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Kernel: Track user accessibility per Region.

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Region now has is_user_accessible(), which informs the memory manager how
to map these pages. Previously, we were just passing a "bool user_allowed"
to various functions and I'm not at all sure that any of that was correct.

All the Region constructors are now hidden, and you must go through one of
these helpers to construct a region:

- Region::create_user_accessible(...)
- Region::create_kernel_only(...)

That ensures that we don't accidentally create a Region without specifying
user accessibility. :^)
This commit is contained in:
Andreas Kling 2019-07-19 16:09:34 +02:00
parent 4547a301c4
commit 5b2447a27b
6 changed files with 73 additions and 30 deletions
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29
Kernel/VM/MemoryManager.cpp
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@ -305,7 +305,7 @@ bool MemoryManager::zero_page(Region& region, unsigned page_index_in_region)
#ifdef PAGE_FAULT_DEBUG
dbgprintf("MM: zero_page() but page already present. Fine with me!\n");
#endif
remap_region_page(region, page_index_in_region, true);
remap_region_page(region, page_index_in_region);
return true;
}
auto physical_page = allocate_user_physical_page(ShouldZeroFill::Yes);
@ -314,7 +314,7 @@ bool MemoryManager::zero_page(Region& region, unsigned page_index_in_region)
#endif
region.set_should_cow(page_index_in_region, false);
vmo.physical_pages()[page_index_in_region] = move(physical_page);
remap_region_page(region, page_index_in_region, true);
remap_region_page(region, page_index_in_region);
return true;
}
@ -327,7 +327,7 @@ bool MemoryManager::copy_on_write(Region& region, unsigned page_index_in_region)
dbgprintf(" >> It's a COW page but nobody is sharing it anymore. Remap r/w\n");
#endif
region.set_should_cow(page_index_in_region, false);
remap_region_page(region, page_index_in_region, true);
remap_region_page(region, page_index_in_region);
return true;
}
@ -345,7 +345,7 @@ bool MemoryManager::copy_on_write(Region& region, unsigned page_index_in_region)
vmo.physical_pages()[page_index_in_region] = move(physical_page);
unquickmap_page();
region.set_should_cow(page_index_in_region, false);
remap_region_page(region, page_index_in_region, true);
remap_region_page(region, page_index_in_region);
return true;
}
@ -366,7 +366,7 @@ bool MemoryManager::page_in_from_inode(Region& region, unsigned page_index_in_re
if (!vmo_page.is_null()) {
dbgprintf("MM: page_in_from_inode() but page already present. Fine with me!\n");
remap_region_page(region, page_index_in_region, true);
remap_region_page(region, page_index_in_region);
return true;
}
@ -391,7 +391,7 @@ bool MemoryManager::page_in_from_inode(Region& region, unsigned page_index_in_re
kprintf("MM: page_in_from_inode was unable to allocate a physical page\n");
return false;
}
remap_region_page(region, page_index_in_region, true);
remap_region_page(region, page_index_in_region);
u8* dest_ptr = region.vaddr().offset(page_index_in_region * PAGE_SIZE).as_ptr();
memcpy(dest_ptr, page_buffer, PAGE_SIZE);
return true;
@ -457,8 +457,9 @@ RefPtr<Region> MemoryManager::allocate_kernel_region(size_t size, String&& name)
ASSERT(!(size % PAGE_SIZE));
auto range = kernel_page_directory().range_allocator().allocate_anywhere(size);
ASSERT(range.is_valid());
auto region = adopt(*new Region(range, move(name), PROT_READ | PROT_WRITE | PROT_EXEC, false));
MM.map_region_at_address(*m_kernel_page_directory, *region, range.base(), false);
auto region = Region::create_kernel_only(range, move(name), PROT_READ | PROT_WRITE | PROT_EXEC, false);
region->set_user_accessible(false);
MM.map_region_at_address(*m_kernel_page_directory, *region, range.base());
// FIXME: It would be cool if these could zero-fill on demand instead.
region->commit();
return region;
@ -641,7 +642,7 @@ void MemoryManager::unquickmap_page()
m_quickmap_in_use = false;
}
void MemoryManager::remap_region_page(Region& region, unsigned page_index_in_region, bool user_allowed)
void MemoryManager::remap_region_page(Region& region, unsigned page_index_in_region)
{
ASSERT(region.page_directory());
InterruptDisabler disabler;
@ -657,7 +658,7 @@ void MemoryManager::remap_region_page(Region& region, unsigned page_index_in_reg
pte.set_writable(region.is_writable());
pte.set_cache_disabled(!region.vmo().m_allow_cpu_caching);
pte.set_write_through(!region.vmo().m_allow_cpu_caching);
pte.set_user_allowed(user_allowed);
pte.set_user_allowed(region.is_user_accessible());
region.page_directory()->flush(page_vaddr);
#ifdef MM_DEBUG
dbgprintf("MM: >> remap_region_page (PD=%x, PTE=P%x) '%s' L%x => P%x (@%p)\n", region.page_directory()->cr3(), pte.ptr(), region.name().characters(), page_vaddr.get(), physical_page->paddr().get(), physical_page.ptr());
@ -668,10 +669,10 @@ void MemoryManager::remap_region(PageDirectory& page_directory, Region& region)
{
InterruptDisabler disabler;
ASSERT(region.page_directory() == &page_directory);
map_region_at_address(page_directory, region, region.vaddr(), true);
map_region_at_address(page_directory, region, region.vaddr());
}
void MemoryManager::map_region_at_address(PageDirectory& page_directory, Region& region, VirtualAddress vaddr, bool user_allowed)
void MemoryManager::map_region_at_address(PageDirectory& page_directory, Region& region, VirtualAddress vaddr)
{
InterruptDisabler disabler;
region.set_page_directory(page_directory);
@ -698,7 +699,7 @@ void MemoryManager::map_region_at_address(PageDirectory& page_directory, Region&
pte.set_present(false);
pte.set_writable(region.is_writable());
}
pte.set_user_allowed(user_allowed);
pte.set_user_allowed(region.is_user_accessible());
page_directory.flush(page_vaddr);
#ifdef MM_DEBUG
dbgprintf("MM: >> map_region_at_address (PD=%x) '%s' L%x => P%x (@%p)\n", &page_directory, region.name().characters(), page_vaddr, physical_page ? physical_page->paddr().get() : 0, physical_page.ptr());
@ -729,7 +730,7 @@ bool MemoryManager::unmap_region(Region& region)
bool MemoryManager::map_region(Process& process, Region& region)
{
map_region_at_address(process.page_directory(), region, region.vaddr(), true);
map_region_at_address(process.page_directory(), region, region.vaddr());
return true;
}