romutil.py revision 5948:871fccb3fb7a 
1# Copyright (c) 2008 The Regents of The University of Michigan
2# All rights reserved.
3#
4# Redistribution and use in source and binary forms, with or without
5# modification, are permitted provided that the following conditions are
6# met: redistributions of source code must retain the above copyright
7# notice, this list of conditions and the following disclaimer;
8# redistributions in binary form must reproduce the above copyright
9# notice, this list of conditions and the following disclaimer in the
10# documentation and/or other materials provided with the distribution;
11# neither the name of the copyright holders nor the names of its
12# contributors may be used to endorse or promote products derived from
13# this software without specific prior written permission.
14#
15# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
18# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
19# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
21# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26#
27# Authors: Gabe Black
28
29intCodeTemplate = '''
30def rom
31{
32    # This vectors the CPU into an interrupt handler in long mode.
33    # On entry, t1 is set to the vector of the interrupt and t7 is the current
34    # ip. We need that because rdip returns the next ip.
35    extern %(startLabel)s:
36
37    #
38    # Get the 64 bit interrupt or trap gate descriptor from the IDT
39    #
40
41    # Load the gate descriptor from the IDT
42    slli t4, t1, 4, dataSize=8
43    ld t2, idtr, [1, t0, t4], 8, dataSize=8, addressSize=8, atCPL0=True
44    ld t4, idtr, [1, t0, t4], dataSize=8, addressSize=8, atCPL0=True
45
46    # Make sure the descriptor is a legal gate.
47    chks t1, t4, %(gateCheckType)s
48
49    #
50    # Get the target CS descriptor using the selector in the gate
51    # descriptor.
52    #
53    srli t10, t4, 16, dataSize=8
54    andi t5, t10, 0xF8, dataSize=8
55    andi t0, t10, 0x4, flags=(EZF,), dataSize=2
56    br rom_local_label("%(startLabel)s_globalDescriptor"), flags=(CEZF,)
57    ld t3, tsl, [1, t0, t5], dataSize=8, addressSize=8, atCPL0=True
58    br rom_local_label("%(startLabel)s_processDescriptor")
59%(startLabel)s_globalDescriptor:
60    ld t3, tsg, [1, t0, t5], dataSize=8, addressSize=8, atCPL0=True
61%(startLabel)s_processDescriptor:
62    chks t10, t3, IntCSCheck, dataSize=8
63    wrdl hs, t3, t10, dataSize=8
64
65    # Stick the target offset in t9.
66    wrdh t9, t4, t2, dataSize=8
67
68
69    #
70    # Figure out where the stack should be
71    #
72
73    # Record what we might set the stack selector to.
74    rdsel t11, ss
75
76    # Check if we're changing privelege level. At this point we can assume
77    # we're going to a DPL that's less than or equal to the CPL.
78    rdattr t10, hs, dataSize=8
79    srli t10, t10, 3, dataSize=8
80    andi t10, t10, 3, dataSize=8
81    rdattr t5, cs, dataSize=8
82    srli t5, t5, 3, dataSize=8
83    andi t5, t5, 0x3, dataSize=8
84    sub t0, t5, t10, flags=(EZF,), dataSize=8
85    # We're going to change priviledge, so zero out the stack selector. We
86    # need to let the IST have priority so we don't branch yet.
87    wrsel t11, t0, flags=(nCEZF,)
88
89    # Check the IST field of the gate descriptor
90    srli t12, t4, 32, dataSize=8
91    andi t12, t12, 0x7, dataSize=8
92    subi t0, t12, 1, flags=(ECF,), dataSize=8
93    br rom_local_label("%(startLabel)s_istStackSwitch"), flags=(nCECF,)
94    br rom_local_label("%(startLabel)s_cplStackSwitch"), flags=(nCEZF,)
95
96    # If we're here, it's because the stack isn't being switched.
97    # Set t6 to the new aligned rsp.
