libgcc/config/i386/freebsd-unwind.h

   1 /* DWARF2 EH unwinding support for FreeBSD: AMD x86-64 and x86.
   2    Copyright (C) 2015-2016 Free Software Foundation, Inc.
   3    Contributed by John Marino <gnugcc@marino.st>
   4
   5 This file is part of GCC.
   6
   7 GCC 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, or (at your option)
  10 any later version.
  11
  12 GCC 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 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see 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 <sys/ucontext.h>
  32 #include <machine/sigframe.h>
  33
  34 #define REG_NAME(reg)   sf_uc.uc_mcontext.mc_## reg
  35
  36 #ifdef __x86_64__
  37 #define MD_FALLBACK_FRAME_STATE_FOR x86_64_freebsd_fallback_frame_state
  38
  39 static _Unwind_Reason_Code
  40 x86_64_freebsd_fallback_frame_state
  41 (struct _Unwind_Context *context, _Unwind_FrameState *fs)
  42 {
  43   struct sigframe *sf;
  44   long new_cfa;
  45
  46   /* Prior to FreeBSD 9, the signal trampoline was located immediately
  47      before the ps_strings.  To support non-executable stacks on AMD64,
  48      the sigtramp was moved to a shared page for FreeBSD 9.  Unfortunately
  49      this means looking frame patterns again (sys/amd64/amd64/sigtramp.S)
  50      rather than using the robust and convenient KERN_PS_STRINGS trick.
  51
  52      <pc + 00>:  lea     0x10(%rsp),%rdi
  53      <pc + 05>:  pushq   $0x0
  54      <pc + 17>:  mov     $0x1a1,%rax
  55      <pc + 14>:  syscall
  56
  57      If we can't find this pattern, we're at the end of the stack.
  58   */
  59
  60   if (!(   *(unsigned int *)(context->ra)      == 0x247c8d48
  61         && *(unsigned int *)(context->ra +  4) == 0x48006a10
  62         && *(unsigned int *)(context->ra +  8) == 0x01a1c0c7
  63         && *(unsigned int *)(context->ra + 12) == 0x050f0000 ))
  64     return _URC_END_OF_STACK;
  65
  66   sf = (struct sigframe *) context->cfa;
  67   new_cfa = sf->REG_NAME(rsp);
  68   fs->regs.cfa_how = CFA_REG_OFFSET;
  69   /* Register 7 is rsp  */
  70   fs->regs.cfa_reg = 7;
  71   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
  72
  73   /* The SVR4 register numbering macros aren't usable in libgcc.  */
  74   fs->regs.reg[0].how = REG_SAVED_OFFSET;
  75   fs->regs.reg[0].loc.offset = (long)&sf->REG_NAME(rax) - new_cfa;
  76   fs->regs.reg[1].how = REG_SAVED_OFFSET;
  77   fs->regs.reg[1].loc.offset = (long)&sf->REG_NAME(rdx) - new_cfa;
  78   fs->regs.reg[2].how = REG_SAVED_OFFSET;
  79   fs->regs.reg[2].loc.offset = (long)&sf->REG_NAME(rcx) - new_cfa;
  80   fs->regs.reg[3].how = REG_SAVED_OFFSET;
  81   fs->regs.reg[3].loc.offset = (long)&sf->REG_NAME(rbx) - new_cfa;
  82   fs->regs.reg[4].how = REG_SAVED_OFFSET;
  83   fs->regs.reg[4].loc.offset = (long)&sf->REG_NAME(rsi) - new_cfa;
  84   fs->regs.reg[5].how = REG_SAVED_OFFSET;
  85   fs->regs.reg[5].loc.offset = (long)&sf->REG_NAME(rdi) - new_cfa;
  86   fs->regs.reg[6].how = REG_SAVED_OFFSET;
  87   fs->regs.reg[6].loc.offset = (long)&sf->REG_NAME(rbp) - new_cfa;
  88   fs->regs.reg[8].how = REG_SAVED_OFFSET;
  89   fs->regs.reg[8].loc.offset = (long)&sf->REG_NAME(r8) - new_cfa;
  90   fs->regs.reg[9].how = REG_SAVED_OFFSET;
  91   fs->regs.reg[9].loc.offset = (long)&sf->REG_NAME(r9) - new_cfa;
  92   fs->regs.reg[10].how = REG_SAVED_OFFSET;
  93   fs->regs.reg[10].loc.offset = (long)&sf->REG_NAME(r10) - new_cfa;
  94   fs->regs.reg[11].how = REG_SAVED_OFFSET;
  95   fs->regs.reg[11].loc.offset = (long)&sf->REG_NAME(r11) - new_cfa;
  96   fs->regs.reg[12].how = REG_SAVED_OFFSET;
  97   fs->regs.reg[12].loc.offset = (long)&sf->REG_NAME(r12) - new_cfa;
  98   fs->regs.reg[13].how = REG_SAVED_OFFSET;
  99   fs->regs.reg[13].loc.offset = (long)&sf->REG_NAME(r13) - new_cfa;
 100   fs->regs.reg[14].how = REG_SAVED_OFFSET;
 101   fs->regs.reg[14].loc.offset = (long)&sf->REG_NAME(r14) - new_cfa;
 102   fs->regs.reg[15].how = REG_SAVED_OFFSET;
 103   fs->regs.reg[15].loc.offset = (long)&sf->REG_NAME(r15) - new_cfa;
 104   fs->regs.reg[16].how = REG_SAVED_OFFSET;
 105   fs->regs.reg[16].loc.offset = (long)&sf->REG_NAME(rip) - new_cfa;
 106   fs->retaddr_column = 16;
 107   fs->signal_frame = 1;
 108   return _URC_NO_REASON;
 109 }
 110
 111 #else /* Next section is for i386  */
 112
 113 #define MD_FALLBACK_FRAME_STATE_FOR x86_freebsd_fallback_frame_state
 114
 115 /*
 116  * We can't use KERN_PS_STRINGS anymore if we want to support FreeBSD32
 117  * compat on AMD64.  The sigtramp is in a shared page in that case so the
 118  * x86_sigtramp_range only works on a true i386 system.  We have to
 119  * search for the sigtramp frame if we want it working everywhere.
