1 /* Native-dependent code for FreeBSD/i386. 2 3 Copyright (C) 2001-2017 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 "inferior.h" 22 #include "regcache.h" 23 #include "target.h" 24 25 #include <sys/types.h> 26 #include <sys/ptrace.h> 27 #include <sys/sysctl.h> 28 #include <sys/user.h> 29 30 #include "fbsd-nat.h" 31 #include "i386-tdep.h" 32 #include "x86-nat.h" 33 #include "x86-bsd-nat.h" 34 #include "i386-bsd-nat.h" 35 36 /* Resume execution of the inferior process. If STEP is nonzero, 37 single-step it. If SIGNAL is nonzero, give it that signal. */ 38 39 static void 40 i386fbsd_resume (struct target_ops *ops, 41 ptid_t ptid, int step, enum gdb_signal signal) 42 { 43 pid_t pid = ptid_get_pid (ptid); 44 int request = PT_STEP; 45 46 if (pid == -1) 47 /* Resume all threads. This only gets used in the non-threaded 48 case, where "resume all threads" and "resume inferior_ptid" are 49 the same. */ 50 pid = ptid_get_pid (inferior_ptid); 51 52 if (!step) 53 { 54 struct regcache *regcache = get_current_regcache (); 55 ULONGEST eflags; 56 57 /* Workaround for a bug in FreeBSD. Make sure that the trace 58 flag is off when doing a continue. There is a code path 59 through the kernel which leaves the flag set when it should 60 have been cleared. If a process has a signal pending (such 61 as SIGALRM) and we do a PT_STEP, the process never really has 62 a chance to run because the kernel needs to notify the 63 debugger that a signal is being sent. Therefore, the process 64 never goes through the kernel's trap() function which would 65 normally clear it. */ 66 67 regcache_cooked_read_unsigned (regcache, I386_EFLAGS_REGNUM, 68 &eflags); 69 if (eflags & 0x0100) 70 regcache_cooked_write_unsigned (regcache, I386_EFLAGS_REGNUM, 71 eflags & ~0x0100); 72 73 request = PT_CONTINUE; 74 } 75 76 /* An addres of (caddr_t) 1 tells ptrace to continue from where it 77 was. (If GDB wanted it to start some other way, we have already 78 written a new PC value to the child.) */ 79 if (ptrace (request, pid, (caddr_t) 1, 80 gdb_signal_to_host (signal)) == -1) 81 perror_with_name (("ptrace")); 82 } 83 84 85 /* Support for debugging kernel virtual memory images. */ 86 87 #include <machine/pcb.h> 88 89 #include "bsd-kvm.h" 90 91 static int 92 i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb) 93 { 94 /* The following is true for FreeBSD 4.7: 95 96 The pcb contains %eip, %ebx, %esp, %ebp, %esi, %edi and %gs. 97 This accounts for all callee-saved registers specified by the 98 psABI and then some. Here %esp contains the stack pointer at the 99 point just after the call to cpu_switch(). From this information 100 we reconstruct the register state as it would look when we just 101 returned from cpu_switch(). */ 102 103 /* The stack pointer shouldn't be zero. */ 104 if (pcb->pcb_esp == 0) 105 return 0; 106 107 pcb->pcb_esp += 4; 108 regcache_raw_supply (regcache, I386_EDI_REGNUM, &pcb->pcb_edi); 109 regcache_raw_supply (regcache, I386_ESI_REGNUM, &pcb->pcb_esi); 110 regcache_raw_supply (regcache, I386_EBP_REGNUM, &pcb->pcb_ebp); 111 regcache_raw_supply (regcache, I386_ESP_REGNUM, &pcb->pcb_esp); 112 regcache_raw_supply (regcache, I386_EBX_REGNUM, &pcb->pcb_ebx); 113 regcache_raw_supply (regcache, I386_EIP_REGNUM, &pcb->pcb_eip); 114 regcache_raw_supply (regcache, I386_GS_REGNUM, &pcb->pcb_gs); 115 116 return 1; 117 } 118 119 120 #ifdef PT_GETXSTATE_INFO 121 /* Implement the to_read_description method. */ 122 123 static const struct target_desc * 124 i386fbsd_read_description (struct target_ops *ops) 125 { 126 static int xsave_probed; 127 static uint64_t xcr0; 128 129 if (!xsave_probed) 130 { 131 struct ptrace_xstate_info info; 132 133 if (ptrace (PT_GETXSTATE_INFO, ptid_get_pid (inferior_ptid), 134 (PTRACE_TYPE_ARG3) &info, sizeof (info)) == 0) 135 { 136 x86bsd_xsave_len = info.xsave_len; 137 xcr0 = info.xsave_mask; 138 } 139 xsave_probed = 1; 140 } 141 142 if (x86bsd_xsave_len != 0) 143 { 144 return i386_target_description (xcr0); 145 } 146 else 147 return tdesc_i386; 148 } 149 #endif 150 151 /* Prevent warning from -Wmissing-prototypes. */ 152 void _initialize_i386fbsd_nat (void); 153 154 void 155 _initialize_i386fbsd_nat (void) 156 { 157 struct target_ops *t; 158 159 /* Add some extra features to the common *BSD/i386 target. */ 160 t = i386bsd_target (); 161 162 #ifdef PT_GETXSTATE_INFO 163 t->to_read_description = i386fbsd_read_description; 164 #endif 165 166 t->to_resume = i386fbsd_resume; 167 fbsd_nat_add_target (t); 168 169 /* Support debugging kernel virtual memory images. */ 170 bsd_kvm_add_target (i386fbsd_supply_pcb); 171 172 #ifdef KERN_PROC_SIGTRAMP 173 /* Normally signal frames are detected via i386fbsd_sigtramp_p. 174 However, FreeBSD 9.2 through 10.1 do not include the page holding 175 the signal code in core dumps. These releases do provide a 176 kern.proc.sigtramp.<pid> sysctl that returns the location of the 177 signal trampoline for a running process. We fetch the location 178 of the current (gdb) process and use this to identify signal 179 frames in core dumps from these releases. */ 180 { 181 int mib[4]; 182 struct kinfo_sigtramp kst; 183 size_t len; 184 185 mib[0] = CTL_KERN; 186 mib[1] = KERN_PROC; 187 mib[2] = KERN_PROC_SIGTRAMP; 188 mib[3] = getpid (); 189 len = sizeof (kst); 190 if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0) 191 { 192 i386fbsd_sigtramp_start_addr = (uintptr_t) kst.ksigtramp_start; 193 i386fbsd_sigtramp_end_addr = (uintptr_t) kst.ksigtramp_end; 194 } 195 } 196 #endif 197 } 198