StubLayout.cpp revision 30e2a4c8d848bc788cc5600e6b929b4f761f3f03 
1/*
2 * Copyright 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 "StubLayout.h"
18
19#include "utils/flush_cpu_cache.h"
20#include "utils/raw_ostream.h"
21#include "utils/rsl_assert.h"
22
23#include <stdint.h>
24#include <stdlib.h>
25
26StubLayout::StubLayout() : table(NULL), count(0) {
27}
28
29void StubLayout::initStubTable(unsigned char *table_, size_t count_) {
30  table = table_;
31  count = count_;
32}
33
34void *StubLayout::allocateStub(void *addr) {
35  // Check if we have created this stub or not.
36  std::map<void *, void *>::iterator index_iter = stub_index.find(addr);
37
38  if (index_iter != stub_index.end()) {
39    return index_iter->second;
40  }
41
42  // We have to create a new stub
43  if (count == 0) {
44    // No free stub slot is available
45    return NULL;
46  }
47
48  // Initialize the stub
49  unsigned char *stub = table;
50  setStubAddress(stub, addr);
51  stub_index.insert(std::make_pair(addr, stub));
52
53  // Increase the free stub slot pointer
54  table += getUnitStubSize();
55  count--;
56
57  return stub;
58}
59
60size_t StubLayout::calcStubTableSize(size_t count) const {
61  return count * getUnitStubSize();
62}
63
64size_t StubLayoutAARCH64::getUnitStubSize() const {
65  return 16;
66}
67
68void StubLayoutAARCH64::setStubAddress(void *stub_, void *addr) {
69  uint8_t *stub = (uint8_t *)stub_;
70
71  // First instruction:
72  // ldr x16,[pc,#8]        LDR literal (pc relative)
73  // +--+---+-+--+-------------------+-----+
74  // |01|011|0|00| (#8 >> 2) = 10    |10000|
75  // +--+---+-+--+-------------------+-----+
76  // 0x58000050
77  // Little endian.
78  stub[0] = 0x50;
79  stub[1] = 0x00;
80  stub[2] = 0x0f;
81  stub[3] = 0x58;
82
83  // Next Instruction:
84  // br x16
85  // +-------+--+--+-----+------+-----+-----+
86  // |1101011|00|00|11111|000000|10000|00000|
87  // +-------+--+--+-----+------+-----+-----+
88  // 0xd61f0200
89
90  stub += 4;
91  stub[0] = 0x00;
92  stub[1] = 0x02;
93  stub[2] = 0x1f;
94  stub[3] = 0xd6;
95
96  // Now the absolute address (64 bits).
97  uint64_t *target = reinterpret_cast<uint64_t*>(stub + 4);
98  *target = reinterpret_cast<uint64_t>(addr);
99}
100
101size_t StubLayoutARM::getUnitStubSize() const {
102  return 8;
103}
104
105void StubLayoutARM::setStubAddress(void *stub_, void *addr) {
106  uint8_t *stub = (uint8_t *)stub_;
107  stub[0] = 0x04; // ldr pc, [pc, #-4]
108  stub[1] = 0xf0; // ldr pc, [pc, #-4]
109  stub[2] = 0x1f; // ldr pc, [pc, #-4]
110  stub[3] = 0xe5; // ldr pc, [pc, #-4]
111
112  void **target = (void **)(stub + 4);
113  *target = addr;
114}
115
116size_t StubLayoutMIPS::getUnitStubSize() const {
117  return 16;
118}
119
120void StubLayoutMIPS::setStubAddress(void *stub_, void *addr) {
121  uint32_t addr32 = (uint32_t)(uintptr_t)addr;
122  uint16_t addr_hi16 = (addr32 >> 16) &  0xffff;
123  uint16_t addr_lo16 = addr32 & 0xffff;
124
125  uint32_t *stub = (uint32_t *)stub_;
126  stub[0] = 0x3c190000ul | addr_hi16; // lui
127  stub[1] = 0x37390000ul | addr_lo16; // ori
128  stub[2] = 0x03200008ul; // jr (jump register)
129  stub[3] = 0x00000000ul; // nop
130}
131