1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/Memory.h>
#include <AK/Singleton.h>
#include <Kernel/Process.h>
#include <Kernel/Random.h>
#include <Kernel/Thread.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/VM/PageDirectory.h>
namespace Kernel {
static const FlatPtr userspace_range_base = 0x00800000;
static const FlatPtr userspace_range_ceiling = 0xbe000000;
static const FlatPtr kernelspace_range_base = 0xc0800000;
static AK::Singleton<HashMap<u32, PageDirectory*>> s_cr3_map;
static HashMap<u32, PageDirectory*>& cr3_map()
{
ASSERT_INTERRUPTS_DISABLED();
return *s_cr3_map;
}
RefPtr<PageDirectory> PageDirectory::find_by_cr3(u32 cr3)
{
ScopedSpinLock lock(s_mm_lock);
return cr3_map().get(cr3).value_or({});
}
extern "C" PageDirectoryEntry* boot_pdpt[4];
extern "C" PageDirectoryEntry boot_pd0[1024];
extern "C" PageDirectoryEntry boot_pd3[1024];
PageDirectory::PageDirectory()
{
m_range_allocator.initialize_with_range(VirtualAddress(0xc0800000), 0x3f000000);
m_identity_range_allocator.initialize_with_range(VirtualAddress(FlatPtr(0x00000000)), 0x00200000);
// Adopt the page tables already set up by boot.S
PhysicalAddress boot_pdpt_paddr(virtual_to_low_physical((FlatPtr)boot_pdpt));
PhysicalAddress boot_pd0_paddr(virtual_to_low_physical((FlatPtr)boot_pd0));
PhysicalAddress boot_pd3_paddr(virtual_to_low_physical((FlatPtr)boot_pd3));
klog() << "MM: boot_pdpt @ " << boot_pdpt_paddr;
klog() << "MM: boot_pd0 @ " << boot_pd0_paddr;
klog() << "MM: boot_pd3 @ " << boot_pd3_paddr;
m_directory_table = PhysicalPage::create(boot_pdpt_paddr, true, false);
m_directory_pages[0] = PhysicalPage::create(boot_pd0_paddr, true, false);
m_directory_pages[3] = PhysicalPage::create(boot_pd3_paddr, true, false);
}
PageDirectory::PageDirectory(Process& process, const RangeAllocator* parent_range_allocator)
{
ScopedSpinLock lock(s_mm_lock);
if (parent_range_allocator) {
m_range_allocator.initialize_from_parent(*parent_range_allocator);
} else {
size_t random_offset = (get_fast_random<u8>() % 32 * MiB) & PAGE_MASK;
u32 base = userspace_range_base + random_offset;
m_range_allocator.initialize_with_range(VirtualAddress(base), userspace_range_ceiling - base);
}
// Set up a userspace page directory
m_directory_table = MM.allocate_user_physical_page();
if (!m_directory_table)
return;
m_directory_pages[0] = MM.allocate_user_physical_page();
if (!m_directory_pages[0])
return;
m_directory_pages[1] = MM.allocate_user_physical_page();
if (!m_directory_pages[1])
return;
m_directory_pages[2] = MM.allocate_user_physical_page();
if (!m_directory_pages[2])
return;
// Share the top 1 GiB of kernel-only mappings (>=3GiB or >=0xc0000000)
m_directory_pages[3] = MM.kernel_page_directory().m_directory_pages[3];
{
auto& table = *(PageDirectoryPointerTable*)MM.quickmap_page(*m_directory_table);
table.raw[0] = (FlatPtr)m_directory_pages[0]->paddr().as_ptr() | 1;
table.raw[1] = (FlatPtr)m_directory_pages[1]->paddr().as_ptr() | 1;
table.raw[2] = (FlatPtr)m_directory_pages[2]->paddr().as_ptr() | 1;
table.raw[3] = (FlatPtr)m_directory_pages[3]->paddr().as_ptr() | 1;
// 2 ** MAXPHYADDR - 1
// Where MAXPHYADDR = physical_address_bit_width
u64 max_physical_address = (1ULL << Processor::current().physical_address_bit_width()) - 1;
// bit 63 = no execute
// bit 7 = page size
// bit 5 = accessed
// bit 4 = cache disable
// bit 3 = write through
// bit 2 = user/supervisor
// bit 1 = read/write
// bit 0 = present
constexpr u64 pdpte_bit_flags = 0x80000000000000BF;
// This is to notify us of bugs where we're:
// 1. Going over what the processor is capable of.
// 2. Writing into the reserved bits (51:MAXPHYADDR), where doing so throws a GPF
// when writing out the PDPT pointer to CR3.
// The reason we're not checking the page directory's physical address directly is because
// we're checking for sign extension when putting it into a PDPTE. See issue #4584.
ASSERT((table.raw[0] & ~pdpte_bit_flags) <= max_physical_address);
ASSERT((table.raw[1] & ~pdpte_bit_flags) <= max_physical_address);
ASSERT((table.raw[2] & ~pdpte_bit_flags) <= max_physical_address);
ASSERT((table.raw[3] & ~pdpte_bit_flags) <= max_physical_address);
MM.unquickmap_page();
}
// Clone bottom 2 MiB of mappings from kernel_page_directory
PageDirectoryEntry buffer;
auto* kernel_pd = MM.quickmap_pd(MM.kernel_page_directory(), 0);
memcpy(&buffer, kernel_pd, sizeof(PageDirectoryEntry));
auto* new_pd = MM.quickmap_pd(*this, 0);
memcpy(new_pd, &buffer, sizeof(PageDirectoryEntry));
// If we got here, we successfully created it. Set m_process now
m_process = &process;
cr3_map().set(cr3(), this);
}
PageDirectory::~PageDirectory()
{
#ifdef MM_DEBUG
dbg() << "MM: ~PageDirectory K" << this;
#endif
ScopedSpinLock lock(s_mm_lock);
if (m_process)
cr3_map().remove(cr3());
}
}
|
