xreturn.py revision 5590:2ff5831fd2eb 
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54# Authors: Gabe Black
55
56microcode = '''
57def macroop RET_NEAR
58{
59    # Make the default data size of rets 64 bits in 64 bit mode
60    .adjust_env oszIn64Override
61
62    ld t1, ss, [1, t0, rsp]
63    # Check address of return
64    addi rsp, rsp, dsz
65    wripi t1, 0
66};
67
68def macroop RET_NEAR_I
69{
70    # Make the default data size of rets 64 bits in 64 bit mode
71    .adjust_env oszIn64Override
72
73    limm t2, imm
74    ld t1, ss, [1, t0, rsp]
75    # Check address of return
76    addi rsp, rsp, dsz
77    add rsp, rsp, t2
78    wripi t1, 0
79};
80
81def macroop RET_FAR {
82    .adjust_env oszIn64Override
83
84    # Get the return RIP
85    ld t1, ss, [1, t0, rsp]
86
87    # Get the return CS
88    ld t2, ss, [1, t0, rsp], ssz
89
90    # Get the rpl
91    andi t3, t2, 0x3
92
93    # Get the cpl
94
95    # Here we'd check if we're changing priviledge levels. We'll just hope
96    # that doesn't happen yet.
97
98    # Do stuff if they're equal
99    andi t0, t2, 0xFC, flags=(EZF,), dataSize=2
100    bri t0, label("processDescriptor"), flags=(CEZF,)
101    andi t3, t2, 0xF8, dataSize=8
102    andi t0, t2, 0x4, flags=(EZF,), dataSize=2
103    bri t0, label("globalDescriptor"), flags=(CEZF,)
104    ld t3, tsl, [1, t0, t3], dataSize=8
105    bri t0, label("processDescriptor")
106globalDescriptor:
107    ld t3, tsg, [1, t0, t3], dataSize=8
108processDescriptor:
109    chks t2, t3, IretCheck, dataSize=8
110    # There should be validity checks on the RIP checks here, but I'll do
111    # that later.
112    wrdl cs, t3, t2
113    wrsel cs, t2
114    wrip t0, t1
115    bri t0, label("end")
116
117    # Do other stuff if they're not.
118end:
119    fault "NoFault"
120};
121'''
122