1/* DWARF2 EH unwinding support for ARC Linux.
2   Copyright (C) 2017-2020 Free Software Foundation, Inc.
3
4   This file is part of GCC.
5
6   GCC is free software; you can redistribute it and/or modify it
7   under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 3, or (at your option)
9   any later version.
10
11   GCC is distributed in the hope that it will be useful, but WITHOUT
12   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
14   License for more details.
15
16   Under Section 7 of GPL version 3, you are granted additional
17   permissions described in the GCC Runtime Library Exception, version
18   3.1, as published by the Free Software Foundation.
19
20   You should have received a copy of the GNU General Public License
21   and a copy of the GCC Runtime Library Exception along with this
22   program; see the files COPYING3 and COPYING.RUNTIME respectively.
23   If not, see <http://www.gnu.org/licenses/>.  */
24
25/* This order is defined by a structure in the kernel, in file
26   arch/arc/kernel/signal.c.  */
27
28#define REGISTER_IN_STACK(REG_NAME, ID) \
29  REG_NAME,
30enum registers_stack_order {
31  REGISTER_STACK_ORDER_START = -1,
32  #include "config/arc/linux-unwind-reg.def"
33  REGISTER_STACK_ORDER_SIZE,
34};
35
36struct register_position {
37  int reg_id;
38  int offset_in_stack;
39};
40#undef REGISTER_IN_STACK
41
42#define REGISTER_SIZE_IN_WORDS 4
43#define REGISTER_IN_STACK(REG_NAME, ID) (int) ID,
44int
45register_id_for_index[REGISTER_STACK_ORDER_SIZE] = {
46  #include "config/arc/linux-unwind-reg.def"
47};
48#undef REGISTER_IN_STACK
49
50#ifndef inhibit_libc
51/* Do code reading to identify a signal frame, and set the frame
52   state data appropriately.  See unwind-dw2.c for the structs.  */
53
54#include <signal.h>
55#include <asm/unistd.h>
56
57/*
5800010edc <__default_rt_sa_restorer>:
59   10edc:	208a 12c2		mov     r8,139
60   10ee0:	781e			trap_s  0
61   10ee2:	7ee0			j_s     [blink]
62*/
63
64#if __BIG_ENDIAN__
65#define MOV_R8_139	  0x8a20c212
66#define TRAP_S_J_S_BLINK  0x1e78e07e
67#define SWI		  0x6f223f00
68#elif __LITTLE_ENDIAN__
69#define MOV_R8_139	  0x12c2208a
70#define TRAP_S_J_S_BLINK  0x7ee0781e
71#define SWI		  0x003f226f
72#endif
73
74#define MD_FALLBACK_FRAME_STATE_FOR arc_fallback_frame_state
75
76static __attribute__((noinline)) _Unwind_Reason_Code
77arc_fallback_frame_state (struct _Unwind_Context *context,
78			   _Unwind_FrameState *fs)
79{
80  struct rt_sigframe {
81    siginfo_t info;
82    ucontext_t uc;
83    unsigned int sigret_magic;
84  };
85
86  struct rt_sigframe *rt_;
87  u_int32_t *pc = (u_int32_t *) context->ra;
88  struct sigcontext *sc;
89  _Unwind_Ptr new_cfa;
90  int i;
91
92#ifdef __ARC700__
93  if (pc[1] != SWI)
94    return _URC_END_OF_STACK;
95#else
96  if (pc[1] != TRAP_S_J_S_BLINK)
97    return _URC_END_OF_STACK;
98#endif
99
100  if (pc[0] == MOV_R8_139)
101    {
102      rt_ = context->cfa;
103      sc = &rt_->uc.uc_mcontext;
104    }
105  else
106    return _URC_END_OF_STACK;
107
108  new_cfa = (_Unwind_Ptr) sc;
109  fs->regs.cfa_how = CFA_REG_OFFSET;
110  fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__;
111  fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
112
113  unsigned long *regs = &sc->regs.scratch.bta;
114  for (i = 0; i < REGISTER_STACK_ORDER_SIZE; i++)
115    {
116      if (register_id_for_index[i] == -1)
117	continue;
118      fs->regs.reg[register_id_for_index[i]].how = REG_SAVED_OFFSET;
119      fs->regs.reg[register_id_for_index[i]].loc.offset
120	= ((_Unwind_Ptr) &(regs[i])) - new_cfa;
121    }
122
123  fs->regs.reg[31].how = REG_SAVED_VAL_OFFSET;
124  fs->regs.reg[31].loc.offset = ((_Unwind_Ptr) (regs[ret])) - new_cfa;
125
126  fs->retaddr_column = 31;
127
128  return _URC_NO_REASON;
129}
130#endif
131
132#define MD_FROB_UPDATE_CONTEXT arc_frob_update_context
133/* Save fp register for unwinding to work.  */
134
135static void
136arc_frob_update_context (struct _Unwind_Context *context,
137			 _Unwind_FrameState *fs)
138{
139  _Unwind_Word fp_val;
140  asm ("mov %0,fp" : "=r" (fp_val));
141
142  switch (fs->regs.reg[27].how)
143    {
144    case REG_UNSAVED:
145    case REG_UNDEFINED:
146      if (context->reg[27] == NULL)
147	_Unwind_SetGRValue (context, 27, fp_val);
148      break;
149
150    default:
151      break;
152    }
153}
154