kernel: vm: Port TLSF allocator

This commit adds a Two-Level Segregated Fit memory allocator port to the
Hyra kernelspace.

Signed-off-by: Ian Moffett <ian@osmora.org>

3 files changed, 1357 insertions, 0 deletions

diff --git a/sys/vm/tlsf.c b/sys/vm/tlsf.c
new file mode 100644
index 0000000..d4a6ddf
--- /dev/null
+++ b/sys/vm/tlsf.c
@@ -0,0 +1,1264 @@
+#include <sys/syslog.h>

+#include <sys/types.h>

+#include <assert.h>

+#include <limits.h>

+#include <string.h>

+#include <vm/tlsf.h>

+

+#define printf kprintf

+

+#if defined(__cplusplus)

+#define tlsf_decl inline

+#else

+#define tlsf_decl static

+#endif

+

+/*

+** Architecture-specific bit manipulation routines.

+**

+** TLSF achieves O(1) cost for malloc and free operations by limiting

+** the search for a free block to a free list of guaranteed size

+** adequate to fulfill the request, combined with efficient free list

+** queries using bitmasks and architecture-specific bit-manipulation

+** routines.

+**

+** Most modern processors provide instructions to count leading zeroes

+** in a word, find the lowest and highest set bit, etc. These

+** specific implementations will be used when available, falling back

+** to a reasonably efficient generic implementation.

+**

+** NOTE: TLSF spec relies on ffs/fls returning value 0..31.

+** ffs/fls return 1-32 by default, returning 0 for error.

+*/

+

+/*

+** Detect whether or not we are building for a 32- or 64-bit (LP/LLP)

+** architecture. There is no reliable portable method at compile-time.

+*/

+#if defined (__alpha__) || defined (__ia64__) || defined (__x86_64__) \

+	|| defined (_WIN64) || defined (__LP64__) || defined (__LLP64__)

+#define TLSF_64BIT

+#endif

+

+/*

+** gcc 3.4 and above have builtin support, specialized for architecture.

+** Some compilers masquerade as gcc; patchlevel test filters them out.

+*/

+#if defined (__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) \

+	&& defined (__GNUC_PATCHLEVEL__)

+

+#if defined (__SNC__)

+/* SNC for Playstation 3. */

+

+tlsf_decl int tlsf_ffs(unsigned int word)

+{

+	const unsigned int reverse = word & (~word + 1);

+	const int bit = 32 - __builtin_clz(reverse);

+	return bit - 1;

+}

+

+#else

+

+tlsf_decl int tlsf_ffs(unsigned int word)

+{

+	return __builtin_ffs(word) - 1;

+}

+

+#endif

+

+tlsf_decl int tlsf_fls(unsigned int word)

+{

+	const int bit = word ? 32 - __builtin_clz(word) : 0;

+	return bit - 1;

+}

+

+#elif defined (_MSC_VER) && (_MSC_VER >= 1400) && (defined (_M_IX86) || defined (_M_X64))

+/* Microsoft Visual C++ support on x86/X64 architectures. */

+

+#include <intrin.h>

+

+#pragma intrinsic(_BitScanReverse)

+#pragma intrinsic(_BitScanForward)

+

+tlsf_decl int tlsf_fls(unsigned int word)

+{

+	unsigned long index;

+	return _BitScanReverse(&index, word) ? index : -1;

+}

+

+tlsf_decl int tlsf_ffs(unsigned int word)

+{

+	unsigned long index;

+	return _BitScanForward(&index, word) ? index : -1;

+}

+

+#elif defined (_MSC_VER) && defined (_M_PPC)

+/* Microsoft Visual C++ support on PowerPC architectures. */

+

+#include <ppcintrinsics.h>

+

+tlsf_decl int tlsf_fls(unsigned int word)

+{

+	const int bit = 32 - _CountLeadingZeros(word);

+	return bit - 1;

+}

+

+tlsf_decl int tlsf_ffs(unsigned int word)

+{

+	const unsigned int reverse = word & (~word + 1);

+	const int bit = 32 - _CountLeadingZeros(reverse);

+	return bit - 1;

+}

+

+#elif defined (__ARMCC_VERSION)

+/* RealView Compilation Tools for ARM */

+

+tlsf_decl int tlsf_ffs(unsigned int word)

+{

+	const unsigned int reverse = word & (~word + 1);

+	const int bit = 32 - __clz(reverse);

+	return bit - 1;

+}

+

+tlsf_decl int tlsf_fls(unsigned int word)

+{

+	const int bit = word ? 32 - __clz(word) : 0;

+	return bit - 1;

+}

+

+#elif defined (__ghs__)

+/* Green Hills support for PowerPC */

+

+#include <ppc_ghs.h>

+

+tlsf_decl int tlsf_ffs(unsigned int word)

+{

+	const unsigned int reverse = word & (~word + 1);

+	const int bit = 32 - __CLZ32(reverse);

+	return bit - 1;

+}

+

+tlsf_decl int tlsf_fls(unsigned int word)

+{

+	const int bit = word ? 32 - __CLZ32(word) : 0;

+	return bit - 1;

+}

+

+#else

+/* Fall back to generic implementation. */

+

+tlsf_decl int tlsf_fls_generic(unsigned int word)

+{

+	int bit = 32;

+

+	if (!word) bit -= 1;

+	if (!(word & 0xffff0000)) { word <<= 16; bit -= 16; }

+	if (!(word & 0xff000000)) { word <<= 8; bit -= 8; }

+	if (!(word & 0xf0000000)) { word <<= 4; bit -= 4; }

+	if (!(word & 0xc0000000)) { word <<= 2; bit -= 2; }

+	if (!(word & 0x80000000)) { word <<= 1; bit -= 1; }

+

+	return bit;

+}

+

+/* Implement ffs in terms of fls. */

+tlsf_decl int tlsf_ffs(unsigned int word)

