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- /* Native-dependent code for OpenBSD/i386.
- Copyright (C) 2002-2022 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 = 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
- %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 (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);
- }
- 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 (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 ();
- void
- _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. */
- #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
- }
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