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kernel/MMU: Don't copy pages on clone and allow manipulating other page directories

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This commit is contained in:
apio 2023-08-02 22:17:32 +02:00
parent 3aaf1c5d84
commit b4527786d4
Signed by: apio
GPG Key ID: B8A7D06E42258954
2 changed files with 22 additions and 25 deletions
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12
kernel/src/arch/MMU.h
View File

@ -29,15 +29,15 @@ namespace MMU
u64 translate_physical_address(u64 phys); u64 translate_physical_address(u64 phys);
Result<void> map(u64 virt, u64 phys, int flags, UseHugePages use_huge_pages);
Result<u64> unmap(u64 virt);
Result<u64> get_physical(u64 virt);
Result<int> get_flags(u64 virt);
Result<void> remap(u64 virt, int flags);
void switch_page_directory(PageDirectory* dir); void switch_page_directory(PageDirectory* dir);
PageDirectory* get_page_directory(); PageDirectory* get_page_directory();
Result<void> map(u64 virt, u64 phys, int flags, UseHugePages use_huge_pages, PageDirectory* directory = nullptr);
Result<u64> unmap(u64 virt, PageDirectory* directory = nullptr);
Result<u64> get_physical(u64 virt, PageDirectory* directory = nullptr);
Result<int> get_flags(u64 virt, PageDirectory* directory = nullptr);
Result<void> remap(u64 virt, int flags);
void flush_all(); void flush_all();
Result<PageDirectory*> create_page_directory_for_userspace(); Result<PageDirectory*> create_page_directory_for_userspace();

35
kernel/src/arch/x86_64/MMU.cpp
View File

@ -110,10 +110,11 @@ namespace MMU
return result; return result;
} }
PageTableEntry& l4_entry(u64 virt) PageTableEntry& l4_entry(u64 virt, PageDirectory* directory = nullptr)
{ {
auto index = l4_index(virt); auto index = l4_index(virt);
return get_virtual_page_directory()->entries[index]; auto* vdir = directory ? translate_physical(directory) : get_virtual_page_directory();
return vdir->entries[index];
} }
PageDirectory& page_table(const PageTableEntry& entry) PageDirectory& page_table(const PageTableEntry& entry)
@ -139,9 +140,9 @@ namespace MMU
return page_table(entry).entries[index]; return page_table(entry).entries[index];
} }
Result<PageTableEntry*> find_entry(u64 virt) Result<PageTableEntry*> find_entry(u64 virt, PageDirectory* directory = nullptr)
{ {
const auto& l4 = l4_entry(virt); const auto& l4 = l4_entry(virt, directory);
if (!l4.present) return err(EFAULT); if (!l4.present) return err(EFAULT);
auto& l3 = l3_entry(l4, virt); auto& l3 = l3_entry(l4, virt);
if (!l3.present) return err(EFAULT); if (!l3.present) return err(EFAULT);
@ -152,9 +153,9 @@ namespace MMU
return &l1_entry(l2, virt); return &l1_entry(l2, virt);
} }
Result<PageTableEntry*> apply_cascading_flags(u64 virt, int flags) Result<PageTableEntry*> apply_cascading_flags(u64 virt, int flags, PageDirectory* directory = nullptr)
{ {
auto& l4 = l4_entry(virt); auto& l4 = l4_entry(virt, directory);
if (!l4.present) return err(EFAULT); if (!l4.present) return err(EFAULT);
if (flags & Flags::ReadWrite) l4.read_write = true; if (flags & Flags::ReadWrite) l4.read_write = true;
if (flags & Flags::User) l4.user = true; if (flags & Flags::User) l4.user = true;
@ -183,9 +184,9 @@ namespace MMU
entry.set_address(phys); entry.set_address(phys);
} }
Result<void> map(u64 virt, u64 phys, int flags, UseHugePages use_huge_pages) Result<void> map(u64 virt, u64 phys, int flags, UseHugePages use_huge_pages, PageDirectory* directory)
{ {
auto& l4 = l4_entry(virt); auto& l4 = l4_entry(virt, directory);
if (!l4.present) if (!l4.present)
{ {
const u64 addr = TRY(MemoryManager::alloc_frame()); const u64 addr = TRY(MemoryManager::alloc_frame());
@ -252,9 +253,9 @@ namespace MMU
return {}; return {};
} }
Result<u64> unmap(u64 virt) Result<u64> unmap(u64 virt, PageDirectory* directory)
{ {
auto& l1 = *TRY(find_entry(virt)); auto& l1 = *TRY(find_entry(virt, directory));
if (!l1.present) return err(EFAULT); if (!l1.present) return err(EFAULT);
const u64 address = l1.get_address(); const u64 address = l1.get_address();
l1.clear(); l1.clear();
@ -262,16 +263,16 @@ namespace MMU
return address; return address;
} }
Result<u64> get_physical(u64 virt) Result<u64> get_physical(u64 virt, PageDirectory* directory)
{ {
const auto& l1 = *TRY(find_entry(virt)); const auto& l1 = *TRY(find_entry(virt, directory));
if (!l1.present) return err(EFAULT); if (!l1.present) return err(EFAULT);
return l1.get_address(); return l1.get_address();
} }
Result<int> get_flags(u64 virt) Result<int> get_flags(u64 virt, PageDirectory* directory)
{ {
const auto& l1 = *TRY(find_entry(virt)); const auto& l1 = *TRY(find_entry(virt, directory));
if (!l1.present) return err(EFAULT); if (!l1.present) return err(EFAULT);
return arch_flags_to_mmu(l1); return arch_flags_to_mmu(l1);
} }
@ -440,12 +441,8 @@ namespace MMU
for (u64 l = 0; l < 512; l++) for (u64 l = 0; l < 512; l++)
{ {
PageTableEntry& old_l1 = old_pt->entries[l];
if (!old_l1.present) continue;
PageTableEntry& new_l1 = new_pt->entries[l]; PageTableEntry& new_l1 = new_pt->entries[l];
new_l1.set_address(TRY(MemoryManager::alloc_frame())); new_l1.present = false; // The entry must be filled in by the caller.
memcpy(&page_table(new_l1), &page_table(old_l1), ARCH_PAGE_SIZE);
} }
} }
} }