# Copyright (c) 2007-2008 The Hewlett-Packard Development Company
# All rights reserved.
#
# Redistribution and use of this software in source and binary forms,
# with or without modification, are permitted provided that the
# following conditions are met:
#
# The software must be used only for Non-Commercial Use which means any
# use which is NOT directed to receiving any direct monetary
# compensation for, or commercial advantage from such use.  Illustrative
# examples of non-commercial use are academic research, personal study,
# teaching, education and corporate research & development.
# Illustrative examples of commercial use are distributing products for
# commercial advantage and providing services using the software for
# commercial advantage.
#
# If you wish to use this software or functionality therein that may be
# covered by patents for commercial use, please contact:
#     Director of Intellectual Property Licensing
#     Office of Strategy and Technology
#     Hewlett-Packard Company
#     1501 Page Mill Road
#     Palo Alto, California  94304
#
# 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.  Neither the name of
# the COPYRIGHT HOLDER(s), HEWLETT-PACKARD COMPANY, nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.  No right of
# sublicense is granted herewith.  Derivatives of the software and
# output created using the software may be prepared, but only for
# Non-Commercial Uses.  Derivatives of the software may be shared with
# others provided: (i) the others agree to abide by the list of
# conditions herein which includes the Non-Commercial Use restrictions;
# and (ii) such Derivatives of the software include the above copyright
# notice to acknowledge the contribution from this software where
# applicable, this list of conditions and the disclaimer below.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
# Authors: Gabe Black

microcode = '''
def macroop RET_NEAR
{
    # Make the default data size of rets 64 bits in 64 bit mode
    .adjust_env oszIn64Override

    ld t1, ss, [1, t0, rsp]
    # Check address of return
    addi rsp, rsp, dsz
    wripi t1, 0
};

def macroop RET_NEAR_I
{
    # Make the default data size of rets 64 bits in 64 bit mode
    .adjust_env oszIn64Override

    limm t2, imm
    ld t1, ss, [1, t0, rsp]
    # Check address of return
    addi rsp, rsp, dsz
    add rsp, rsp, t2
    wripi t1, 0
};

def macroop RET_FAR {
    .adjust_env oszIn64Override

    # Get the return RIP
    ld t1, ss, [1, t0, rsp]

    # Get the return CS
    ld t2, ss, [1, t0, rsp], ssz

    # Get the rpl
    andi t3, t2, 0x3

    # Get the cpl

    # Here we'd check if we're changing priviledge levels. We'll just hope
    # that doesn't happen yet.

    # Do stuff if they're equal
    andi t0, t2, 0xFC, flags=(EZF,), dataSize=2
    bri t0, label("processDescriptor"), flags=(CEZF,)
    andi t3, t2, 0xF8, dataSize=8
    andi t0, t2, 0x4, flags=(EZF,), dataSize=2
    bri t0, label("globalDescriptor"), flags=(CEZF,)
    ld t3, tsl, [1, t0, t3], dataSize=8
    bri t0, label("processDescriptor")
globalDescriptor:
    ld t3, tsg, [1, t0, t3], dataSize=8
processDescriptor:
    chks t2, t3, IretCheck, dataSize=8
    # There should be validity checks on the RIP checks here, but I'll do
    # that later.
    wrdl cs, t3, t2
    wrsel cs, t2
    wrip t0, t1
    bri t0, label("end")

    # Do other stuff if they're not.
end:
    fault "NoFault"
};
'''