Bananymous
b74812d669
On-demand paging has not been used ever since I made userspace stack be a normal MemoryRegion.
77 lines
2.1 KiB
C++
77 lines
2.1 KiB
C++
#include <BAN/ScopeGuard.h>
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#include <kernel/Memory/Heap.h>
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#include <kernel/Memory/VirtualRange.h>
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namespace Kernel
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{
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BAN::ErrorOr<BAN::UniqPtr<VirtualRange>> VirtualRange::create_to_vaddr_range(PageTable& page_table, AddressRange address_range, size_t size, PageTable::flags_t flags, bool add_guard_pages)
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{
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if (add_guard_pages)
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size += 2 * PAGE_SIZE;
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ASSERT(size % PAGE_SIZE == 0);
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// Align vaddr range to page boundaries
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if (const size_t rem = address_range.start % PAGE_SIZE)
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address_range.start += PAGE_SIZE - rem;
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if (const size_t rem = address_range.end % PAGE_SIZE)
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address_range.end -= rem;
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const vaddr_t vaddr = page_table.reserve_free_contiguous_pages(size / PAGE_SIZE, address_range.start, address_range.end);
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if (vaddr == 0)
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return BAN::Error::from_errno(ENOMEM);
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BAN::ScopeGuard vaddr_cleaner([&page_table, vaddr, size] {
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page_table.unmap_range(vaddr, size);
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});
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auto result = TRY(BAN::UniqPtr<VirtualRange>::create(
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page_table,
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add_guard_pages,
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vaddr,
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size,
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flags)
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);
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TRY(result->initialize());
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vaddr_cleaner.disable();
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return result;
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}
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VirtualRange::VirtualRange(PageTable& page_table, bool has_guard_pages, vaddr_t vaddr, size_t size, PageTable::flags_t flags)
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: m_page_table(page_table)
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, m_has_guard_pages(has_guard_pages)
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, m_vaddr(vaddr)
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, m_size(size)
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, m_flags(flags)
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{ }
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VirtualRange::~VirtualRange()
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{
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ASSERT(m_vaddr);
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for (size_t off = 0; off < size(); off += PAGE_SIZE)
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if (const auto paddr = m_page_table.physical_address_of(vaddr() + off))
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Heap::get().release_page(paddr);
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m_page_table.unmap_range(m_vaddr, m_size);
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}
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BAN::ErrorOr<void> VirtualRange::initialize()
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{
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const size_t page_count = size() / PAGE_SIZE;
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for (size_t i = 0; i < page_count; i++)
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{
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const auto paddr = Heap::get().take_free_page();
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if (paddr == 0)
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return BAN::Error::from_errno(ENOMEM);
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PageTable::with_fast_page(paddr, [] {
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memset(PageTable::fast_page_as_ptr(), 0, PAGE_SIZE);
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});
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m_page_table.map_page_at(paddr, vaddr() + i * PAGE_SIZE, m_flags);
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}
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return {};
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}
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}
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