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/* DWARF2 EH unwinding support for NDS32 Linux signal frame.
Copyright (C) 2014-2021 Free Software Foundation, Inc.
Contributed by Andes Technology Corporation.
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
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
<>. */
#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/nds32/kernel/signal.c. */
#include <signal.h>
#include <asm/unistd.h>
#include <sys/ucontext.h>
/* Exactly the same layout as the kernel structures, unique names. */
/* arch/nds32/kernel/signal.c */
struct _rt_sigframe {
siginfo_t info;
struct ucontext_t uc;
#define RT_SIGRETURN 0x8b00f044
#define MD_FALLBACK_FRAME_STATE_FOR nds32_fallback_frame_state
/* This function is supposed to be invoked by uw_frame_state_for()
when there is no unwind data available.
Generally, given the _Unwind_Context CONTEXT for a stack frame,
we need to look up its caller and decode information into FS.
However, if the exception handling happens within a signal handler,
the return address of signal handler is a special module, which
contains signal return syscall and has no FDE in the .eh_frame section.
We need to implement MD_FALLBACK_FRAME_STATE_FOR so that we can
unwind through signal frames. */
static _Unwind_Reason_Code
nds32_fallback_frame_state (struct _Unwind_Context *context,
_Unwind_FrameState *fs)
u_int32_t *pc = (u_int32_t *) context->ra;
struct sigcontext *sc_;
_Unwind_Ptr new_cfa;
#ifdef __NDS32_EB__
#error "Signal handler is not supported for force unwind."
if ((_Unwind_Ptr) pc & 3)
/* Check if we are going through a signal handler.
See arch/nds32/kernel/signal.c implementation.
FIXME: Currently we only handle little endian (EL) case. */
if (pc[0] == RT_SIGRETURN)
/* Using '_sigfame' memory address to locate kernal's sigcontext.
The sigcontext structures in arch/nds32/include/asm/sigcontext.h. */
struct _rt_sigframe *rt_;
rt_ = context->cfa;
sc_ = &rt_->uc.uc_mcontext;
/* Update cfa from sigcontext. */
new_cfa = (_Unwind_Ptr) sc_;
fs->regs.cfa_how = CFA_REG_OFFSET;
fs->regs.cfa_reg = STACK_POINTER_REGNUM;
fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
#define NDS32_PUT_FS_REG(NUM, NAME) \
(fs->regs.reg[NUM].how = REG_SAVED_OFFSET, \
fs->regs.reg[NUM].loc.offset = (_Unwind_Ptr) &(sc_->NAME) - new_cfa)
/* Restore all registers value. */
NDS32_PUT_FS_REG (0, nds32_r0);
NDS32_PUT_FS_REG (1, nds32_r1);
NDS32_PUT_FS_REG (2, nds32_r2);
NDS32_PUT_FS_REG (3, nds32_r3);
NDS32_PUT_FS_REG (4, nds32_r4);
NDS32_PUT_FS_REG (5, nds32_r5);
NDS32_PUT_FS_REG (6, nds32_r6);
NDS32_PUT_FS_REG (7, nds32_r7);
NDS32_PUT_FS_REG (8, nds32_r8);
NDS32_PUT_FS_REG (9, nds32_r9);
NDS32_PUT_FS_REG (10, nds32_r10);
NDS32_PUT_FS_REG (11, nds32_r11);
NDS32_PUT_FS_REG (12, nds32_r12);
NDS32_PUT_FS_REG (13, nds32_r13);
NDS32_PUT_FS_REG (14, nds32_r14);
NDS32_PUT_FS_REG (15, nds32_r15);
NDS32_PUT_FS_REG (16, nds32_r16);
NDS32_PUT_FS_REG (17, nds32_r17);
NDS32_PUT_FS_REG (18, nds32_r18);
NDS32_PUT_FS_REG (19, nds32_r19);
NDS32_PUT_FS_REG (20, nds32_r20);
NDS32_PUT_FS_REG (21, nds32_r21);
NDS32_PUT_FS_REG (22, nds32_r22);
NDS32_PUT_FS_REG (23, nds32_r23);
NDS32_PUT_FS_REG (24, nds32_r24);
NDS32_PUT_FS_REG (25, nds32_r25);
NDS32_PUT_FS_REG (28, nds32_fp);
NDS32_PUT_FS_REG (29, nds32_gp);
NDS32_PUT_FS_REG (30, nds32_lp);
NDS32_PUT_FS_REG (31, nds32_sp);
/* Restore PC, point to trigger signal instruction. */
NDS32_PUT_FS_REG (32, nds32_ipc);
#undef NDS32_PUT_FS_REG
/* The retaddr is PC, use PC to find FDE. */
fs->retaddr_column = 32;
fs->signal_frame = 1;
return _URC_NO_REASON;