libgcc/config/nds32/linux-unwind.h

   1 /* DWARF2 EH unwinding support for NDS32 Linux signal frame.
   2    Copyright (C) 2014-2015 Free Software Foundation, Inc.
   3    Contributed by Andes Technology Corporation.
   4
   5    This file is part of GCC.
   6
   7    GCC is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published
   9    by the Free Software Foundation; either version 3, or (at your
  10    option) any later version.
  11
  12    GCC is distributed in the hope that it will be useful, but WITHOUT
  13    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  15    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 #ifndef inhibit_libc
  27
  28 /* Do code reading to identify a signal frame, and set the frame
  29    state data appropriately.  See unwind-dw2.c for the structs.
  30    The corresponding bits in the Linux kernel are in
  31    arch/nds32/kernel/signal.c.  */
  32
  33 #include <signal.h>
  34 #include <asm/unistd.h>
  35
  36 /* Exactly the same layout as the kernel structures, unique names.  */
  37
  38 /* arch/nds32/kernel/signal.c */
  39 struct _sigframe {
  40     struct ucontext uc;
  41     unsigned long retcode;
  42 };
  43
  44 struct _rt_sigframe {
  45   siginfo_t info;
  46   struct _sigframe sig;
  47 };
  48 #define SIGRETURN 0xeb0e0a64
  49 #define RT_SIGRETURN 0xab150a64
  50
  51 #define MD_FALLBACK_FRAME_STATE_FOR nds32_fallback_frame_state
  52
  53 /* This function is supposed to be invoked by uw_frame_state_for()
  54    when there is no unwind data available.
  55
  56    Generally, given the _Unwind_Context CONTEXT for a stack frame,
  57    we need to look up its caller and decode information into FS.
  58    However, if the exception handling happens within a signal handler,
  59    the return address of signal handler is a special module, which
  60    contains signal return syscall and has no FDE in the .eh_frame section.
  61    We need to implement MD_FALLBACK_FRAME_STATE_FOR so that we can
  62    unwind through signal frames.  */
  63 static _Unwind_Reason_Code
  64 nds32_fallback_frame_state (struct _Unwind_Context *context,
  65                             _Unwind_FrameState *fs)
  66 {
  67   u_int32_t *pc = (u_int32_t *) context->ra;
  68   struct sigcontext *sc_;
  69   _Unwind_Ptr new_cfa;
  70
  71 #ifdef __NDS32_EB__
  72 #error "Signal handler is not supported for force unwind."
  73 #endif
  74
  75   if ((_Unwind_Ptr) pc & 3)
  76     return _URC_END_OF_STACK;
  77
  78   /* Check if we are going through a signal handler.
  79      See arch/nds32/kernel/signal.c implementation.
  80        SWI_SYS_SIGRETURN    -> (0xeb0e0a64)
  81        SWI_SYS_RT_SIGRETURN -> (0xab150a64)
  82      FIXME: Currently we only handle little endian (EL) case.  */
  83   if (pc[0] == SIGRETURN)
  84     {
  85       /* Using '_sigfame' memory address to locate kernal's sigcontext.
  86          The sigcontext structures in arch/nds32/include/asm/sigcontext.h.  */
  87       struct _sigframe *rt_;
  88       rt_ = context->cfa;
  89       sc_ = &rt_->uc.uc_mcontext;
  90     }
  91   else if (pc[0] == RT_SIGRETURN)
  92     {
  93       /* Using '_sigfame' memory address to locate kernal's sigcontext.  */
  94       struct _rt_sigframe *rt_;
  95       rt_ = context->cfa;
  96       sc_ = &rt_->sig.uc.uc_mcontext;
  97     }
  98   else
  99     return _URC_END_OF_STACK;
 100
 101   /* Update cfa from sigcontext.  */
 102   new_cfa = (_Unwind_Ptr) sc_;
 103   fs->regs.cfa_how = CFA_REG_OFFSET;
 104   fs->regs.cfa_reg = STACK_POINTER_REGNUM;
 105   fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
 106
 107 #define NDS32_PUT_FS_REG(NUM, NAME) \
 108   (fs->regs.reg[NUM].how = REG_SAVED_OFFSET, \
 109    fs->regs.reg[NUM].loc.offset = (_Unwind_Ptr) &(sc_->NAME) - new_cfa)
 110
 111   /* Restore all registers value.  */
 112   NDS32_PUT_FS_REG (0, nds32_r0);
 113   NDS32_PUT_FS_REG (1, nds32_r1);
 114   NDS32_PUT_FS_REG (2, nds32_r2);
 115   NDS32_PUT_FS_REG (3, nds32_r3);
 116   NDS32_PUT_FS_REG (4, nds32_r4);
 117   NDS32_PUT_FS_REG (5, nds32_r5);
 118   NDS32_PUT_FS_REG (6, nds32_r6);
 119   NDS32_PUT_FS_REG (7, nds32_r7);
 120   NDS32_PUT_FS_REG (8, nds32_r8);
 121   NDS32_PUT_FS_REG (9, nds32_r9);
 122   NDS32_PUT_FS_REG (10, nds32_r10);
 123   NDS32_PUT_FS_REG (11, nds32_r11);
 124   NDS32_PUT_FS_REG (12, nds32_r12);
 125   NDS32_PUT_FS_REG (13, nds32_r13);
 126   NDS32_PUT_FS_REG (14, nds32_r14);
 127   NDS32_PUT_FS_REG (15, nds32_r15);
 128   NDS32_PUT_FS_REG (16, nds32_r16);
 129   NDS32_PUT_FS_REG (17, nds32_r17);
 130   NDS32_PUT_FS_REG (18, nds32_r18);
 131   NDS32_PUT_FS_REG (19, nds32_r19);
 132   NDS32_PUT_FS_REG (20, nds32_r20);
 133   NDS32_PUT_FS_REG (21, nds32_r21);
 134   NDS32_PUT_FS_REG (22, nds32_r22);
 135   NDS32_PUT_FS_REG (23, nds32_r23);
 136   NDS32_PUT_FS_REG (24, nds32_r24);
 137   NDS32_PUT_FS_REG (25, nds32_r25);
 138
 139   NDS32_PUT_FS_REG (28, nds32_fp);
 140   NDS32_PUT_FS_REG (29, nds32_gp);
 141   NDS32_PUT_FS_REG (30, nds32_lp);
 142   NDS32_PUT_FS_REG (31, nds32_sp);
 143
 144   /* Restore PC, point to trigger signal instruction.  */
 145   NDS32_PUT_FS_REG (32, nds32_ipc);
 146
 147 #undef NDS32_PUT_FS_REG
 148
 149   /* The retaddr is PC, use PC to find FDE.  */
 150   fs->retaddr_column = 32;
 151   fs->signal_frame = 1;
 152
 153   return _URC_NO_REASON;
 154 }
 155
 156 #endif