1 /* Native-dependent code for OpenBSD/i386. 2 3 Copyright 2002, 2003, 2004 Free Software Foundation, Inc. 4 5 This file is part of GDB. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 2 of the License, or 10 (at your option) any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program; if not, write to the Free Software 19 Foundation, Inc., 59 Temple Place - Suite 330, 20 Boston, MA 02111-1307, USA. */ 21 22 #include "defs.h" 23 #include "gdbcore.h" 24 #include "regcache.h" 25 #include "target.h" 26 27 #include "i386-tdep.h" 28 #include "i386bsd-nat.h" 29 30 #include <sys/param.h> 31 #include <sys/sysctl.h> 32 33 /* Support for debugging kernel virtual memory images. */ 34 35 #include <machine/frame.h> 36 #include <machine/pcb.h> 37 38 #include "bsd-kvm.h" 39 40 static int 41 i386obsd_supply_pcb (struct regcache *regcache, struct pcb *pcb) 42 { 43 struct switchframe sf; 44 45 /* The following is true for OpenBSD 4.3: 46 47 The pcb contains %esp and %ebp at the point of the context switch 48 in cpu_switchto(). At that point we have a stack frame as 49 described by `struct switchframe', which for OpenBSD 4.3 has the 50 following layout: 51 52 %edi 53 %esi 54 %ebx 55 %eip 56 57 we reconstruct the register state as it would look when we just 58 returned from cpu_switchto(). 59 60 For crash dumps, the state is saved by savectx(). In that case 61 we just reconstruct the register state as if we just returned 62 from dumsys(). */ 63 64 /* The stack pointer shouldn't be zero. */ 65 if (pcb->pcb_esp == 0) 66 return 0; 67 68 if ((pcb->pcb_flags & PCB_SAVECTX) == 0) 69 { 70 /* Yes, we have a frame that matches cpu_switchto(). */ 71 read_memory (pcb->pcb_esp, (char *) &sf, sizeof sf); 72 pcb->pcb_esp += sizeof (struct switchframe); 73 regcache_raw_supply (regcache, I386_EDI_REGNUM, &sf.sf_edi); 74 regcache_raw_supply (regcache, I386_ESI_REGNUM, &sf.sf_esi); 75 regcache_raw_supply (regcache, I386_EBX_REGNUM, &sf.sf_ebx); 76 regcache_raw_supply (regcache, I386_EIP_REGNUM, &sf.sf_eip); 77 } 78 else 79 { 80 /* No, the pcb must have been last updated by savectx(). */ 81 pcb->pcb_esp = pcb->pcb_ebp; 82 pcb->pcb_ebp = read_memory_integer(pcb->pcb_esp, 4); 83 sf.sf_eip = read_memory_integer(pcb->pcb_esp + 4, 4); 84 regcache_raw_supply (regcache, I386_EIP_REGNUM, &sf.sf_eip); 85 } 86 87 regcache_raw_supply (regcache, I386_EBP_REGNUM, &pcb->pcb_ebp); 88 regcache_raw_supply (regcache, I386_ESP_REGNUM, &pcb->pcb_esp); 89 90 return 1; 91 } 92 93 94 /* Prevent warning from -Wmissing-prototypes. */ 95 void _initialize_i386obsd_nat (void); 96 97 void 98 _initialize_i386obsd_nat (void) 99 { 100 /* OpenBSD provides a vm.psstrings sysctl that we can use to locate 101 the sigtramp. That way we can still recognize a sigtramp if its 102 location is changed in a new kernel. This is especially 103 important for OpenBSD, since it uses a different memory layout 104 than NetBSD, yet we cannot distinguish between the two. 105 106 Of course this is still based on the assumption that the sigtramp 107 is placed directly under the location where the program arguments 108 and environment can be found. */ 109 #ifdef VM_PSSTRINGS 110 { 111 struct _ps_strings _ps; 112 int mib[2]; 113 size_t len; 114 115 mib[0] = CTL_VM; 116 mib[1] = VM_PSSTRINGS; 117 len = sizeof (_ps); 118 if (sysctl (mib, 2, &_ps, &len, NULL, 0) == 0) 119 { 120 i386obsd_sigtramp_start_addr = (CORE_ADDR)_ps.val - 128; 121 i386obsd_sigtramp_end_addr = (CORE_ADDR)_ps.val; 122 } 123 } 124 #endif 125 126 /* We've got nothing to add to the common *BSD/i386 target. */ 127 add_target (i386bsd_target ()); 128 129 /* Support debugging kernel virtual memory images. */ 130 bsd_kvm_add_target (i386obsd_supply_pcb); 131 } 132