xreturn.py revision 7087:fb8d5786ff30 
1# Copyright (c) 2007-2008 The Hewlett-Packard Development Company
2# All rights reserved.
3#
4# The license below extends only to copyright in the software and shall
5# not be construed as granting a license to any other intellectual
6# property including but not limited to intellectual property relating
7# to a hardware implementation of the functionality of the software
8# licensed hereunder.  You may use the software subject to the license
9# terms below provided that you ensure that this notice is replicated
10# unmodified and in its entirety in all distributions of the software,
11# modified or unmodified, in source code or in binary form.
12#
13# Redistribution and use in source and binary forms, with or without
14# modification, are permitted provided that the following conditions are
15# met: redistributions of source code must retain the above copyright
16# notice, this list of conditions and the following disclaimer;
17# redistributions in binary form must reproduce the above copyright
18# notice, this list of conditions and the following disclaimer in the
19# documentation and/or other materials provided with the distribution;
20# neither the name of the copyright holders nor the names of its
21# contributors may be used to endorse or promote products derived from
22# this software without specific prior written permission.
23#
24# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
25# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
26# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
27# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
28# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
29# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
30# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
31# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
32# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
34# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35#
36# Authors: Gabe Black
37
38microcode = '''
39def macroop RET_NEAR
40{
41    # Make the default data size of rets 64 bits in 64 bit mode
42    .adjust_env oszIn64Override
43
44    ld t1, ss, [1, t0, rsp]
45    # Check address of return
46    addi rsp, rsp, dsz
47    wripi t1, 0
48};
49
50def macroop RET_NEAR_I
51{
52    # Make the default data size of rets 64 bits in 64 bit mode
53    .adjust_env oszIn64Override
54
55    limm t2, imm
56    ld t1, ss, [1, t0, rsp]
57    # Check address of return
58    addi rsp, rsp, dsz
59    add rsp, rsp, t2
60    wripi t1, 0
61};
62
63def macroop RET_FAR {
64    .adjust_env oszIn64Override
65
66    # Get the return RIP
67    ld t1, ss, [1, t0, rsp]
68
69    # Get the return CS
70    ld t2, ss, [1, t0, rsp], ssz
71
72    # Get the rpl
73    andi t3, t2, 0x3
74
75    # Get the cpl
76
77    # Here we'd check if we're changing priviledge levels. We'll just hope
78    # that doesn't happen yet.
79
80    # Do stuff if they're equal
81    andi t0, t2, 0xFC, flags=(EZF,), dataSize=2
82    br label("processDescriptor"), flags=(CEZF,)
83    andi t3, t2, 0xF8, dataSize=8
84    andi t0, t2, 0x4, flags=(EZF,), dataSize=2
85    br label("globalDescriptor"), flags=(CEZF,)
86    ld t3, tsl, [1, t0, t3], dataSize=8
87    br label("processDescriptor")
88globalDescriptor:
89    ld t3, tsg, [1, t0, t3], dataSize=8
90processDescriptor:
91    chks t2, t3, IretCheck, dataSize=8
92    # There should be validity checks on the RIP checks here, but I'll do
93    # that later.
94    wrdl cs, t3, t2
95    wrsel cs, t2
96    wrip t0, t1
97    br label("end")
98
99    # Do other stuff if they're not.
100end:
101    fault "NoFault"
102};
103'''
104