libgcc/config/i386/linux-unwind.h

   1 /* DWARF2 EH unwinding support for AMD x86-64 and x86.
   2    Copyright (C) 2004-2019 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 3, or (at your option)
   9 any later version.
  10
  11 GCC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 Under Section 7 of GPL version 3, you are granted additional
  17 permissions described in the GCC Runtime Library Exception, version
  18 3.1, as published by the Free Software Foundation.
  19
  20 You should have received a copy of the GNU General Public License and
  21 a copy of the GCC Runtime Library Exception along with this program;
  22 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 <http://www.gnu.org/licenses/>.  */
  24
  25 /* Unwind shadow stack for -fcf-protection -mshstk.  */
  26 #if defined __SHSTK__ && defined __CET__ && (__CET__ & 2) != 0
  27 # include "config/i386/shadow-stack-unwind.h"
  28 #endif
  29
  30 /* Do code reading to identify a signal frame, and set the frame
  31    state data appropriately.  See unwind-dw2.c for the structs.
  32    Don't use this at all if inhibit_libc is used.  */
  33
  34 #ifndef inhibit_libc
  35
  36 /* There's no sys/ucontext.h for glibc 2.0, so no
  37    signal-turned-exceptions for them.  There's also no configure-run for
  38    the target, so we can't check on (e.g.) HAVE_SYS_UCONTEXT_H.  Using the
  39    target libc version macro should be enough.  */
  40 #if defined __GLIBC__ && !(__GLIBC__ == 2 && __GLIBC_MINOR__ == 0)
  41
  42 #include <signal.h>
  43 #include <sys/ucontext.h>
  44
  45 #ifdef __x86_64__
  46
  47 #define MD_FALLBACK_FRAME_STATE_FOR x86_64_fallback_frame_state
  48
  49 static _Unwind_Reason_Code
  50 x86_64_fallback_frame_state (struct _Unwind_Context *context,
  51                              _Unwind_FrameState *fs)
  52 {
  53   unsigned char *pc = context->ra;
  54   struct sigcontext *sc;
  55   long new_cfa;
  56
  57   /* movq $__NR_rt_sigreturn, %rax ; syscall.  */
  58 #ifdef __LP64__
  59 #define RT_SIGRETURN_SYSCALL    0x050f0000000fc0c7ULL
  60 #else
  61 #define RT_SIGRETURN_SYSCALL    0x050f40000201c0c7ULL
  62 #endif
  63   if (*(unsigned char *)(pc+0) == 0x48
  64       && *(unsigned long long *)(pc+1) == RT_SIGRETURN_SYSCALL)
  65     {
  66       ucontext_t *uc_ = context->cfa;
  67       /* The void * cast is necessary to avoid an aliasing warning.
  68          The aliasing warning is correct, but should not be a problem
  69          because it does not alias anything.  */
  70       sc = (struct sigcontext *) (void *) &uc_->uc_mcontext;
  71     }
  72   else
  73     return _URC_END_OF_STACK;
  74
  75   new_cfa = sc->rsp;
  76   fs->regs.cfa_how = CFA_REG_OFFSET;
  77   /* Register 7 is rsp  */
  78   fs->regs.cfa_reg = 7;
  79   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
  80
  81   /* The SVR4 register numbering macros aren't usable in libgcc.  */
  82   fs->regs.reg[0].how = REG_SAVED_OFFSET;
  83   fs->regs.reg[0].loc.offset = (long)&sc->rax - new_cfa;
  84   fs->regs.reg[1].how = REG_SAVED_OFFSET;
  85   fs->regs.reg[1].loc.offset = (long)&sc->rdx - new_cfa;
  86   fs->regs.reg[2].how = REG_SAVED_OFFSET;
  87   fs->regs.reg[2].loc.offset = (long)&sc->rcx - new_cfa;
  88   fs->regs.reg[3].how = REG_SAVED_OFFSET;
  89   fs->regs.reg[3].loc.offset = (long)&sc->rbx - new_cfa;
  90   fs->regs.reg[4].how = REG_SAVED_OFFSET;
  91   fs->regs.reg[4].loc.offset = (long)&sc->rsi - new_cfa;
  92   fs->regs.reg[5].how = REG_SAVED_OFFSET;
  93   fs->regs.reg[5].loc.offset = (long)&sc->rdi - new_cfa;
  94   fs->regs.reg[6].how = REG_SAVED_OFFSET;
  95   fs->regs.reg[6].loc.offset = (long)&sc->rbp - new_cfa;
  96   fs->regs.reg[8].how = REG_SAVED_OFFSET;
  97   fs->regs.reg[8].loc.offset = (long)&sc->r8 - new_cfa;
  98   fs->regs.reg[9].how = REG_SAVED_OFFSET;
  99   fs->regs.reg[9].loc.offset = (long)&sc->r9 - new_cfa;
 100   fs->regs.reg[10].how = REG_SAVED_OFFSET;
 101   fs->regs.reg[10].loc.offset = (long)&sc->r10 - new_cfa;
 102   fs->regs.reg[11].how = REG_SAVED_OFFSET;