+{

+	return tlsf_fls_generic(word & (~word + 1)) - 1;

+}

+

+tlsf_decl int tlsf_fls(unsigned int word)

+{

+	return tlsf_fls_generic(word) - 1;

+}

+

+#endif

+

+/* Possibly 64-bit version of tlsf_fls. */

+#if defined (TLSF_64BIT)

+tlsf_decl int tlsf_fls_sizet(size_t size)

+{

+	int high = (int)(size >> 32);

+	int bits = 0;

+	if (high)

+	{

+		bits = 32 + tlsf_fls(high);

+	}

+	else

+	{

+		bits = tlsf_fls((int)size & 0xffffffff);

+

+	}

+	return bits;

+}

+#else

+#define tlsf_fls_sizet tlsf_fls

+#endif

+

+#undef tlsf_decl

+

+/*

+** Constants.

+*/

+

+/* Public constants: may be modified. */

+enum tlsf_public

+{

+	/* log2 of number of linear subdivisions of block sizes. Larger

+	** values require more memory in the control structure. Values of

+	** 4 or 5 are typical.

+	*/

+	SL_INDEX_COUNT_LOG2 = 5,

+};

+

+/* Private constants: do not modify. */

+enum tlsf_private

+{

+#if defined (TLSF_64BIT)

+	/* All allocation sizes and addresses are aligned to 8 bytes. */

+	ALIGN_SIZE_LOG2 = 3,

+#else

+	/* All allocation sizes and addresses are aligned to 4 bytes. */

+	ALIGN_SIZE_LOG2 = 2,

+#endif

+	ALIGN_SIZE = (1 << ALIGN_SIZE_LOG2),

+

+	/*

+	** We support allocations of sizes up to (1 << FL_INDEX_MAX) bits.

+	** However, because we linearly subdivide the second-level lists, and

+	** our minimum size granularity is 4 bytes, it doesn't make sense to

+	** create first-level lists for sizes smaller than SL_INDEX_COUNT * 4,

+	** or (1 << (SL_INDEX_COUNT_LOG2 + 2)) bytes, as there we will be

+	** trying to split size ranges into more slots than we have available.

+	** Instead, we calculate the minimum threshold size, and place all

+	** blocks below that size into the 0th first-level list.

+	*/

+

+#if defined (TLSF_64BIT)

+	/*

+	** TODO: We can increase this to support larger sizes, at the expense

+	** of more overhead in the TLSF structure.

+	*/

+	FL_INDEX_MAX = 32,

+#else

+	FL_INDEX_MAX = 30,

+#endif

+	SL_INDEX_COUNT = (1 << SL_INDEX_COUNT_LOG2),

+	FL_INDEX_SHIFT = (SL_INDEX_COUNT_LOG2 + ALIGN_SIZE_LOG2),

+	FL_INDEX_COUNT = (FL_INDEX_MAX - FL_INDEX_SHIFT + 1),

+

+	SMALL_BLOCK_SIZE = (1 << FL_INDEX_SHIFT),

+};

+

+/*

+** Cast and min/max macros.

+*/

+

+#define tlsf_cast(t, exp)	((t) (exp))

+#define tlsf_min(a, b)		((a) < (b) ? (a) : (b))

+#define tlsf_max(a, b)		((a) > (b) ? (a) : (b))

+

+/*

+** Set assert macro, if it has not been provided by the user.

+*/

+#if !defined (tlsf_assert)

+#define tlsf_assert __assert

+#endif

+

+/*

+** Static assertion mechanism.

+*/

+

+#define _tlsf_glue2(x, y) x ## y

+#define _tlsf_glue(x, y) _tlsf_glue2(x, y)

+#define tlsf_static_assert(exp) \

+	typedef char _tlsf_glue(static_assert, __LINE__) [(exp) ? 1 : -1]

+

+/* This code has been tested on 32- and 64-bit (LP/LLP) architectures. */

+tlsf_static_assert(sizeof(int) * CHAR_BIT == 32);

+tlsf_static_assert(sizeof(size_t) * CHAR_BIT >= 32);

+tlsf_static_assert(sizeof(size_t) * CHAR_BIT <= 64);

+

+/* SL_INDEX_COUNT must be <= number of bits in sl_bitmap's storage type. */

+tlsf_static_assert(sizeof(unsigned int) * CHAR_BIT >= SL_INDEX_COUNT);

+

+/* Ensure we've properly tuned our sizes. */

+tlsf_static_assert(ALIGN_SIZE == SMALL_BLOCK_SIZE / SL_INDEX_COUNT);

+

+/*

+** Data structures and associated constants.

+*/

+

+/*

+** Block header structure.

+**

+** There are several implementation subtleties involved:

+** - The prev_phys_block field is only valid if the previous block is free.

+** - The prev_phys_block field is actually stored at the end of the

+**   previous block. It appears at the beginning of this structure only to

+**   simplify the implementation.

+** - The next_free / prev_free fields are only valid if the block is free.

+*/

+typedef struct block_header_t

+{

+	/* Points to the previous physical block. */

+	struct block_header_t* prev_phys_block;

+

+	/* The size of this block, excluding the block header. */

+	size_t size;

+

+	/* Next and previous free blocks. */

+	struct block_header_t* next_free;

+	struct block_header_t* prev_free;

+} block_header_t;

+

+/*

+** Since block sizes are always at least a multiple of 4, the two least

+** significant bits of the size field are used to store the block status:

+** - bit 0: whether block is busy or free

+** - bit 1: whether previous block is busy or free

+*/

+static const size_t block_header_free_bit = 1 << 0;

+static const size_t block_header_prev_free_bit = 1 << 1;

+

+/*

+** The size of the block header exposed to used blocks is the size field.

+** The prev_phys_block field is stored *inside* the previous free block.

