RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-05-30 22:08:12 +00:00
Code Issues Activity Actions

Kernel: Handle committing pages in regions more gracefully

Browse source 
Sometimes a physical underlying page may be there, but we may be
unable to allocate a page table that may be needed to map it. Bubble
up such mapping errors so that they can be handled more appropriately.
This commit is contained in:
Tom 2020-09-01 16:10:54 -06:00 • committed by Andreas Kling
parent 1ece93c805
commit bf268a0185
4 changed files with 58 additions and 31 deletions
Download patch file Download diff file Expand all files Collapse all files

14
Kernel/VM/MemoryManager.cpp
View file

@ -89,18 +89,18 @@ void MemoryManager::protect_kernel_image()
{
// Disable writing to the kernel text and rodata segments.
for (size_t i = (FlatPtr)&start_of_kernel_text; i < (FlatPtr)&start_of_kernel_data; i += PAGE_SIZE) {
auto& pte = ensure_pte(kernel_page_directory(), VirtualAddress(i));
auto& pte = *ensure_pte(kernel_page_directory(), VirtualAddress(i));
pte.set_writable(false);
}
if (Processor::current().has_feature(CPUFeature::NX)) {
// Disable execution of the kernel data and bss segments, as well as the kernel heap.
for (size_t i = (FlatPtr)&start_of_kernel_data; i < (FlatPtr)&end_of_kernel_bss; i += PAGE_SIZE) {
auto& pte = ensure_pte(kernel_page_directory(), VirtualAddress(i));
auto& pte = *ensure_pte(kernel_page_directory(), VirtualAddress(i));
pte.set_execute_disabled(true);
}
for (size_t i = FlatPtr(kmalloc_start); i < FlatPtr(kmalloc_end); i += PAGE_SIZE) {
auto& pte = ensure_pte(kernel_page_directory(), VirtualAddress(i));
auto& pte = *ensure_pte(kernel_page_directory(), VirtualAddress(i));
pte.set_execute_disabled(true);
}
}
@ -209,7 +209,7 @@ PageTableEntry* MemoryManager::pte(const PageDirectory& page_directory, VirtualA
return &quickmap_pt(PhysicalAddress((FlatPtr)pde.page_table_base()))[page_table_index];
}
PageTableEntry& MemoryManager::ensure_pte(PageDirectory& page_directory, VirtualAddress vaddr)
PageTableEntry* MemoryManager::ensure_pte(PageDirectory& page_directory, VirtualAddress vaddr)
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(s_mm_lock.own_lock());
@ -225,6 +225,10 @@ PageTableEntry& MemoryManager::ensure_pte(PageDirectory& page_directory, Virtual
#endif
bool did_purge = false;
auto page_table = allocate_user_physical_page(ShouldZeroFill::Yes, &did_purge);
if (!page_table) {
dbg() << "MM: Unable to allocate page table to map " << vaddr;
return nullptr;
}
if (did_purge) {
// If any memory had to be purged, ensure_pte may have been called as part
// of the purging process. So we need to re-map the pd in this case to ensure
@ -247,7 +251,7 @@ PageTableEntry& MemoryManager::ensure_pte(PageDirectory& page_directory, Virtual
ASSERT(result == AK::HashSetResult::InsertedNewEntry);
}
return quickmap_pt(PhysicalAddress((FlatPtr)pde.page_table_base()))[page_table_index];
return &quickmap_pt(PhysicalAddress((FlatPtr)pde.page_table_base()))[page_table_index];
}
void MemoryManager::release_pte(PageDirectory& page_directory, VirtualAddress vaddr, bool is_last_release)