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/* DWARF2 EH unwinding support for S/390 Linux.
Copyright (C) 2004-2021 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
/* Do code reading to identify a signal frame, and set the frame
state data appropriately. See unwind-dw2.c for the structs. */
#define MD_FALLBACK_FRAME_STATE_FOR s390_fallback_frame_state
static _Unwind_Reason_Code
s390_fallback_frame_state (struct _Unwind_Context *context,
_Unwind_FrameState *fs)
{
static const unsigned char dwarf_to_fpr_map[16] =
{ 0, 2, 4, 6, 1, 3, 5, 7, 8, 10, 12, 14, 9, 11, 13, 15 };
unsigned char *pc = context->ra;
long new_cfa;
int i;
typedef struct
{
unsigned long psw_mask;
unsigned long psw_addr;
unsigned long gprs[16];
unsigned int acrs[16];
unsigned int fpc;
unsigned int __pad;
double fprs[16];
} __attribute__ ((__aligned__ (8))) sigregs_;
sigregs_ *regs;
int *signo;
/* svc $__NR_sigreturn or svc $__NR_rt_sigreturn */
if (pc[0] != 0x0a || (pc[1] != 119 && pc[1] != 173))
return _URC_END_OF_STACK;
/* Legacy frames:
old signal mask (8 bytes)
pointer to sigregs (8 bytes) - points always to next location
sigregs
retcode
This frame layout was used on kernels < 2.6.9 for non-RT frames,
and on kernels < 2.4.13 for RT frames as well. Note that we need
to look at RA to detect this layout -- this means that if you use
sa_restorer to install a different signal restorer on a legacy
kernel, unwinding from signal frames will not work. */
if (context->ra == context->cfa + 16 + sizeof (sigregs_))
{
regs = (sigregs_ *)(context->cfa + 16);
signo = NULL;
}
/* New-style RT frame:
retcode + alignment (8 bytes)
siginfo (128 bytes)
ucontext (contains sigregs) */
else if (pc[1] == 173 /* __NR_rt_sigreturn */)
{
struct ucontext_
{
unsigned long uc_flags;
struct ucontext_ *uc_link;
unsigned long uc_stack[3];
sigregs_ uc_mcontext;
} *uc = context->cfa + 8 + 128;
regs = &uc->uc_mcontext;
signo = context->cfa + sizeof(long);
}
/* New-style non-RT frame:
old signal mask (8 bytes)
pointer to sigregs (followed by signal number) */
else
{
regs = *(sigregs_ **)(context->cfa + 8);
signo = (int *)(regs + 1);
}
new_cfa = regs->gprs[15] + 16*sizeof(long) + 32;
fs->regs.cfa_how = CFA_REG_OFFSET;
fs->regs.cfa_reg = 15;
fs->regs.cfa_offset =
new_cfa - (long) context->cfa + 16*sizeof(long) + 32;
for (i = 0; i < 16; i++)
{
fs->regs.reg[i].how = REG_SAVED_OFFSET;
fs->regs.reg[i].loc.offset =
(long)®s->gprs[i] - new_cfa;
}
for (i = 0; i < 16; i++)
{
fs->regs.reg[16+i].how = REG_SAVED_OFFSET;
fs->regs.reg[16+i].loc.offset =
(long)®s->fprs[dwarf_to_fpr_map[i]] - new_cfa;
}
/* Load return addr from PSW into dummy register 32. */
fs->regs.reg[32].how = REG_SAVED_OFFSET;
fs->regs.reg[32].loc.offset = (long)®s->psw_addr - new_cfa;
fs->retaddr_column = 32;
/* SIGILL, SIGFPE and SIGTRAP are delivered with psw_addr
after the faulting instruction rather than before it.
Don't set FS->signal_frame in that case. */
if (!signo || (*signo != 4 && *signo != 5 && *signo != 8))
fs->signal_frame = 1;
return _URC_NO_REASON;
}
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