 120  */
 121
 122 static _Unwind_Reason_Code
 123 x86_freebsd_fallback_frame_state
 124 (struct _Unwind_Context *context, _Unwind_FrameState *fs)
 125 {
 126   struct sigframe *sf;
 127   long new_cfa;
 128
 129 /*
 130  * i386 sigtramp frame we are looking for follows.
 131  * Apparently PSL_VM is variable, so we can't look past context->ra + 4
 132  * <sigcode>:
 133  *   0: ff 54 24 10             call   *0x10(%esp)          *SIGF_HANDLER
 134  *   4: 8d 44 24 20             lea    0x20(%esp),%eax       SIGF_UC
 135  *   8: 50                      push   %eax
 136  *   9: f7 40 54 00 00 02 00    testl  $0x20000,0x54(%eax)  $PSL_VM
 137  *  10: 75 03                   jne    15 <sigcode+0x15>
 138  *  12: 8e 68 14                mov    0x14(%eax),%gs        UC_GS
 139  *  15: b8 a1 01 00 00          mov    0x1a1,%eax           $SYS_sigreturn
 140  */
 141
 142   if (!(   *(unsigned int *)(context->ra - 4) == 0x102454ff
 143         && *(unsigned int *)(context->ra)     == 0x2024448d ))
 144     return _URC_END_OF_STACK;
 145
 146   sf = (struct sigframe *) context->cfa;
 147   new_cfa = sf->REG_NAME(esp);
 148   fs->regs.cfa_how = CFA_REG_OFFSET;
 149   fs->regs.cfa_reg = 4;
 150   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 151
 152   /* The SVR4 register numbering macros aren't usable in libgcc.  */
 153   fs->regs.reg[0].how = REG_SAVED_OFFSET;
 154   fs->regs.reg[0].loc.offset = (long)&sf->REG_NAME(eax) - new_cfa;
 155   fs->regs.reg[3].how = REG_SAVED_OFFSET;
 156   fs->regs.reg[3].loc.offset = (long)&sf->REG_NAME(ebx) - new_cfa;
 157   fs->regs.reg[1].how = REG_SAVED_OFFSET;
 158   fs->regs.reg[1].loc.offset = (long)&sf->REG_NAME(ecx) - new_cfa;
 159   fs->regs.reg[2].how = REG_SAVED_OFFSET;
 160   fs->regs.reg[2].loc.offset = (long)&sf->REG_NAME(edx) - new_cfa;
 161   fs->regs.reg[6].how = REG_SAVED_OFFSET;
 162   fs->regs.reg[6].loc.offset = (long)&sf->REG_NAME(esi) - new_cfa;
 163   fs->regs.reg[7].how = REG_SAVED_OFFSET;
 164   fs->regs.reg[7].loc.offset = (long)&sf->REG_NAME(edi) - new_cfa;
 165   fs->regs.reg[5].how = REG_SAVED_OFFSET;
 166   fs->regs.reg[5].loc.offset = (long)&sf->REG_NAME(ebp) - new_cfa;
 167   fs->regs.reg[8].how = REG_SAVED_OFFSET;
 168   fs->regs.reg[8].loc.offset = (long)&sf->REG_NAME(eip) - new_cfa;
 169   fs->retaddr_column = 8;
 170   fs->signal_frame = 1;
 171   return _URC_NO_REASON;
 172 }
 173 #endif /* ifdef __x86_64__  */