1 | /* |
2 | * Copyright (C) 2018 Apple Inc. All rights reserved. |
3 | * |
4 | * Redistribution and use in source and binary forms, with or without |
5 | * modification, are permitted provided that the following conditions |
6 | * are met: |
7 | * 1. Redistributions of source code must retain the above copyright |
8 | * notice, this list of conditions and the following disclaimer. |
9 | * 2. Redistributions in binary form must reproduce the above copyright |
10 | * notice, this list of conditions and the following disclaimer in the |
11 | * documentation and/or other materials provided with the distribution. |
12 | * |
13 | * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
14 | * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
15 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
16 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
17 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
18 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
19 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
20 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
21 | * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
22 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
23 | * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
24 | */ |
25 | |
26 | #include "config.h" |
27 | #include "SpectreGadget.h" |
28 | |
29 | #include "RuntimeEnabledFeatures.h" |
30 | #include <wtf/text/WTFString.h> |
31 | |
32 | namespace WebCore { |
33 | |
34 | inline SpectreGadget::SpectreGadget(const String& text) |
35 | { |
36 | if (RuntimeEnabledFeatures::sharedFeatures().spectreGadgetsEnabled()) { |
37 | m_data.resize(text.length()); |
38 | setReadLength(text.length()); |
39 | m_data.fill(0); |
40 | m_dataPtr = m_data.data(); |
41 | |
42 | for (size_t i = 0; i < m_readLength; i++) |
43 | m_data[i] = text.characterAt(i); |
44 | } else { |
45 | setReadLength(0); |
46 | m_dataPtr = nullptr; |
47 | } |
48 | } |
49 | |
50 | Ref<SpectreGadget> SpectreGadget::create(const String& text) |
51 | { |
52 | return adoptRef(*new SpectreGadget(text)); |
53 | } |
54 | |
55 | void SpectreGadget::setReadLength(size_t readLength) |
56 | { |
57 | m_readLength = std::min(readLength, m_data.size()); |
58 | } |
59 | |
60 | unsigned SpectreGadget::charCodeAt(size_t index) |
61 | { |
62 | if (index < m_readLength) |
63 | return m_dataPtr[index]; |
64 | |
65 | return 0; |
66 | } |
67 | |
68 | void SpectreGadget::clflushReadLength() |
69 | { |
70 | #if CPU(X86_64) && !OS(WINDOWS) |
71 | auto clflush = [] (void* ptr) { |
72 | char* ptrToFlush = static_cast<char*>(ptr); |
73 | asm volatile ("clflush %0" :: "m" (*ptrToFlush) : "memory" ); |
74 | }; |
75 | |
76 | clflush(&m_readLength); |
77 | #endif |
78 | } |
79 | |
80 | } // namespace WebCore |
81 | |