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Kernel: Clean up a bunch of wrong-looking Region/VMObject code

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Since a Region is merely a "window" onto a VMObject, it can both begin
and end at a distance from the VMObject's boundaries.
Therefore, we should always be computing indices into a VMObject's
physical page array by adding the Region's "first_page_index()".

There was a whole bunch of code that forgot to do that. This fixes
many wrong behaviors for Regions that start part-way into a VMObject.
This commit is contained in:
Andreas Kling 2019-11-03 15:41:49 +01:00
parent fe455c5ac4
commit a221cddeec
2 changed files with 25 additions and 23 deletions
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9
Kernel/VM/Region.cpp
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@ -87,16 +87,17 @@ int Region::commit()
#ifdef MM_DEBUG
dbgprintf("MM: commit %u pages in Region %p (VMO=%p) at V%p\n", vmobject().page_count(), this, &vmobject(), vaddr().get());
#endif
for (size_t i = first_page_index(); i <= last_page_index(); ++i) {
if (!vmobject().physical_pages()[i].is_null())
for (size_t i = 0; i < page_count(); ++i) {
auto& vmobject_physical_page_entry = vmobject().physical_pages()[first_page_index() + i];
if (!vmobject_physical_page_entry.is_null())
continue;
auto physical_page = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::Yes);
if (!physical_page) {
kprintf("MM: commit was unable to allocate a physical page\n");
return -ENOMEM;
}
vmobject().physical_pages()[i] = move(physical_page);
remap_page(i - first_page_index());
vmobject_physical_page_entry = move(physical_page);
remap_page(i);
}
return 0;
}