90 lines
2.7 KiB
C
90 lines
2.7 KiB
C
/* Copyright (C) 2016-2020 Free Software Foundation, Inc.
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This file is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 3, or (at your option) any
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later version.
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This file is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef inhibit_libc
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#include <signal.h>
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#include <stdint.h>
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#include <sys/ucontext.h>
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#define LI_A7_8B 0x08b00893
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#define ECALL 0x00000073
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#define MD_FALLBACK_FRAME_STATE_FOR riscv_fallback_frame_state
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static _Unwind_Reason_Code
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riscv_fallback_frame_state (struct _Unwind_Context *context,
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_Unwind_FrameState * fs)
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{
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/* The kernel creates an rt_sigframe on the stack immediately prior
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to delivering a signal.
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This structure must have the same shape as the linux kernel
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equivalent. */
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struct rt_sigframe
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{
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siginfo_t info;
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ucontext_t uc;
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};
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struct rt_sigframe *rt_;
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_Unwind_Ptr new_cfa;
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uint16_t *pc = context->ra;
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struct sigcontext *sc;
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int i;
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/* A signal frame will have a return address pointing to
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__default_sa_restorer. This code is hardwired as:
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0x08b00893 li a7,0x8b
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0x00000073 ecall
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Note, the PC might only have 2-byte alignment.
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*/
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if (pc[0] != (uint16_t)LI_A7_8B || pc[1] != (uint16_t)(LI_A7_8B >> 16)
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|| pc[2] != (uint16_t)ECALL || pc[3] != (uint16_t)(ECALL >> 16))
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return _URC_END_OF_STACK;
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rt_ = context->cfa;
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sc = &rt_->uc.uc_mcontext;
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new_cfa = (_Unwind_Ptr) sc;
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fs->regs.cfa_how = CFA_REG_OFFSET;
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fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__;
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fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
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for (i = 0; i < 32; i++)
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{
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fs->regs.reg[i].how = REG_SAVED_OFFSET;
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fs->regs.reg[i].loc.offset = (_Unwind_Ptr) &sc->gregs[i] - new_cfa;
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}
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fs->signal_frame = 1;
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fs->retaddr_column = __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__;
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fs->regs.reg[fs->retaddr_column].how = REG_SAVED_VAL_OFFSET;
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fs->regs.reg[fs->retaddr_column].loc.offset =
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(_Unwind_Ptr) sc->gregs[0] - new_cfa;
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return _URC_NO_REASON;
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}
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#endif
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