PMM and liballoc port

kernel/Makefile

@@ -5,11 +5,8 @@ ldflags :=
 cflags  :=
 buildtype ?= release
 
-include $(platform)/flags.mk
-include generic/flags.mk
-
-include $(platform)/src.mk
-include libk/src.mk
+include flags.mk
+include src.mk
 
 all: build/kernel.elf
 

kernel/amd64/bootmain.c

@@ -1,11 +1,18 @@
 #include <limine/limine.h>
 #include <amd64/init.h>
 #include <sys/debug.h>
+#include <mm/pmm.h>
+#include <mm/liballoc.h>
 
 void bootmain(void) {
   amd64_init();
-
   DEBUG("Hello from amd64!\n");
 
+  pmm_init();
+
+  int *a = malloc(sizeof(int));
+  *a = 6969;
+  DEBUG("a=%p, *a=%d\n", a, *a);
+
   for (;;);
 }

kernel/amd64/mm.h

@@ -0,0 +1,6 @@
+#ifndef _KERNEL_AMD64_MM_H
+#define _KERNEL_AMD64_MM_H
+
+#define PAGE_SIZE   4096
+
+#endif // _KERNEL_AMD64_MM_H

kernel/amd64/spin_lock.c

@@ -0,0 +1,5 @@
+#include <sys/spin_lock.h>
+
+void spin_lock_relax(void) {
+  __asm__ volatile("pause");
+}

kernel/amd64/src.mk

@@ -2,10 +2,12 @@ c += amd64/bootmain.c \
 		 amd64/init.c \
 		 amd64/tss.c \
 		 amd64/io.c \
-		 amd64/debug.c
+		 amd64/debug.c \
+		 amd64/spin_lock.c
 
 o += amd64/bootmain.o \
 		 amd64/init.o \
 		 amd64/tss.o \
 		 amd64/io.o \
-		 amd64/debug.o
+		 amd64/debug.o \
+		 amd64/spin_lock.o

