1 files changed, 129 insertions, 0 deletions
diff --git a/gdb/i386-obsd-nat.c b/gdb/i386-obsd-nat.c
new file mode 100644
index 0000000..42fedee
--- /dev/null
+++ b/gdb/i386-obsd-nat.c
@@ -0,0 +1,129 @@
+/* Native-dependent code for OpenBSD/i386.
+
+   Copyright (C) 2002-2016 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 3 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, see <http://www.gnu.org/licenses/>.  */
+
+#include "defs.h"
+#include "gdbcore.h"
+#include "regcache.h"
+#include "target.h"
+
+#include <sys/sysctl.h>
+#include <machine/frame.h>
+#include <machine/pcb.h>
+
+#include "i386-tdep.h"
+#include "i386-bsd-nat.h"
+#include "obsd-nat.h"
+#include "bsd-kvm.h"
+
+static int
+i386obsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
+{
+  struct gdbarch *gdbarch = get_regcache_arch (regcache);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  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..  */
+#ifdef PCB_SAVECTX
+  if ((pcb->pcb_flags & PCB_SAVECTX) == 0)
+    {
+      /* Yes, we have a frame that matches cpu_switch().  */
+      read_memory (pcb->pcb_esp, (gdb_byte *) &sf, sizeof sf);
+      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
+#endif
+    {
+      /* No, the pcb must have been last updated by savectx().  */
+      pcb->pcb_esp = pcb->pcb_ebp;
+      pcb->pcb_ebp = read_memory_integer(pcb->pcb_esp, 4, byte_order);
+      sf.sf_eip = read_memory_integer(pcb->pcb_esp + 4, 4, byte_order);
+      regcache_raw_supply (regcache, I386_EIP_REGNUM, &sf.sf_eip);
+    }
+
+  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);
+
+void
+_initialize_i386obsd_nat (void)
+{
+  /* Add some extra features to the common *BSD/i386 target.  */
+  obsd_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
+     important for OpenBSD, since it uses a different memory layout
+     than NetBSD, yet we cannot distinguish between the two.
+
+     Of course this is still based on the assumption that the sigtramp
+     is placed directly under the location where the program arguments
+     and environment can be found.  */
+#ifdef VM_PSSTRINGS
+  {
+    struct _ps_strings _ps;
+    int mib[2];
+    size_t len;
+
+    mib[0] = CTL_VM;
+    mib[1] = VM_PSSTRINGS;
+    len = sizeof (_ps);
+    if (sysctl (mib, 2, &_ps, &len, NULL, 0) == 0)
+      {
+	i386obsd_sigtramp_start_addr = (u_long) _ps.val - 128;
+	i386obsd_sigtramp_end_addr = (u_long) _ps.val;
+      }
+  }
+#endif
+}