1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
|
(*========================================================================*)
(* *)
(* Copyright (c) 2015-2017 Robert M. Norton *)
(* Copyright (c) 2015-2017 Kathyrn Gray *)
(* All rights reserved. *)
(* *)
(* This software was developed by the University of Cambridge Computer *)
(* Laboratory as part of the Rigorous Engineering of Mainstream Systems *)
(* (REMS) project, funded by EPSRC grant EP/K008528/1. *)
(* *)
(* Redistribution and use in source and binary forms, with or without *)
(* modification, are permitted provided that the following conditions *)
(* are met: *)
(* 1. Redistributions of source code must retain the above copyright *)
(* notice, this list of conditions and the following disclaimer. *)
(* 2. Redistributions in binary form must reproduce the above copyright *)
(* notice, this list of conditions and the following disclaimer in *)
(* the documentation and/or other materials provided with the *)
(* distribution. *)
(* *)
(* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' *)
(* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED *)
(* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A *)
(* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR *)
(* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, *)
(* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT *)
(* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF *)
(* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND *)
(* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, *)
(* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT *)
(* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF *)
(* SUCH DAMAGE. *)
(*========================================================================*)
(* 256 bit cap + tag *)
typedef CapReg = bit[257]
val cast extern bool -> bit effect pure cast_bool_bit
val cast extern forall 'n, 'm. vector<'n,'m,dec,bool> -> vector<'n,'m,dec,bit> effect pure cast_boolvec_bitvec
val cast forall 'm. [|0:2**'m - 1|] -> vector<'m - 1,'m,dec,bit> effect pure cast_range_bitvec
function vector<'m - 1,'m,dec,bit> cast_range_bitvec (v) = to_vec (v)
val extern bool -> bool effect pure not
typedef uint64 = range<0, (2** 64) - 1>
typedef CapStruct = const struct {
bool tag;
bit[8] padding;
bit[24] otype;
bit[16] uperms;
bit[4] perm_reserved11_14;
bool access_system_regs;
bool perm_reserved9;
bool permit_ccall;
bool permit_seal;
bool permit_store_local_cap;
bool permit_store_cap;
bool permit_load_cap;
bool permit_store;
bool permit_load;
bool permit_execute;
bool global;
bool sealed;
bit[64] offset;
bit[64] base;
bit[64] length;
}
let (CapStruct) null_cap = {
tag = false;
padding = 0;
otype = 0;
uperms = 0;
perm_reserved11_14 = 0;
access_system_regs = false;
perm_reserved9 = false;
permit_ccall = false;
permit_seal = false;
permit_store_local_cap = false;
permit_store_cap = false;
permit_load_cap = false;
permit_store = false;
permit_load = false;
permit_execute = false;
global = false;
sealed = false;
offset = 0;
base = 0;
length = 0;
}
def Nat cap_size_t = 32 (* cap size in bytes *)
let ([:cap_size_t:]) cap_size = 32
function CapStruct capRegToCapStruct((CapReg) capReg) =
{
tag = capReg[256];
padding = capReg[255..248];
otype = capReg[247..224];
uperms = capReg[223..208];
perm_reserved11_14 = capReg[207..204];
access_system_regs = capReg[203];
perm_reserved9 = capReg[202];
permit_ccall = capReg[201];
permit_seal = capReg[200];
permit_store_local_cap = capReg[199];
permit_store_cap = capReg[198];
permit_load_cap = capReg[197];
permit_store = capReg[196];
permit_load = capReg[195];
permit_execute = capReg[194];
global = capReg[193];
sealed = capReg[192];
offset = capReg[191..128];
base = capReg[127..64];
length = capReg[63..0];
}
function (bit[31]) getCapPerms((CapStruct) cap) =
(
cap.uperms
: cap.perm_reserved11_14
: [cap.access_system_regs]
: [cap.perm_reserved9]
: [cap.permit_ccall]
: [cap.permit_seal]
: [cap.permit_store_local_cap]
: [cap.permit_store_cap]
: [cap.permit_load_cap]
: [cap.permit_store]
: [cap.permit_load]
: [cap.permit_execute]
: [cap.global]
)
(* Function used to convert capabilities to in-memory format
- this is the same as register format except for the offset,
field which is stored as an absolute cursor on CHERI
due to uarch optimisation *)
function (bit[256]) capStructToMemBits((CapStruct) cap) =
(
cap.padding
: cap.otype
: getCapPerms(cap)
: [cap.sealed]
(* NB in memory format stores cursor, not offset *)
: (cap.base + cap.offset)
: cap.base
: cap.length
)
(* Reverse of above used when reading from memory *)
function (bit[257]) memBitsToCapBits((bool) tag, (bit[256]) b) =
([tag]
: b[255..192]
: ((bit[64])(b[191..128] - b[127..64]))
: b[127..0]
)
function (CapReg) capStructToCapReg((CapStruct) cap) =
(
[cap.tag]
: cap.padding
: cap.otype
: getCapPerms(cap)
: [cap.sealed]
: cap.offset
: cap.base
: cap.length
)
function CapStruct setCapPerms((CapStruct) cap, (bit[31]) perms) =
{ cap with
uperms = perms[30..15];
perm_reserved11_14 = perms[14..11];
access_system_regs = perms[10];
perm_reserved9 = perms[9];
permit_ccall = perms[8];
permit_seal = perms[7];
permit_store_local_cap = perms[6];
permit_store_cap = perms[5];
permit_load_cap = perms[4];
permit_store = perms[3];
permit_load = perms[2];
permit_execute = perms[1];
global = perms[0];
}
function (bool, CapStruct) sealCap((CapStruct) cap, (bit[24]) otype) =
(true, {cap with sealed=true; otype=otype})
function bit[64] getCapBase((CapStruct) c) = c.base
function [|0:2**65 - 2|] getCapTop((CapStruct) c) = unsigned(c.base) + unsigned(c.length)
function bit[64] getCapOffset((CapStruct) c) = c.offset
function CapLen getCapLength((CapStruct) c) = unsigned(c.length)
function uint64 getCapCursor((CapStruct) cap) =
(unsigned(cap.base) + unsigned(cap.offset)) mod (pow2(64))
function (bool, CapStruct) setCapOffset((CapStruct) c, (bit[64]) offset) =
(true, {c with offset=offset})
function (bool, CapStruct) incCapOffset((CapStruct) c, (bit[64]) delta) =
let (bit[64]) newOffset = c.offset + delta in
(true, {c with offset = newOffset})
function (bool, CapStruct) setCapBounds((CapStruct) cap, (bit[64]) base, (bit[65]) top) =
let (bit[65]) length = top - (0b0 : base) in
(true, {cap with base = base; length = length[63..0]; offset = 0})
function CapStruct int_to_cap ((bit[64]) offset) =
{null_cap with offset = offset}
|
