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Kernel: Add mapping from page directory base (PDB) to PageDirectory

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This allows the page fault code to find the owning PageDirectory and
corresponding process for faulting regions.

The mapping is implemented as a global hash map right now, which is
definitely not optimal. We can come up with something better when it
becomes necessary.
This commit is contained in:
Andreas Kling 2019-08-06 11:19:16 +02:00
parent 8d07bce12a
commit 2ad963d261
5 changed files with 60 additions and 16 deletions
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27
Kernel/VM/MemoryManager.cpp
View file

@ -257,7 +257,8 @@ void MemoryManager::initialize()
Region* MemoryManager::kernel_region_from_vaddr(VirtualAddress vaddr)
{
ASSERT(vaddr.get() >= 0xc0000000);
if (vaddr.get() < 0xc0000000)
return nullptr;
for (auto& region : MM.m_kernel_regions) {
if (region->contains(vaddr))
return region;
@ -279,18 +280,15 @@ Region* MemoryManager::user_region_from_vaddr(Process& process, VirtualAddress v
Region* MemoryManager::region_from_vaddr(Process& process, VirtualAddress vaddr)
{
ASSERT_INTERRUPTS_DISABLED();
if (vaddr.get() >= 0xc0000000)
return kernel_region_from_vaddr(vaddr);
if (auto* region = kernel_region_from_vaddr(vaddr))
return region;
return user_region_from_vaddr(process, vaddr);
}
const Region* MemoryManager::region_from_vaddr(const Process& process, VirtualAddress vaddr)
{
if (vaddr.get() >= 0xc0000000)
return kernel_region_from_vaddr(vaddr);
if (auto* region = kernel_region_from_vaddr(vaddr))
return region;
return user_region_from_vaddr(const_cast<Process&>(process), vaddr);
}
@ -398,6 +396,17 @@ bool MemoryManager::page_in_from_inode(Region& region, unsigned page_index_in_re
return true;
}
Region* MemoryManager::region_from_vaddr(VirtualAddress vaddr)
{
if (auto* region = kernel_region_from_vaddr(vaddr))
return region;
auto page_directory = PageDirectory::find_by_pdb(cpu_cr3());
if (!page_directory)
return nullptr;
ASSERT(page_directory->process());
return user_region_from_vaddr(*page_directory->process(), vaddr);
}
PageFaultResponse MemoryManager::handle_page_fault(const PageFault& fault)
{
ASSERT_INTERRUPTS_DISABLED();
@ -417,7 +426,7 @@ PageFaultResponse MemoryManager::handle_page_fault(const PageFault& fault)
return PageFaultResponse::Continue;
}
}
auto* region = region_from_vaddr(current->process(), fault.vaddr());
auto* region = region_from_vaddr(fault.vaddr());
if (!region) {
kprintf("NP(error) fault at invalid address L%x\n", fault.vaddr().get());
return PageFaultResponse::ShouldCrash;