kernel/c_headers/include/stdatomic.h

@@ -0,0 +1,95 @@
+#ifndef _STD_ATOMIC_H
+#define _STD_ATOMIC_H
+
+#include <stdint.h>
+#include <stddef.h>
+
+// modified version of: https://github.com/llvm/llvm-project/blob/main/clang/lib/Headers/stdatomic.h
+
+typedef enum memory_order {
+  memory_order_relaxed = __ATOMIC_RELAXED,
+  memory_order_consume = __ATOMIC_CONSUME,
+  memory_order_acquire = __ATOMIC_ACQUIRE,
+  memory_order_release = __ATOMIC_RELEASE,
+  memory_order_acq_rel = __ATOMIC_ACQ_REL,
+  memory_order_seq_cst = __ATOMIC_SEQ_CST
+} memory_order;
+
+typedef _Atomic(_Bool)              atomic_bool;
+typedef _Atomic(char)               atomic_char;
+typedef _Atomic(signed char)        atomic_schar;
+typedef _Atomic(unsigned char)      atomic_uchar;
+typedef _Atomic(short)              atomic_short;
+typedef _Atomic(unsigned short)     atomic_ushort;
+typedef _Atomic(int)                atomic_int;
+typedef _Atomic(unsigned int)       atomic_uint;
+typedef _Atomic(long)               atomic_long;
+typedef _Atomic(unsigned long)      atomic_ulong;
+typedef _Atomic(long long)          atomic_llong;
+typedef _Atomic(unsigned long long) atomic_ullong;
+typedef _Atomic(uint_least16_t)     atomic_char16_t;
+typedef _Atomic(uint_least32_t)     atomic_char32_t;
+typedef _Atomic(wchar_t)            atomic_wchar_t;
+typedef _Atomic(int_least8_t)       atomic_int_least8_t;
+typedef _Atomic(uint_least8_t)      atomic_uint_least8_t;
+typedef _Atomic(int_least16_t)      atomic_int_least16_t;
+typedef _Atomic(uint_least16_t)     atomic_uint_least16_t;
+typedef _Atomic(int_least32_t)      atomic_int_least32_t;
+typedef _Atomic(uint_least32_t)     atomic_uint_least32_t;
+typedef _Atomic(int_least64_t)      atomic_int_least64_t;
+typedef _Atomic(uint_least64_t)     atomic_uint_least64_t;
+typedef _Atomic(int_fast8_t)        atomic_int_fast8_t;
+typedef _Atomic(uint_fast8_t)       atomic_uint_fast8_t;
+typedef _Atomic(int_fast16_t)       atomic_int_fast16_t;
+typedef _Atomic(uint_fast16_t)      atomic_uint_fast16_t;
+typedef _Atomic(int_fast32_t)       atomic_int_fast32_t;
+typedef _Atomic(uint_fast32_t)      atomic_uint_fast32_t;
+typedef _Atomic(int_fast64_t)       atomic_int_fast64_t;
+typedef _Atomic(uint_fast64_t)      atomic_uint_fast64_t;
+typedef _Atomic(intptr_t)           atomic_intptr_t;
+typedef _Atomic(uintptr_t)          atomic_uintptr_t;
+typedef _Atomic(size_t)             atomic_size_t;
+typedef _Atomic(ptrdiff_t)          atomic_ptrdiff_t;
+typedef _Atomic(intmax_t)           atomic_intmax_t;
+typedef _Atomic(uintmax_t)          atomic_uintmax_t;
+
+typedef struct atomic_flag { atomic_bool _Value; } atomic_flag;
+#define ATOMIC_FLAG_INIT ((atomic_flag){ 0 })
+
+#define atomic_store(object, desired) __c11_atomic_store(object, desired, __ATOMIC_SEQ_CST)
+#define atomic_store_explicit __c11_atomic_store
+
+#define atomic_load(object) __c11_atomic_load(object, __ATOMIC_SEQ_CST)
+#define atomic_load_explicit __c11_atomic_load
+
+#define atomic_exchange(object, desired) __c11_atomic_exchange(object, desired, __ATOMIC_SEQ_CST)
+#define atomic_exchange_explicit __c11_atomic_exchange
+
+#define atomic_compare_exchange_strong(object, expected, desired) __c11_atomic_compare_exchange_strong(object, expected, desired, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)
+#define atomic_compare_exchange_strong_explicit __c11_atomic_compare_exchange_strong
+
+#define atomic_compare_exchange_weak(object, expected, desired) __c11_atomic_compare_exchange_weak(object, expected, desired, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)
+#define atomic_compare_exchange_weak_explicit __c11_atomic_compare_exchange_weak
+
+#define atomic_fetch_add(object, operand) __c11_atomic_fetch_add(object, operand, __ATOMIC_SEQ_CST)
+#define atomic_fetch_add_explicit __c11_atomic_fetch_add
+
+#define atomic_fetch_sub(object, operand) __c11_atomic_fetch_sub(object, operand, __ATOMIC_SEQ_CST)
+#define atomic_fetch_sub_explicit __c11_atomic_fetch_sub
+
+#define atomic_fetch_or(object, operand) __c11_atomic_fetch_or(object, operand, __ATOMIC_SEQ_CST)
+#define atomic_fetch_or_explicit __c11_atomic_fetch_or
+
+#define atomic_fetch_xor(object, operand) __c11_atomic_fetch_xor(object, operand, __ATOMIC_SEQ_CST)
+#define atomic_fetch_xor_explicit __c11_atomic_fetch_xor
+
+#define atomic_fetch_and(object, operand) __c11_atomic_fetch_and(object, operand, __ATOMIC_SEQ_CST)
+#define atomic_fetch_and_explicit __c11_atomic_fetch_and
+
+#define atomic_flag_test_and_set(object) __c11_atomic_exchange(&(object)->_Value, 1, __ATOMIC_SEQ_CST)
+#define atomic_flag_test_and_set_explicit(object, order) __c11_atomic_exchange(&(object)->_Value, 1, order)
+
+#define atomic_flag_clear(object) __c11_atomic_store(&(object)->_Value, 0, __ATOMIC_SEQ_CST)
+#define atomic_flag_clear_explicit(object, order) __c11_atomic_store(&(object)->_Value, 0, order)
+
+#endif // _STD_ATOMIC_H

