1/* DWARF2 EH unwinding support for FreeBSD: AMD x86-64 and x86. 2 Copyright (C) 2015-2022 Free Software Foundation, Inc. 3 Contributed by John Marino <gnugcc@marino.st> 4 5This file is part of GCC. 6 7GCC is free software; you can redistribute it and/or modify 8it under the terms of the GNU General Public License as published by 9the Free Software Foundation; either version 3, or (at your option) 10any later version. 11 12GCC is distributed in the hope that it will be useful, 13but WITHOUT ANY WARRANTY; without even the implied warranty of 14MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15GNU General Public License for more details. 16 17Under Section 7 of GPL version 3, you are granted additional 18permissions described in the GCC Runtime Library Exception, version 193.1, as published by the Free Software Foundation. 20 21You should have received a copy of the GNU General Public License and 22a copy of the GCC Runtime Library Exception along with this program; 23see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24<http://www.gnu.org/licenses/>. */ 25 26/* Do code reading to identify a signal frame, and set the frame 27 state data appropriately. See unwind-dw2.c for the structs. */ 28 29#include <sys/types.h> 30#include <signal.h> 31#include <unistd.h> 32#include <sys/sysctl.h> 33#include <sys/ucontext.h> 34#include <sys/user.h> 35#include <machine/sigframe.h> 36 37#define REG_NAME(reg) sf_uc.uc_mcontext.mc_## reg 38 39#ifdef __x86_64__ 40#define MD_FALLBACK_FRAME_STATE_FOR x86_64_freebsd_fallback_frame_state 41 42#ifdef KERN_PROC_SIGTRAMP 43/* FreeBSD past 9.3 provides a kern.proc.sigtramp.<pid> sysctl that 44 returns the location of the signal trampoline. Use this to find 45 out whether we're in a trampoline. 46*/ 47static int 48x86_64_outside_sigtramp_range (unsigned char *pc) 49{ 50 static int sigtramp_range_determined = 0; 51 static unsigned char *sigtramp_start, *sigtramp_end; 52 53 if (sigtramp_range_determined == 0) 54 { 55 struct kinfo_sigtramp kst = {0}; 56 size_t len = sizeof (kst); 57 int mib[4] = { CTL_KERN, KERN_PROC, KERN_PROC_SIGTRAMP, getpid() }; 58 59 sigtramp_range_determined = 1; 60 if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0) 61 { 62 sigtramp_range_determined = 2; 63 sigtramp_start = kst.ksigtramp_start; 64 sigtramp_end = kst.ksigtramp_end; 65 } 66 } 67 if (sigtramp_range_determined < 2) /* sysctl failed if < 2 */ 68 return 1; 69 70 return (pc < sigtramp_start || pc >= sigtramp_end); 71} 72#endif 73 74static _Unwind_Reason_Code 75x86_64_freebsd_fallback_frame_state 76(struct _Unwind_Context *context, _Unwind_FrameState *fs) 77{ 78 struct sigframe *sf; 79 long new_cfa; 80 81#ifndef KERN_PROC_SIGTRAMP 82 /* Prior to FreeBSD 9, the signal trampoline was located immediately 83 before the ps_strings. To support non-executable stacks on AMD64, 84 the sigtramp was moved to a shared page for FreeBSD 9. Unfortunately 85 this means looking frame patterns again (sys/amd64/amd64/sigtramp.S) 86 rather than using the robust and convenient KERN_PS_STRINGS trick. 87 88 <pc + 00>: lea 0x10(%rsp),%rdi 89 <pc + 05>: pushq $0x0 90 <pc + 17>: mov $0x1a1,%rax 91 <pc + 14>: syscall 92 93 If we can't find this pattern, we're at the end of the stack. 94 */ 95 96 if (!( *(unsigned int *)(context->ra) == 0x247c8d48 97 && *(unsigned int *)(context->ra + 4) == 0x48006a10 98 && *(unsigned int *)(context->ra + 8) == 0x01a1c0c7 99 && *(unsigned int *)(context->ra + 12) == 0x050f0000 )) 100 return _URC_END_OF_STACK; 101#else 102 if (x86_64_outside_sigtramp_range(context->ra)) 103 return _URC_END_OF_STACK; 104#endif 105 106 sf = (struct sigframe *) context->cfa; 107 new_cfa = sf->REG_NAME(rsp); 108 fs->regs.cfa_how = CFA_REG_OFFSET; 109 fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__; 110 fs->regs.cfa_offset = new_cfa - (long) context->cfa; 111 112 /* The SVR4 register numbering macros aren't usable in libgcc. */ 113 fs->regs.reg[0].how = REG_SAVED_OFFSET; 114 fs->regs.reg[0].loc.offset = (long)&sf->REG_NAME(rax) - new_cfa; 115 fs->regs.reg[1].how = REG_SAVED_OFFSET; 116 fs->regs.reg[1].loc.offset = (long)&sf->REG_NAME(rdx) - new_cfa; 117 fs->regs.reg[2].how = REG_SAVED_OFFSET; 