44 .adjust_env oszIn64Override
45
46 # Check for a nested task. This isn't supported at the moment.
47 rflag t1, 14; #NT bit
48 panic "Task switching with iret is unimplemented!", flags=(nCEZF,)
49
50 #t1 = temp_RIP
51 #t2 = temp_CS
52 #t3 = temp_RFLAGS
53 #t4 = handy m5 register
54
55 # Pop temp_RIP, temp_CS, and temp_RFLAGS
56 ld t1, ss, [1, t0, rsp], "0 * env.stackSize", dataSize=ssz
57 ld t2, ss, [1, t0, rsp], "1 * env.stackSize", dataSize=ssz
58 ld t3, ss, [1, t0, rsp], "2 * env.stackSize", dataSize=ssz
59
60 # Read the handy m5 register for use later
61 rdm5reg t4
62
63
64###
65### Handle if we're returning to virtual 8086 mode.
66###
67
68 #IF ((temp_RFLAGS.VM=1) && (CPL=0) && (LEGACY_MODE))
69 # IRET_FROM_PROTECTED_TO_VIRTUAL
70
71 #temp_RFLAGS.VM != 1
72 rcri t0, t3, 18, flags=(ECF,)
73 br label("protToVirtFallThrough"), flags=(nCECF,)
74
75 #CPL=0
76 andi t0, t4, 0x30, flags=(EZF,)
77 br label("protToVirtFallThrough"), flags=(nCEZF,)
78
79 #(LEGACY_MODE)
80 rcri t0, t4, 1, flags=(ECF,)
81 br label("protToVirtFallThrough"), flags=(nCECF,)
82
83 panic "iret to virtual mode not supported"
84
85protToVirtFallThrough:
86
87
88
89 #temp_CPL = temp_CS.rpl
90 andi t5, t2, 0x3
91
92
93###
94### Read in the info for the new CS segment.
95###
96
97 #CS = READ_DESCRIPTOR (temp_CS, iret_chk)
98 andi t0, t2, 0xFC, flags=(EZF,), dataSize=2
99 br label("processCSDescriptor"), flags=(CEZF,)
100 andi t6, t2, 0xF8, dataSize=8
101 andi t0, t2, 0x4, flags=(EZF,), dataSize=2
102 br label("globalCSDescriptor"), flags=(CEZF,)
103 ld t8, tsl, [1, t0, t6], dataSize=8
104 br label("processCSDescriptor")
105globalCSDescriptor:
106 ld t8, tsg, [1, t0, t6], dataSize=8
107processCSDescriptor:
108 chks t2, t6, dataSize=8
109
110
111###
112### Get the new stack pointer and stack segment off the old stack if necessary,
113### and piggyback on the logic to check the new RIP value.
114###
115 #IF ((64BIT_MODE) || (temp_CPL!=CPL))
116 #{
117
118 #(64BIT_MODE)
119 andi t0, t4, 0xE, flags=(EZF,)
120 # Since we just found out we're in 64 bit mode, take advantage and
121 # do the appropriate RIP checks.
122 br label("doPopStackStuffAndCheckRIP"), flags=(CEZF,)
123
124 # Here, we know we're -not- in 64 bit mode, so we should do the
125 # appropriate/other RIP checks.
126 # if temp_RIP > CS.limit throw #GP(0)
127 rdlimit t6, cs, dataSize=8
128 sub t0, t1, t6, flags=(ECF,)
129 fault "new GeneralProtection(0)", flags=(CECF,)
130
131 #(temp_CPL!=CPL)
132 srli t7, t4, 4
133 xor t7, t7, t5
134 andi t0, t7, 0x3, flags=(EZF,)
135 br label("doPopStackStuff"), flags=(nCEZF,)
136 # We can modify user visible state here because we're know
137 # we're done with things that can fault.
138 addi rsp, rsp, "3 * env.stackSize"
139 br label("fallThroughPopStackStuff")
140
141doPopStackStuffAndCheckRIP:
142 # Check if the RIP is canonical.
143 srai t7, t1, 47, flags=(EZF,), dataSize=ssz
144 # if t7 isn't 0 or -1, it wasn't canonical.
145 br label("doPopStackStuff"), flags=(CEZF,)
146 addi t0, t7, 1, flags=(EZF,), dataSize=ssz
147 fault "new GeneralProtection(0)", flags=(nCEZF,)
148
149doPopStackStuff:
150 # POP.v temp_RSP
151 ld t6, ss, [1, t0, rsp], "3 * env.dataSize", dataSize=ssz
152 # POP.v temp_SS
153 ld t9, ss, [1, t0, rsp], "4 * env.dataSize", dataSize=ssz
154 # SS = READ_DESCRIPTOR (temp_SS, ss_chk)
155 andi t0, t9, 0xFC, flags=(EZF,), dataSize=2
156 br label("processSSDescriptor"), flags=(CEZF,)
157 andi t7, t9, 0xF8, dataSize=8
158 andi t0, t9, 0x4, flags=(EZF,), dataSize=2
159 br label("globalSSDescriptor"), flags=(CEZF,)
160 ld t7, tsl, [1, t0, t7], dataSize=8
161 br label("processSSDescriptor")
162globalSSDescriptor:
163 ld t7, tsg, [1, t0, t7], dataSize=8
164processSSDescriptor:
165 chks t9, t7, dataSize=8
166
167 # This actually updates state which is wrong. It should wait until we know
168 # we're not going to fault. Unfortunately, that's hard to do.
