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完善页表拷贝逻辑
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@MemoryShore
MemoryShore committed Apr 14, 2024
1 parent 29cc1df commit f8cf44d
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Showing 2 changed files with 47 additions and 29 deletions.
59 changes: 34 additions & 25 deletions kernel/src/mm/page.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -298,8 +298,16 @@ impl<Arch: MemoryManagementArch> PageTable<Arch> {
));
}

// 克隆页表
pub unsafe fn clone(&self, allocator: &mut impl FrameAllocator) -> Option<PageTable<Arch>> {
/// 拷贝页表
/// ## 参数
///
/// - `allocator`: 物理页框分配器
/// - `copy_on_write`: 是否写时复制
pub unsafe fn clone(
&self,
allocator: &mut impl FrameAllocator,
copy_on_write: bool,
) -> Option<PageTable<Arch>> {
// 分配新页面作为新的页表
let phys = allocator.allocate_one()?;
let frame = MMArch::phys_2_virt(phys).unwrap();
Expand All @@ -309,33 +317,33 @@ impl<Arch: MemoryManagementArch> PageTable<Arch> {
for i in 0..Arch::PAGE_ENTRY_NUM {
if let Some(mut entry) = self.entry(i) {
if entry.present() {
let mut new_flags = entry.flags().set_write(false);
entry.set_flags(new_flags);
self.set_entry(i, entry);
new_flags = new_flags.set_dirty(false);
entry.set_flags(new_flags);
new_table.set_entry(i, entry);
if copy_on_write {
let mut new_flags = entry.flags().set_write(false);
entry.set_flags(new_flags);
self.set_entry(i, entry);
new_flags = new_flags.set_dirty(false);
entry.set_flags(new_flags);
new_table.set_entry(i, entry);
} else {
let phys = allocator.allocate_one()?;
let mut anon_vma_guard = page_manager_lock_irqsave();
anon_vma_guard.insert(phys, Page::new(false));
let old_phys = entry.address().unwrap();
let frame = MMArch::phys_2_virt(phys).unwrap().data() as *mut u8;
frame.copy_from_nonoverlapping(
MMArch::phys_2_virt(old_phys).unwrap().data() as *mut u8,
MMArch::PAGE_SIZE,
);
new_table.set_entry(i, PageEntry::new(phys, entry.flags()));
}
}

// if entry.present() {
// let phys = allocator.allocate_one()?;
// let mut anon_vma_guard = page_manager_lock_irqsave();
// anon_vma_guard.insert(phys, Page::new(false));
// let old_phys = entry.address().unwrap();
// let frame = MMArch::phys_2_virt(phys).unwrap().data() as *mut u8;
// frame.copy_from_nonoverlapping(
// MMArch::phys_2_virt(old_phys).unwrap().data() as *mut u8,
// MMArch::PAGE_SIZE,
// );
// new_table.set_entry(i, PageEntry::new(phys, entry.flags()));
// }
}
}
} else {
// 非一级页表拷贝时，对每个页表项对应的页表都进行拷贝
for i in 0..MMArch::PAGE_ENTRY_NUM {
if let Some(next_table) = self.next_level_table(i) {
let table = next_table.clone(allocator)?;
let table = next_table.clone(allocator, copy_on_write)?;
let old_entry = self.entry(i).unwrap();
let entry = PageEntry::new(table.phys(), old_entry.flags());
new_table.set_entry(i, entry);
Expand Down Expand Up @@ -689,7 +697,7 @@ impl<Arch: MemoryManagementArch> PageFlags<Arch> {
///
/// ## 参数
///
/// - value: 如果为true，那么将当前页表项的写穿策略设置为写穿。
/// - value: 如果为true，那么将当前页表项的访问标志设置为已访问。
#[inline(always)]
pub fn set_access(self, value: bool) -> Self {
return self.update_flags(Arch::ENTRY_FLAG_ACCESSED, value);
Expand Down Expand Up @@ -1071,14 +1079,15 @@ impl<Arch: MemoryManagementArch, F: FrameAllocator> PageMapper<Arch, F> {
/// ## 参数
///
/// - `umapper`: 要拷贝的用户空间
pub unsafe fn clone_user_mapping(&mut self, umapper: &mut Self) {
/// - `copy_on_write`: 是否写时复制
pub unsafe fn clone_user_mapping(&mut self, umapper: &mut Self, copy_on_write: bool) {
let old_table = umapper.table();
let new_table = self.table();
let allocator = self.allocator_mut();
// 顶级页表的[0, PAGE_KERNEL_INDEX)项为用户空间映射
for entry_index in 0..Arch::PAGE_KERNEL_INDEX {
if let Some(next_table) = old_table.next_level_table(entry_index) {
let table = next_table.clone(allocator).unwrap();
let table = next_table.clone(allocator, copy_on_write).unwrap();
let old_entry = old_table.entry(entry_index).unwrap();
let entry = PageEntry::new(table.phys(), old_entry.flags());
new_table.set_entry(entry_index, entry);
Expand Down
17 changes: 13 additions & 4 deletions kernel/src/mm/ucontext.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -160,7 +160,11 @@ impl InnerAddressSpace {
let irq_guard = unsafe { CurrentIrqArch::save_and_disable_irq() };
let new_addr_space = AddressSpace::new(false)?;
let mut new_guard = new_addr_space.write();
unsafe { new_guard.user_mapper.clone_from(&mut self.user_mapper) };
unsafe {
new_guard
.user_mapper
.clone_from(&mut self.user_mapper, true)
};

// 拷贝用户栈的结构体信息，但是不拷贝用户栈的内容（因为后面VMA的拷贝会拷贝用户栈的内容）
unsafe {
Expand Down Expand Up @@ -708,9 +712,14 @@ impl UserMapper {
return Self { utable };
}

// 拷贝用户空间映射
pub unsafe fn clone_from(&mut self, umapper: &mut Self) {
self.utable.clone_user_mapping(&mut umapper.utable);
/// 拷贝用户空间映射
/// ## 参数
///
/// - `umapper`: 要拷贝的用户空间
/// - `copy_on_write`: 是否写时复制
pub unsafe fn clone_from(&mut self, umapper: &mut Self, copy_on_write: bool) {
self.utable
.clone_user_mapping(&mut umapper.utable, copy_on_write);
}
}

Expand Down

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