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/* Native-dependent code for OpenBSD/i386.
Copyright (C) 2002-2021 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
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 <>. */
#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 = regcache->arch ();
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
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.. */
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 (I386_EDI_REGNUM, &sf.sf_edi);
regcache->raw_supply (I386_ESI_REGNUM, &sf.sf_esi);
regcache->raw_supply (I386_EBX_REGNUM, &sf.sf_ebx);
regcache->raw_supply (I386_EIP_REGNUM, &sf.sf_eip);
/* 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 (I386_EIP_REGNUM, &sf.sf_eip);
regcache->raw_supply (I386_EBP_REGNUM, &pcb->pcb_ebp);
regcache->raw_supply (I386_ESP_REGNUM, &pcb->pcb_esp);
return 1;
static i386_bsd_nat_target<obsd_nat_target> the_i386_obsd_nat_target;
void _initialize_i386obsd_nat ();
_initialize_i386obsd_nat ()
add_inf_child_target (&i386_obsd_nat_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. */
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;