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
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
|
// Copyright 2015 The Crashpad Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#[derive(Copy, Clone)]
#[repr(C, align(16))]
pub struct M128A {
pub Low: u64,
pub High: i64,
}
#[derive(Copy, Clone)]
#[repr(C, align(16))]
pub struct XSAVE_FORMAT {
pub ControlWord: u16,
pub StatusWord: u16,
pub TagWord: u8,
pub Reserved1: u8,
pub ErrorOpcode: u16,
pub ErrorOffset: u32,
pub ErrorSelector: u16,
pub Reserved2: u16,
pub DataOffset: u32,
pub DataSelector: u16,
pub Reserved3: u16,
pub MxCsr: u32,
pub MxCsr_Mask: u32,
pub FloatRegisters: [M128A; 8],
pub XmmRegisters: [M128A; 16],
pub Reserved4: [u8; 96],
}
#[derive(Copy, Clone)]
#[repr(C, align(16))]
pub struct CONTEXT {
pub P1Home: u64,
pub P2Home: u64,
pub P3Home: u64,
pub P4Home: u64,
pub P5Home: u64,
pub P6Home: u64,
pub ContextFlags: u32,
pub MxCsr: u32,
pub SegCs: u16,
pub SegDs: u16,
pub SegEs: u16,
pub SegFs: u16,
pub SegGs: u16,
pub SegSs: u16,
pub EFlags: u32,
pub Dr0: u64,
pub Dr1: u64,
pub Dr2: u64,
pub Dr3: u64,
pub Dr6: u64,
pub Dr7: u64,
pub Rax: u64,
pub Rcx: u64,
pub Rdx: u64,
pub Rbx: u64,
pub Rsp: u64,
pub Rbp: u64,
pub Rsi: u64,
pub Rdi: u64,
pub R8: u64,
pub R9: u64,
pub R10: u64,
pub R11: u64,
pub R12: u64,
pub R13: u64,
pub R14: u64,
pub R15: u64,
pub Rip: u64,
pub Anonymous: CONTEXT_0,
pub VectorRegister: [M128A; 26],
pub VectorControl: u64,
pub DebugControl: u64,
pub LastBranchToRip: u64,
pub LastBranchFromRip: u64,
pub LastExceptionToRip: u64,
pub LastExceptionFromRip: u64,
}
#[derive(Copy, Clone)]
#[repr(C, align(16))]
pub union CONTEXT_0 {
pub FltSave: XSAVE_FORMAT,
pub Anonymous: CONTEXT_0_0,
}
#[derive(Copy, Clone)]
#[repr(C, align(16))]
pub struct CONTEXT_0_0 {
pub Header: [M128A; 2],
pub Legacy: [M128A; 8],
pub Xmm0: M128A,
pub Xmm1: M128A,
pub Xmm2: M128A,
pub Xmm3: M128A,
pub Xmm4: M128A,
pub Xmm5: M128A,
pub Xmm6: M128A,
pub Xmm7: M128A,
pub Xmm8: M128A,
pub Xmm9: M128A,
pub Xmm10: M128A,
pub Xmm11: M128A,
pub Xmm12: M128A,
pub Xmm13: M128A,
pub Xmm14: M128A,
pub Xmm15: M128A,
}
std::arch::global_asm! {
".text",
".global capture_context",
"capture_context:",
".seh_proc capture_context",
"push rbp",
".seh_pushreg rbp",
"mov rbp, rsp",
".seh_setframe rbp, 0",
// Note that 16-byte stack alignment is not maintained because this function
// does not call out to any other.
// pushfq first, because some instructions affect rflags. rflags will be in [rbp-8].
"pushfq",
".seh_stackalloc 8",
".seh_endprologue",
"mov dword ptr [rcx+0x30], 0x10000", // ContextFlags
// General-purpose registers whose values haven’t changed can be captured directly.
