFILES): Remove i386nbsd-nat.c
+
 	* sparcobsd-tdep.c: Fix typo.
 
 	Add OpenBSD/sh native support.

gdb/Makefile.in

@@ -2132,7 +2132,8 @@ i386nbsd-tdep.o: i386nbsd-tdep.c $(defs_h) $(arch_utils_h) $(frame_h) \
 i386-nto-tdep.o: i386-nto-tdep.c $(defs_h) $(frame_h) $(osabi_h) \
 	$(regcache_h) $(target_h) $(gdb_assert_h) $(gdb_string_h) \
 	$(i386_tdep_h) $(i387_tdep_h) $(nto_tdep_h) $(solib_svr4_h)
-i386obsd-nat.o: i386obsd-nat.c $(defs_h) $(i386_tdep_h)
+i386obsd-nat.o: i386obsd-nat.c $(defs_h) $(gdbcore_h) $(regcache_h) \
+	$(target_h) $(i386_tdep_h) $(i386bsd_nat_h) $(bsd_kvm_h)
 i386obsd-tdep.o: i386obsd-tdep.c $(defs_h) $(arch_utils_h) $(frame_h) \
 	$(frame_unwind_h) $(gdbcore_h) $(regcache_h) $(regset_h) $(symtab_h) \
 	$(objfiles_h) $(osabi_h) $(target_h) $(trad_frame_h) $(gdb_assert_h) \

gdb/config/i386/obsd.mh

@@ -1,5 +1,5 @@
 # Host: OpenBSD/i386 ELF
 NATDEPFILES= fork-child.o inf-ptrace.o \
-	i386bsd-nat.o i386obsd-nat.o i386nbsd-nat.o bsd-kvm.o
+	i386bsd-nat.o i386obsd-nat.o bsd-kvm.o
 
 LOADLIBES= -lkvm

gdb/i386obsd-nat.c

@@ -1,6 +1,6 @@
 /* Native-dependent code for OpenBSD/i386.
 
-   Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
+   Copyright (C) 2002, 2003, 2004, 2006 Free Software Foundation, Inc.
 
    This file is part of GDB.
 
@@ -20,11 +20,70 @@
    Boston, MA 02110-1301, USA.  */
 
 #include "defs.h"
+#include "gdbcore.h"
+#include "regcache.h"
+#include "target.h"
 
 #include <sys/param.h>
 #include <sys/sysctl.h>
+#include <machine/frame.h>
+#include <machine/pcb.h>
 
 #include "i386-tdep.h"
+#include "i386bsd-nat.h"
+#include "bsd-kvm.h"
+
+static int
+i386obsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
+{
+  struct switchframe sf;
+
+  /* The following is true for OpenBSD 3.6:
+
+     The pcb contains %esp and %ebp at the point of the context switch
+     in cpu_switch().  At that point we have a stack frame as
+     described by `struct switchframe', which for OpenBSD 3.6 has the
+     following layout:
+
+     interrupt level
+     %edi
+     %esi
+     %ebx
+     %eip
+
+     we reconstruct the register state as it would look when we just
+     returned from cpu_switch().  */
+
+  /* The stack pointer shouldn't be zero.  */
+  if (pcb->pcb_esp == 0)
+    return 0;
+
+  /* Read the stack frame, and check its validity.  We do this by
+     checking if the saved interrupt priority level in the stack frame
+     looks reasonable..  */
+  read_memory (pcb->pcb_esp, (char *) &sf, sizeof sf);
+  if ((unsigned int) sf.sf_ppl < 0x100 && (sf.sf_ppl & 0xf) == 0)
+    {
+      /* Yes, we have a frame that matches cpu_switch().  */
+      pcb->pcb_esp += sizeof (struct switchframe);
+      regcache_raw_supply (regcache, I386_EDI_REGNUM, &sf.sf_edi);
+      regcache_raw_supply (regcache, I386_ESI_REGNUM, &sf.sf_esi);
+      regcache_raw_supply (regcache, I386_EBX_REGNUM, &sf.sf_ebx);
+      regcache_raw_supply (regcache, I386_EIP_REGNUM, &sf.sf_eip);
+    }
+  else
+    {
+      /* No, the pcb must have been last updated by savectx().  */
+      pcb->pcb_esp += 4;
+      regcache_raw_supply (regcache, I386_EIP_REGNUM, &sf);
+    }
+
+  regcache_raw_supply (regcache, I386_EBP_REGNUM, &pcb->pcb_ebp);
+  regcache_raw_supply (regcache, I386_ESP_REGNUM, &pcb->pcb_esp);
+
+  return 1;
+}
+
 
 /* Prevent warning from -Wmissing-prototypes.  */
 void _initialize_i386obsd_nat (void);
@@ -32,6 +91,12 @@ void _initialize_i386obsd_nat (void);
 void
 _initialize_i386obsd_nat (void)
 {
+  /* We've got nothing to add to the common *BSD/i386 target.  */
+  add_target (i386bsd_target ());
+
+  /* Support debugging kernel virtual memory images.  */
+  bsd_kvm_add_target (i386obsd_supply_pcb);
+
   /* OpenBSD provides a vm.psstrings sysctl that we can use to locate
      the sigtramp.  That way we can still recognize a sigtramp if its
      location is changed in a new kernel.  This is especially