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jeremybenn |
/* DWARF2 EH unwinding support for Xtensa.
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Copyright (C) 2008, 2009 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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GCC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU 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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/* Do code reading to identify a signal frame, and set the frame
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state data appropriately. See unwind-dw2-xtensa.c for the structs.
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Don't use this at all if inhibit_libc is used. */
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#ifndef inhibit_libc
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#include <signal.h>
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#include <sys/ucontext.h>
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/* Encoded bytes for Xtensa instructions:
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movi a2, __NR_rt_sigreturn
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syscall
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entry (first byte only)
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Some of the bytes are endian-dependent. */
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#define MOVI_BYTE0 0x22
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#define MOVI_BYTE2 225 /* __NR_rt_sigreturn */
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#define SYSC_BYTE0 0
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#define SYSC_BYTE2 0
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#ifdef __XTENSA_EB__
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#define MOVI_BYTE1 0x0a
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#define SYSC_BYTE1 0x05
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#define ENTRY_BYTE 0x6c
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#else
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#define MOVI_BYTE1 0xa0
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#define SYSC_BYTE1 0x50
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#define ENTRY_BYTE 0x36
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#endif
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#define MD_FALLBACK_FRAME_STATE_FOR xtensa_fallback_frame_state
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static _Unwind_Reason_Code
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xtensa_fallback_frame_state (struct _Unwind_Context *context,
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_Unwind_FrameState *fs)
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{
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unsigned char *pc = context->ra;
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struct sigcontext *sc;
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struct rt_sigframe {
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struct siginfo info;
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struct ucontext uc;
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} *rt_;
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/* movi a2, __NR_rt_sigreturn; syscall */
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if (pc[0] != MOVI_BYTE0
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|| pc[1] != MOVI_BYTE1
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|| pc[2] != MOVI_BYTE2
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|| pc[3] != SYSC_BYTE0
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|| pc[4] != SYSC_BYTE1
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|| pc[5] != SYSC_BYTE2)
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return _URC_END_OF_STACK;
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rt_ = context->sp;
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sc = &rt_->uc.uc_mcontext;
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fs->signal_regs = (_Unwind_Word *) sc->sc_a;
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/* If the signal arrived just before an ENTRY instruction, find the return
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address and pretend the signal arrived before executing the CALL. */
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if (*(unsigned char *) sc->sc_pc == ENTRY_BYTE)
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{
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unsigned callinc = (sc->sc_ps >> 16) & 3;
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fs->signal_ra = ((sc->sc_a[callinc << 2] & XTENSA_RA_FIELD_MASK)
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| context->ra_high_bits) - 3;
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}
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else
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fs->signal_ra = sc->sc_pc;
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fs->signal_frame = 1;
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return _URC_NO_REASON;
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}
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#endif /* ifdef inhibit_libc */
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