+*/

+static const size_t block_header_overhead = sizeof(size_t);

+

+/* User data starts directly after the size field in a used block. */

+static const size_t block_start_offset =

+	offsetof(block_header_t, size) + sizeof(size_t);

+

+/*

+** A free block must be large enough to store its header minus the size of

+** the prev_phys_block field, and no larger than the number of addressable

+** bits for FL_INDEX.

+*/

+static const size_t block_size_min =

+	sizeof(block_header_t) - sizeof(block_header_t*);

+static const size_t block_size_max = tlsf_cast(size_t, 1) << FL_INDEX_MAX;

+

+

+/* The TLSF control structure. */

+typedef struct control_t

+{

+	/* Empty lists point at this block to indicate they are free. */

+	block_header_t block_null;

+

+	/* Bitmaps for free lists. */

+	unsigned int fl_bitmap;

+	unsigned int sl_bitmap[FL_INDEX_COUNT];

+

+	/* Head of free lists. */

+	block_header_t* blocks[FL_INDEX_COUNT][SL_INDEX_COUNT];

+} control_t;

+

+/* A type used for casting when doing pointer arithmetic. */

+typedef ptrdiff_t tlsfptr_t;

+

+/*

+** block_header_t member functions.

+*/

+

+static size_t block_size(const block_header_t* block)

+{

+	return block->size & ~(block_header_free_bit | block_header_prev_free_bit);

+}

+

+static void block_set_size(block_header_t* block, size_t size)

+{

+	const size_t oldsize = block->size;

+	block->size = size | (oldsize & (block_header_free_bit | block_header_prev_free_bit));

+}

+

+static int block_is_last(const block_header_t* block)

+{

+	return block_size(block) == 0;

+}

+

+static int block_is_free(const block_header_t* block)

+{

+	return tlsf_cast(int, block->size & block_header_free_bit);

+}

+

+static void block_set_free(block_header_t* block)

+{

+	block->size |= block_header_free_bit;

+}

+

+static void block_set_used(block_header_t* block)

+{

+	block->size &= ~block_header_free_bit;

+}

+

+static int block_is_prev_free(const block_header_t* block)

+{

+	return tlsf_cast(int, block->size & block_header_prev_free_bit);

+}

+

+static void block_set_prev_free(block_header_t* block)

+{

+	block->size |= block_header_prev_free_bit;

+}

+

+static void block_set_prev_used(block_header_t* block)

+{

+	block->size &= ~block_header_prev_free_bit;

+}

+

+static block_header_t* block_from_ptr(const void* ptr)

+{

+	return tlsf_cast(block_header_t*,

+		tlsf_cast(unsigned char*, ptr) - block_start_offset);

+}

+

+static void* block_to_ptr(const block_header_t* block)

+{

+	return tlsf_cast(void*,

+		tlsf_cast(unsigned char*, block) + block_start_offset);

+}

+

+/* Return location of next block after block of given size. */

+static block_header_t* offset_to_block(const void* ptr, size_t size)

+{

+	return tlsf_cast(block_header_t*, tlsf_cast(tlsfptr_t, ptr) + size);

+}

+

+/* Return location of previous block. */

+static block_header_t* block_prev(const block_header_t* block)

+{

+	tlsf_assert(block_is_prev_free(block) && "previous block must be free");

+	return block->prev_phys_block;

+}

+

+/* Return location of next existing block. */

+static block_header_t* block_next(const block_header_t* block)

+{

+	block_header_t* next = offset_to_block(block_to_ptr(block),

+		block_size(block) - block_header_overhead);

+	tlsf_assert(!block_is_last(block));

+	return next;

+}

+

+/* Link a new block with its physical neighbor, return the neighbor. */

+static block_header_t* block_link_next(block_header_t* block)

+{

+	block_header_t* next = block_next(block);

+	next->prev_phys_block = block;

+	return next;

+}

+

+static void block_mark_as_free(block_header_t* block)

+{

+	/* Link the block to the next block, first. */

+	block_header_t* next = block_link_next(block);

+	block_set_prev_free(next);

+	block_set_free(block);

+}

+

+static void block_mark_as_used(block_header_t* block)

+{

+	block_header_t* next = block_next(block);

+	block_set_prev_used(next);

+	block_set_used(block);

+}

+

+static size_t align_up(size_t x, size_t align)

+{

+	tlsf_assert(0 == (align & (align - 1)) && "must align to a power of two");

+	return (x + (align - 1)) & ~(align - 1);

+}

+

+static size_t align_down(size_t x, size_t align)

+{

+	tlsf_assert(0 == (align & (align - 1)) && "must align to a power of two");

+	return x - (x & (align - 1));

+}

+

+static void* align_ptr(const void* ptr, size_t align)

+{

+	const tlsfptr_t aligned =

+		(tlsf_cast(tlsfptr_t, ptr) + (align - 1)) & ~(align - 1);

+	tlsf_assert(0 == (align & (align - 1)) && "must align to a power of two");

+	return tlsf_cast(void*, aligned);

+}

+

+/*

+** Adjust an allocation size to be aligned to word size, and no smaller

+** than internal minimum.

+*/

+static size_t adjust_request_size(size_t size, size_t align)

+{

+	size_t adjust = 0;

+	if (size)

+	{

+		const size_t aligned = align_up(size, align);

+

+		/* aligned sized must not exceed block_size_max or we'll go out of bounds on sl_bitmap */

+		if (aligned < block_size_max)

+		{

+			adjust = tlsf_max(aligned, block_size_min);

+		}

+	}

+	return adjust;

+}

+

+/*

+** TLSF utility functions. In most cases, these are direct translations of

+** the documentation found in the white paper.

