libgcc/config/aarch64/linux-unwind.h

   1 /* Copyright (C) 2009-2015 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 #ifndef inhibit_libc
  24
  25 #include <signal.h>
  26 #include <sys/ucontext.h>
  27
  28
  29 /* Since insns are always stored LE, on a BE system the opcodes will
  30    be loaded byte-reversed.  Therefore, define two sets of opcodes,
  31    one for LE and one for BE.  */
  32
  33 #if __AARCH64EB__
  34 #define MOVZ_X8_8B      0x681180d2
  35 #define SVC_0           0x010000d4
  36 #else
  37 #define MOVZ_X8_8B      0xd2801168
  38 #define SVC_0           0xd4000001
  39 #endif
  40
  41 #define MD_FALLBACK_FRAME_STATE_FOR aarch64_fallback_frame_state
  42
  43 static _Unwind_Reason_Code
  44 aarch64_fallback_frame_state (struct _Unwind_Context *context,
  45                               _Unwind_FrameState * fs)
  46 {
  47   /* The kernel creates an rt_sigframe on the stack immediately prior
  48      to delivering a signal.
  49
  50      This structure must have the same shape as the linux kernel
  51      equivalent.  */
  52   struct rt_sigframe
  53   {
  54     siginfo_t info;
  55     struct ucontext uc;
  56   };
  57
  58   struct rt_sigframe *rt_;
  59   _Unwind_Ptr new_cfa;
  60   unsigned *pc = context->ra;
  61   struct sigcontext *sc;
  62   struct _aarch64_ctx *extension_marker;
  63   int i;
  64
  65   /* A signal frame will have a return address pointing to
  66      __default_sa_restorer. This code is hardwired as:
  67
  68      0xd2801168         movz x8, #0x8b
  69      0xd4000001         svc  0x0
  70    */
  71   if (pc[0] != MOVZ_X8_8B || pc[1] != SVC_0)
  72     {
  73       return _URC_END_OF_STACK;
  74     }
  75
  76   rt_ = context->cfa;
  77   sc = &rt_->uc.uc_mcontext;
  78
  79 /* This define duplicates the definition in aarch64.md */
  80 #define SP_REGNUM 31
  81
  82   new_cfa = (_Unwind_Ptr) sc;
  83   fs->regs.cfa_how = CFA_REG_OFFSET;
  84   fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__;
  85   fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
  86
  87   for (i = 0; i < AARCH64_DWARF_NUMBER_R; i++)
  88     {
  89       fs->regs.reg[AARCH64_DWARF_R0 + i].how = REG_SAVED_OFFSET;
  90       fs->regs.reg[AARCH64_DWARF_R0 + i].loc.offset =
  91         (_Unwind_Ptr) & (sc->regs[i]) - new_cfa;
  92     }
  93
  94   /* The core context may be extended with an arbitrary set of
  95      additional contexts appended sequentially. Each additional
  96      context contains a magic identifier and size in bytes.  The size
  97      field can be used to skip over unrecognized context extensions.
  98      The end of the context sequence is marked by a context with magic
  99      0 or size 0.  */
 100   for (extension_marker = (struct _aarch64_ctx *) &sc->__reserved;
 101        extension_marker->magic;
 102        extension_marker = (struct _aarch64_ctx *)
 103        ((unsigned char *) extension_marker + extension_marker->size))
 104     {
 105       if (extension_marker->magic == FPSIMD_MAGIC)
 106         {
 107           struct fpsimd_context *ctx =
 108             (struct fpsimd_context *) extension_marker;
 109           int i;
 110
 111           for (i = 0; i < AARCH64_DWARF_NUMBER_V; i++)
 112             {
 113               _Unwind_Sword offset;
 114
 115               fs->regs.reg[AARCH64_DWARF_V0 + i].how = REG_SAVED_OFFSET;
 116
 117               /* sigcontext contains 32 128bit registers for V0 to
 118                  V31.  The kernel will have saved the contents of the
 119                  V registers.  We want to unwind the callee save D
 120                  registers.  Each D register comprises the least
 121                  significant half of the corresponding V register.  We
 122                  need to offset into the saved V register dependent on
 123                  our endianness to find the saved D register.  */
 124
 125               offset = (_Unwind_Ptr) & (ctx->vregs[i]) - new_cfa;
 126
 127               /* The endianness adjustment code below expects that a
 128                  saved V register is 16 bytes.  */
 129               gcc_assert (sizeof (ctx->vregs[0]) == 16);
 130 #if defined (__AARCH64EB__)
 131               offset = offset + 8;
 132 #endif
 133               fs->regs.reg[AARCH64_DWARF_V0 + i].loc.offset = offset;
 134             }
 135         }
 136       else
 137         {
 138           /* There is context provided that we do not recognize!  */
 139         }
 140     }
 141
 142   fs->regs.reg[31].how = REG_SAVED_OFFSET;
 143   fs->regs.reg[31].loc.offset = (_Unwind_Ptr) & (sc->sp) - new_cfa;
 144
 145   fs->signal_frame = 1;
 146
 147   fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].how =
 148     REG_SAVED_VAL_OFFSET;
 149   fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].loc.offset =
 150     (_Unwind_Ptr) (sc->pc) - new_cfa;
 151
 152   fs->retaddr_column = __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__;
 153
 154   return _URC_NO_REASON;
 155 }
 156
 157 #endif