116 lines
4.8 KiB
C
116 lines
4.8 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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static exception_handler_fn load_store_handler;
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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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uint32_t val, insn;
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(void)cause; /* If this is not EXCCAUSE_LOAD_STORE_ERROR you're doing it wrong! */
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asm (
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/*
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* Move the aligned content of the exception addr to val
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*/
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"rsr a6, EXCVADDR;" /* read out the faulting address */
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"movi a5, ~3;" /* prepare a mask for the EPC */
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"and a5, a5, a6;" /* apply mask for 32bit aligned base */
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"l32i a5, a5, 0;" /* load aligned value */
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"ssa8l a6;" /* set up shift register for value */
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"srl %[val], a5;" /* shift left to align value */
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/* we are done with a6 = EXCVADDR */
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/*
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* Move the aligned instruction to insn
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*/
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"movi a5, ~3;" /* prepare a mask for the insn */
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"and a6, a5, %[epc];" /* apply mask for 32bit aligned base */
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"l32i a5, a6, 0;" /* load part 1 */
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"l32i a6, a6, 4;" /* load part 2 */
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"ssa8l %[epc];" /* set up shift register for src op */
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"src %[op], a6, a5;" /* right shift to get faulting instruction */
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:[val]"=r"(val), [op]"=r"(insn)
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:[epc]"r"(ef->epc)
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:"a5", "a6"
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);
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/* These instructions have the format 0xADSBII where AB = opcode and D = dest reg */
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uint32_t regno = (insn>>4)&0x0f; /* pick out nibble D*/
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uint32_t opcode = (uint8_t) (((insn>>12)<<4)|(insn&0xf)); /* and nibbles AB */
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#define L8UI 0x02u
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#define L16UI 0x12u
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#define L16SI 0x92u
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if (opcode == L8UI) { /* L8UI */
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val = (uint8_t) val;
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} else {
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val = (uint16_t) val; /* assume L16SI or L16UI */
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if (opcode == L16SI) {
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val = (unsigned)((int)((sint16_t)val)); /* force signed 16->32 bit */
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} else if (opcode != L16UI) {
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/*
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* Anything other than L8UI, L16SI or L16UI then chain to the next handler
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* if set (typically a remote GDB break). Otherwise execute the default action
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* which is to trigger a system break and hang if the break doesn't get handled
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*/
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if (load_store_handler) {
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load_store_handler(NULL, 0 /* ef , cause */);
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return;
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} else {
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asm ("break 1, 1");
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while (1) {}
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}
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}
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}
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ef->a_reg[regno ? regno-1: 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. We do save the EXCCAUSE_LOAD_STORE_ERROR handler so that
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* we can chain to it above.
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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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else
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load_store_handler = fn;
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}
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