+*/

+

+static void mapping_insert(size_t size, int* fli, int* sli)

+{

+	int fl, sl;

+	if (size < SMALL_BLOCK_SIZE)

+	{

+		/* Store small blocks in first list. */

+		fl = 0;

+		sl = tlsf_cast(int, size) / (SMALL_BLOCK_SIZE / SL_INDEX_COUNT);

+	}

+	else

+	{

+		fl = tlsf_fls_sizet(size);

+		sl = tlsf_cast(int, size >> (fl - SL_INDEX_COUNT_LOG2)) ^ (1 << SL_INDEX_COUNT_LOG2);

+		fl -= (FL_INDEX_SHIFT - 1);

+	}

+	*fli = fl;

+	*sli = sl;

+}

+

+/* This version rounds up to the next block size (for allocations) */

+static void mapping_search(size_t size, int* fli, int* sli)

+{

+	if (size >= SMALL_BLOCK_SIZE)

+	{

+		const size_t round = (1 << (tlsf_fls_sizet(size) - SL_INDEX_COUNT_LOG2)) - 1;

+		size += round;

+	}

+	mapping_insert(size, fli, sli);

+}

+

+static block_header_t* search_suitable_block(control_t* control, int* fli, int* sli)

+{

+	int fl = *fli;

+	int sl = *sli;

+

+	/*

+	** First, search for a block in the list associated with the given

+	** fl/sl index.

+	*/

+	unsigned int sl_map = control->sl_bitmap[fl] & (~0U << sl);

+	if (!sl_map)

+	{

+		/* No block exists. Search in the next largest first-level list. */

+		const unsigned int fl_map = control->fl_bitmap & (~0U << (fl + 1));

+		if (!fl_map)

+		{

+			/* No free blocks available, memory has been exhausted. */

+			return 0;

+		}

+

+		fl = tlsf_ffs(fl_map);

+		*fli = fl;

+		sl_map = control->sl_bitmap[fl];

+	}

+	tlsf_assert(sl_map && "internal error - second level bitmap is null");

+	sl = tlsf_ffs(sl_map);

+	*sli = sl;

+

+	/* Return the first block in the free list. */

+	return control->blocks[fl][sl];

+}

+

+/* Remove a free block from the free list.*/

+static void remove_free_block(control_t* control, block_header_t* block, int fl, int sl)

+{

+	block_header_t* prev = block->prev_free;

+	block_header_t* next = block->next_free;

+	tlsf_assert(prev && "prev_free field can not be null");

+	tlsf_assert(next && "next_free field can not be null");

+	next->prev_free = prev;

+	prev->next_free = next;

+

+	/* If this block is the head of the free list, set new head. */

+	if (control->blocks[fl][sl] == block)

+	{

+		control->blocks[fl][sl] = next;

+

+		/* If the new head is null, clear the bitmap. */

+		if (next == &control->block_null)

+		{

+			control->sl_bitmap[fl] &= ~(1U << sl);

+

+			/* If the second bitmap is now empty, clear the fl bitmap. */

+			if (!control->sl_bitmap[fl])

+			{

+				control->fl_bitmap &= ~(1U << fl);

+			}

+		}

+	}

+}

+

+/* Insert a free block into the free block list. */

+static void insert_free_block(control_t* control, block_header_t* block, int fl, int sl)

+{

+	block_header_t* current = control->blocks[fl][sl];

+	tlsf_assert(current && "free list cannot have a null entry");

+	tlsf_assert(block && "cannot insert a null entry into the free list");

+	block->next_free = current;

+	block->prev_free = &control->block_null;

+	current->prev_free = block;

+

+	tlsf_assert((uintptr_t)block_to_ptr(block) == (uintptr_t)align_ptr(block_to_ptr(block), ALIGN_SIZE)

+		&& "block not aligned properly");

+	/*

+	** Insert the new block at the head of the list, and mark the first-

+	** and second-level bitmaps appropriately.

+	*/

+	control->blocks[fl][sl] = block;

+	control->fl_bitmap |= (1U << fl);

+	control->sl_bitmap[fl] |= (1U << sl);

+}

+

+/* Remove a given block from the free list. */

+static void block_remove(control_t* control, block_header_t* block)

+{

+	int fl, sl;

+	mapping_insert(block_size(block), &fl, &sl);

+	remove_free_block(control, block, fl, sl);

+}

+

+/* Insert a given block into the free list. */

+static void block_insert(control_t* control, block_header_t* block)

+{

+	int fl, sl;

+	mapping_insert(block_size(block), &fl, &sl);

+	insert_free_block(control, block, fl, sl);

+}

+

+static int block_can_split(block_header_t* block, size_t size)

+{

+	return block_size(block) >= sizeof(block_header_t) + size;

+}

+

+/* Split a block into two, the second of which is free. */

+static block_header_t* block_split(block_header_t* block, size_t size)

+{

+	/* Calculate the amount of space left in the remaining block. */

+	block_header_t* remaining =

+		offset_to_block(block_to_ptr(block), size - block_header_overhead);

+

+	const size_t remain_size = block_size(block) - (size + block_header_overhead);

+

+	tlsf_assert((uintptr_t)block_to_ptr(remaining) == (uintptr_t)align_ptr(block_to_ptr(remaining), ALIGN_SIZE)

+		&& "remaining block not aligned properly");

+

+	tlsf_assert(block_size(block) == remain_size + size + block_header_overhead);

+	block_set_size(remaining, remain_size);

+	tlsf_assert(block_size(remaining) >= block_size_min && "block split with invalid size");

+

+	block_set_size(block, size);

+	block_mark_as_free(remaining);

+

+	return remaining;

+}

+

+/* Absorb a free block's storage into an adjacent previous free block. */

+static block_header_t* block_absorb(block_header_t* prev, block_header_t* block)

+{

+	tlsf_assert(!block_is_last(prev) && "previous block can't be last");

+	/* Note: Leaves flags untouched. */

+	prev->size += block_size(block) + block_header_overhead;

