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Kernel+LibC: Add minherit() and MAP_INHERIT_ZERO

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This patch adds the minherit() syscall originally invented by OpenBSD.
Only the MAP_INHERIT_ZERO mode is supported for now. If set on an mmap
region, that region will be zeroed out on fork().
This commit is contained in:
Andreas Kling 2020-04-12 20:22:26 +02:00
parent dd00175ae2
commit c19b56dc99
8 changed files with 58 additions and 1 deletions
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8
Kernel/VM/Region.h
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@ -55,6 +55,11 @@ public:
Execute = 4,
};
enum class InheritMode {
Default,
ZeroedOnFork,
};
static NonnullOwnPtr<Region> create_user_accessible(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable = true);
static NonnullOwnPtr<Region> create_kernel_only(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable = true);
@ -160,6 +165,8 @@ public:
// NOTE: These are public so we can make<> them.
Region(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const String&, u8 access, bool cacheable);
void set_inherit_mode(InheritMode inherit_mode) { m_inherit_mode = inherit_mode; }
private:
Bitmap& ensure_cow_map() const;
@ -183,6 +190,7 @@ private:
NonnullRefPtr<VMObject> m_vmobject;
String m_name;
u8 m_access { 0 };
InheritMode m_inherit_mode : 3 { InheritMode::Default };
bool m_shared : 1 { false };
bool m_user_accessible : 1 { false };
bool m_cacheable : 1 { false };