+++ /dev/null
-/* exc-syscall-c-handler.c - SYSCALL instruction XTOS handler in C */
-
-/*
- * Copyright (c) 1999-2006 Tensilica Inc.
- *
- * 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.
- */
-
-#include <xtensa/config/core.h>
-#include "xtos-internal.h"
-
-
-/*
- * User vector mode exception handler for the SYSCALL cause.
- *
- * NOTE: This function is NOT used by default. The assembly-level
- * handler version of this function is normally used instead.
- * This function is provided as an example only.
- * To use it instead of the default assembly-level version,
- * you can register it using _xtos_set_exception_handler().
- * For example:
- *
- * #include <xtensa/xtruntime.h>
- * #include <xtensa/corebits.h>
- * _xtos_set_exception_handler( EXCCAUSE_SYSCALL,
- * (_xtos_handler)_xtos_p_syscall_handler );
- */
-UserFrame* _xtos_p_syscall_handler( UserFrame *uf /*, int cause */ )
-{
- uf->pc += 3; /* skip SYSCALL instruction */
-
-#if XCHAL_HAVE_LOOPS
- /*
- * If the SYSCALL instruction was the last instruction in the body
- * of a zero-overhead loop, then we should decrement the loop count
- * and resume execution at the head of the loop.
- */
-
- if( uf->pc == uf->lend && uf->lcount != 0 )
- {
- uf->lcount--;
- uf->pc = uf->lbeg;
- }
-#endif /*XCHAL_HAVE_LOOP*/
-
- /*
- * Handle the system call.
- *
- * A typical SYSCALL handler uses code such as this to handle
- * the system call, where the operation to be done is determined
- * by the a2 register. Parameters to the operation are typically
- * passed in address registers a3 and up. Results are typically
- * returned in a2. (See Linux source code for example.)
- */
- switch( uf->a2 ) {
- case 0:
- /* Spill register windows to the stack. */
- /*
- * The Xtensa architecture reserves the a2==0 condition as a request
- * to flush (spill) register windows to the stack. The current exception
- * handling implementation never spills windows to the stack (it used
- * to always spill, not true anymore), so we have to spill windows
- * explicitly here. (Note that xthal_window_spill() spills windows
- * that are part of the interrupt handling context, that don't
- * really need to be spilled, but that's harmless other than being
- * less than optimally efficient.)
- *
- * Also, be nice to programmers here. If they're
- * building for Call0 ABI, silently do nothing for
- * syscall a2==0.
- */
-#ifdef __XTENSA_WINDOWED_ABI__
- xthal_window_spill();
-#endif
- break;
-
- default:
- uf->a2 = -1 /*ENOSYS*/; /* system call not supported */
- break;
- }
-
- return( uf );
-}
-