118 fs->regs.reg[2].loc.offset = (long)&sf->REG_NAME(rcx) - new_cfa; 119 fs->regs.reg[3].how = REG_SAVED_OFFSET; 120 fs->regs.reg[3].loc.offset = (long)&sf->REG_NAME(rbx) - new_cfa; 121 fs->regs.reg[4].how = REG_SAVED_OFFSET; 122 fs->regs.reg[4].loc.offset = (long)&sf->REG_NAME(rsi) - new_cfa; 123 fs->regs.reg[5].how = REG_SAVED_OFFSET; 124 fs->regs.reg[5].loc.offset = (long)&sf->REG_NAME(rdi) - new_cfa; 125 fs->regs.reg[6].how = REG_SAVED_OFFSET; 126 fs->regs.reg[6].loc.offset = (long)&sf->REG_NAME(rbp) - new_cfa; 127 fs->regs.reg[8].how = REG_SAVED_OFFSET; 128 fs->regs.reg[8].loc.offset = (long)&sf->REG_NAME(r8) - new_cfa; 129 fs->regs.reg[9].how = REG_SAVED_OFFSET; 130 fs->regs.reg[9].loc.offset = (long)&sf->REG_NAME(r9) - new_cfa; 131 fs->regs.reg[10].how = REG_SAVED_OFFSET; 132 fs->regs.reg[10].loc.offset = (long)&sf->REG_NAME(r10) - new_cfa; 133 fs->regs.reg[11].how = REG_SAVED_OFFSET; 134 fs->regs.reg[11].loc.offset = (long)&sf->REG_NAME(r11) - new_cfa; 135 fs->regs.reg[12].how = REG_SAVED_OFFSET; 136 fs->regs.reg[12].loc.offset = (long)&sf->REG_NAME(r12) - new_cfa; 137 fs->regs.reg[13].how = REG_SAVED_OFFSET; 138 fs->regs.reg[13].loc.offset = (long)&sf->REG_NAME(r13) - new_cfa; 139 fs->regs.reg[14].how = REG_SAVED_OFFSET; 140 fs->regs.reg[14].loc.offset = (long)&sf->REG_NAME(r14) - new_cfa; 141 fs->regs.reg[15].how = REG_SAVED_OFFSET; 142 fs->regs.reg[15].loc.offset = (long)&sf->REG_NAME(r15) - new_cfa; 143 fs->regs.reg[16].how = REG_SAVED_OFFSET; 144 fs->regs.reg[16].loc.offset = (long)&sf->REG_NAME(rip) - new_cfa; 145 fs->retaddr_column = 16; 146 fs->signal_frame = 1; 147 return _URC_NO_REASON; 148} 149 150#else /* Next section is for i386 */ 151 152#define MD_FALLBACK_FRAME_STATE_FOR x86_freebsd_fallback_frame_state 153 154/* 155 * We can't use KERN_PS_STRINGS anymore if we want to support FreeBSD32 156 * compat on AMD64. The sigtramp is in a shared page in that case so the 157 * x86_sigtramp_range only works on a true i386 system. We have to 158 * search for the sigtramp frame if we want it working everywhere. 159 */ 160 161static _Unwind_Reason_Code 162x86_freebsd_fallback_frame_state 163(struct _Unwind_Context *context, _Unwind_FrameState *fs) 164{ 165 struct sigframe *sf; 166 long new_cfa; 167 168/* 169 * i386 sigtramp frame we are looking for follows. 170 * Apparently PSL_VM is variable, so we can't look past context->ra + 4 171 * <sigcode>: 172 * 0: ff 54 24 10 call *0x10(%esp) *SIGF_HANDLER 173 * 4: 8d 44 24 20 lea 0x20(%esp),%eax SIGF_UC 174 * 8: 50 push %eax 175 * 9: f7 40 54 00 00 02 00 testl $0x20000,0x54(%eax) $PSL_VM 176 * 10: 75 03 jne 15 <sigcode+0x15> 177 * 12: 8e 68 14 mov 0x14(%eax),%gs UC_GS 178 * 15: b8 a1 01 00 00 mov 0x1a1,%eax $SYS_sigreturn 179 */ 180 181 if (!( *(unsigned int *)(context->ra - 4) == 0x102454ff 182 && *(unsigned int *)(context->ra) == 0x2024448d )) 183 return _URC_END_OF_STACK; 184 185 sf = (struct sigframe *) context->cfa; 186 new_cfa = sf->REG_NAME(esp); 187 fs->regs.cfa_how = CFA_REG_OFFSET; 188 fs->regs.cfa_reg = 4; 189 fs->regs.cfa_offset = new_cfa - (long) context->cfa; 190 191 /* The SVR4 register numbering macros aren't usable in libgcc. */ 192 fs->regs.reg[0].how = REG_SAVED_OFFSET; 193 fs->regs.reg[0].loc.offset = (long)&sf->REG_NAME(eax) - new_cfa; 194 fs->regs.reg[3].how = REG_SAVED_OFFSET; 195 fs->regs.reg[3].loc.offset = (long)&sf->REG_NAME(ebx) - new_cfa; 196 fs->regs.reg[1].how = REG_SAVED_OFFSET; 197 fs->regs.reg[1].loc.offset = (long)&sf->REG_NAME(ecx) - new_cfa; 198 fs->regs.reg[2].how = REG_SAVED_OFFSET; 199 fs->regs.reg[2].loc.offset = (long)&sf->REG_NAME(edx) - new_cfa; 200 fs->regs.reg[6].how = REG_SAVED_OFFSET; 201 fs->regs.reg[6].loc.offset = (long)&sf->REG_NAME(esi) - new_cfa; 202 fs->regs.reg[7].how = REG_SAVED_OFFSET; 203 fs->regs.reg[7].loc.offset = (long)&sf->REG_NAME(edi) - new_cfa; 204 fs->regs.reg[5].how = REG_SAVED_OFFSET; 205 fs->regs.reg[5].loc.offset = (long)&sf->REG_NAME(ebp) - new_cfa; 206 fs->regs.reg[8].how = REG_SAVED_OFFSET; 207 fs->regs.reg[8].loc.offset = (long)&sf->REG_NAME(eip) - new_cfa; 208 fs->retaddr_column = 8; 209 fs->signal_frame = 1; 210 return _URC_NO_REASON; 211} 212#endif /* ifdef __x86_64__ */ 213