169 wrdl ss, t7, t9
170 wrsel ss, t9
171
172###
173### From this point downwards, we can't fault. We can update user visible state.
174###
175 # RSP.s = temp_RSP
176 mov rsp, rsp, t6, dataSize=ssz
177
178 #}
179
180fallThroughPopStackStuff:
181
182 # Update CS
183 wrdl cs, t8, t2
184 wrsel cs, t2
185
186 #CPL = temp_CPL
187
188 #IF (changing CPL)
189 #{
190 srli t7, t4, 4
191 xor t7, t7, t5
192 andi t0, t7, 0x3, flags=(EZF,)
193 br label("skipSegmentSquashing"), flags=(CEZF,)
194
195 # The attribute register needs to keep track of more info before this will
196 # work the way it needs to.
197 # FOR (seg = ES, DS, FS, GS)
198 # IF ((seg.attr.dpl < cpl && ((seg.attr.type = 'data')
199 # || (seg.attr.type = 'non-conforming-code')))
200 # {
201 # seg = NULL
202 # }
203 #}
204
205skipSegmentSquashing:
206
207 # Ignore this for now.
208 #RFLAGS.v = temp_RFLAGS
209 wrflags t0, t3
210 # VIF,VIP,IOPL only changed if (old_CPL = 0)
211 # IF only changed if (old_CPL <= old_RFLAGS.IOPL)
212 # VM unchanged
213 # RF cleared
214
215 #RIP = temp_RIP
216 wrip t0, t1, dataSize=ssz
217};
218
219def macroop IRET_VIRT {
220 panic "Virtual mode iret isn't implemented!"
221};
222'''
223#let {{
224# class INT(Inst):
225# "GenFault ${new UnimpInstFault}"
226# class INTO(Inst):
227# "GenFault ${new UnimpInstFault}"
228#}};
| 46 .adjust_env oszIn64Override
47
48 # Check for a nested task. This isn't supported at the moment.
49 rflag t1, 14; #NT bit
50 panic "Task switching with iret is unimplemented!", flags=(nCEZF,)
51
52 #t1 = temp_RIP
53 #t2 = temp_CS
54 #t3 = temp_RFLAGS
55 #t4 = handy m5 register
56
57 # Pop temp_RIP, temp_CS, and temp_RFLAGS
58 ld t1, ss, [1, t0, rsp], "0 * env.stackSize", dataSize=ssz
59 ld t2, ss, [1, t0, rsp], "1 * env.stackSize", dataSize=ssz
60 ld t3, ss, [1, t0, rsp], "2 * env.stackSize", dataSize=ssz
61
62 # Read the handy m5 register for use later
63 rdm5reg t4
64
65
66###
67### Handle if we're returning to virtual 8086 mode.
68###
69
70 #IF ((temp_RFLAGS.VM=1) && (CPL=0) && (LEGACY_MODE))
71 # IRET_FROM_PROTECTED_TO_VIRTUAL
72
73 #temp_RFLAGS.VM != 1
74 rcri t0, t3, 18, flags=(ECF,)
75 br label("protToVirtFallThrough"), flags=(nCECF,)
76
77 #CPL=0
78 andi t0, t4, 0x30, flags=(EZF,)
79 br label("protToVirtFallThrough"), flags=(nCEZF,)
80
81 #(LEGACY_MODE)
82 rcri t0, t4, 1, flags=(ECF,)
83 br label("protToVirtFallThrough"), flags=(nCECF,)
84
85 panic "iret to virtual mode not supported"
86
87protToVirtFallThrough:
88
89
90
91 #temp_CPL = temp_CS.rpl
92 andi t5, t2, 0x3
93
94
95###
96### Read in the info for the new CS segment.
97###
98
99 #CS = READ_DESCRIPTOR (temp_CS, iret_chk)
100 andi t0, t2, 0xFC, flags=(EZF,), dataSize=2
101 br label("processCSDescriptor"), flags=(CEZF,)
102 andi t6, t2, 0xF8, dataSize=8
103 andi t0, t2, 0x4, flags=(EZF,), dataSize=2
104 br label("globalCSDescriptor"), flags=(CEZF,)
105 ld t8, tsl, [1, t0, t6], dataSize=8
106 br label("processCSDescriptor")
107globalCSDescriptor:
108 ld t8, tsg, [1, t0, t6], dataSize=8
109processCSDescriptor:
110 chks t2, t6, dataSize=8
111
112
113###
114### Get the new stack pointer and stack segment off the old stack if necessary,
115### and piggyback on the logic to check the new RIP value.
