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1 /*
2  * Copyright (C) 2016 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #include <stdint.h>
18 #include <string.h>
19 
20 #include <functional>
21 
22 #include <unwindstack/Elf.h>
23 #include <unwindstack/MachineX86_64.h>
24 #include <unwindstack/MapInfo.h>
25 #include <unwindstack/Memory.h>
26 #include <unwindstack/RegsX86_64.h>
27 #include <unwindstack/UcontextX86_64.h>
28 #include <unwindstack/UserX86_64.h>
29 
30 namespace unwindstack {
31 
RegsX86_64()32 RegsX86_64::RegsX86_64() : RegsImpl<uint64_t>(X86_64_REG_LAST, Location(LOCATION_SP_OFFSET, -8)) {}
33 
Arch()34 ArchEnum RegsX86_64::Arch() {
35   return ARCH_X86_64;
36 }
37 
pc()38 uint64_t RegsX86_64::pc() {
39   return regs_[X86_64_REG_PC];
40 }
41 
sp()42 uint64_t RegsX86_64::sp() {
43   return regs_[X86_64_REG_SP];
44 }
45 
set_pc(uint64_t pc)46 void RegsX86_64::set_pc(uint64_t pc) {
47   regs_[X86_64_REG_PC] = pc;
48 }
49 
set_sp(uint64_t sp)50 void RegsX86_64::set_sp(uint64_t sp) {
51   regs_[X86_64_REG_SP] = sp;
52 }
53 
GetPcAdjustment(uint64_t rel_pc,Elf *)54 uint64_t RegsX86_64::GetPcAdjustment(uint64_t rel_pc, Elf*) {
55   if (rel_pc == 0) {
56     return 0;
57   }
58   return 1;
59 }
60 
SetPcFromReturnAddress(Memory * process_memory)61 bool RegsX86_64::SetPcFromReturnAddress(Memory* process_memory) {
62   // Attempt to get the return address from the top of the stack.
63   uint64_t new_pc;
64   if (!process_memory->ReadFully(regs_[X86_64_REG_SP], &new_pc, sizeof(new_pc)) ||
65       new_pc == regs_[X86_64_REG_PC]) {
66     return false;
67   }
68 
69   regs_[X86_64_REG_PC] = new_pc;
70   return true;
71 }
72 
IterateRegisters(std::function<void (const char *,uint64_t)> fn)73 void RegsX86_64::IterateRegisters(std::function<void(const char*, uint64_t)> fn) {
74   fn("rax", regs_[X86_64_REG_RAX]);
75   fn("rbx", regs_[X86_64_REG_RBX]);
76   fn("rcx", regs_[X86_64_REG_RCX]);
77   fn("rdx", regs_[X86_64_REG_RDX]);
78   fn("r8", regs_[X86_64_REG_R8]);
79   fn("r9", regs_[X86_64_REG_R9]);
80   fn("r10", regs_[X86_64_REG_R10]);
81   fn("r11", regs_[X86_64_REG_R11]);
82   fn("r12", regs_[X86_64_REG_R12]);
83   fn("r13", regs_[X86_64_REG_R13]);
84   fn("r14", regs_[X86_64_REG_R14]);
85   fn("r15", regs_[X86_64_REG_R15]);
86   fn("rdi", regs_[X86_64_REG_RDI]);
87   fn("rsi", regs_[X86_64_REG_RSI]);
88   fn("rbp", regs_[X86_64_REG_RBP]);
89   fn("rsp", regs_[X86_64_REG_RSP]);
90   fn("rip", regs_[X86_64_REG_RIP]);
91 }
92 
Read(void * remote_data)93 Regs* RegsX86_64::Read(void* remote_data) {
94   x86_64_user_regs* user = reinterpret_cast<x86_64_user_regs*>(remote_data);
95 
96   RegsX86_64* regs = new RegsX86_64();
97   (*regs)[X86_64_REG_RAX] = user->rax;
98   (*regs)[X86_64_REG_RBX] = user->rbx;
99   (*regs)[X86_64_REG_RCX] = user->rcx;
100   (*regs)[X86_64_REG_RDX] = user->rdx;
101   (*regs)[X86_64_REG_R8] = user->r8;
102   (*regs)[X86_64_REG_R9] = user->r9;
