| /* 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 |
| 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 |
| } |