interrupts_and_exceptions.py revision 5661:443e6f925027 
1# Copyright (c) 2007-2008 The Hewlett-Packard Development Company
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42# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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53#
54# Authors: Gabe Black
55
56microcode = '''
57def macroop IRET_REAL {
58    panic "Real mode iret isn't implemented!"
59};
60
61def macroop IRET_PROT {
62    .adjust_env oszIn64Override
63
64    # Check for a nested task. This isn't supported at the moment.
65    rflag t1, NT
66    panic "Task switching with iret is unimplemented!", flags=(nCEZF,)
67
68    #t1 = temp_RIP
69    #t2 = temp_CS
70    #t3 = temp_RFLAGS
71    #t4 = handy m5 register
72
73    # Pop temp_RIP, temp_CS, and temp_RFLAGS
74    ld t1, ss, [1, t0, rsp], "0 * env.stackSize", dataSize=ssz
75    ld t2, ss, [1, t0, rsp], "1 * env.stackSize", dataSize=ssz
76    ld t3, ss, [1, t0, rsp], "2 * env.stackSize", dataSize=ssz
77
78
79
80###
81### Handle if we're returning to virtual 8086 mode.
82###
83
84    #IF ((temp_RFLAGS.VM=1) && (CPL=0) && (LEGACY_MODE))
85    #    IRET_FROM_PROTECTED_TO_VIRTUAL
86
87    #temp_RFLAGS.VM != 1
88    rcri t0, t3, 18, flags=(ECF,)
89    br label("protToVirtFallThrough"), flags=(nCECF,)
90
91    #CPL=0
92    rdm5reg t4
93    andi t0, t4, 0x30, flags=(EZF,)
94    br label("protToVirtFallThrough"), flags=(nCEZF,)
95
96    #(LEGACY_MODE)
97    rcri t0, t4, 1, flags=(ECF,)
98    br label("protToVirtFallThrough"), flags=(nCECF,)
99
100    panic "iret to virtual mode not supported"
101
102protToVirtFallThrough:
103
104
105
106    #temp_CPL = temp_CS.rpl
107    andi t5, t2, 0x3
108
109
110###
111### Read in the info for the new CS segment.
112###
113
114    #CS = READ_DESCRIPTOR (temp_CS, iret_chk)
115    andi t0, t2, 0xFC, flags=(EZF,), dataSize=2
116    br label("processCSDescriptor"), flags=(CEZF,)
117    andi t6, t2, 0xF8, dataSize=8
118    andi t0, t2, 0x4, flags=(EZF,), dataSize=2
119    br label("globalCSDescriptor"), flags=(CEZF,)
120    ld t6, tsl, [1, t0, t6], dataSize=8
121    br label("processCSDescriptor")
122globalCSDescriptor:
123    ld t6, tsg, [1, t0, t6], dataSize=8
124processCSDescriptor:
125    chks t2, t6, dataSize=8
126
127    # This actually updates state which is wrong. It should wait until we know
128    # we're not going to fault. Unfortunately, that's hard to do.
129    wrdl cs, t6, t2
130    wrsel cs, t2
131
132    #CPL = temp_CPL
133
134
135###
136### Get the new stack pointer and stack segment off the old stack if necessary,
137### and piggyback on the logic to check the new RIP value.
138###
139    #IF ((64BIT_MODE) || (temp_CPL!=CPL))
140    #{
141
142    #(64BIT_MODE)
143    andi t0, t4, 0xE, flags=(EZF,)
144    # Since we just found out we're in 64 bit mode, take advantage and
145    # do the appropriate RIP checks.
146    br label("doPopStackStuffAndCheckRIP"), flags=(CEZF,)
147
148    # Here, we know we're -not- in 64 bit mode, so we should do the
149    # appropriate/other RIP checks.
150    # if temp_RIP > CS.limit throw #GP(0)
151    rdlimit t6, cs
152    subi t0, t1, t6, flags=(ECF,)
153    fault "new GeneralProtection(0)", flags=(CECF,)
154
155    #(temp_CPL!=CPL)
156    srli t7, t4, 4
157    xor t7, t7, t5
158    andi t0, t7, 0x3, flags=(EZF,)
159    br label("doPopStackStuff"), flags=(nCEZF,)
160    # We can modify user visible state here because we're know
161    # we're done with things that can fault.
162    addi rsp, rsp, "3 * env.stackSize"
163    br label("fallThroughPopStackStuff")
164
165doPopStackStuffAndCheckRIP:
166    # Check if the RIP is canonical.
167    sra t7, t1, 47, flags=(EZF,), dataSize=ssz
168    # if t7 isn't 0 or -1, it wasn't canonical.
169    br label("doPopStackStuff"), flags=(CEZF,)
170    addi t0, t7, 1, flags=(EZF,), dataSize=ssz
171    fault "new GeneralProtection(0)", flags=(nCEZF,)
172
173doPopStackStuff:
174    #    POP.v temp_RSP
175    ld t6, ss, [1, t0, rsp], "3 * env.dataSize", dataSize=ssz
176    #    POP.v temp_SS
177    ld t2, ss, [1, t0, rsp], "4 * env.dataSize", dataSize=ssz
178    #    SS = READ_DESCRIPTOR (temp_SS, ss_chk)
179    andi t0, t2, 0xFC, flags=(EZF,), dataSize=2
180    br label("processSSDescriptor"), flags=(CEZF,)
181    andi t7, t2, 0xF8, dataSize=8
182    andi t0, t2, 0x4, flags=(EZF,), dataSize=2
183    br label("globalSSDescriptor"), flags=(CEZF,)
184    ld t7, tsl, [1, t0, t7], dataSize=8
185    br label("processSSDescriptor")
186globalSSDescriptor:
187    ld t7, tsg, [1, t0, t7], dataSize=8
188processSSDescriptor:
189    chks t2, t7, dataSize=8
190
191    # This actually updates state which is wrong. It should wait until we know
192    # we're not going to fault. Unfortunately, that's hard to do.
193    wrdl cs, t7, t2
194    wrsel cs, t2
195
196###
197### From this point downwards, we can't fault. We can update user visible state.
198###
199    #    RSP.s = temp_RSP
200    mov rsp, rsp, t6, dataSize=ssz
201
202    #}
203
204fallThroughPopStackStuff:
205
206    #IF (changing CPL)
207    #{
208    srli t7, t4, 4
209    xor t7, t7, t5
210    andi t0, t7, 0x3, flags=(EZF,)
211    br label("skipSegmentSquashing"), flags=(CEZF,)
212
213    # The attribute register needs to keep track of more info before this will
214    # work the way it needs to.
215    #    FOR (seg = ES, DS, FS, GS)
216    #        IF ((seg.attr.dpl < cpl && ((seg.attr.type = 'data')
217    #            || (seg.attr.type = 'non-conforming-code')))
218    #        {
219    #            seg = NULL
220    #        }
221    #}
222
223skipSegmentSquashing:
224
225    # Ignore this for now.
226    #RFLAGS.v = temp_RFLAGS
227    #  VIF,VIP,IOPL only changed if (old_CPL = 0)
228    #  IF only changed if (old_CPL <= old_RFLAGS.IOPL)
229    #  VM unchanged
230    #  RF cleared
231
232    #RIP = temp_RIP
233    wrip t0, t1, dataSize=ssz
234};
235
236def macroop IRET_VIRT {
237    panic "Virtual mode iret isn't implemented!"
238};
239'''
240#let {{
241#    class INT(Inst):
242#       "GenFault ${new UnimpInstFault}"
243#    class INTO(Inst):
244#       "GenFault ${new UnimpInstFault}"
245#}};
246