[kernel] Add spinlocks to vm_space, frame_allocator

Also updated spinlock interface to be an object, and added a scoped lock
object that uses it as well.

src/kernel/cpu.h

@@ -32,8 +32,6 @@ struct cpu_data
 	TSS *tss;
 	GDT *gdt;
 
-	// Values from here on don't need to be in the asm version
-	kutil::spinlock::node spinner;
 };
 
 extern "C" cpu_data * _current_gsbase();

src/kernel/frame_allocator.cpp

@@ -1,6 +1,6 @@
-#include "kernel_memory.h"
 #include "kutil/assert.h"
 #include "kutil/memory.h"
+
 #include "frame_allocator.h"
 #include "kernel_args.h"
 #include "kernel_memory.h"
@@ -17,8 +17,8 @@ frame_allocator::get()
 }
 
 frame_allocator::frame_allocator(kernel::args::frame_block *frames, size_t count) :
-	m_blocks(frames),
-	m_count(count)
+	m_blocks {frames},
+	m_count {count}
 {
 }
 
@@ -32,6 +32,8 @@ bsf(uint64_t v)
 size_t
 frame_allocator::allocate(size_t count, uintptr_t *address)
 {
+	kutil::scoped_lock lock {m_lock};
+
 	for (long i = m_count - 1; i >= 0; --i) {
 		frame_block &block = m_blocks[i];
 
@@ -80,6 +82,8 @@ frame_allocator::allocate(size_t count, uintptr_t *address)
 void
 frame_allocator::free(uintptr_t address, size_t count)
 {
+	kutil::scoped_lock lock {m_lock};
+
 	kassert(address % frame_size == 0, "Trying to free a non page-aligned frame!");
 
 	if (!count)
@@ -116,6 +120,8 @@ frame_allocator::free(uintptr_t address, size_t count)
 void
 frame_allocator::used(uintptr_t address, size_t count)
 {
+	kutil::scoped_lock lock {m_lock};
+
 	kassert(address % frame_size == 0, "Trying to mark a non page-aligned frame!");
 
 	if (!count)

src/kernel/frame_allocator.h

@@ -3,6 +3,7 @@
 /// Allocator for physical memory frames
 
 #include <stdint.h>
+#include "kutil/spinlock.h"
 
 namespace kernel {
 namespace args {
@@ -43,7 +44,9 @@ public:
 
 private:
 	frame_block *m_blocks;
-	long m_count;
+	size_t m_count;
+
+	kutil::spinlock m_lock;
 
 	frame_allocator() = delete;
 	frame_allocator(const frame_allocator &) = delete;

src/kernel/vm_space.cpp

@@ -33,7 +33,7 @@ vm_space::vm_space(page_table *p) :
 {}
 
 vm_space::vm_space() :
-	m_kernel(false)
+	m_kernel {false}
 {
 	m_pml4 = page_table::get_table_page();
 	page_table *kpml4 = kernel_space().m_pml4;
@@ -163,6 +163,7 @@ void
 vm_space::page_in(const vm_area &vma, uintptr_t offset, uintptr_t phys, size_t count)
 {
 	using memory::frame_size;
+	kutil::scoped_lock lock {m_lock};
 
 	uintptr_t base = 0;
 	if (!find_vma(vma, base))
@@ -190,6 +191,7 @@ void
 vm_space::clear(const vm_area &vma, uintptr_t offset, size_t count, bool free)
 {
 	using memory::frame_size;
+	kutil::scoped_lock lock {m_lock};
 
 	uintptr_t base = 0;
 	if (!find_vma(vma, base))

src/kernel/vm_space.h

@@ -4,6 +4,7 @@
 
 #include <stdint.h>
 #include "kutil/enum_bitfields.h"
+#include "kutil/spinlock.h"
 #include "kutil/vector.h"
 #include "page_table.h"
 
@@ -127,6 +128,8 @@ private:
 		bool operator==(const struct area &o) const;
 	};
 	kutil::vector<area> m_areas;
+
+	kutil::spinlock m_lock;
 };
 
 IS_BITFIELD(vm_space::fault_type);

src/libraries/kutil/include/kutil/spinlock.h

@@ -4,17 +4,43 @@
 #pragma once
 
 namespace kutil {
-namespace spinlock {
 
-/// An MCS based spinlock node
-struct node
+/// An MCS based spinlock
+class spinlock
+{
+public:
+	spinlock();
+	~spinlock();
+
+	/// A node in the wait queue.
+	struct waiter
 	{
 		bool locked;
-	node *next;
+		waiter *next;
 	};
 
-void aquire(node *lock, node *waiter);
-void release(node *lock, node *waiter);
+	void acquire(waiter *w);
+	void release(waiter *w);
+
+private:
+	waiter *m_lock;
+};
+
+/// Scoped lock that owns a spinlock::waiter
+class scoped_lock
+{
+public:
+	inline scoped_lock(spinlock &lock) : m_lock(lock) {
+		m_lock.acquire(&m_waiter);
+	}
+
+	inline ~scoped_lock() {
+		m_lock.release(&m_waiter);
+	}
+
+private:
+	spinlock &m_lock;
+	spinlock::waiter m_waiter;
+};
 
-} // namespace spinlock
 } // namespace kutil

src/libraries/kutil/spinlock.cpp

@@ -1,48 +1,49 @@
 #include "kutil/spinlock.h"
 
 namespace kutil {
-namespace spinlock {
 
 static constexpr int memorder = __ATOMIC_SEQ_CST;
 
+spinlock::spinlock() : m_lock {nullptr} {}
+spinlock::~spinlock() {}
+
 void
-aquire(node * &lock, node *waiter)
+spinlock::acquire(waiter *w)
 {
-	waiter->next = nullptr;
-	waiter->locked = true;
+	w->next = nullptr;
+	w->locked = true;
 
 	// Point the lock at this waiter
-	node *prev = __atomic_exchange_n(&lock, waiter, memorder);
+	waiter *prev = __atomic_exchange_n(&m_lock, w, memorder);
 	if (prev) {
 		// If there was a previous waiter, wait for them to
 		// unblock us
-		prev->next = waiter;
-		while (waiter->locked) {
+		prev->next = w;
+		while (w->locked) {
 			asm ("pause");
 		}
 	} else {
-		waiter->locked = false;
+		w->locked = false;
 	}
 }
 
 void
-release(node * &lock, node *waiter)
+spinlock::release(waiter *w)
 {
-	if (!waiter->next) {
+	if (!w->next) {
 		// If we're still the last waiter, we're done
-		if(__atomic_compare_exchange_n(&lock, &waiter, nullptr, false, memorder, memorder))
+		if(__atomic_compare_exchange_n(&m_lock, &w, nullptr, false, memorder, memorder))
 			return;
 	}
 
 	// Wait for the subseqent waiter to tell us who they are
-	while (!waiter->next) {
+	while (!w->next) {
 		asm ("pause");
 	}
 
 	// Unblock the subseqent waiter
-	waiter->next->locked = false;
+	w->next->locked = false;
 }
 
 
-} // namespace spinlock
 } // namespace kutil