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/****************************************************************************** * * * License Agreement * * * * Copyright (c) 2008 Altera Corporation, San Jose, California, USA. * * All rights reserved. * * * * Permission is hereby granted, free of charge, to any person obtaining a * * copy of this software and associated documentation files (the "Software"), * * to deal in the Software without restriction, including without limitation * * the rights to use, copy, modify, merge, publish, distribute, sublicense, * * and/or sell copies of the Software, and to permit persons to whom the * * Software is furnished to do so, subject to the following conditions: * * * * The above copyright notice and this permission notice shall be included in * * all copies or substantial portions of the Software. * * * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER * * DEALINGS IN THE SOFTWARE. * * * * This agreement shall be governed in all respects by the laws of the State * * of California and by the laws of the United States of America. * * * * Altera does not recommend, suggest or require that this reference design * * file be used in conjunction or combination with any other product. * ******************************************************************************/ #include "sys/alt_exceptions.h" #include "nios2.h" #include "alt_types.h" #include "system.h" /* * This file implements support for calling user-registered handlers for * instruction-generated exceptions. This handler could also be reached * in the event of a spurious interrupt. * * The handler code is optionally enabled through the "Enable * Instruction-related Exception API" HAL BSP setting, which will * define the macro below. */ #ifdef ALT_INCLUDE_INSTRUCTION_RELATED_EXCEPTION_API /* Function pointer to exception callback routine */ alt_exception_result (*alt_instruction_exception_handler) (alt_exception_cause, alt_u32, alt_u32) = 0x0; /* Link entry routine to .exceptions section */ int alt_instruction_exception_entry (alt_u32 exception_pc) __attribute__ ((section (".exceptions"))); /* * This is the entry point for instruction-generated exceptions handling. * This routine will be called by alt_exceptions_entry.S, after it determines * that an exception could not be handled by handlers that preceed that * of instruction-generated exceptions (such as interrupts). * * For this to function properly, you must register an exception handler * using alt_instruction_exception_register(). This routine will call * that handler if it has been registered. Absent a handler, it will * break break or hang as discussed below. */ int alt_instruction_exception_entry (alt_u32 exception_pc) { alt_u32 cause, badaddr; /* * If the processor hardware has the optional EXCEPTIONS & BADADDR registers, * read them and pass their content to the user handler. These are always * present if the MMU or MPU is enabled, and optionally for other advanced * exception types via the "Extra exceptions information" setting in the * processor (hardware) configuration. * * If these registers are not present, the cause field will be set to * NIOS2_EXCEPTION_CAUSE_NOT_PRESENT. Your handling routine should * check the validity of the cause argument before proceeding. */ #ifdef NIOS2_HAS_EXTRA_EXCEPTION_INFO /* Get exception cause & "badaddr" */ NIOS2_READ_EXCEPTION(cause); cause = ( (cause & NIOS2_EXCEPTION_REG_CAUSE_MASK) >> NIOS2_EXCEPTION_REG_CAUSE_OFST ); NIOS2_READ_BADADDR(badaddr); #else cause = NIOS2_EXCEPTION_CAUSE_NOT_PRESENT; badaddr = 0; #endif /* NIOS2_HAS_EXTRA_EXCEPTION_INFO */ if(alt_instruction_exception_handler) { /* * Call handler. Its return value indicates whether the exception-causing * instruction should be re-issued. The code that called us, * alt_eceptions_entry.S, will look at this value and adjust the ea * register as necessary */ return alt_instruction_exception_handler(cause, exception_pc, badaddr); } /* * We got here because an instruction-generated exception occured, but no * handler is present. We do not presume to know how to handle it. If the * debugger is present, break, otherwise hang. * * If you've reached here in the debugger, consider examining the * EXCEPTIONS register cause bit-field, which was read into the 'cause' * variable above, and compare it against the exceptions-type enumeration * in alt_exceptions.h. This register is availabe if the MMU or MPU is * present, or if the "Extra exceptions information" hardware option is * selected. * * If you get here then one of the following could have happened: * * - An instruction-generated exception occured, and the processor * does not have the extra exceptions feature enabled, or you * have not registered a handler using * alt_instruction_exception_register() * * Some examples of instruction-generated exceptions and why they * might occur: * * - Your program could have been compiled for a full-featured * Nios II core, but it is running on a smaller core, and * instruction emulation has been disabled by defining * ALT_NO_INSTRUCTION_EMULATION. * * You can work around the problem by re-enabling instruction * emulation, or you can figure out why your program is being * compiled for a system other than the one that it is running on. * * - Your program has executed a trap instruction, but has not * implemented a handler for this instruction. * * - Your program has executed an illegal instruction (one which is * not defined in the instruction set). * * - Your processor includes an MMU or MPU, and you have enabled it * before registering an exception handler to service exceptions it * generates. * * The problem could also be hardware related: * - If your hardware is broken and is generating spurious interrupts * (a peripheral which negates its interrupt output before its * interrupt handler has been executed will cause spurious interrupts) */ else { #ifdef NIOS2_HAS_DEBUG_STUB NIOS2_BREAK(); #else while(1) ; #endif /* NIOS2_HAS_DEBUG_STUB */ } /* // We should not get here. Remove compiler warning. */ return NIOS2_EXCEPTION_RETURN_REISSUE_INST; } #endif /* ALT_INCLUDE_INSTRUCTION_RELATED_EXCEPTION_API */ /* * This routine indicates whether a particular exception cause will have * set a valid address into the BADADDR register, which is included * in the arguments to a user-registered instruction-generated exception * handler. Many exception types do not set valid contents in BADADDR; * this is a convenience routine to easily test the validity of that * argument in your handler. * * Note that this routine will return false (0) for cause '12', * TLB miss. This is because there are four exception types that * share that cause, two of which do not have a valid BADADDR. You * must determine BADADDR's validity for these. * * Arguments: * cause: The 5-bit exception cause field of the EXCEPTIONS register, * shifted to the LSB position. You may pass the 'cause' argument * in a handler you registered directy to this routine. * * Return: 1: BADADDR (bad_addr argument to handler) is valid * 0: BADADDR is not valid */ int alt_exception_cause_generated_bad_addr(alt_exception_cause cause) { switch (cause) { case NIOS2_EXCEPTION_SUPERVISOR_ONLY_DATA_ADDR: return 1; case NIOS2_EXCEPTION_MISALIGNED_DATA_ADDR: return 1; case NIOS2_EXCEPTION_MISALIGNED_TARGET_PC: return 1; case NIOS2_EXCEPTION_TLB_READ_PERM_VIOLATION: return 1; case NIOS2_EXCEPTION_TLB_WRITE_PERM_VIOLATION: return 1; case NIOS2_EXCEPTION_MPU_DATA_REGION_VIOLATION: return 1; default: return 0; } }