116###
117 #IF ((64BIT_MODE) || (temp_CPL!=CPL))
118 #{
119
120 #(64BIT_MODE)
121 andi t0, t4, 0xE, flags=(EZF,)
122 # Since we just found out we're in 64 bit mode, take advantage and
123 # do the appropriate RIP checks.
124 br label("doPopStackStuffAndCheckRIP"), flags=(CEZF,)
125
126 # Here, we know we're -not- in 64 bit mode, so we should do the
127 # appropriate/other RIP checks.
128 # if temp_RIP > CS.limit throw #GP(0)
129 rdlimit t6, cs, dataSize=8
130 sub t0, t1, t6, flags=(ECF,)
131 fault "new GeneralProtection(0)", flags=(CECF,)
132
133 #(temp_CPL!=CPL)
134 srli t7, t4, 4
135 xor t7, t7, t5
136 andi t0, t7, 0x3, flags=(EZF,)
137 br label("doPopStackStuff"), flags=(nCEZF,)
138 # We can modify user visible state here because we're know
139 # we're done with things that can fault.
140 addi rsp, rsp, "3 * env.stackSize"
141 br label("fallThroughPopStackStuff")
142
143doPopStackStuffAndCheckRIP:
144 # Check if the RIP is canonical.
145 srai t7, t1, 47, flags=(EZF,), dataSize=ssz
146 # if t7 isn't 0 or -1, it wasn't canonical.
147 br label("doPopStackStuff"), flags=(CEZF,)
148 addi t0, t7, 1, flags=(EZF,), dataSize=ssz
149 fault "new GeneralProtection(0)", flags=(nCEZF,)
150
151doPopStackStuff:
152 # POP.v temp_RSP
153 ld t6, ss, [1, t0, rsp], "3 * env.dataSize", dataSize=ssz
154 # POP.v temp_SS
155 ld t9, ss, [1, t0, rsp], "4 * env.dataSize", dataSize=ssz
156 # SS = READ_DESCRIPTOR (temp_SS, ss_chk)
157 andi t0, t9, 0xFC, flags=(EZF,), dataSize=2
158 br label("processSSDescriptor"), flags=(CEZF,)
159 andi t7, t9, 0xF8, dataSize=8
160 andi t0, t9, 0x4, flags=(EZF,), dataSize=2
161 br label("globalSSDescriptor"), flags=(CEZF,)
162 ld t7, tsl, [1, t0, t7], dataSize=8
163 br label("processSSDescriptor")
164globalSSDescriptor:
165 ld t7, tsg, [1, t0, t7], dataSize=8
166processSSDescriptor:
167 chks t9, t7, dataSize=8
168
169 # This actually updates state which is wrong. It should wait until we know
170 # we're not going to fault. Unfortunately, that's hard to do.
171 wrdl ss, t7, t9
172 wrsel ss, t9
173
174###
175### From this point downwards, we can't fault. We can update user visible state.
176###
177 # RSP.s = temp_RSP
178 mov rsp, rsp, t6, dataSize=ssz
179
180 #}
181
182fallThroughPopStackStuff:
183
184 # Update CS
185 wrdl cs, t8, t2
186 wrsel cs, t2
187
188 #CPL = temp_CPL
189
190 #IF (changing CPL)
191 #{
192 srli t7, t4, 4
193 xor t7, t7, t5
194 andi t0, t7, 0x3, flags=(EZF,)
195 br label("skipSegmentSquashing"), flags=(CEZF,)
196
197 # The attribute register needs to keep track of more info before this will
198 # work the way it needs to.
199 # FOR (seg = ES, DS, FS, GS)
200 # IF ((seg.attr.dpl < cpl && ((seg.attr.type = 'data')
201 # || (seg.attr.type = 'non-conforming-code')))
202 # {
203 # seg = NULL
204 # }
205 #}
206
207skipSegmentSquashing:
208
209 # Ignore this for now.
210 #RFLAGS.v = temp_RFLAGS
211 wrflags t0, t3
212 # VIF,VIP,IOPL only changed if (old_CPL = 0)
213 # IF only changed if (old_CPL <= old_RFLAGS.IOPL)
214 # VM unchanged
215 # RF cleared
216
217 #RIP = temp_RIP
218 wrip t0, t1, dataSize=ssz
219};
220
221def macroop IRET_VIRT {
222 panic "Virtual mode iret isn't implemented!"
223};
224'''
225#let {{
226# class INT(Inst):
227# "GenFault ${new UnimpInstFault}"
228# class INTO(Inst):
229# "GenFault ${new UnimpInstFault}"
230#}};
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