98    mov t6, t6, rsp, dataSize=8
99    br rom_local_label("%(startLabel)s_stackSwitched")
100
101%(startLabel)s_istStackSwitch:
102    ld t6, tr, [8, t12, t0], 0x1c, dataSize=8, addressSize=8, atCPL0=True
103    br rom_local_label("%(startLabel)s_stackSwitched")
104
105%(startLabel)s_cplStackSwitch:
106    # Get the new rsp from the TSS
107    ld t6, tr, [8, t10, t0], 4, dataSize=8, addressSize=8, atCPL0=True
108
109%(startLabel)s_stackSwitched:
110
111    andi t6, t6, 0xF0, dataSize=1
112    subi t6, t6, 40 + %(errorCodeSize)d, dataSize=8
113
114    ##
115    ## Point of no return.
116    ## We're now going to irrevocably modify visible state.
117    ## Anything bad that's going to happen should have happened by now or will
118    ## happen right now.
119    ##
120    wrip t0, t9, dataSize=8
121
122    #
123    # Set up the target code segment. Do this now so we have the right
124    # permissions when setting up the stack frame.
125    #
126    srli t5, t4, 16, dataSize=8
127    andi t5, t5, 0xFF, dataSize=8
128    wrdl cs, t3, t5, dataSize=8
129    # Tuck away the old CS for use below
130    limm t10, 0, dataSize=8
131    rdsel t10, cs, dataSize=2
132    wrsel cs, t5, dataSize=2
133
134    # Check that we can access everything we need to on the stack
135    ldst t0, hs, [1, t0, t6], dataSize=8, addressSize=8
136    ldst t0, hs, [1, t0, t6], \
137         32 + %(errorCodeSize)d, dataSize=8, addressSize=8
138
139
140    #
141    # Build up the interrupt stack frame
142    #
143
144
145    # Write out the contents of memory
146    %(errorCodeCode)s
147    st t7, hs, [1, t0, t6], %(errorCodeSize)d, dataSize=8, addressSize=8
148    st t10, hs, [1, t0, t6], 8 + %(errorCodeSize)d, dataSize=8, addressSize=8
149    rflags t10, dataSize=8
150    st t10, hs, [1, t0, t6], 16 + %(errorCodeSize)d, dataSize=8, addressSize=8
151    st rsp, hs, [1, t0, t6], 24 + %(errorCodeSize)d, dataSize=8, addressSize=8
152    rdsel t5, ss, dataSize=2
153    st t5, hs, [1, t0, t6], 32 + %(errorCodeSize)d, dataSize=8, addressSize=8
154
155    # Set the stack segment
156    mov rsp, rsp, t6, dataSize=8
157    wrsel ss, t11, dataSize=2
158
159    #
160    # Adjust rflags which is still in t10 from above
161    #
162
163    # Set IF to the lowest bit of the original gate type.
164    # The type field of the original gate starts at bit 40.
165
166    # Set the TF, NT, and RF bits. We'll flip them at the end.
167    limm t6, (1 << 8) | (1 << 14) | (1 << 16)
168    or t10, t10, t6
169    srli t5, t4, 40, dataSize=8
170    srli t7, t10, 9, dataSize=8
171    xor t5, t7, t5, dataSize=8
172    andi t5, t5, 1, dataSize=8
173    slli t5, t5, 9, dataSize=8
174    or t6, t5, t6, dataSize=8
175
176    # Put the results into rflags
177    wrflags t6, t10
178
179    eret
180};
181'''
182
183microcode = \
184intCodeTemplate % {\
185    "startLabel" : "longModeInterrupt",
186    "gateCheckType" : "IntGateCheck",
187    "errorCodeSize" : 0,
188    "errorCodeCode" : ""
189} + \
190intCodeTemplate % {\
191    "startLabel" : "longModeSoftInterrupt",
192    "gateCheckType" : "SoftIntGateCheck",
193    "errorCodeSize" : 0,
194    "errorCodeCode" : ""
195} + \
196intCodeTemplate % {\
197    "startLabel" : "longModeInterruptWithError",
198    "gateCheckType" : "IntGateCheck",
199    "errorCodeSize" : 8,
200    "errorCodeCode" : '''
201    st t15, hs, [1, t0, t6], dataSize=8, addressSize=8
202    '''
203} + \
204'''
205def rom
206{
207    # This vectors the CPU into an interrupt handler in legacy mode.
208    extern legacyModeInterrupt:
209    panic "Legacy mode interrupts not implemented (in microcode)"
210    eret
211};
212'''
213