kernel/flags.mk

@@ -0,0 +1,2 @@
+include $(platform)/flags.mk
+include generic/flags.mk

kernel/generic/flags.mk

@@ -10,7 +10,8 @@ cflags += -nostdinc \
 
 cflags += -isystem . -isystem c_headers/include
 
-cflags += -DPRINTF_INCLUDE_CONFIG_H=1
+cflags += -DPRINTF_INCLUDE_CONFIG_H=1 \
+					-D_ALLOC_SKIP_DEFINE
 
 ifeq ($(buildtype),debug)
 	cflags += -O0 -g

kernel/libk/align.h

@@ -0,0 +1,8 @@
+#ifndef _KERNEL_LIBK_ALIGN_H
+#define _KERNEL_LIBK_ALIGN_H
+
+#define div_align_up(x, div) (((x) + (div) - 1) / (div))
+#define align_down(x, a)  ((x) & ~((a) - 1))
+#define align_up(x, a)  (((x) + ((a) - 1)) & ~((a) - 1))
+
+#endif // _KERNEL_LIBK_ALIGN_H

kernel/libk/bm.c

@@ -0,0 +1,91 @@
+#include <libk/std.h>
+#include <libk/bm.h>
+#include <libk/string.h>
+
+void bm_init(struct bm *bm, uint8_t *base, size_t nbits) {
+  bm->base = base;
+  bm->nbits = nbits;
+  memset(bm->base, 0, (nbits + 7) / 8);
+}
+
+/*
+ * Set a bit in a bitmap.
+ */
+void bm_set(struct bm *bm, size_t k) {
+  if (k >= bm->nbits)
+    return;
+
+  uint8_t *b = (uint8_t *)((uintptr_t)bm->base + (k / 8));
+  *b = ((*b) | (1 << (k % 8)));
+}
+
+/*
+ * Clear a bit in a bitmap.
+ */
+void bm_clear(struct bm *bm, size_t k) {
+  if (k >= bm->nbits)
+    return;
+
+  uint8_t *b = (uint8_t *)((uintptr_t)bm->base + (k / 8));
+  *b = ((*b) & ~(1 << (k % 8)));
+}
+
+/*
+ * Test (true/false) a bit in a bitmap.
+ */
+bool bm_test(struct bm *bm, size_t k) {
+  if (k >= bm->nbits)
+    return false;
+
+  uint8_t *b = (uint8_t *)((uintptr_t)bm->base + (k / 8));
+  return (*b) & (1 << (k % 8));
+}
+
+/*
+ * Set a range of bits in a bitmap. if starting bit is out of range, we fail.
+ */
+bool bm_set_region(struct bm *bm, size_t k, size_t m) {
+  if ((k >= m) || (k >= bm->nbits) || (k + m >= bm->nbits))
+    return false;
+
+  for (size_t i = k; i < m; i++) {
+    bool taken = bm_test(bm, i);
+    if (taken)
+      return false;
+  }
+
+  for (size_t i = k; i < m; i++)
+    bm_set(bm, i);
+  
+  return true;
+}
+
+/*
+ * Clear a range of bits in a bitmap. starting bit must be in range.
+ */
+void bm_clear_region(struct bm *bm, size_t k, size_t m) {
+  if ((k >= m) || (k >= bm->nbits) || (k + m >= bm->nbits))
+    return;
+
+  for (size_t i = k; i < m; i++)
+    bm_clear(bm, i);
+}
+
+/*
+ * Test a range if bits in a bitmap. Return true if at least one bit
+ * is set, else return false (all bits clear). For convenience, if k or m
+ * are out of range, act as if the bits are set / bitmap is full - this is
+ * useful for implementing the physical memory manager algorithm.
+ */
+bool bm_test_region(struct bm *bm, size_t k, size_t m) {
+  if ((k >= m) || (k >= bm->nbits) || (k + m >= bm->nbits))
+    return true;
+
+  for (size_t i = k; i < m; i++) {
+    bool test = bm_test(bm, i);
+    if (test)
+      return true;
+  }
+
+  return false;
+}