 103   fs->regs.reg[11].loc.offset = (long)&sc->r11 - new_cfa;
 104   fs->regs.reg[12].how = REG_SAVED_OFFSET;
 105   fs->regs.reg[12].loc.offset = (long)&sc->r12 - new_cfa;
 106   fs->regs.reg[13].how = REG_SAVED_OFFSET;
 107   fs->regs.reg[13].loc.offset = (long)&sc->r13 - new_cfa;
 108   fs->regs.reg[14].how = REG_SAVED_OFFSET;
 109   fs->regs.reg[14].loc.offset = (long)&sc->r14 - new_cfa;
 110   fs->regs.reg[15].how = REG_SAVED_OFFSET;
 111   fs->regs.reg[15].loc.offset = (long)&sc->r15 - new_cfa;
 112   fs->regs.reg[16].how = REG_SAVED_OFFSET;
 113   fs->regs.reg[16].loc.offset = (long)&sc->rip - new_cfa;
 114   fs->retaddr_column = 16;
 115   fs->signal_frame = 1;
 116   return _URC_NO_REASON;
 117 }
 118
 119 #else /* ifdef __x86_64__  */
 120
 121 #define MD_FALLBACK_FRAME_STATE_FOR x86_fallback_frame_state
 122
 123 static _Unwind_Reason_Code
 124 x86_fallback_frame_state (struct _Unwind_Context *context,
 125                           _Unwind_FrameState *fs)
 126 {
 127   unsigned char *pc = context->ra;
 128   struct sigcontext *sc;
 129   long new_cfa;
 130
 131   /* popl %eax ; movl $__NR_sigreturn,%eax ; int $0x80  */
 132   if (*(unsigned short *)(pc+0) == 0xb858
 133       && *(unsigned int *)(pc+2) == 119
 134       && *(unsigned short *)(pc+6) == 0x80cd)
 135     sc = context->cfa + 4;
 136   /* movl $__NR_rt_sigreturn,%eax ; int $0x80  */
 137   else if (*(unsigned char *)(pc+0) == 0xb8
 138            && *(unsigned int *)(pc+1) == 173
 139            && *(unsigned short *)(pc+5) == 0x80cd)
 140     {
 141       struct rt_sigframe {
 142         int sig;
 143         siginfo_t *pinfo;
 144         void *puc;
 145         siginfo_t info;
 146         ucontext_t uc;
 147       } *rt_ = context->cfa;
 148       /* The void * cast is necessary to avoid an aliasing warning.
 149          The aliasing warning is correct, but should not be a problem
 150          because it does not alias anything.  */
 151       sc = (struct sigcontext *) (void *) &rt_->uc.uc_mcontext;
 152     }
 153   else
 154     return _URC_END_OF_STACK;
 155
 156   new_cfa = sc->esp;
 157   fs->regs.cfa_how = CFA_REG_OFFSET;
 158   fs->regs.cfa_reg = 4;
 159   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 160
 161   /* The SVR4 register numbering macros aren't usable in libgcc.  */
 162   fs->regs.reg[0].how = REG_SAVED_OFFSET;
 163   fs->regs.reg[0].loc.offset = (long)&sc->eax - new_cfa;
 164   fs->regs.reg[3].how = REG_SAVED_OFFSET;
 165   fs->regs.reg[3].loc.offset = (long)&sc->ebx - new_cfa;
 166   fs->regs.reg[1].how = REG_SAVED_OFFSET;
 167   fs->regs.reg[1].loc.offset = (long)&sc->ecx - new_cfa;
 168   fs->regs.reg[2].how = REG_SAVED_OFFSET;
 169   fs->regs.reg[2].loc.offset = (long)&sc->edx - new_cfa;
 170   fs->regs.reg[6].how = REG_SAVED_OFFSET;
 171   fs->regs.reg[6].loc.offset = (long)&sc->esi - new_cfa;
 172   fs->regs.reg[7].how = REG_SAVED_OFFSET;
 173   fs->regs.reg[7].loc.offset = (long)&sc->edi - new_cfa;
 174   fs->regs.reg[5].how = REG_SAVED_OFFSET;
 175   fs->regs.reg[5].loc.offset = (long)&sc->ebp - new_cfa;
 176   fs->regs.reg[8].how = REG_SAVED_OFFSET;
 177   fs->regs.reg[8].loc.offset = (long)&sc->eip - new_cfa;
 178   fs->retaddr_column = 8;
 179   fs->signal_frame = 1;
 180   return _URC_NO_REASON;
 181 }
 182
 183 #define MD_FROB_UPDATE_CONTEXT x86_frob_update_context
 184
 185 /* Fix up for kernels that have vDSO, but don't have S flag in it.  */
 186
 187 static void
 188 x86_frob_update_context (struct _Unwind_Context *context,
 189                          _Unwind_FrameState *fs ATTRIBUTE_UNUSED)
 190 {
 191   unsigned char *pc = context->ra;
 192
 193   /* movl $__NR_rt_sigreturn,%eax ; {int $0x80 | syscall}  */
 194   if (*(unsigned char *)(pc+0) == 0xb8
 195       && *(unsigned int *)(pc+1) == 173
 196       && (*(unsigned short *)(pc+5) == 0x80cd
 197           || *(unsigned short *)(pc+5) == 0x050f))
 198     _Unwind_SetSignalFrame (context, 1);
 199 }
 200
 201 #endif /* ifdef __x86_64__  */
 202 #endif /* not glibc 2.0 */
 203 #endif /* ifdef inhibit_libc  */