1/* DWARF2 EH unwinding support for FreeBSD/ARM64 (aarch64).
2   Copyright (C) 2017-2020 Free Software Foundation, Inc.
3   Contributed by John Marino <gnugcc@marino.st>
4
5This file is part of GCC.
6
7GCC is free software; you can redistribute it and/or modify
8it under the terms of the GNU General Public License as published by
9the Free Software Foundation; either version 3, or (at your option)
10any later version.
11
12GCC is distributed in the hope that it will be useful,
13but WITHOUT ANY WARRANTY; without even the implied warranty of
14MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15GNU General Public License for more details.
16
17Under Section 7 of GPL version 3, you are granted additional
18permissions described in the GCC Runtime Library Exception, version
193.1, as published by the Free Software Foundation.
20
21You should have received a copy of the GNU General Public License and
22a copy of the GCC Runtime Library Exception along with this program;
23see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
24<http://www.gnu.org/licenses/>.  */
25
26/* Identify a signal frame, and set the frame state data appropriately.
27   See unwind-dw2.c for the structs. */
28
29/* Always include AArch64 unwinder header file.  */
30#include "config/aarch64/aarch64-unwind.h"
31
32#include <sys/types.h>
33#include <signal.h>
34#include <unistd.h>
35#include <sys/ucontext.h>
36#include <machine/frame.h>
37#include <sys/user.h>
38#include <sys/sysctl.h>
39
40#define REG_NAME(reg)   mc_gpregs.gp_## reg
41#define XREG(num)       mc_gpregs.gp_x[num]
42#define DARC            __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__
43
44#define MD_FALLBACK_FRAME_STATE_FOR aarch64_freebsd_fallback_frame_state
45
46static int
47aarch64_outside_sigtramp_range (unsigned char *pc)
48{
49  static int sigtramp_range_determined = 0;
50  static unsigned char *sigtramp_start, *sigtramp_end;
51
52  if (sigtramp_range_determined == 0)
53    {
54      struct kinfo_sigtramp kst = {0};
55      size_t len = sizeof (kst);
56      int mib[4] = { CTL_KERN, KERN_PROC, KERN_PROC_SIGTRAMP, getpid() };
57
58      sigtramp_range_determined = 1;
59      if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0)
60      {
61        sigtramp_range_determined = 2;
62        sigtramp_start = kst.ksigtramp_start;
63        sigtramp_end   = kst.ksigtramp_end;
64      }
65    }
66  if (sigtramp_range_determined < 2)  /* sysctl failed if < 2 */
67    return 1;
68
69  return (pc < sigtramp_start || pc >= sigtramp_end);
70}
71
72static _Unwind_Reason_Code
73aarch64_freebsd_fallback_frame_state
74(struct _Unwind_Context *context, _Unwind_FrameState *fs)
75{
76  int n;
77  struct sigframe *sf;
78  mcontext_t *sc;
79  _Unwind_Ptr new_cfa;
80
81  if (aarch64_outside_sigtramp_range(context->ra))
82    return _URC_END_OF_STACK;
83
84  sf = (struct sigframe *) context->cfa;
85  sc = &sf->sf_uc.uc_mcontext;
86
87  new_cfa = (_Unwind_Ptr) sc;
88  fs->regs.cfa_how = CFA_REG_OFFSET;
89  fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__;
90  fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
91
92  for (n = 0; n < 32; n++)
93    fs->regs.reg[n].how = REG_SAVED_OFFSET;
94
95  for (n = 0; n < 30; n++)
96    fs->regs.reg[n].loc.offset = (_Unwind_Ptr) &(sc->XREG(n)) - new_cfa;
97
98  fs->regs.reg[30].loc.offset = (_Unwind_Ptr) &(sc->REG_NAME(lr)) - new_cfa;
99  fs->regs.reg[31].loc.offset = (_Unwind_Ptr) &(sc->REG_NAME(sp)) - new_cfa;
100
101  fs->regs.reg[DARC].how = REG_SAVED_OFFSET;
102  fs->regs.reg[DARC].loc.offset = (_Unwind_Ptr) &(sc->REG_NAME(elr)) - new_cfa;
103
104  fs->retaddr_column = DARC;
105  fs->signal_frame = 1;
106
107  return _URC_NO_REASON;
108}
109