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
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
use core::fmt;
use core::ops::{Deref, DerefMut};

const PAGE_SIZE: u64 = 4096;

const MAX_MEMORY_MAP_SIZE: usize = 64;

/// A map of the physical memory regions of the underlying machine.
#[repr(C)]
pub struct MemoryMap {
    entries: [MemoryRegion; MAX_MEMORY_MAP_SIZE],
    // u64 instead of usize so that the structure layout is platform
    // independent
    next_entry_index: u64,
}

#[doc(hidden)]
#[allow(clippy::new_without_default)]
impl MemoryMap {
    pub fn new() -> Self {
        MemoryMap {
            entries: [MemoryRegion::empty(); MAX_MEMORY_MAP_SIZE],
            next_entry_index: 0,
        }
    }

    pub fn add_region(&mut self, region: MemoryRegion) {
        assert!(
            self.next_entry_index() < MAX_MEMORY_MAP_SIZE,
            "too many memory regions in memory map"
        );
        self.entries[self.next_entry_index()] = region;
        self.next_entry_index += 1;
        self.sort();
    }

    pub fn sort(&mut self) {
        use core::cmp::Ordering;

        self.entries.sort_unstable_by(|r1, r2| {
            if r1.range.is_empty() {
                Ordering::Greater
            } else if r2.range.is_empty() {
                Ordering::Less
            } else {
                let ordering = r1
                    .range
                    .start_frame_number
                    .cmp(&r2.range.start_frame_number);

                if ordering == Ordering::Equal {
                    r1.range.end_frame_number.cmp(&r2.range.end_frame_number)
                } else {
                    ordering
                }
            }
        });
        if let Some(first_zero_index) = self.entries.iter().position(|r| r.range.is_empty()) {
            self.next_entry_index = first_zero_index as u64;
        }
    }

    fn next_entry_index(&self) -> usize {
        self.next_entry_index as usize
    }
}

impl Deref for MemoryMap {
    type Target = [MemoryRegion];

    fn deref(&self) -> &Self::Target {
        &self.entries[0..self.next_entry_index()]
    }
}

impl DerefMut for MemoryMap {
    fn deref_mut(&mut self) -> &mut Self::Target {
        let next_index = self.next_entry_index();
        &mut self.entries[0..next_index]
    }
}

impl fmt::Debug for MemoryMap {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.debug_list().entries(self.iter()).finish()
    }
}

/// Represents a region of physical memory.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(C)]
pub struct MemoryRegion {
    /// The range of frames that belong to the region.
    pub range: FrameRange,
    /// The type of the region.
    pub region_type: MemoryRegionType,
}

#[doc(hidden)]
impl MemoryRegion {
    pub fn empty() -> Self {
        MemoryRegion {
            range: FrameRange {
                start_frame_number: 0,
                end_frame_number: 0,
            },
            region_type: MemoryRegionType::Empty,
        }
    }
}

/// A range of frames with an exclusive upper bound.
#[derive(Clone, Copy, PartialEq, Eq)]
#[repr(C)]
pub struct FrameRange {
    /// The frame _number_ of the first 4KiB frame in the region.
    ///
    /// To convert this frame number to a physical address, multiply it with the
    /// page size (4KiB).
    pub start_frame_number: u64,
    /// The frame _number_ of the first 4KiB frame that does no longer belong to the region.
    ///
    /// To convert this frame number to a physical address, multiply it with the
    /// page size (4KiB).
    pub end_frame_number: u64,
}

impl FrameRange {
    /// Create a new FrameRange from the passed start_addr and end_addr.
    ///
    /// The end_addr is exclusive.
    pub fn new(start_addr: u64, end_addr: u64) -> Self {
        let last_byte = end_addr - 1;
        FrameRange {
            start_frame_number: start_addr / PAGE_SIZE,
            end_frame_number: (last_byte / PAGE_SIZE) + 1,
        }
    }

    /// Returns true if the frame range contains no frames.
    pub fn is_empty(&self) -> bool {
        self.start_frame_number == self.end_frame_number
    }

    /// Returns the physical start address of the memory region.
    pub fn start_addr(&self) -> u64 {
        self.start_frame_number * PAGE_SIZE
    }

    /// Returns the physical end address of the memory region.
    pub fn end_addr(&self) -> u64 {
        self.end_frame_number * PAGE_SIZE
    }
}

impl fmt::Debug for FrameRange {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(
            f,
            "FrameRange({:#x}..{:#x})",
            self.start_addr(),
            self.end_addr()
        )
    }
}

/// Represents possible types for memory regions.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(C)]
pub enum MemoryRegionType {
    /// Unused memory, can be freely used by the kernel.
    Usable,
    /// Memory that is already in use.
    InUse,
    /// Memory reserved by the hardware. Not usable.
    Reserved,
    /// ACPI reclaimable memory
    AcpiReclaimable,
    /// ACPI NVS memory
    AcpiNvs,
    /// Area containing bad memory
    BadMemory,
    /// Memory used for loading the kernel.
    Kernel,
    /// Memory used for the kernel stack.
    KernelStack,
    /// Memory used for creating page tables.
    PageTable,
    /// Memory used by the bootloader.
    Bootloader,
    /// Frame at address zero.
    ///
    /// (shouldn't be used because it's easy to make mistakes related to null pointers)
    FrameZero,
    /// An empty region with size 0
    Empty,
    /// Memory used for storing the boot information.
    BootInfo,
    /// Memory used for storing the supplied package
    Package,
    /// Additional variant to ensure that we can add more variants in the future without
    /// breaking backwards compatibility.
    #[doc(hidden)]
    NonExhaustive,
}

#[doc(hidden)]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(C)]
pub struct E820MemoryRegion {
    pub start_addr: u64,
    pub len: u64,
    pub region_type: u32,
    pub acpi_extended_attributes: u32,
}

impl From<E820MemoryRegion> for MemoryRegion {
    fn from(region: E820MemoryRegion) -> MemoryRegion {
        let region_type = match region.region_type {
            1 => MemoryRegionType::Usable,
            2 => MemoryRegionType::Reserved,
            3 => MemoryRegionType::AcpiReclaimable,
            4 => MemoryRegionType::AcpiNvs,
            5 => MemoryRegionType::BadMemory,
            t => panic!("invalid region type {}", t),
        };
        MemoryRegion {
            range: FrameRange::new(region.start_addr, region.start_addr + region.len),
            region_type,
        }
    }
}

extern "C" {
    fn _improper_ctypes_check_memory_map(_memory_map: MemoryMap);
}