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Kernel: Implement proper memory region splitting

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Memory regions are now splitted when they get munmapped, mprotected, or
mmapped with MAP_FIXED. This is used by couple of ports, and without
this we were just leaking up memory or straight up crashing programs.
This commit is contained in:
Bananymous
2025-11-10 19:57:26 +02:00
parent a39aa73e21
commit 9537922acc
10 changed files with 145 additions and 46 deletions
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1
kernel/include/kernel/Memory/FileBackedRegion.h
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@@ -33,6 +33,7 @@ namespace Kernel
BAN::ErrorOr<void> msync(vaddr_t, size_t, int) override;
BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> clone(PageTable& new_page_table) override;
BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> split(size_t offset) override;
protected:
BAN::ErrorOr<bool> allocate_page_containing_impl(vaddr_t vaddr, bool wants_write) override;

1
kernel/include/kernel/Memory/MemoryBackedRegion.h
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@@ -15,6 +15,7 @@ namespace Kernel
~MemoryBackedRegion();
BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> clone(PageTable& new_page_table) override;
BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> split(size_t offset) override;
BAN::ErrorOr<void> msync(vaddr_t, size_t, int) override { return {}; }

3
kernel/include/kernel/Memory/MemoryRegion.h
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@@ -60,6 +60,7 @@ namespace Kernel
BAN::ErrorOr<bool> allocate_page_containing(vaddr_t address, bool wants_write);
virtual BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> clone(PageTable& new_page_table) = 0;
virtual BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> split(size_t offset) = 0;
protected:
MemoryRegion(PageTable&, size_t size, Type type, PageTable::flags_t flags, int status_flags);
@@ -69,7 +70,7 @@ namespace Kernel
protected:
PageTable& m_page_table;
const size_t m_size;
size_t m_size { 0 };
const Type m_type;
PageTable::flags_t m_flags;
const int m_status_flags;

1
kernel/include/kernel/Memory/SharedMemoryObject.h
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@@ -58,6 +58,7 @@ namespace Kernel
static BAN::ErrorOr<BAN::UniqPtr<SharedMemoryObject>> create(BAN::RefPtr<SharedMemoryObjectManager::Object>, PageTable&, AddressRange);
BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> clone(PageTable& new_page_table) override;
BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> split(size_t offset) override;
BAN::ErrorOr<void> msync(vaddr_t, size_t, int) override { return {}; }

1
kernel/include/kernel/Process.h
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@@ -172,6 +172,7 @@ namespace Kernel
BAN::ErrorOr<long> sys_readdir(int fd, struct dirent* list, size_t list_len);
BAN::ErrorOr<BAN::Vector<BAN::UniqPtr<MemoryRegion>>> split_memory_region(BAN::UniqPtr<MemoryRegion>&& region, vaddr_t base, size_t length);
BAN::ErrorOr<long> sys_mmap(const sys_mmap_t*);
BAN::ErrorOr<long> sys_munmap(void* addr, size_t len);
BAN::ErrorOr<long> sys_mprotect(void* addr, size_t len, int prot);