+	block_link_next(prev);

+	return prev;

+}

+

+/* Merge a just-freed block with an adjacent previous free block. */

+static block_header_t* block_merge_prev(control_t* control, block_header_t* block)

+{

+	if (block_is_prev_free(block))

+	{

+		block_header_t* prev = block_prev(block);

+		tlsf_assert(prev && "prev physical block can't be null");

+		tlsf_assert(block_is_free(prev) && "prev block is not free though marked as such");

+		block_remove(control, prev);

+		block = block_absorb(prev, block);

+	}

+

+	return block;

+}

+

+/* Merge a just-freed block with an adjacent free block. */

+static block_header_t* block_merge_next(control_t* control, block_header_t* block)

+{

+	block_header_t* next = block_next(block);

+	tlsf_assert(next && "next physical block can't be null");

+

+	if (block_is_free(next))

+	{

+		tlsf_assert(!block_is_last(block) && "previous block can't be last");

+		block_remove(control, next);

+		block = block_absorb(block, next);

+	}

+

+	return block;

+}

+

+/* Trim any trailing block space off the end of a block, return to pool. */

+static void block_trim_free(control_t* control, block_header_t* block, size_t size)

+{

+	tlsf_assert(block_is_free(block) && "block must be free");

+	if (block_can_split(block, size))

+	{

+		block_header_t* remaining_block = block_split(block, size);

+		block_link_next(block);

+		block_set_prev_free(remaining_block);

+		block_insert(control, remaining_block);

+	}

+}

+

+/* Trim any trailing block space off the end of a used block, return to pool. */

+static void block_trim_used(control_t* control, block_header_t* block, size_t size)

+{

+	tlsf_assert(!block_is_free(block) && "block must be used");

+	if (block_can_split(block, size))

+	{

+		/* If the next block is free, we must coalesce. */

+		block_header_t* remaining_block = block_split(block, size);

+		block_set_prev_used(remaining_block);

+

+		remaining_block = block_merge_next(control, remaining_block);

+		block_insert(control, remaining_block);

+	}

+}

+

+static block_header_t* block_trim_free_leading(control_t* control, block_header_t* block, size_t size)

+{

+	block_header_t* remaining_block = block;

+	if (block_can_split(block, size))

+	{

+		/* We want the 2nd block. */

+		remaining_block = block_split(block, size - block_header_overhead);

+		block_set_prev_free(remaining_block);

+

+		block_link_next(block);

+		block_insert(control, block);

+	}

+

+	return remaining_block;

+}

+

+static block_header_t* block_locate_free(control_t* control, size_t size)

+{

+	int fl = 0, sl = 0;

+	block_header_t* block = 0;

+

+	if (size)

+	{

+		mapping_search(size, &fl, &sl);

+

+		/*

+		** mapping_search can futz with the size, so for excessively large sizes it can sometimes wind up

+		** with indices that are off the end of the block array.

+		** So, we protect against that here, since this is the only callsite of mapping_search.

+		** Note that we don't need to check sl, since it comes from a modulo operation that guarantees it's always in range.

+		*/

+		if (fl < FL_INDEX_COUNT)

+		{

+			block = search_suitable_block(control, &fl, &sl);

+		}

+	}

+

+	if (block)

+	{

+		tlsf_assert(block_size(block) >= size);

+		remove_free_block(control, block, fl, sl);

+	}

+

+	return block;

+}

+

+static void* block_prepare_used(control_t* control, block_header_t* block, size_t size)

+{

+	void* p = 0;

+	if (block)

+	{

+		tlsf_assert(size && "size must be non-zero");

+		block_trim_free(control, block, size);

+		block_mark_as_used(block);

+		p = block_to_ptr(block);

+	}

+	return p;

+}

+

+/* Clear structure and point all empty lists at the null block. */

+static void control_construct(control_t* control)

+{

+	int i, j;

+

+	control->block_null.next_free = &control->block_null;

+	control->block_null.prev_free = &control->block_null;

+

+	control->fl_bitmap = 0;

+	for (i = 0; i < FL_INDEX_COUNT; ++i)

+	{

+		control->sl_bitmap[i] = 0;

+		for (j = 0; j < SL_INDEX_COUNT; ++j)

+		{

+			control->blocks[i][j] = &control->block_null;

+		}

+	}

+}

+

+/*

+** Debugging utilities.

+*/

+

+typedef struct integrity_t

+{

+	int prev_status;

+	int status;

+} integrity_t;

+

+#define tlsf_insist(x) { tlsf_assert(x); if (!(x)) { status--; } }

+

+static void integrity_walker(void* ptr, size_t size, int used, void* user)

+{

+	block_header_t* block = block_from_ptr(ptr);

+	integrity_t* integ = tlsf_cast(integrity_t*, user);

+	const int this_prev_status = block_is_prev_free(block) ? 1 : 0;

+	const int this_status = block_is_free(block) ? 1 : 0;

+	const size_t this_block_size = block_size(block);

+

+	int status = 0;

+	(void)used;

+	tlsf_insist(integ->prev_status == this_prev_status && "prev status incorrect");

+	tlsf_insist(size == this_block_size && "block size incorrect");

+

+	integ->prev_status = this_status;

+	integ->status += status;

+}

+

+int tlsf_check(tlsf_t tlsf)

+{

+	int i, j;

+

+	control_t* control = tlsf_cast(control_t*, tlsf);

+	int status = 0;

+

+	/* Check that the free lists and bitmaps are accurate. */

+	for (i = 0; i < FL_INDEX_COUNT; ++i)

+	{

+		for (j = 0; j < SL_INDEX_COUNT; ++j)

+		{

+			const int fl_map = control->fl_bitmap & (1U << i);

+			const int sl_list = control->sl_bitmap[i];

