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Implement address validation by querying the task's page directory.

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This is way better than walking the region lists. I suppose we could
even let the hardware trigger a page fault and handle that. That'll
be the next step in the evolution here I guess.
This commit is contained in:
Andreas Kling 2018-11-01 12:45:51 +01:00
parent f76fcd1e62
commit 0f70b9105f
5 changed files with 82 additions and 34 deletions
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38
Kernel/MemoryManager.cpp
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@ -90,12 +90,12 @@ auto MemoryManager::ensurePTE(dword* page_directory, LinearAddress laddr) -> Pag
#endif
if (pageDirectoryIndex == 0) {
pde.setPageTableBase((dword)m_pageTableZero);
pde.setUserAllowed(true);
pde.setUserAllowed(false);
pde.setPresent(true);
pde.setWritable(true);
} else if (pageDirectoryIndex == 1) {
pde.setPageTableBase((dword)m_pageTableOne);
pde.setUserAllowed(true);
pde.setUserAllowed(false);
pde.setPresent(true);
pde.setWritable(true);
} else {
@ -135,7 +135,7 @@ void MemoryManager::identityMap(LinearAddress linearAddress, size_t length)
auto pteAddress = linearAddress.offset(offset);
auto pte = ensurePTE(m_kernel_page_directory, pteAddress);
pte.setPhysicalPageBase(pteAddress.get());
pte.setUserAllowed(true);
pte.setUserAllowed(false);
pte.setPresent(true);
pte.setWritable(true);
flushTLB(pteAddress);
@ -375,6 +375,38 @@ bool MemoryManager::mapRegion(Task& task, Task::Region& region)
return true;
}
bool MemoryManager::validate_user_read(const Task& task, LinearAddress laddr) const
{
dword pageDirectoryIndex = (laddr.get() >> 22) & 0x3ff;
dword pageTableIndex = (laddr.get() >> 12) & 0x3ff;
auto pde = PageDirectoryEntry(&task.m_pageDirectory[pageDirectoryIndex]);
if (!pde.isPresent())
return false;
auto pte = PageTableEntry(&pde.pageTableBase()[pageTableIndex]);
if (!pte.isPresent())
return false;
if (!pte.isUserAllowed())
return false;
return true;
}
bool MemoryManager::validate_user_write(const Task& task, LinearAddress laddr) const
{
dword pageDirectoryIndex = (laddr.get() >> 22) & 0x3ff;
dword pageTableIndex = (laddr.get() >> 12) & 0x3ff;
auto pde = PageDirectoryEntry(&task.m_pageDirectory[pageDirectoryIndex]);
if (!pde.isPresent())
return false;
auto pte = PageTableEntry(&pde.pageTableBase()[pageTableIndex]);
if (!pte.isPresent())
return false;
if (!pte.isUserAllowed())
return false;
if (!pte.isWritable())
return false;
return true;
}
bool MemoryManager::mapRegionsForTask(Task& task)
{
ASSERT_INTERRUPTS_DISABLED();