1/* Native-dependent code for OpenBSD/i386. 2 3 Copyright (C) 2002-2023 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 3 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, see <http://www.gnu.org/licenses/>. */ 19 20#include "defs.h" 21#include "gdbcore.h" 22#include "regcache.h" 23#include "target.h" 24 25#include <sys/sysctl.h> 26#include <machine/frame.h> 27#include <machine/pcb.h> 28 29#include "i386-tdep.h" 30#include "i386-bsd-nat.h" 31#include "obsd-nat.h" 32#include "bsd-kvm.h" 33 34static int 35i386obsd_supply_pcb (struct regcache *regcache, struct pcb *pcb) 36{ 37 struct gdbarch *gdbarch = regcache->arch (); 38 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); 39 struct switchframe sf; 40 41 /* The following is true for OpenBSD 3.6: 42 43 The pcb contains %esp and %ebp at the point of the context switch 44 in cpu_switch(). At that point we have a stack frame as 45 described by `struct switchframe', which for OpenBSD 3.6 has the 46 following layout: 47 48 interrupt level 49 %edi 50 %esi 51 %ebx 52 %eip 53 54 we reconstruct the register state as it would look when we just 55 returned from cpu_switch(). */ 56 57 /* The stack pointer shouldn't be zero. */ 58 if (pcb->pcb_esp == 0) 59 return 0; 60 61 /* Read the stack frame, and check its validity. We do this by 62 checking if the saved interrupt priority level in the stack frame 63 looks reasonable.. */ 64#ifdef PCB_SAVECTX 65 if ((pcb->pcb_flags & PCB_SAVECTX) == 0) 66 { 67 /* Yes, we have a frame that matches cpu_switch(). */ 68 read_memory (pcb->pcb_esp, (gdb_byte *) &sf, sizeof sf); 69 pcb->pcb_esp += sizeof (struct switchframe); 70 regcache->raw_supply (I386_EDI_REGNUM, &sf.sf_edi); 71 regcache->raw_supply (I386_ESI_REGNUM, &sf.sf_esi); 72 regcache->raw_supply (I386_EBX_REGNUM, &sf.sf_ebx); 73 regcache->raw_supply (I386_EIP_REGNUM, &sf.sf_eip); 74 } 75 else 76#endif 77 { 78 /* No, the pcb must have been last updated by savectx(). */ 79 pcb->pcb_esp = pcb->pcb_ebp; 80 pcb->pcb_ebp = read_memory_integer(pcb->pcb_esp, 4, byte_order); 81 sf.sf_eip = read_memory_integer(pcb->pcb_esp + 4, 4, byte_order); 82 regcache->raw_supply (I386_EIP_REGNUM, &sf.sf_eip); 83 } 84 85 regcache->raw_supply (I386_EBP_REGNUM, &pcb->pcb_ebp); 86 regcache->raw_supply (I386_ESP_REGNUM, &pcb->pcb_esp); 87 88 return 1; 89} 90 91static i386_bsd_nat_target<obsd_nat_target> the_i386_obsd_nat_target; 92 93void _initialize_i386obsd_nat (); 94void 95_initialize_i386obsd_nat () 96{ 97 add_inf_child_target (&i386_obsd_nat_target); 98 99 /* Support debugging kernel virtual memory images. */ 100 bsd_kvm_add_target (i386obsd_supply_pcb); 101 102 /* OpenBSD provides a vm.psstrings sysctl that we can use to locate 103 the sigtramp. That way we can still recognize a sigtramp if its 104 location is changed in a new kernel. This is especially 105 important for OpenBSD, since it uses a different memory layout 106 than NetBSD, yet we cannot distinguish between the two. 107 108 Of course this is still based on the assumption that the sigtramp 109 is placed directly under the location where the program arguments 110 and environment can be found. */ 111#ifdef VM_PSSTRINGS 112 { 113 struct _ps_strings _ps; 114 int mib[2]; 115 size_t len; 116 117 mib[0] = CTL_VM; 118 mib[1] = VM_PSSTRINGS; 119 len = sizeof (_ps); 120 if (sysctl (mib, 2, &_ps, &len, NULL, 0) == 0) 121 { 122 i386obsd_sigtramp_start_addr = (u_long) _ps.val - 128; 123 i386obsd_sigtramp_end_addr = (u_long) _ps.val; 124 } 125 } 126#endif 127} 128