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Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#pragma once
28
29// KBuffer: Statically sized kernel-only memory buffer.
30//
31// A KBuffer is a value-type convenience class that wraps a NonnullRefPtr<KBufferImpl>.
32// The memory is allocated via the global kernel-only page allocator, rather than via
33// kmalloc() which is what ByteBuffer/Vector/etc will use.
34//
35// This makes KBuffer a little heavier to allocate, but much better for large and/or
36// long-lived allocations, since they don't put all that weight and pressure on the
37// severely limited kmalloc heap.
38
39#include <AK/Assertions.h>
40#include <AK/ByteBuffer.h>
41#include <AK/LogStream.h>
42#include <AK/Memory.h>
43#include <AK/StringView.h>
44#include <Kernel/VM/MemoryManager.h>
45#include <Kernel/VM/Region.h>
46
47namespace Kernel {
48
49class KBufferImpl : public RefCounted<KBufferImpl> {
50public:
51 static NonnullRefPtr<KBufferImpl> create_with_size(size_t size, u8 access, const char* name)
52 {
53 auto region = MM.allocate_kernel_region(PAGE_ROUND_UP(size), name, access, false, false);
54 ASSERT(region);
55 return adopt(*new KBufferImpl(region.release_nonnull(), size));
56 }
57
58 static NonnullRefPtr<KBufferImpl> copy(const void* data, size_t size, u8 access, const char* name)
59 {
60 auto buffer = create_with_size(size, access, name);
61 buffer->region().commit();
62 memcpy(buffer->data(), data, size);
63 return buffer;
64 }
65
66 u8* data() { return m_region->vaddr().as_ptr(); }
67 const u8* data() const { return m_region->vaddr().as_ptr(); }
68 size_t size() const { return m_size; }
69 size_t capacity() const { return m_region->size(); }
70
71 void set_size(size_t size)
72 {
73 ASSERT(size <= capacity());
74 m_size = size;
75 }
76
77 const Region& region() const { return *m_region; }
78 Region& region() { return *m_region; }
79
80private:
81 explicit KBufferImpl(NonnullOwnPtr<Region>&& region, size_t size)
82 : m_size(size)
83 , m_region(move(region))
84 {
85 }
86
87 size_t m_size { 0 };
88 NonnullOwnPtr<Region> m_region;
89};
90
91class KBuffer {
92public:
93 static KBuffer create_with_size(size_t size, u8 access = Region::Access::Read | Region::Access::Write, const char* name = "KBuffer")
94 {
95 return KBuffer(KBufferImpl::create_with_size(size, access, name));
96 }
97
98 static KBuffer copy(const void* data, size_t size, u8 access = Region::Access::Read | Region::Access::Write, const char* name = "KBuffer")
99 {
100 return KBuffer(KBufferImpl::copy(data, size, access, name));
101 }
102
103 u8* data() { return m_impl->data(); }
104 const u8* data() const { return m_impl->data(); }
105 size_t size() const { return m_impl->size(); }
106 size_t capacity() const { return m_impl->capacity(); }
107
108 void set_size(size_t size) { m_impl->set_size(size); }
109
110 const KBufferImpl& impl() const { return m_impl; }
111
112 KBuffer(const ByteBuffer& buffer, u8 access = Region::Access::Read | Region::Access::Write, const char* name = "KBuffer")
113 : m_impl(KBufferImpl::copy(buffer.data(), buffer.size(), access, name))
114 {
115 }
116
117private:
118 explicit KBuffer(NonnullRefPtr<KBufferImpl>&& impl)
119 : m_impl(move(impl))
120 {
121 }
122
123 NonnullRefPtr<KBufferImpl> m_impl;
124};
125
126inline const LogStream& operator<<(const LogStream& stream, const KBuffer& value)
127{
128 return stream << StringView(value.data(), value.size());
129}
130
131}