103   (*regs)[X86_64_REG_R10] = user->r10;
104   (*regs)[X86_64_REG_R11] = user->r11;
105   (*regs)[X86_64_REG_R12] = user->r12;
106   (*regs)[X86_64_REG_R13] = user->r13;
107   (*regs)[X86_64_REG_R14] = user->r14;
108   (*regs)[X86_64_REG_R15] = user->r15;
109   (*regs)[X86_64_REG_RDI] = user->rdi;
110   (*regs)[X86_64_REG_RSI] = user->rsi;
111   (*regs)[X86_64_REG_RBP] = user->rbp;
112   (*regs)[X86_64_REG_RSP] = user->rsp;
113   (*regs)[X86_64_REG_RIP] = user->rip;
114 
115   return regs;
116 }
117 
SetFromUcontext(x86_64_ucontext_t * ucontext)118 void RegsX86_64::SetFromUcontext(x86_64_ucontext_t* ucontext) {
119   // R8-R15
120   memcpy(&regs_[X86_64_REG_R8], &ucontext->uc_mcontext.r8, 8 * sizeof(uint64_t));
121 
122   // Rest of the registers.
123   regs_[X86_64_REG_RDI] = ucontext->uc_mcontext.rdi;
124   regs_[X86_64_REG_RSI] = ucontext->uc_mcontext.rsi;
125   regs_[X86_64_REG_RBP] = ucontext->uc_mcontext.rbp;
126   regs_[X86_64_REG_RBX] = ucontext->uc_mcontext.rbx;
127   regs_[X86_64_REG_RDX] = ucontext->uc_mcontext.rdx;
128   regs_[X86_64_REG_RAX] = ucontext->uc_mcontext.rax;
129   regs_[X86_64_REG_RCX] = ucontext->uc_mcontext.rcx;
130   regs_[X86_64_REG_RSP] = ucontext->uc_mcontext.rsp;
131   regs_[X86_64_REG_RIP] = ucontext->uc_mcontext.rip;
132 }
133 
CreateFromUcontext(void * ucontext)134 Regs* RegsX86_64::CreateFromUcontext(void* ucontext) {
135   x86_64_ucontext_t* x86_64_ucontext = reinterpret_cast<x86_64_ucontext_t*>(ucontext);
136 
137   RegsX86_64* regs = new RegsX86_64();
138   regs->SetFromUcontext(x86_64_ucontext);
139   return regs;
140 }
141 
StepIfSignalHandler(uint64_t rel_pc,Elf * elf,Memory * process_memory)142 bool RegsX86_64::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
143   uint64_t data;
144   Memory* elf_memory = elf->memory();
145   // Read from elf memory since it is usually more expensive to read from
146   // process memory.
147   if (!elf_memory->ReadFully(rel_pc, &data, sizeof(data)) || data != 0x0f0000000fc0c748) {
148     return false;
149   }
150 
151   uint16_t data2;
152   if (!elf_memory->ReadFully(rel_pc + 8, &data2, sizeof(data2)) || data2 != 0x0f05) {
153     return false;
154   }
155 
156   // __restore_rt:
157   // 0x48 0xc7 0xc0 0x0f 0x00 0x00 0x00   mov $0xf,%rax
158   // 0x0f 0x05                            syscall
159   // 0x0f                                 nopl 0x0($rax)
160 
161   // Read the mcontext data from the stack.
162   // sp points to the ucontext data structure, read only the mcontext part.
163   x86_64_ucontext_t x86_64_ucontext;
164   if (!process_memory->ReadFully(regs_[X86_64_REG_SP] + 0x28, &x86_64_ucontext.uc_mcontext,
165                                  sizeof(x86_64_mcontext_t))) {
166     return false;
167   }
168   SetFromUcontext(&x86_64_ucontext);
169   return true;
170 }
171 
Clone()172 Regs* RegsX86_64::Clone() {
173   return new RegsX86_64(*this);
174 }
175 
176 }  // namespace unwindstack
177