1 /* Native-dependent code for FreeBSD/i386. 2 3 Copyright (C) 2001-2020 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 "gdbsupport/x86-xstate.h" 34 #include "x86-bsd-nat.h" 35 #include "i386-bsd-nat.h" 36 37 class i386_fbsd_nat_target final 38 : public i386_bsd_nat_target<fbsd_nat_target> 39 { 40 public: 41 /* Add some extra features to the common *BSD/i386 target. */ 42 #ifdef PT_GETXSTATE_INFO 43 const struct target_desc *read_description () override; 44 #endif 45 46 void resume (ptid_t, int, enum gdb_signal) override; 47 48 #if defined(HAVE_PT_GETDBREGS) && defined(USE_SIGTRAP_SIGINFO) 49 bool supports_stopped_by_hw_breakpoint () override; 50 #endif 51 }; 52 53 static i386_fbsd_nat_target the_i386_fbsd_nat_target; 54 55 /* Resume execution of the inferior process. If STEP is nonzero, 56 single-step it. If SIGNAL is nonzero, give it that signal. */ 57 58 void 59 i386_fbsd_nat_target::resume (ptid_t ptid, int step, enum gdb_signal signal) 60 { 61 pid_t pid = ptid.pid (); 62 int request = PT_STEP; 63 64 if (pid == -1) 65 /* Resume all threads. This only gets used in the non-threaded 66 case, where "resume all threads" and "resume inferior_ptid" are 67 the same. */ 68 pid = inferior_ptid.pid (); 69 70 if (!step) 71 { 72 struct regcache *regcache = get_current_regcache (); 73 ULONGEST eflags; 74 75 /* Workaround for a bug in FreeBSD. Make sure that the trace 76 flag is off when doing a continue. There is a code path 77 through the kernel which leaves the flag set when it should 78 have been cleared. If a process has a signal pending (such 79 as SIGALRM) and we do a PT_STEP, the process never really has 80 a chance to run because the kernel needs to notify the 81 debugger that a signal is being sent. Therefore, the process 82 never goes through the kernel's trap() function which would 83 normally clear it. */ 84 85 regcache_cooked_read_unsigned (regcache, I386_EFLAGS_REGNUM, 86 &eflags); 87 if (eflags & 0x0100) 88 regcache_cooked_write_unsigned (regcache, I386_EFLAGS_REGNUM, 89 eflags & ~0x0100); 90 91 request = PT_CONTINUE; 92 } 93 94 /* An addres of (caddr_t) 1 tells ptrace to continue from where it 95 was. (If GDB wanted it to start some other way, we have already 96 written a new PC value to the child.) */ 97 if (ptrace (request, pid, (caddr_t) 1, 98 gdb_signal_to_host (signal)) == -1) 99 perror_with_name (("ptrace")); 100 } 101 102 103 /* Support for debugging kernel virtual memory images. */ 104 105 #include <machine/pcb.h> 106 107 #include "bsd-kvm.h" 108 109 static int 110 i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb) 111 { 112 /* The following is true for FreeBSD 4.7: 113 114 The pcb contains %eip, %ebx, %esp, %ebp, %esi, %edi and %gs. 115 This accounts for all callee-saved registers specified by the 116 psABI and then some. Here %esp contains the stack pointer at the 117 point just after the call to cpu_switch(). From this information 118 we reconstruct the register state as it would look when we just 119 returned from cpu_switch(). */ 120 121 /* The stack pointer shouldn't be zero. */ 122 if (pcb->pcb_esp == 0) 123 return 0; 124 125 pcb->pcb_esp += 4; 126 regcache->raw_supply (I386_EDI_REGNUM, &pcb->pcb_edi); 127 regcache->raw_supply (I386_ESI_REGNUM, &pcb->pcb_esi); 128 regcache->raw_supply (I386_EBP_REGNUM, &pcb->pcb_ebp); 129 regcache->raw_supply (I386_ESP_REGNUM, &pcb->pcb_esp); 130 regcache->raw_supply (I386_EBX_REGNUM, &pcb->pcb_ebx); 131 regcache->raw_supply (I386_EIP_REGNUM, &pcb->pcb_eip); 132 regcache->raw_supply (I386_GS_REGNUM, &pcb->pcb_gs); 133 134 return 1; 135 } 136 137 138 #ifdef PT_GETXSTATE_INFO 139 /* Implement the read_description method. */ 140 141 const struct target_desc * 142 i386_fbsd_nat_target::read_description () 143 { 144 static int xsave_probed; 145 static uint64_t xcr0; 146 147 if (!xsave_probed) 148 { 149 struct ptrace_xstate_info info; 150 151 if (ptrace (PT_GETXSTATE_INFO, inferior_ptid.pid (), 152 (PTRACE_TYPE_ARG3) &info, sizeof (info)) == 0) 153 { 154 x86bsd_xsave_len = info.xsave_len; 155 xcr0 = info.xsave_mask; 156 } 157 xsave_probed = 1; 158 } 159 160 if (x86bsd_xsave_len == 0) 161 xcr0 = X86_XSTATE_SSE_MASK; 162 163 return i386_target_description (xcr0, true); 164 } 165 #endif 166 167 #if defined(HAVE_PT_GETDBREGS) && defined(USE_SIGTRAP_SIGINFO) 168 /* Implement the supports_stopped_by_hw_breakpoints method. */ 169 170 bool 171 i386_fbsd_nat_target::supports_stopped_by_hw_breakpoint () 172 { 173 return true; 174 } 175 #endif 176 177 void _initialize_i386fbsd_nat (); 178 void 179 _initialize_i386fbsd_nat () 180 { 181 add_inf_child_target (&the_i386_fbsd_nat_target); 182 183 /* Support debugging kernel virtual memory images. */ 184 bsd_kvm_add_target (i386fbsd_supply_pcb); 185 186 #ifdef KERN_PROC_SIGTRAMP 187 /* Normally signal frames are detected via i386fbsd_sigtramp_p. 188 However, FreeBSD 9.2 through 10.1 do not include the page holding 189 the signal code in core dumps. These releases do provide a 190 kern.proc.sigtramp.<pid> sysctl that returns the location of the 191 signal trampoline for a running process. We fetch the location 192 of the current (gdb) process and use this to identify signal 193 frames in core dumps from these releases. */ 194 { 195 int mib[4]; 196 struct kinfo_sigtramp kst; 197 size_t len; 198 199 mib[0] = CTL_KERN; 200 mib[1] = KERN_PROC; 201 mib[2] = KERN_PROC_SIGTRAMP; 202 mib[3] = getpid (); 203 len = sizeof (kst); 204 if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0) 205 { 206 i386fbsd_sigtramp_start_addr = (uintptr_t) kst.ksigtramp_start; 207 i386fbsd_sigtramp_end_addr = (uintptr_t) kst.ksigtramp_end; 208 } 209 } 210 #endif 211 } 212