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-inl.h"
20#include "mirror/object-inl.h"
21#include "quick/quick_method_frame_info.h"
22#include "stack.h"
23
24namespace art {
25namespace x86 {
26
27static constexpr uintptr_t gZero = 0;
28
29void X86Context::Reset() {
30  for (size_t  i = 0; i < kNumberOfCpuRegisters; i++) {
31    gprs_[i] = nullptr;
32  }
33  gprs_[ESP] = &esp_;
34  // Initialize registers with easy to spot debug values.
35  esp_ = X86Context::kBadGprBase + ESP;
36  eip_ = X86Context::kBadGprBase + kNumberOfCpuRegisters;
37}
38
39void X86Context::FillCalleeSaves(const StackVisitor& fr) {
40  mirror::ArtMethod* method = fr.GetMethod();
41  const QuickMethodFrameInfo frame_info = method->GetQuickFrameInfo();
42  size_t spill_count = POPCOUNT(frame_info.CoreSpillMask());
43  DCHECK_EQ(frame_info.FpSpillMask(), 0u);
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 (((frame_info.CoreSpillMask() >> i) & 1) != 0) {
49        gprs_[i] = fr.CalleeSaveAddress(spill_count - j, frame_info.FrameSizeInBytes());
50        j++;
51      }
52    }
53  }
54}
55
56void X86Context::SmashCallerSaves() {
57  // This needs to be 0 because we want a null/zero return value.
58  gprs_[EAX] = const_cast<uintptr_t*>(&gZero);
59  gprs_[EDX] = const_cast<uintptr_t*>(&gZero);
60  gprs_[ECX] = nullptr;
61  gprs_[EBX] = nullptr;
62}
63
64bool X86Context::SetGPR(uint32_t reg, uintptr_t value) {
65  CHECK_LT(reg, static_cast<uint32_t>(kNumberOfCpuRegisters));
66  CHECK_NE(gprs_[reg], &gZero);
67  if (gprs_[reg] != nullptr) {
68    *gprs_[reg] = value;
69    return true;
70  } else {
71    return false;
72  }
73}
74
75void X86Context::DoLongJump() {
76#if defined(__i386__)
77  // Array of GPR values, filled from the context backward for the long jump pop. We add a slot at
78  // the top for the stack pointer that doesn't get popped in a pop-all.
79  volatile uintptr_t gprs[kNumberOfCpuRegisters + 1];
80  for (size_t i = 0; i < kNumberOfCpuRegisters; ++i) {
81    gprs[kNumberOfCpuRegisters - i - 1] = gprs_[i] != nullptr ? *gprs_[i] : X86Context::kBadGprBase + i;
82  }
83  // We want to load the stack pointer one slot below so that the ret will pop eip.
84  uintptr_t esp = gprs[kNumberOfCpuRegisters - ESP - 1] - kWordSize;
85  gprs[kNumberOfCpuRegisters] = esp;
86  *(reinterpret_cast<uintptr_t*>(esp)) = eip_;
87  __asm__ __volatile__(
88      "movl %0, %%esp\n\t"  // ESP points to gprs.
89      "popal\n\t"           // Load all registers except ESP and EIP with values in gprs.
90      "popl %%esp\n\t"      // Load stack pointer.
91      "ret\n\t"             // From higher in the stack pop eip.
92      :  // output.
93      : "g"(&gprs[0])  // input.
94      :);  // clobber.
95#else
96  UNIMPLEMENTED(FATAL);
97#endif
98}
99
100}  // namespace x86
101}  // namespace art
102