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Kernel: Fix GDT and segment selectors to make userland work on x86_64

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Userland faulted on the very first instruction before because the
PML4T/PDPT/etc. weren't marked as user-accessible. For some reason
x86 doesn't care about that.

Also, we need to provide an appropriate userspace stack segment
selector to iretq.
This commit is contained in:
Gunnar Beutner 2021-06-28 17:03:08 +02:00 • committed by Andreas Kling
parent 04fc7d708c
commit b5aad1c81d
4 changed files with 16 additions and 9 deletions
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10
Kernel/VM/PageDirectory.cpp
View file

@ -95,7 +95,7 @@ PageDirectory::PageDirectory(const RangeAllocator* parent_range_allocator)
#if ARCH(X86_64)
{
auto& table = *(PageDirectoryPointerTable*)MM.quickmap_page(*m_pml4t);
table.raw[0] = (FlatPtr)m_directory_table->paddr().as_ptr() | 3;
table.raw[0] = (FlatPtr)m_directory_table->paddr().as_ptr() | 7;
MM.unquickmap_page();
}
#endif
@ -108,10 +108,10 @@ PageDirectory::PageDirectory(const RangeAllocator* parent_range_allocator)
table.raw[2] = (FlatPtr)m_directory_pages[2]->paddr().as_ptr() | 1;
table.raw[3] = (FlatPtr)m_directory_pages[3]->paddr().as_ptr() | 1;
#else
table.raw[0] = (FlatPtr)m_directory_pages[0]->paddr().as_ptr() | 3;
table.raw[1] = (FlatPtr)m_directory_pages[1]->paddr().as_ptr() | 3;
table.raw[2] = (FlatPtr)m_directory_pages[2]->paddr().as_ptr() | 3;
table.raw[3] = (FlatPtr)m_directory_pages[3]->paddr().as_ptr() | 3;
table.raw[0] = (FlatPtr)m_directory_pages[0]->paddr().as_ptr() | 7;
table.raw[1] = (FlatPtr)m_directory_pages[1]->paddr().as_ptr() | 7;
table.raw[2] = (FlatPtr)m_directory_pages[2]->paddr().as_ptr() | 7;
table.raw[3] = (FlatPtr)m_directory_pages[3]->paddr().as_ptr() | 7;
#endif
// 2 ** MAXPHYADDR - 1