84 lines
3.2 KiB
C
84 lines
3.2 KiB
C
/*
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* Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
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* The President and Fellows of Harvard College.
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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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* 1. 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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* 2. 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 distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR 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, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <stdlib.h>
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#include <unistd.h>
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/*
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* C standard function: exit process.
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*/
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void
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exit(int code)
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{
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/*
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* In a more complicated libc, this would call functions registered
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* with atexit() before calling the syscall to actually exit.
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*/
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#ifdef __mips__
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/*
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* Because gcc knows that _exit doesn't return, if we call it
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* directly it will drop any code that follows it. This means
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* that if _exit *does* return, as happens before it's
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* implemented, undefined and usually weird behavior ensues.
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*
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* As a hack (this is quite gross) do the call by hand in an
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* asm block. Then gcc doesn't know what it is, and won't
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* optimize the following code out, and we can make sure
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* that exit() at least really does not return.
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*
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* This asm block violates gcc's asm rules by destroying a
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* register it doesn't declare ($4, which is a0) but this
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* hopefully doesn't matter as the only local it can lose
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* track of is "code" and we don't use it afterwards.
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*/
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__asm volatile("jal _exit;" /* call _exit */
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"move $4, %0" /* put code in a0 (delay slot) */
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: /* no outputs */
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: "r" (code)); /* code is an input */
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/*
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* Ok, exiting doesn't work; see if we can get our process
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* killed by making an illegal memory access. Use a magic
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* number address so the symptoms are recognizable and
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* unlikely to occur by accident otherwise.
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*/
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__asm volatile("li $2, 0xeeeee00f;" /* load magic addr into v0 */
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"lw $2, 0($2)" /* fetch from it */
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:: ); /* no args */
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#else
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_exit(code);
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#endif
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/*
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* We can't return; so if we can't exit, the only other choice
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* is to loop.
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*/
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while (1) { }
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}
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