kernel/libk/bm.h

@@ -0,0 +1,19 @@
+#ifndef _KERNEL_LIBK_BM_H
+#define _KERNEL_LIBK_BM_H
+
+#include <libk/std.h>
+
+struct bm {
+  uint8_t *base;
+  size_t nbits;
+};
+
+void bm_init(struct bm *bm, uint8_t *base, size_t nbits);
+void bm_set(struct bm *bm, size_t k);
+bool bm_set_region(struct bm *bm, size_t k, size_t m);
+void bm_clear(struct bm *bm, size_t k);
+void bm_clear_region(struct bm *bm, size_t k, size_t m);
+bool bm_test(struct bm *bm, size_t k);
+bool bm_test_region(struct bm *bm, size_t k, size_t m);
+
+#endif // _KERNEL_LIBK_BM_H

kernel/libk/src.mk

@@ -1,7 +1,9 @@
 c += libk/string.c \
 		 libk/printf.c \
-		 libk/putchar_.c
+		 libk/putchar_.c \
+		 libk/bm.c
 
 o += libk/string.o \
 		 libk/printf.o \
-		 libk/putchar_.o
+		 libk/putchar_.o \
+		 libk/bm.o

kernel/libk/std.h

@@ -8,5 +8,6 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <stdnoreturn.h>
+#include <stdatomic.h>
 
 #endif // _KERNEL_LIBK_STD_H

kernel/limine/.gitignore

@@ -0,0 +1 @@
+*.o

kernel/limine/requests.c

@@ -0,0 +1,20 @@
+#include <limine/limine.h>
+
+#define DECL_REQ(small, big) \
+  __attribute__((used, section(".limine_requests"))) \
+  struct limine_ ## small ## _request limine_ ## small ## _request = { \
+    .id = LIMINE_ ## big ## _REQUEST_ID, \
+    .revision = 4 \
+  }
+
+__attribute__((used, section(".limine_requests")))
+volatile uint64_t limine_base_revision[] = LIMINE_BASE_REVISION(4);
+
+__attribute__((used, section(".limine_requests_start")))
+volatile uint64_t limine_requests_start_marker[] = LIMINE_REQUESTS_START_MARKER;
+
+__attribute__((used, section(".limine_requests_end")))
+volatile uint64_t limine_requests_end_marker[] = LIMINE_REQUESTS_END_MARKER;
+
+DECL_REQ(hhdm, HHDM);
+DECL_REQ(memmap, MEMMAP);

kernel/limine/requests.h

@@ -0,0 +1,12 @@
+#ifndef _KERNEL_LIMINE_REQUESTS_H
+#define _KERNEL_LIMINE_REQUESTS_H
+
+#include <limine/limine.h>
+
+#define EXTERN_REQ(small) \
+  extern struct limine_ ## small ## _request limine_ ## small ## _request
+
+EXTERN_REQ(hhdm);
+EXTERN_REQ(memmap);
+
+#endif // _KERNEL_LIMINE_REQUESTS_H

