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Add basic zero faults.

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mmap() will now map uncommitted pages that get allocated and zeroed upon the
first access. I also made /proc/PID/vm show number of "committed" bytes in
each region. This is so cool! :^)
This commit is contained in:
Andreas Kling 2018-11-19 02:17:20 +01:00
parent e88f306d07
commit 629c5be10b
5 changed files with 42 additions and 7 deletions
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32
Kernel/MemoryManager.cpp
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@ -224,6 +224,24 @@ Region* MemoryManager::region_from_laddr(Process& process, LinearAddress laddr)
return nullptr;
}
bool MemoryManager::zero_page(PageDirectory& page_directory, Region& region, unsigned page_index_in_region)
{
ASSERT_INTERRUPTS_DISABLED();
auto& vmo = region.vmo();
auto physical_page = allocate_physical_page();
byte* dest_ptr = quickmap_page(*physical_page);
memset(dest_ptr, 0, PAGE_SIZE);
#ifdef PAGE_FAULT_DEBUG
dbgprintf(" >> ZERO P%x\n", physical_page->paddr().get());
#endif
unquickmap_page();
region.cow_map.set(page_index_in_region, false);
vmo.physical_pages()[page_index_in_region] = move(physical_page);
unquickmap_page();
remap_region_page(&page_directory, region, page_index_in_region, true);
return true;
}
bool MemoryManager::copy_on_write(Process& process, Region& region, unsigned page_index_in_region)
{
ASSERT_INTERRUPTS_DISABLED();
@ -325,7 +343,9 @@ PageFaultResponse MemoryManager::handle_page_fault(const PageFault& fault)
page_in_from_vnode(*current->m_page_directory, *region, page_index_in_region);
return PageFaultResponse::Continue;
} else {
kprintf("NP(error) fault in Region{%p}[%u]\n", region, page_index_in_region);
dbgprintf("NP(zero) fault in Region{%p}[%u]\n", region, page_index_in_region);
zero_page(*current->m_page_directory, *region, page_index_in_region);
return PageFaultResponse::Continue;
}
} else if (fault.is_protection_violation()) {
if (region->cow_map.get(page_index_in_region)) {
@ -761,3 +781,13 @@ inline bool PageDirectory::is_active() const
{
return &current->page_directory() == this;
}
size_t Region::committed() const
{
size_t bytes = 0;
for (size_t i = 0; i < page_count(); ++i) {
if (m_vmo->physical_pages()[first_page_index() + i])
bytes += PAGE_SIZE;
}
return bytes;
}