libgcc/config/nds32/linux-unwind.h

   1 /* DWARF2 EH unwinding support for NDS32 Linux signal frame.
   2    Copyright (C) 2014-2024 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 #include <sys/ucontext.h>
  36
  37 /* Exactly the same layout as the kernel structures, unique names.  */
  38
  39 /* arch/nds32/kernel/signal.c */
  40 struct _rt_sigframe {
  41   siginfo_t info;
  42   struct ucontext_t uc;
  43 };
  44
  45 #define RT_SIGRETURN 0x8b00f044
  46
  47 #define MD_FALLBACK_FRAME_STATE_FOR nds32_fallback_frame_state
  48
  49 /* This function is supposed to be invoked by uw_frame_state_for()
  50    when there is no unwind data available.
  51
  52    Generally, given the _Unwind_Context CONTEXT for a stack frame,
  53    we need to look up its caller and decode information into FS.
  54    However, if the exception handling happens within a signal handler,
  55    the return address of signal handler is a special module, which
  56    contains signal return syscall and has no FDE in the .eh_frame section.
  57    We need to implement MD_FALLBACK_FRAME_STATE_FOR so that we can
  58    unwind through signal frames.  */
  59 static _Unwind_Reason_Code
  60 nds32_fallback_frame_state (struct _Unwind_Context *context,
  61                             _Unwind_FrameState *fs)
  62 {
  63   u_int32_t *pc = (u_int32_t *) context->ra;
  64   struct sigcontext *sc_;
  65   _Unwind_Ptr new_cfa;
  66
  67 #ifdef __NDS32_EB__
  68 #error "Signal handler is not supported for force unwind."
  69 #endif
  70
  71   if ((_Unwind_Ptr) pc & 3)
  72     return _URC_END_OF_STACK;
  73
  74   /* Check if we are going through a signal handler.
  75      See arch/nds32/kernel/signal.c implementation.
  76      FIXME: Currently we only handle little endian (EL) case.  */
  77   if (pc[0] == RT_SIGRETURN)
  78     {
  79       /* Using '_sigfame' memory address to locate kernal's sigcontext.
  80          The sigcontext structures in arch/nds32/include/asm/sigcontext.h.  */
  81       struct _rt_sigframe *rt_;
  82       rt_ = context->cfa;
  83       sc_ = &rt_->uc.uc_mcontext;
  84     }
  85   else
  86     return _URC_END_OF_STACK;
  87
  88   /* Update cfa from sigcontext.  */
  89   new_cfa = (_Unwind_Ptr) sc_;
  90   fs->regs.cfa_how = CFA_REG_OFFSET;
  91   fs->regs.cfa_reg = STACK_POINTER_REGNUM;
  92   fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
  93
  94 #define NDS32_PUT_FS_REG(NUM, NAME) \
  95   (fs->regs.how[NUM] = REG_SAVED_OFFSET, \
  96    fs->regs.reg[NUM].loc.offset = (_Unwind_Ptr) &(sc_->NAME) - new_cfa)
  97
  98   /* Restore all registers value.  */
  99   NDS32_PUT_FS_REG (0, nds32_r0);
 100   NDS32_PUT_FS_REG (1, nds32_r1);
 101   NDS32_PUT_FS_REG (2, nds32_r2);
 102   NDS32_PUT_FS_REG (3, nds32_r3);
 103   NDS32_PUT_FS_REG (4, nds32_r4);
 104   NDS32_PUT_FS_REG (5, nds32_r5);
 105   NDS32_PUT_FS_REG (6, nds32_r6);
 106   NDS32_PUT_FS_REG (7, nds32_r7);
 107   NDS32_PUT_FS_REG (8, nds32_r8);
 108   NDS32_PUT_FS_REG (9, nds32_r9);
 109   NDS32_PUT_FS_REG (10, nds32_r10);
 110   NDS32_PUT_FS_REG (11, nds32_r11);
 111   NDS32_PUT_FS_REG (12, nds32_r12);
 112   NDS32_PUT_FS_REG (13, nds32_r13);
 113   NDS32_PUT_FS_REG (14, nds32_r14);
 114   NDS32_PUT_FS_REG (15, nds32_r15);
 115   NDS32_PUT_FS_REG (16, nds32_r16);
 116   NDS32_PUT_FS_REG (17, nds32_r17);
 117   NDS32_PUT_FS_REG (18, nds32_r18);
 118   NDS32_PUT_FS_REG (19, nds32_r19);
 119   NDS32_PUT_FS_REG (20, nds32_r20);
 120   NDS32_PUT_FS_REG (21, nds32_r21);
 121   NDS32_PUT_FS_REG (22, nds32_r22);
 122   NDS32_PUT_FS_REG (23, nds32_r23);
 123   NDS32_PUT_FS_REG (24, nds32_r24);
 124   NDS32_PUT_FS_REG (25, nds32_r25);
 125
 126   NDS32_PUT_FS_REG (28, nds32_fp);
 127   NDS32_PUT_FS_REG (29, nds32_gp);
 128   NDS32_PUT_FS_REG (30, nds32_lp);
 129   NDS32_PUT_FS_REG (31, nds32_sp);
 130
 131   /* Restore PC, point to trigger signal instruction.  */
 132   NDS32_PUT_FS_REG (32, nds32_ipc);
 133
 134 #undef NDS32_PUT_FS_REG
 135
 136   /* The retaddr is PC, use PC to find FDE.  */
 137   fs->retaddr_column = 32;
 138   fs->signal_frame = 1;
 139
 140   return _URC_NO_REASON;
 141 }
 142
 143 #endif