kernel/limine/src.mk

@@ -0,0 +1,3 @@
+c += limine/requests.c
+
+o += limine/requests.o

kernel/mm/.gitignore

@@ -0,0 +1 @@
+*.o

kernel/mm/liballoc.c

@@ -0,0 +1,575 @@
+/* liballoc breaks when optimized too aggressively, for eg. clang's -Oz */
+#pragma clang optimize off
+
+#include <mm/liballoc.h>
+#include <mm/pmm.h>
+#include <mm/types.h>
+#include <sync/spin_lock.h>
+#include <limine/requests.h>
+
+/* Porting */
+spin_lock_t _liballoc_lock = SPIN_LOCK_INIT;
+
+int liballoc_lock(void) {
+  spin_lock(&_liballoc_lock);
+  return 0;
+}
+
+int liballoc_unlock(void) {
+  spin_unlock(&_liballoc_lock);
+  return 0;
+}
+
+void *liballoc_alloc(int pages) {
+  physaddr_t p_addr = pmm_alloc(pages);
+
+  if (p_addr == PMM_ALLOC_ERR)
+    return NULL;
+
+  struct limine_hhdm_response *hhdm = limine_hhdm_request.response;
+  uintptr_t addr = (uintptr_t)(p_addr + hhdm->offset);
+  return (void *)addr;
+}
+
+int liballoc_free(void *ptr, int pages) {
+  struct limine_hhdm_response *hhdm = limine_hhdm_request.response;
+
+  physaddr_t p_addr = (uintptr_t)ptr - hhdm->offset;
+
+  pmm_free(p_addr, pages);
+
+  return 0;
+}
+
+/**  Durand's Ridiculously Amazing Super Duper Memory functions.  */
+
+//#define DEBUG	
+
+#define LIBALLOC_MAGIC	0xc001c0de
+#define MAXCOMPLETE		5
+#define MAXEXP	32
+#define MINEXP	8	
+
+#define MODE_BEST			0
+#define MODE_INSTANT		1
+
+#define MODE	MODE_BEST
+
+#ifdef DEBUG
+#include <stdio.h>
+#endif
+
+
+struct boundary_tag* l_freePages[MAXEXP];		//< Allowing for 2^MAXEXP blocks
+int 				 l_completePages[MAXEXP];	//< Allowing for 2^MAXEXP blocks
+
+
+#ifdef DEBUG
+unsigned int l_allocated = 0;		//< The real amount of memory allocated.
+unsigned int l_inuse = 0;			//< The amount of memory in use (malloc'ed). 
+#endif
+
+
+static int l_initialized = 0;			//< Flag to indicate initialization.	
+static int l_pageSize  = 4096;			//< Individual page size
+static int l_pageCount = 16;			//< Minimum number of pages to allocate.
+
+
+// ***********   HELPER FUNCTIONS  *******************************
+
+/** Returns the exponent required to manage 'size' amount of memory. 
+ *
+ *  Returns n where  2^n <= size < 2^(n+1)
+ */
+static inline int getexp( unsigned int size )
+{
+	if ( size < (1<<MINEXP) ) 
+	{
+		#ifdef DEBUG
+		printf("getexp returns -1 for %i less than MINEXP\n", size );
+		#endif
+		return -1;	// Smaller than the quantum.
+	}
+		
+		
+	int shift = MINEXP;
+
+	while ( shift < MAXEXP )
+	{
+		if ( (1<<shift) > size ) break;
+		shift += 1;
+	}
+
+	#ifdef DEBUG
+	printf("getexp returns %i (%i bytes) for %i size\n", shift - 1, (1<<(shift -1)), size );
+	#endif
+
+	return shift - 1;	
+}
+
+
+static void* 	liballoc_memset(void* s, int c, size_t n)
+{
+	size_t i;
+	for ( i = 0; i < n ; i++)
+		((char*)s)[i] = c;
+	
+	return s;
+}
+
+static void* 	liballoc_memcpy(void* s1, const void* s2, size_t n)
+{
+  char *cdest;
+  char *csrc;
+  unsigned int *ldest = (unsigned int*)s1;
+  unsigned int *lsrc  = (unsigned int*)s2;
+
+  while ( n >= sizeof(unsigned int) )
+  {
+      *ldest++ = *lsrc++;
+	  n -= sizeof(unsigned int);
+  }
+
+  cdest = (char*)ldest;
+  csrc  = (char*)lsrc;
+  
+  while ( n > 0 )
+  {
+      *cdest++ = *csrc++;
+	  n -= 1;
+  }
+  
+  return s1;
+}
+
+ 
+
+#ifdef DEBUG
+static void dump_array()
+{
+	int i = 0;
+	struct boundary_tag *tag = NULL;
+
+	printf("------ Free pages array ---------\n");
+	printf("System memory allocated: %i\n", l_allocated );
+	printf("Memory in used (malloc'ed): %i\n", l_inuse );
+
+		for ( i = 0; i < MAXEXP; i++ )
+		{
