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/* DWARF2 EH unwinding support for Nios II Linux.
Copyright (C) 2008-2022 Free Software Foundation, Inc.
This file 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.
This file 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/>. */
#ifndef inhibit_libc
/* Do code reading to identify a signal frame, and set the frame
state data appropriately. See unwind-dw2.c for the structs.
The corresponding bits in the Linux kernel are in
arch/nios2/kernel/signal.c. */
#include <signal.h>
#include <asm/unistd.h>
/* Exactly the same layout as the kernel structures, unique names. */
struct nios2_mcontext {
int version;
int gregs[32];
};
struct nios2_ucontext {
unsigned long uc_flags;
ucontext_t *uc_link;
stack_t uc_stack;
struct nios2_mcontext uc_mcontext;
sigset_t uc_sigmask; /* mask last for extensibility */
};
#define MD_FALLBACK_FRAME_STATE_FOR nios2_fallback_frame_state
static _Unwind_Reason_Code
nios2_fallback_frame_state (struct _Unwind_Context *context,
_Unwind_FrameState *fs)
{
u_int32_t *pc = (u_int32_t *) context->ra;
_Unwind_Ptr new_cfa;
/* The expected sequence of instructions is:
movi r2,(rt_sigreturn)
trap
Check for the trap first. */
if (pc[1] != 0x003b683a)
return _URC_END_OF_STACK;
#define NIOS2_REG(NUM,NAME) \
(fs->regs.reg[NUM].how = REG_SAVED_OFFSET, \
fs->regs.reg[NUM].loc.offset = (_Unwind_Ptr)&(regs->NAME) - new_cfa)
if (pc[0] == (0x00800004 | (__NR_rt_sigreturn << 6)))
{
struct rt_sigframe {
siginfo_t info;
struct nios2_ucontext uc;
} *rt_ = context->cfa;
struct nios2_mcontext *regs = &rt_->uc.uc_mcontext;
int i;
/* MCONTEXT_VERSION is defined to 2 in the kernel. */
if (regs->version != 2)
return _URC_END_OF_STACK;
/* The CFA is the user's incoming stack pointer value. */
new_cfa = (_Unwind_Ptr)regs->gregs[28];
fs->regs.cfa_how = CFA_REG_OFFSET;
fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__;
fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
/* The sequential registers. */
for (i = 1; i < 24; i++)
NIOS2_REG (i, gregs[i-1]);
/* The random registers. The kernel stores these in a funny order
in the gregs array. */
NIOS2_REG (RA_REGNO, gregs[23]);
NIOS2_REG (FP_REGNO, gregs[24]);
NIOS2_REG (GP_REGNO, gregs[25]);
NIOS2_REG (EA_REGNO, gregs[27]);
fs->retaddr_column = EA_REGNO;
fs->signal_frame = 1;
return _URC_NO_REASON;
}
#undef NIOS2_REG
return _URC_END_OF_STACK;
}
#endif
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