113 lines
4.1 KiB
C
113 lines
4.1 KiB
C
/*
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* Copyright 2015 Dius Computing Pty Ltd. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the
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* distribution.
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* - Neither the name of the copyright holders nor the names of
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* its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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* THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* @author Johny Mattsson <jmattsson@dius.com.au>
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*/
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#include "user_exceptions.h"
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#define LOAD_MASK 0x00f00fu
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#define L8UI_MATCH 0x000002u
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#define L16UI_MATCH 0x001002u
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#define L16SI_MATCH 0x009002u
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void load_non_32_wide_handler (struct exception_frame *ef, uint32_t cause)
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{
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/* If this is not EXCCAUSE_LOAD_STORE_ERROR you're doing it wrong! */
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(void)cause;
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uint32_t epc1 = ef->epc;
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uint32_t excvaddr;
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uint32_t insn;
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asm (
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"rsr %0, EXCVADDR;" /* read out the faulting address */
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"movi a4, ~3;" /* prepare a mask for the EPC */
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"and a4, a4, %2;" /* apply mask for 32bit aligned base */
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"l32i a5, a4, 0;" /* load part 1 */
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"l32i a6, a4, 4;" /* load part 2 */
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"ssa8l %2;" /* set up shift register for src op */
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"src %1, a6, a5;" /* right shift to get faulting instruction */
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:"=r"(excvaddr), "=r"(insn)
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:"r"(epc1)
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:"a4", "a5", "a6"
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);
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uint32_t valmask = 0;
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uint32_t what = insn & LOAD_MASK;
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if (what == L8UI_MATCH)
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valmask = 0xffu;
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else if (what == L16UI_MATCH || what == L16SI_MATCH)
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valmask = 0xffffu;
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else
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{
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die:
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/* Turns out we couldn't fix this, trigger a system break instead
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* and hang if the break doesn't get handled. This is effectively
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* what would happen if the default handler was installed. */
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asm ("break 1, 1");
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while (1) {}
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}
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/* Load, shift and mask down to correct size */
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uint32_t val = (*(uint32_t *)(excvaddr & ~0x3));
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val >>= (excvaddr & 0x3) * 8;
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val &= valmask;
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/* Sign-extend for L16SI, if applicable */
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if (what == L16SI_MATCH && (val & 0x8000))
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val |= 0xffff0000;
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int regno = (insn & 0x0000f0u) >> 4;
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if (regno == 1)
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goto die; /* we can't support loading into a1, just die */
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else if (regno != 0)
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--regno; /* account for skipped a1 in exception_frame */
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ef->a_reg[regno] = val; /* carry out the load */
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ef->epc += 3; /* resume at following instruction */
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}
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/**
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* The SDK's user_main function installs a debugging handler regardless
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* of whether there's a proper handler installed for EXCCAUSE_LOAD_STORE_ERROR,
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* which of course breaks everything if we allow that to go through. As such,
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* we use the linker to wrap that call and stop the SDK from shooting itself in
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* its proverbial foot.
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*/
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exception_handler_fn TEXT_SECTION_ATTR
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__wrap__xtos_set_exception_handler (uint32_t cause, exception_handler_fn fn)
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{
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if (cause != EXCCAUSE_LOAD_STORE_ERROR)
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__real__xtos_set_exception_handler (cause, fn);
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}
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