source: mainline/uspace/lib/c/arch/amd64/src/syscall.S

#
# Copyright (c) 2006 Ondrej Palkovsky
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# - Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
# - The name of the author may not be used to endorse or promote products
#   derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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#include <abi/asmtool.h>

.text

## Make a system call.
#
# @param rdi            First argument.
# @param rsi            Second argument.
# @param rdx            Third argument.
# @param rcx            Fourth argument.
# @param r8             Fifth argument.
# @param r9             Sixth argument.
# @param 8(%rsp)        Syscall number.
#
# @return               The return value will be stored in RAX.
#
FUNCTION_BEGIN(__syscall)
        #
        # Move the syscall number into RAX.
        movslq 8(%rsp), %rax

        #
        # Save RCX, the 4th argument, aside because RCX gets rewritten by the
        # SYSCALL instruction.
        #
        movq %rcx, %r10
        syscall
        ret
FUNCTION_END(__syscall)