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/* Copyright (C) 2016-2022 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
#include <signal.h>
#include <stdint.h>
#include <sys/ucontext.h>
#define LI_A7_8B 0x08b00893
#define ECALL 0x00000073
#define MD_FALLBACK_FRAME_STATE_FOR riscv_fallback_frame_state
static _Unwind_Reason_Code
riscv_fallback_frame_state (struct _Unwind_Context *context,
_Unwind_FrameState * fs)
{
/* The kernel creates an rt_sigframe on the stack immediately prior
to delivering a signal.
This structure must have the same shape as the linux kernel
equivalent. */
struct rt_sigframe
{
siginfo_t info;
ucontext_t uc;
};
struct rt_sigframe *rt_;
_Unwind_Ptr new_cfa;
uint16_t *pc = context->ra;
struct sigcontext *sc;
int i;
/* A signal frame will have a return address pointing to
__default_sa_restorer. This code is hardwired as:
0x08b00893 li a7,0x8b
0x00000073 ecall
Note, the PC might only have 2-byte alignment.
*/
if (pc[0] != (uint16_t)LI_A7_8B || pc[1] != (uint16_t)(LI_A7_8B >> 16)
|| pc[2] != (uint16_t)ECALL || pc[3] != (uint16_t)(ECALL >> 16))
return _URC_END_OF_STACK;
rt_ = context->cfa;
sc = &rt_->uc.uc_mcontext;
new_cfa = (_Unwind_Ptr) sc;
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;
for (i = 0; i < 32; i++)
{
fs->regs.reg[i].how = REG_SAVED_OFFSET;
fs->regs.reg[i].loc.offset = (_Unwind_Ptr) &sc->gregs[i] - new_cfa;
}
fs->signal_frame = 1;
fs->retaddr_column = __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__;
fs->regs.reg[fs->retaddr_column].how = REG_SAVED_VAL_OFFSET;
fs->regs.reg[fs->retaddr_column].loc.offset =
(_Unwind_Ptr) sc->gregs[0] - new_cfa;
return _URC_NO_REASON;
}
#endif
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