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Teach Process::exec() about the magic of file-backed VMO's.

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This is really sweet! :^) The four instances of /bin/sh spawned at
startup now share their read-only text pages.

There are problems and limitations here, and plenty of room for
improvement. But it kinda works.
This commit is contained in:
Andreas Kling 2018-11-08 21:20:09 +01:00
parent 992769c9d4
commit cd1e7419f0
10 changed files with 159 additions and 70 deletions
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27
Kernel/MemoryManager.h
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@ -91,7 +91,7 @@ private:
struct Region : public Retainable<Region> {
Region(LinearAddress, size_t, String&&, bool r, bool w, bool cow = false);
Region(LinearAddress, size_t, RetainPtr<VMObject>&&, String&&, bool r, bool w, bool cow = false);
Region(LinearAddress, size_t, RetainPtr<VMObject>&&, size_t offset_in_vmo, String&&, bool r, bool w, bool cow = false);
Region(LinearAddress, size_t, RetainPtr<VirtualFileSystem::Node>&&, String&&, bool r, bool w);
~Region();
@ -109,11 +109,28 @@ struct Region : public Retainable<Region> {
return (laddr - linearAddress).get() / PAGE_SIZE;
}
size_t first_page_index() const
{
return m_offset_in_vmo / PAGE_SIZE;
}
size_t last_page_index() const
{
return (first_page_index() + page_count()) - 1;
}
size_t page_count() const
{
return size / PAGE_SIZE;
}
bool page_in(PageDirectory&);
int commit(Process&);
int decommit(Process&);
LinearAddress linearAddress;
size_t size { 0 };
size_t m_offset_in_vmo { 0 };
RetainPtr<VMObject> m_vmo;
String name;
bool is_readable { true };
@ -127,6 +144,7 @@ class MemoryManager {
AK_MAKE_ETERNAL
friend class PhysicalPage;
friend class Region;
friend class VMObject;
friend ByteBuffer procfs$mm();
public:
static MemoryManager& the() PURE;
@ -161,6 +179,9 @@ private:
MemoryManager();
~MemoryManager();
void register_vmo(VMObject&);
void unregister_vmo(VMObject&);
LinearAddress allocate_linear_address_range(size_t);
void map_region_at_address(PageDirectory*, Region&, LinearAddress, bool user_accessible);
void unmap_range(PageDirectory*, LinearAddress, size_t);
@ -181,7 +202,7 @@ private:
static Region* region_from_laddr(Process&, LinearAddress);
bool copy_on_write(Process&, Region&, unsigned page_index_in_region);
bool page_in_from_vnode(Process&, Region&, unsigned page_index_in_region);
bool page_in_from_vnode(PageDirectory&, Region&, unsigned page_index_in_region);
byte* quickmap_page(PhysicalPage&);
void unquickmap_page();
@ -273,6 +294,8 @@ private:
LinearAddress m_next_laddr;
Vector<RetainPtr<PhysicalPage>> m_free_physical_pages;
HashTable<VMObject*> m_vmos;
};
struct KernelPagingScope {