xreturn.py revision 9671:483f5ff33dd1 
1# Copyright (c) 2007-2008 The Hewlett-Packard Development Company
2# All rights reserved.
3#
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5# not be construed as granting a license to any other intellectual
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8# licensed hereunder.  You may use the software subject to the license
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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
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20# neither the name of the copyright holders nor the names of its
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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
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27# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
28# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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30# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
31# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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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    # increment the stack pointer to pop the instruction pointer
73    # and the code segment from the stack.
74    addi rsp, rsp, dsz
75    addi rsp, rsp, dsz
76
77    # Get the rpl
78    andi t3, t2, 0x3
79
80    # Get the cpl
81
82    # Here we'd check if we're changing priviledge levels. We'll just hope
83    # that doesn't happen yet.
84
85    # Do stuff if they're equal
86    andi t0, t2, 0xFC, flags=(EZF,), dataSize=2
87    br label("processDescriptor"), flags=(CEZF,)
88    andi t3, t2, 0xF8, dataSize=8
89    andi t0, t2, 0x4, flags=(EZF,), dataSize=2
90    br label("globalDescriptor"), flags=(CEZF,)
91    ld t3, tsl, [1, t0, t3], dataSize=8
92    br label("processDescriptor")
93globalDescriptor:
94    ld t3, tsg, [1, t0, t3], dataSize=8
95processDescriptor:
96    chks t2, t3, IretCheck, dataSize=8
97    # There should be validity checks on the RIP checks here, but I'll do
98    # that later.
99    wrdl cs, t3, t2
100    wrsel cs, t2
101    wrip t0, t1
102    br label("end")
103
104    # Do other stuff if they're not.
105end:
106    fault "NoFault"
107};
108'''
109