1 /*
2 * Copyright (C) 2011 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 "context_x86.h"
18
19 #include "mirror/art_method.h"
20 #include "mirror/object-inl.h"
21 #include "stack.h"
22
23 namespace art {
24 namespace x86 {
25
26 static const uint32_t gZero = 0;
27
Reset()28 void X86Context::Reset() {
29 for (int i = 0; i < kNumberOfCpuRegisters; i++) {
30 gprs_[i] = NULL;
31 }
32 gprs_[ESP] = &esp_;
33 // Initialize registers with easy to spot debug values.
34 esp_ = X86Context::kBadGprBase + ESP;
35 eip_ = X86Context::kBadGprBase + kNumberOfCpuRegisters;
36 }
37
FillCalleeSaves(const StackVisitor & fr)38 void X86Context::FillCalleeSaves(const StackVisitor& fr) {
39 mirror::ArtMethod* method = fr.GetMethod();
40 uint32_t core_spills = method->GetCoreSpillMask();
41 size_t spill_count = __builtin_popcount(core_spills);
42 DCHECK_EQ(method->GetFpSpillMask(), 0u);
43 size_t frame_size = method->GetFrameSizeInBytes();
44 if (spill_count > 0) {
45 // Lowest number spill is farthest away, walk registers and fill into context.
46 int j = 2; // Offset j to skip return address spill.
47 for (int i = 0; i < kNumberOfCpuRegisters; i++) {
48 if (((core_spills >> i) & 1) != 0) {
49 gprs_[i] = fr.CalleeSaveAddress(spill_count - j, frame_size);
50 j++;
51 }
52 }
53 }
54 }
55
SmashCallerSaves()56 void X86Context::SmashCallerSaves() {
57 // This needs to be 0 because we want a null/zero return value.
58 gprs_[EAX] = const_cast<uint32_t*>(&gZero);
59 gprs_[EDX] = const_cast<uint32_t*>(&gZero);
60 gprs_[ECX] = NULL;
61 gprs_[EBX] = NULL;
62 }
63
SetGPR(uint32_t reg,uintptr_t value)64 void X86Context::SetGPR(uint32_t reg, uintptr_t value) {
65 CHECK_LT(reg, static_cast<uint32_t>(kNumberOfCpuRegisters));
66 CHECK_NE(gprs_[reg], &gZero);
67 CHECK(gprs_[reg] != NULL);
68 *gprs_[reg] = value;
69 }
70
DoLongJump()71 void X86Context::DoLongJump() {
72 #if defined(__i386__)
73 // Array of GPR values, filled from the context backward for the long jump pop. We add a slot at
74 // the top for the stack pointer that doesn't get popped in a pop-all.
75 volatile uintptr_t gprs[kNumberOfCpuRegisters + 1];
76 for (size_t i = 0; i < kNumberOfCpuRegisters; ++i) {
77 gprs[kNumberOfCpuRegisters - i - 1] = gprs_[i] != NULL ? *gprs_[i] : X86Context::kBadGprBase + i;
78 }
79 // We want to load the stack pointer one slot below so that the ret will pop eip.
80 uintptr_t esp = gprs[kNumberOfCpuRegisters - ESP - 1] - kWordSize;
81 gprs[kNumberOfCpuRegisters] = esp;
82 *(reinterpret_cast<uintptr_t*>(esp)) = eip_;
83 __asm__ __volatile__(
84 "movl %0, %%esp\n\t" // ESP points to gprs.
85 "popal\n\t" // Load all registers except ESP and EIP with values in gprs.
86 "popl %%esp\n\t" // Load stack pointer.
87 "ret\n\t" // From higher in the stack pop eip.
88 : // output.
89 : "g"(&gprs[0]) // input.
90 :); // clobber.
91 #else
92 UNIMPLEMENTED(FATAL);
93 #endif
94 }
95
96 } // namespace x86
97 } // namespace art
98