+			const int sl_map = sl_list & (1U << j);

+			const block_header_t* block = control->blocks[i][j];

+

+			/* Check that first- and second-level lists agree. */

+			if (!fl_map)

+			{

+				tlsf_insist(!sl_map && "second-level map must be null");

+			}

+

+			if (!sl_map)

+			{

+				tlsf_insist((uint64_t)block == (uint64_t)&control->block_null && "block list must be null");

+				continue;

+			}

+

+			/* Check that there is at least one free block. */

+			tlsf_insist(sl_list && "no free blocks in second-level map");

+			tlsf_insist((uintptr_t)block != (uintptr_t)&control->block_null && "block should not be null");

+

+			while (block != &control->block_null)

+			{

+				int fli, sli;

+				tlsf_insist(block_is_free(block) && "block should be free");

+				tlsf_insist(!block_is_prev_free(block) && "blocks should have coalesced");

+				tlsf_insist(!block_is_free(block_next(block)) && "blocks should have coalesced");

+				tlsf_insist(block_is_prev_free(block_next(block)) && "block should be free");

+				tlsf_insist(block_size(block) >= block_size_min && "block not minimum size");

+

+				mapping_insert(block_size(block), &fli, &sli);

+				tlsf_insist(fli == i && sli == j && "block size indexed in wrong list");

+				block = block->next_free;

+			}

+		}

+	}

+

+	return status;

+}

+

+#undef tlsf_insist

+

+static void default_walker(void* ptr, size_t size, int used, void* user)

+{

+	(void)user;

+	printf("\t%p %s size: %x (%p)\n", ptr, used ? "used" : "free", (unsigned int)size, block_from_ptr(ptr));

+}

+

+void tlsf_walk_pool(pool_t pool, tlsf_walker walker, void* user)

+{

+	tlsf_walker pool_walker = walker ? walker : default_walker;

+	block_header_t* block =

+		offset_to_block(pool, -(int)block_header_overhead);

+

+	while (block && !block_is_last(block))

+	{

+		pool_walker(

+			block_to_ptr(block),

+			block_size(block),

+			!block_is_free(block),

+			user);

+		block = block_next(block);

+	}

+}

+

+size_t tlsf_block_size(void* ptr)

+{

+	size_t size = 0;

+	if (ptr)

+	{

+		const block_header_t* block = block_from_ptr(ptr);

+		size = block_size(block);

+	}

+	return size;

+}

+

+int tlsf_check_pool(pool_t pool)

+{

+	/* Check that the blocks are physically correct. */

+	integrity_t integ = { 0, 0 };

+	tlsf_walk_pool(pool, integrity_walker, &integ);

+

+	return integ.status;

+}

+

+/*

+** Size of the TLSF structures in a given memory block passed to

+** tlsf_create, equal to the size of a control_t

+*/

+size_t tlsf_size(void)

+{

+	return sizeof(control_t);

+}

+

+size_t tlsf_align_size(void)

+{

+	return ALIGN_SIZE;

+}

+

+size_t tlsf_block_size_min(void)

+{

+	return block_size_min;

+}

+

+size_t tlsf_block_size_max(void)

+{

+	return block_size_max;

+}

+

+/*

+** Overhead of the TLSF structures in a given memory block passed to

+** tlsf_add_pool, equal to the overhead of a free block and the

+** sentinel block.

+*/

+size_t tlsf_pool_overhead(void)

+{

+	return 2 * block_header_overhead;

+}

+

+size_t tlsf_alloc_overhead(void)

+{

+	return block_header_overhead;

+}

+

+pool_t tlsf_add_pool(tlsf_t tlsf, void* mem, size_t bytes)

+{

+	block_header_t* block;

+	block_header_t* next;

+

+	const size_t pool_overhead = tlsf_pool_overhead();

+	const size_t pool_bytes = align_down(bytes - pool_overhead, ALIGN_SIZE);

+

+	if (((ptrdiff_t)mem % ALIGN_SIZE) != 0)

+	{

+		printf("tlsf_add_pool: Memory must be aligned by %u bytes.\n",

+			(unsigned int)ALIGN_SIZE);

+		return 0;

+	}

+

+	if (pool_bytes < block_size_min || pool_bytes > block_size_max)

+	{

+#if defined (TLSF_64BIT)

+		printf("tlsf_add_pool: Memory size must be between 0x%x and 0x%x00 bytes.\n",

+			(unsigned int)(pool_overhead + block_size_min),

+			(unsigned int)((pool_overhead + block_size_max) / 256));

+#else

+		printf("tlsf_add_pool: Memory size must be between %u and %u bytes.\n",

+			(unsigned int)(pool_overhead + block_size_min),

+			(unsigned int)(pool_overhead + block_size_max));

+#endif

+		return 0;

+	}

+

+	/*

+	** Create the main free block. Offset the start of the block slightly

+	** so that the prev_phys_block field falls outside of the pool -

+	** it will never be used.

+	*/

+	block = offset_to_block(mem, -(tlsfptr_t)block_header_overhead);

+	block_set_size(block, pool_bytes);

+	block_set_free(block);

+	block_set_prev_used(block);

+	block_insert(tlsf_cast(control_t*, tlsf), block);

+

+	/* Split the block to create a zero-size sentinel block. */

+	next = block_link_next(block);

+	block_set_size(next, 0);

+	block_set_used(next);

+	block_set_prev_free(next);

+

+	return mem;

+}

+

+void tlsf_remove_pool(tlsf_t tlsf, pool_t pool)

+{

+	control_t* control = tlsf_cast(control_t*, tlsf);

+	block_header_t* block = offset_to_block(pool, -(int)block_header_overhead);

+

+	int fl = 0, sl = 0;

+

+	tlsf_assert(block_is_free(block) && "block should be free");

+	tlsf_assert(!block_is_free(block_next(block)) && "next block should not be free");

+	tlsf_assert(block_size(block_next(block)) == 0 && "next block size should be zero");

+

+	mapping_insert(block_size(block), &fl, &sl);

+	remove_free_block(control, block, fl, sl);

+}

+

+/*

+** TLSF main interface.

