96 lines
3.4 KiB
ArmAsm
96 lines
3.4 KiB
ArmAsm
/*
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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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/*
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* This file is copied to syscalls.S, and then the actual syscalls are
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* appended as lines of the form
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* SYSCALL(symbol, number)
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*
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* Warning: gccs before 3.0 run cpp in -traditional mode on .S files.
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* So if you use an older gcc you'll need to change the token pasting
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* in SYSCALL().
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*/
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#include <kern/syscall.h>
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#include <machine/regdefs.h>
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/*
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* Definition for each syscall.
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* All we do is load the syscall number into v0, the register the
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* kernel expects to find it in, and jump to the shared syscall code.
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* (Note that the addiu instruction is in the jump's delay slot.)
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*/
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#define SYSCALL(sym, num) \
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.set noreorder ; \
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.globl sym ; \
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.type sym,@function ; \
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.ent sym ; \
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sym: ; \
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j __syscall ; \
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addiu v0, $0, SYS_##sym ; \
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.end sym ; \
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.set reorder
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/*
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* Now, the shared system call code.
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* The MIPS syscall ABI is as follows:
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*
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* On entry, call number in v0. The rest is like a normal function
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* call: four args in a0-a3, the other args on the stack.
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*
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* On successful return, zero in a3 register; return value in v0
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* (v0 and v1 for a 64-bit return value).
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*
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* On error return, nonzero in a3 register; errno value in v0.
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*
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* The use of a3 as a return register to hold the success flag is
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* gross, but I didn't make it up.
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*
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* Note that by longstanding Unix convention and POSIX decree, errno
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* is not to be set unless the call actually fails.
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*/
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.set noreorder
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.text
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.type __syscall,@function
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.ent __syscall
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__syscall:
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syscall /* make system call */
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beq a3, $0, 1f /* if a3 is zero, call succeeded */
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nop /* delay slot */
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sw v0, errno /* call failed: store errno */
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li v1, -1 /* and force return value to -1 */
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li v0, -1
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1:
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j ra /* return */
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nop /* delay slot */
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.end __syscall
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.set reorder
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