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127 lines
3.9 KiB
C
127 lines
3.9 KiB
C
/* Native-dependent code for OpenBSD/i386.
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Copyright (C) 2002-2020 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "gdbcore.h"
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#include "regcache.h"
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#include "target.h"
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#include <sys/sysctl.h>
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#include <machine/frame.h>
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#include <machine/pcb.h>
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#include "i386-tdep.h"
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#include "i386-bsd-nat.h"
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#include "obsd-nat.h"
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#include "bsd-kvm.h"
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static int
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i386obsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
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{
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struct gdbarch *gdbarch = regcache->arch ();
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enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
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struct switchframe sf;
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/* The following is true for OpenBSD 3.6:
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The pcb contains %esp and %ebp at the point of the context switch
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in cpu_switch(). At that point we have a stack frame as
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described by `struct switchframe', which for OpenBSD 3.6 has the
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following layout:
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interrupt level
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%edi
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%esi
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%ebx
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%eip
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we reconstruct the register state as it would look when we just
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returned from cpu_switch(). */
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/* The stack pointer shouldn't be zero. */
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if (pcb->pcb_esp == 0)
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return 0;
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/* Read the stack frame, and check its validity. We do this by
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checking if the saved interrupt priority level in the stack frame
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looks reasonable.. */
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#ifdef PCB_SAVECTX
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if ((pcb->pcb_flags & PCB_SAVECTX) == 0)
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{
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/* Yes, we have a frame that matches cpu_switch(). */
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read_memory (pcb->pcb_esp, (gdb_byte *) &sf, sizeof sf);
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pcb->pcb_esp += sizeof (struct switchframe);
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regcache->raw_supply (I386_EDI_REGNUM, &sf.sf_edi);
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regcache->raw_supply (I386_ESI_REGNUM, &sf.sf_esi);
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regcache->raw_supply (I386_EBX_REGNUM, &sf.sf_ebx);
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regcache->raw_supply (I386_EIP_REGNUM, &sf.sf_eip);
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}
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else
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#endif
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{
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/* No, the pcb must have been last updated by savectx(). */
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pcb->pcb_esp = pcb->pcb_ebp;
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pcb->pcb_ebp = read_memory_integer(pcb->pcb_esp, 4, byte_order);
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sf.sf_eip = read_memory_integer(pcb->pcb_esp + 4, 4, byte_order);
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regcache->raw_supply (I386_EIP_REGNUM, &sf.sf_eip);
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}
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regcache->raw_supply (I386_EBP_REGNUM, &pcb->pcb_ebp);
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regcache->raw_supply (I386_ESP_REGNUM, &pcb->pcb_esp);
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return 1;
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}
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static i386_bsd_nat_target<obsd_nat_target> the_i386_obsd_nat_target;
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void
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_initialize_i386obsd_nat (void)
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{
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add_inf_child_target (&i386_obsd_nat_target);
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/* Support debugging kernel virtual memory images. */
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bsd_kvm_add_target (i386obsd_supply_pcb);
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/* OpenBSD provides a vm.psstrings sysctl that we can use to locate
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the sigtramp. That way we can still recognize a sigtramp if its
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location is changed in a new kernel. This is especially
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important for OpenBSD, since it uses a different memory layout
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than NetBSD, yet we cannot distinguish between the two.
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Of course this is still based on the assumption that the sigtramp
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is placed directly under the location where the program arguments
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and environment can be found. */
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#ifdef VM_PSSTRINGS
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{
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struct _ps_strings _ps;
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int mib[2];
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size_t len;
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mib[0] = CTL_VM;
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mib[1] = VM_PSSTRINGS;
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len = sizeof (_ps);
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if (sysctl (mib, 2, &_ps, &len, NULL, 0) == 0)
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{
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i386obsd_sigtramp_start_addr = (u_long) _ps.val - 128;
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i386obsd_sigtramp_end_addr = (u_long) _ps.val;
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}
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}
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#endif
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}
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