+*/

+

+#if _DEBUG

+int test_ffs_fls()

+{

+	/* Verify ffs/fls work properly. */

+	int rv = 0;

+	rv += (tlsf_ffs(0) == -1) ? 0 : 0x1;

+	rv += (tlsf_fls(0) == -1) ? 0 : 0x2;

+	rv += (tlsf_ffs(1) == 0) ? 0 : 0x4;

+	rv += (tlsf_fls(1) == 0) ? 0 : 0x8;

+	rv += (tlsf_ffs(0x80000000) == 31) ? 0 : 0x10;

+	rv += (tlsf_ffs(0x80008000) == 15) ? 0 : 0x20;

+	rv += (tlsf_fls(0x80000008) == 31) ? 0 : 0x40;

+	rv += (tlsf_fls(0x7FFFFFFF) == 30) ? 0 : 0x80;

+

+#if defined (TLSF_64BIT)

+	rv += (tlsf_fls_sizet(0x80000000) == 31) ? 0 : 0x100;

+	rv += (tlsf_fls_sizet(0x100000000) == 32) ? 0 : 0x200;

+	rv += (tlsf_fls_sizet(0xffffffffffffffff) == 63) ? 0 : 0x400;

+#endif

+

+	if (rv)

+	{

+		printf("test_ffs_fls: %x ffs/fls tests failed.\n", rv);

+	}

+	return rv;

+}

+#endif

+

+tlsf_t tlsf_create(void* mem)

+{

+#if _DEBUG

+	if (test_ffs_fls())

+	{

+		return 0;

+	}

+#endif

+

+	if (((tlsfptr_t)mem % ALIGN_SIZE) != 0)

+	{

+		printf("tlsf_create: Memory must be aligned to %u bytes.\n",

+			(unsigned int)ALIGN_SIZE);

+		return 0;

+	}

+

+	control_construct(tlsf_cast(control_t*, mem));

+

+	return tlsf_cast(tlsf_t, mem);

+}

+

+tlsf_t tlsf_create_with_pool(void* mem, size_t bytes)

+{

+	tlsf_t tlsf = tlsf_create(mem);

+	tlsf_add_pool(tlsf, (char*)mem + tlsf_size(), bytes - tlsf_size());

+	return tlsf;

+}

+

+void tlsf_destroy(tlsf_t tlsf)

+{

+	/* Nothing to do. */

+	(void)tlsf;

+}

+

+pool_t tlsf_get_pool(tlsf_t tlsf)

+{

+	return tlsf_cast(pool_t, (char*)tlsf + tlsf_size());

+}

+

+void* tlsf_malloc(tlsf_t tlsf, size_t size)

+{

+	control_t* control = tlsf_cast(control_t*, tlsf);

+	const size_t adjust = adjust_request_size(size, ALIGN_SIZE);

+	block_header_t* block = block_locate_free(control, adjust);

+	return block_prepare_used(control, block, adjust);

+}

+

+void* tlsf_memalign(tlsf_t tlsf, size_t align, size_t size)

+{

+	control_t* control = tlsf_cast(control_t*, tlsf);

+	const size_t adjust = adjust_request_size(size, ALIGN_SIZE);

+

+	/*

+	** We must allocate an additional minimum block size bytes so that if

+	** our free block will leave an alignment gap which is smaller, we can

+	** trim a leading free block and release it back to the pool. We must

+	** do this because the previous physical block is in use, therefore

+	** the prev_phys_block field is not valid, and we can't simply adjust

+	** the size of that block.

+	*/

+	const size_t gap_minimum = sizeof(block_header_t);

+	const size_t size_with_gap = adjust_request_size(adjust + align + gap_minimum, align);

+

+	/*

+	** If alignment is less than or equals base alignment, we're done.

+	** If we requested 0 bytes, return null, as tlsf_malloc(0) does.

+	*/

+	const size_t aligned_size = (adjust && align > ALIGN_SIZE) ? size_with_gap : adjust;

+

+	block_header_t* block = block_locate_free(control, aligned_size);

+

+	/* This can't be a static assert. */

+	tlsf_assert(sizeof(block_header_t) == block_size_min + block_header_overhead);

+

+	if (block)

+	{

+		void* ptr = block_to_ptr(block);

+		void* aligned = align_ptr(ptr, align);

+		size_t gap = tlsf_cast(size_t,

+			tlsf_cast(tlsfptr_t, aligned) - tlsf_cast(tlsfptr_t, ptr));

+

+		/* If gap size is too small, offset to next aligned boundary. */

+		if (gap && gap < gap_minimum)

+		{

+			const size_t gap_remain = gap_minimum - gap;

+			const size_t offset = tlsf_max(gap_remain, align);

+			const void* next_aligned = tlsf_cast(void*,

+				tlsf_cast(tlsfptr_t, aligned) + offset);

+

+			aligned = align_ptr(next_aligned, align);

+			gap = tlsf_cast(size_t,

+				tlsf_cast(tlsfptr_t, aligned) - tlsf_cast(tlsfptr_t, ptr));

+		}

+

+		if (gap)

+		{

+			tlsf_assert(gap >= gap_minimum && "gap size too small");

+			block = block_trim_free_leading(control, block, gap);

+		}

+	}

+

+	return block_prepare_used(control, block, adjust);

+}

+

+void tlsf_free(tlsf_t tlsf, void* ptr)

+{

+	/* Don't attempt to free a NULL pointer. */

+	if (ptr)

+	{

+		control_t* control = tlsf_cast(control_t*, tlsf);

+		block_header_t* block = block_from_ptr(ptr);

+		tlsf_assert(!block_is_free(block) && "block already marked as free");

+		block_mark_as_free(block);

+		block = block_merge_prev(control, block);

+		block = block_merge_next(control, block);

+		block_insert(control, block);

+	}

+}

+

+/*

+** The TLSF block information provides us with enough information to

+** provide a reasonably intelligent implementation of realloc, growing or

+** shrinking the currently allocated block as required.

