libgcc/config/aarch64/linux-unwind.h

   1 /* Copyright (C) 2009-2017 Free Software Foundation, Inc.
   2    Contributed by ARM Ltd.
   3
   4    This file is free software; you can redistribute it and/or modify it
   5    under the terms of the GNU General Public License as published by the
   6    Free Software Foundation; either version 3, or (at your option) any
   7    later version.
   8
   9    This file is distributed in the hope that it will be useful, but
  10    WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    General Public License for more details.
  13
  14    Under Section 7 of GPL version 3, you are granted additional
  15    permissions described in the GCC Runtime Library Exception, version
  16    3.1, as published by the Free Software Foundation.
  17
  18    You should have received a copy of the GNU General Public License and
  19    a copy of the GCC Runtime Library Exception along with this program;
  20    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  21    <http://www.gnu.org/licenses/>.  */
  22
  23 /* Always include AArch64 unwinder header file.  */
  24 #include "config/aarch64/aarch64-unwind.h"
  25
  26 #ifndef inhibit_libc
  27
  28 #include <signal.h>
  29 #include <sys/ucontext.h>
  30
  31
  32 /* Since insns are always stored LE, on a BE system the opcodes will
  33    be loaded byte-reversed.  Therefore, define two sets of opcodes,
  34    one for LE and one for BE.  */
  35
  36 #if __AARCH64EB__
  37 #define MOVZ_X8_8B      0x681180d2
  38 #define SVC_0           0x010000d4
  39 #else
  40 #define MOVZ_X8_8B      0xd2801168
  41 #define SVC_0           0xd4000001
  42 #endif
  43
  44 #define MD_FALLBACK_FRAME_STATE_FOR aarch64_fallback_frame_state
  45
  46 static _Unwind_Reason_Code
  47 aarch64_fallback_frame_state (struct _Unwind_Context *context,
  48                               _Unwind_FrameState * fs)
  49 {
  50   /* The kernel creates an rt_sigframe on the stack immediately prior
  51      to delivering a signal.
  52
  53      This structure must have the same shape as the linux kernel
  54      equivalent.  */
  55   struct rt_sigframe
  56   {
  57     siginfo_t info;
  58     ucontext_t uc;
  59   };
  60
  61   struct rt_sigframe *rt_;
  62   _Unwind_Ptr new_cfa;
  63   unsigned *pc = context->ra;
  64   struct sigcontext *sc;
  65   struct _aarch64_ctx *extension_marker;
  66   int i;
  67
  68   /* A signal frame will have a return address pointing to
  69      __default_sa_restorer. This code is hardwired as:
  70
  71      0xd2801168         movz x8, #0x8b
  72      0xd4000001         svc  0x0
  73    */
  74   if (pc[0] != MOVZ_X8_8B || pc[1] != SVC_0)
  75     {
  76       return _URC_END_OF_STACK;
  77     }
  78
  79   rt_ = context->cfa;
  80   sc = &rt_->uc.uc_mcontext;
  81
  82 /* This define duplicates the definition in aarch64.md */
  83 #define SP_REGNUM 31
  84
  85   new_cfa = (_Unwind_Ptr) sc;
  86   fs->regs.cfa_how = CFA_REG_OFFSET;
  87   fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__;
  88   fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
  89
  90   for (i = 0; i < AARCH64_DWARF_NUMBER_R; i++)
  91     {
  92       fs->regs.reg[AARCH64_DWARF_R0 + i].how = REG_SAVED_OFFSET;
  93       fs->regs.reg[AARCH64_DWARF_R0 + i].loc.offset =
  94         (_Unwind_Ptr) & (sc->regs[i]) - new_cfa;
  95     }
  96
  97   /* The core context may be extended with an arbitrary set of
  98      additional contexts appended sequentially. Each additional
  99      context contains a magic identifier and size in bytes.  The size
 100      field can be used to skip over unrecognized context extensions.
 101      The end of the context sequence is marked by a context with magic
 102      0 or size 0.  */
 103   for (extension_marker = (struct _aarch64_ctx *) &sc->__reserved;
 104        extension_marker->magic;
 105        extension_marker = (struct _aarch64_ctx *)
 106        ((unsigned char *) extension_marker + extension_marker->size))
 107     {
 108       if (extension_marker->magic == FPSIMD_MAGIC)
 109         {
 110           struct fpsimd_context *ctx =
 111             (struct fpsimd_context *) extension_marker;
 112           int i;
 113
 114           for (i = 0; i < AARCH64_DWARF_NUMBER_V; i++)
 115             {
 116               _Unwind_Sword offset;
 117
 118               fs->regs.reg[AARCH64_DWARF_V0 + i].how = REG_SAVED_OFFSET;
 119
 120               /* sigcontext contains 32 128bit registers for V0 to
 121                  V31.  The kernel will have saved the contents of the
 122                  V registers.  We want to unwind the callee save D
 123                  registers.  Each D register comprises the least
 124                  significant half of the corresponding V register.  We
 125                  need to offset into the saved V register dependent on
 126                  our endianness to find the saved D register.  */
 127
 128               offset = (_Unwind_Ptr) & (ctx->vregs[i]) - new_cfa;
 129
 130               /* The endianness adjustment code below expects that a
 131                  saved V register is 16 bytes.  */
 132               gcc_assert (sizeof (ctx->vregs[0]) == 16);
 133 #if defined (__AARCH64EB__)
 134               offset = offset + 8;
 135 #endif
 136               fs->regs.reg[AARCH64_DWARF_V0 + i].loc.offset = offset;
 137             }
 138         }
 139       else
 140         {
 141           /* There is context provided that we do not recognize!  */
 142         }
 143     }
 144
 145   fs->regs.reg[31].how = REG_SAVED_OFFSET;
 146   fs->regs.reg[31].loc.offset = (_Unwind_Ptr) & (sc->sp) - new_cfa;
 147
 148   fs->signal_frame = 1;
 149
 150   fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].how =
 151     REG_SAVED_VAL_OFFSET;
 152   fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].loc.offset =
 153     (_Unwind_Ptr) (sc->pc) - new_cfa;
 154
 155   fs->retaddr_column = __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__;
 156
 157   return _URC_NO_REASON;
 158 }
 159
 160 #endif