"mov qword ptr [rcx+0x78], rax", // Rax
"mov qword ptr [rcx+0x88], rdx", // Rdx
"mov qword ptr [rcx+0x90], rbx", // Rbx
"mov qword ptr [rcx+0xa8], rsi", // Rsi
"mov qword ptr [rcx+0xb0], rdi", // Rdi
"mov qword ptr [rcx+0xb8], r8", // R8
"mov qword ptr [rcx+0xc0], r9", // R9
"mov qword ptr [rcx+0xc8], r10", // R10
"mov qword ptr [rcx+0xd0], r11", // R11
"mov qword ptr [rcx+0xd8], r12", // R12
"mov qword ptr [rcx+0xe0], r13", // R13
"mov qword ptr [rcx+0xe8], r14", // R14
"mov qword ptr [rcx+0xf0], r15", // R15
// Because of the calling convention, there’s no way to recover the value of
// the caller’s rcx as it existed prior to calling this function. This
// function captures a snapshot of the register state at its return, which
// involves rcx containing a pointer to its first argument.
"mov qword ptr [rcx+0x80], rcx", // Rcx
// Now that the original value of rax has been saved, it can be repurposed to
// hold other registers’ values.
// Save mxcsr. This is duplicated in context->FltSave.MxCsr, saved by fxsave
// below.
"stmxcsr [rcx+0x34]", // MxCsr
// Segment registers.
"mov word ptr [rcx+0x38], cs", // SegCs
"mov word ptr [rcx+0x3a], ds", // SegDs
"mov word ptr [rcx+0x3c], es", // SegEs
"mov word ptr [rcx+0x3e], fs", // SegFs
"mov word ptr [rcx+0x40], gs", // SegGs
"mov word ptr [rcx+0x42], ss", // SegSs
// The original rflags was saved on the stack above. Note that the CONTEXT
// structure only stores eflags, the low 32 bits. The high 32 bits in rflags
// are reserved.
"mov rax, [rbp-8]",
"mov dword ptr [rcx+0x44], eax", // EFlags
// rsp was saved in rbp in this function’s prologue, but the caller’s rsp is
// 16 more than this value: 8 for the original rbp saved on the stack in this
// function’s prologue, and 8 for the return address saved on the stack by the
// call instruction that reached this function.
"lea rax, qword ptr [rbp+16]",
"mov qword ptr [rcx+0x98], rax",
// The original rbp was saved on the stack in this function’s prologue.
"mov rax, rbp",
"mov qword ptr [rcx+0xa0], rax",
// rip can’t be accessed directly, but the return address saved on the stack by
// the call instruction that reached this function can be used.
"mov rax, [rbp+8]",
"mov qword ptr [rcx+0xf8], rax",
// Zero out the fxsave area before performing the fxsave. Some of the fxsave
// area may not be written by fxsave, and some is definitely not written by
// fxsave. This also zeroes out the rest of the CONTEXT structure to its end,
// including the unused VectorRegister and VectorControl fields, and the debug
// control register fields.
"mov rbx, rcx",
"cld",
"lea rdi, [rcx+0x100]",
"xor rax, rax",
"mov rcx, 122",
"rep stosq",
"mov rcx, rbx",
// Save the floating point (including SSE) state. The CONTEXT structure is
// declared as 16-byte-aligned, which is correct for this operation.
"fxsave [rcx+0x100]",
// TODO: AVX/xsave support. https://crashpad.chromium.org/bug/58
// The register parameter home address fields aren’t used, so zero them out.
"mov qword ptr [rcx+0], 0",
"mov qword ptr [rcx+0x8], 0",
"mov qword ptr [rcx+0x10], 0",
"mov qword ptr [rcx+0x18], 0",
"mov qword ptr [rcx+0x20], 0",
// The debug registers can’t be read from user code, so zero them out in the
// CONTEXT structure. context->ContextFlags doesn’t indicate that they are
// present.
"mov qword ptr [rcx+0x48], 0",
"mov qword ptr [rcx+0x50], 0",
"mov qword ptr [rcx+0x58], 0",
"mov qword ptr [rcx+0x60], 0",
"mov qword ptr [rcx+0x68], 0",
"mov qword ptr [rcx+0x70], 0",
"mov qword ptr [rcx+0x78], 0",
// Clean up by restoring clobbered registers, even those considered volatile by
// the ABI, so that the captured context represents the state at this
// function’s exit.
"mov rax, [rcx+0x78]",
"mov rbx, [rcx+0x90]",
"mov rdi, [rcx+0xb0]",
"popfq",
"pop rbp",
"ret",
".seh_endproc",
}
|