+**

+** This routine handles the somewhat esoteric edge cases of realloc:

+** - a non-zero size with a null pointer will behave like malloc

+** - a zero size with a non-null pointer will behave like free

+** - a request that cannot be satisfied will leave the original buffer

+**   untouched

+** - an extended buffer size will leave the newly-allocated area with

+**   contents undefined

+*/

+void* tlsf_realloc(tlsf_t tlsf, void* ptr, size_t size)

+{

+	control_t* control = tlsf_cast(control_t*, tlsf);

+	void* p = 0;

+

+	/* Zero-size requests are treated as free. */

+	if (ptr && size == 0)

+	{

+		tlsf_free(tlsf, ptr);

+	}

+	/* Requests with NULL pointers are treated as malloc. */

+	else if (!ptr)

+	{

+		p = tlsf_malloc(tlsf, size);

+	}

+	else

+	{

+		block_header_t* block = block_from_ptr(ptr);

+		block_header_t* next = block_next(block);

+

+		const size_t cursize = block_size(block);

+		const size_t combined = cursize + block_size(next) + block_header_overhead;

+		const size_t adjust = adjust_request_size(size, ALIGN_SIZE);

+

+		tlsf_assert(!block_is_free(block) && "block already marked as free");

+

+		/*

+		** If the next block is used, or when combined with the current

+		** block, does not offer enough space, we must reallocate and copy.

+		*/

+		if (adjust > cursize && (!block_is_free(next) || adjust > combined))

+		{

+			p = tlsf_malloc(tlsf, size);

+			if (p)

+			{

+				const size_t minsize = tlsf_min(cursize, size);

+				memcpy(p, ptr, minsize);

+				tlsf_free(tlsf, ptr);

+			}

+		}

+		else

+		{

+			/* Do we need to expand to the next block? */

+			if (adjust > cursize)

+			{

+				block_merge_next(control, block);

+				block_mark_as_used(block);

+			}

+

+			/* Trim the resulting block and return the original pointer. */

+			block_trim_used(control, block, adjust);

+			p = ptr;

+		}

+	}

+

+	return p;

+}

diff --git a/sys/vm/vm_dynalloc.c b/sys/vm/vm_dynalloc.c
new file mode 100644
index 0000000..8f766a8
--- /dev/null
+++ b/sys/vm/vm_dynalloc.c
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2023 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <vm/dynalloc.h>
+#include <vm/vm.h>
+
+/*
+ * Dynamically allocates memory
+ *
+ * @sz: The amount of bytes to allocate
+ */
+void *
+dynalloc(size_t sz)
+{
+    /* TODO: Per CPU */
+    struct cpu_vm_ctx vm_ctx = vm_get_bsp_ctx();
+
+    return tlsf_malloc(vm_ctx.tlsf_ctx, sz);
+}
+
+/*
+ * Free dynamically allocated memory
+ *
+ * @ptr: Pointer to base of memory.
+ */
+void
+dynfree(void *ptr)
+{
+    /* TODO: Per CPU */
+    struct cpu_vm_ctx vm_ctx = vm_get_bsp_ctx();
+
+    tlsf_free(vm_ctx.tlsf_ctx, ptr);
+}
diff --git a/sys/vm/vm_init.c b/sys/vm/vm_init.c
index ae50a43..600e61d 100644
--- a/sys/vm/vm_init.c
+++ b/sys/vm/vm_init.c
@@ -28,17 +28,51 @@
  */
 
 #include <vm/vm.h>
+#include <vm/vm_physseg.h>
 #include <sys/panic.h>
+#include <assert.h>
+
+/*
+ * XXX: As of now, these are constant... It would be nice if we could
+ *      have this value expanded upon request so we can keep it small
+ *      to not hog up resources. Would make it more flexible too :^)
+ */
+#define DYNALLOC_POOL_SZ        0x400000  /* 4 MiB */
+#define DYNALLOC_POOL_PAGES     (DYNALLOC_POOL_SZ / vm_get_page_size())
 
 static volatile struct vas kernel_vas;
 
+/*
+ * TODO: Move this to a per CPU structure, this kinda sucks
+ *       how it is right now...
+ */
+static volatile struct cpu_vm_ctx bsp_vm_ctx = {0};
+
 volatile struct limine_hhdm_request g_hhdm_request = {
     .id = LIMINE_HHDM_REQUEST,
     .revision = 0
 };
 
+struct cpu_vm_ctx
+vm_get_bsp_ctx(void)
+{
+    return bsp_vm_ctx;
+}
+
 void
 vm_init(void)
 {
+    void *pool_va;
+
     kernel_vas = pmap_read_vas();
+
+    /* Setup virtual memory context */
+    bsp_vm_ctx.dynalloc_pool_sz = DYNALLOC_POOL_SZ;
+    bsp_vm_ctx.dynalloc_pool_phys = vm_alloc_pageframe(DYNALLOC_POOL_PAGES);
+    if (bsp_vm_ctx.dynalloc_pool_phys == 0) {
+        panic("Failed to allocate dynamic pool\n");
+    }
+    pool_va = PHYS_TO_VIRT(bsp_vm_ctx.dynalloc_pool_phys);
+    bsp_vm_ctx.tlsf_ctx = tlsf_create_with_pool(pool_va, DYNALLOC_POOL_SZ);
+    __assert(bsp_vm_ctx.tlsf_ctx != 0);
 }