1 /* DWARF2 EH unwinding support for S/390 Linux.
2 Copyright (C) 2004-2020 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 under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
10
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 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 and
21 a copy of the GCC Runtime Library Exception along with this program;
22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 <http://www.gnu.org/licenses/>. */
24
25 /* Do code reading to identify a signal frame, and set the frame
26 state data appropriately. See unwind-dw2.c for the structs. */
27
28 #define MD_FALLBACK_FRAME_STATE_FOR s390_fallback_frame_state
29
30 static _Unwind_Reason_Code
s390_fallback_frame_state(struct _Unwind_Context * context,_Unwind_FrameState * fs)31 s390_fallback_frame_state (struct _Unwind_Context *context,
32 _Unwind_FrameState *fs)
33 {
34 static const unsigned char dwarf_to_fpr_map[16] =
35 { 0, 2, 4, 6, 1, 3, 5, 7, 8, 10, 12, 14, 9, 11, 13, 15 };
36 unsigned char *pc = context->ra;
37 long new_cfa;
38 int i;
39
40 typedef struct
41 {
42 unsigned long psw_mask;
43 unsigned long psw_addr;
44 unsigned long gprs[16];
45 unsigned int acrs[16];
46 unsigned int fpc;
47 unsigned int __pad;
48 double fprs[16];
49 } __attribute__ ((__aligned__ (8))) sigregs_;
50
51 sigregs_ *regs;
52 int *signo;
53
54 /* svc $__NR_sigreturn or svc $__NR_rt_sigreturn */
55 if (pc[0] != 0x0a || (pc[1] != 119 && pc[1] != 173))
56 return _URC_END_OF_STACK;
57
58 /* Legacy frames:
59 old signal mask (8 bytes)
60 pointer to sigregs (8 bytes) - points always to next location
61 sigregs
62 retcode
63 This frame layout was used on kernels < 2.6.9 for non-RT frames,
64 and on kernels < 2.4.13 for RT frames as well. Note that we need
65 to look at RA to detect this layout -- this means that if you use
66 sa_restorer to install a different signal restorer on a legacy
67 kernel, unwinding from signal frames will not work. */
68 if (context->ra == context->cfa + 16 + sizeof (sigregs_))
69 {
70 regs = (sigregs_ *)(context->cfa + 16);
71 signo = NULL;
72 }
73
74 /* New-style RT frame:
75 retcode + alignment (8 bytes)
76 siginfo (128 bytes)
77 ucontext (contains sigregs) */
78 else if (pc[1] == 173 /* __NR_rt_sigreturn */)
79 {
80 struct ucontext_
81 {
82 unsigned long uc_flags;
83 struct ucontext_ *uc_link;
84 unsigned long uc_stack[3];
85 sigregs_ uc_mcontext;
86 } *uc = context->cfa + 8 + 128;
87
88 regs = &uc->uc_mcontext;
89 signo = context->cfa + sizeof(long);
90 }
91
92 /* New-style non-RT frame:
93 old signal mask (8 bytes)
94 pointer to sigregs (followed by signal number) */
95 else
96 {
97 regs = *(sigregs_ **)(context->cfa + 8);
98 signo = (int *)(regs + 1);
99 }
100
101 new_cfa = regs->gprs[15] + 16*sizeof(long) + 32;
102 fs->regs.cfa_how = CFA_REG_OFFSET;
103 fs->regs.cfa_reg = 15;
104 fs->regs.cfa_offset =
105 new_cfa - (long) context->cfa + 16*sizeof(long) + 32;
106
107 for (i = 0; i < 16; i++)
108 {
109 fs->regs.reg[i].how = REG_SAVED_OFFSET;
110 fs->regs.reg[i].loc.offset =
111 (long)®s->gprs[i] - new_cfa;
112 }
113 for (i = 0; i < 16; i++)
114 {
115 fs->regs.reg[16+i].how = REG_SAVED_OFFSET;
116 fs->regs.reg[16+i].loc.offset =
117 (long)®s->fprs[dwarf_to_fpr_map[i]] - new_cfa;
118 }
119
120 /* Load return addr from PSW into dummy register 32. */
121
122 fs->regs.reg[32].how = REG_SAVED_OFFSET;
123 fs->regs.reg[32].loc.offset = (long)®s->psw_addr - new_cfa;
124 fs->retaddr_column = 32;
125 /* SIGILL, SIGFPE and SIGTRAP are delivered with psw_addr
126 after the faulting instruction rather than before it.
127 Don't set FS->signal_frame in that case. */
128 if (!signo || (*signo != 4 && *signo != 5 && *signo != 8))
129 fs->signal_frame = 1;
130
131 return _URC_NO_REASON;
132 }
133