/* Native-dependent code for OpenBSD/i386. Copyright (C) 2002, 2003, 2004, 2006, 2007, 2008 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/param.h> #include <sys/sysctl.h> #include <machine/frame.h> #include <machine/pcb.h> #include "i386-tdep.h" #include "i386bsd-nat.h" #include "bsd-kvm.h" static int i386obsd_supply_pcb (struct regcache *regcache, struct pcb *pcb) { 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.. */ read_memory (pcb->pcb_esp, (char *) &sf, sizeof sf); if ((unsigned int) sf.sf_ppl < 0x100 && (sf.sf_ppl & 0xf) == 0) { /* Yes, we have a frame that matches cpu_switch(). */ 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 { /* No, the pcb must have been last updated by savectx(). */ pcb->pcb_esp += 4; regcache_raw_supply (regcache, I386_EIP_REGNUM, &sf); } 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) { /* We've got nothing to add to the common *BSD/i386 target. */ 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 }