+			printf("%.2i(%i): ",i, l_completePages[i] );
+	
+			tag = l_freePages[ i ];
+			while ( tag != NULL )
+			{
+				if ( tag->split_left  != NULL  ) printf("*");
+				printf("%i", tag->real_size );
+				if ( tag->split_right != NULL  ) printf("*");
+	
+				printf(" ");
+				tag = tag->next;
+			}
+			printf("\n");
+		}
+
+	printf("'*' denotes a split to the left/right of a tag\n");
+	fflush( stdout );
+}
+#endif
+
+
+
+static inline void insert_tag( struct boundary_tag *tag, int index )
+{
+	int realIndex;
+	
+	if ( index < 0 ) 
+	{
+		realIndex = getexp( tag->real_size - sizeof(struct boundary_tag) );
+		if ( realIndex < MINEXP ) realIndex = MINEXP;
+	}
+	else
+		realIndex = index;
+	
+	tag->index = realIndex;
+	
+	if ( l_freePages[ realIndex ] != NULL ) 
+	{
+		l_freePages[ realIndex ]->prev = tag;
+		tag->next = l_freePages[ realIndex ];
+	}
+
+	l_freePages[ realIndex ] = tag;
+}
+
+static inline void remove_tag( struct boundary_tag *tag )
+{
+	if ( l_freePages[ tag->index ] == tag ) l_freePages[ tag->index ] = tag->next;
+
+	if ( tag->prev != NULL ) tag->prev->next = tag->next;
+	if ( tag->next != NULL ) tag->next->prev = tag->prev;
+
+	tag->next = NULL;
+	tag->prev = NULL;
+	tag->index = -1;
+}
+
+
+static inline struct boundary_tag* melt_left( struct boundary_tag *tag )
+{
+	struct boundary_tag *left = tag->split_left;
+							
+	left->real_size   += tag->real_size;
+	left->split_right  = tag->split_right;
+	
+	if ( tag->split_right != NULL ) tag->split_right->split_left = left;
+
+	return left;
+}
+
+
+static inline struct boundary_tag* absorb_right( struct boundary_tag *tag )
+{
+	struct boundary_tag *right = tag->split_right;
+
+		remove_tag( right );		// Remove right from free pages.
+
+		tag->real_size   += right->real_size;
+
+		tag->split_right  = right->split_right;
+		if ( right->split_right != NULL )
+					right->split_right->split_left = tag;
+
+	return tag;
+}
+
+static inline struct boundary_tag* split_tag( struct boundary_tag* tag )
+{
+	unsigned int remainder = tag->real_size - sizeof(struct boundary_tag) - tag->size;
+		
+	struct boundary_tag *new_tag = 
+				   (struct boundary_tag*)((uintptr_t)tag + sizeof(struct boundary_tag) + tag->size);	
+	
+						new_tag->magic = LIBALLOC_MAGIC;
+						new_tag->real_size = remainder;	
+
+						new_tag->next = NULL;
+						new_tag->prev = NULL;
+	
+						new_tag->split_left = tag;
+						new_tag->split_right = tag->split_right;
+	
+						if (new_tag->split_right != NULL) new_tag->split_right->split_left = new_tag;
+						tag->split_right = new_tag;
+	
+						tag->real_size -= new_tag->real_size;
+	
+						insert_tag( new_tag, -1 );
+	
+	return new_tag;
+}
+
+
+// ***************************************************************
+
+
+
+
+static struct boundary_tag* allocate_new_tag( unsigned int size )
+{
+	unsigned int pages;
+	unsigned int usage;
+	struct boundary_tag *tag;
+
+		// This is how much space is required.
+		usage  = size + sizeof(struct boundary_tag);
+
+				// Perfect amount of space
+		pages = usage / l_pageSize;
+		if ( (usage % l_pageSize) != 0 ) pages += 1;
+
+		// Make sure it's >= the minimum size.
+		if ( pages < (unsigned int)l_pageCount ) pages = l_pageCount;
+
+		tag = (struct boundary_tag*)liballoc_alloc( pages );
+
+		if ( tag == NULL ) return NULL;	// uh oh, we ran out of memory.
+		
+				tag->magic 		= LIBALLOC_MAGIC;
+				tag->size 		= size;
+				tag->real_size 	= pages * l_pageSize;
+				tag->index 		= -1;
+
+				tag->next		= NULL;
+				tag->prev		= NULL;
+				tag->split_left 	= NULL;
+				tag->split_right 	= NULL;
+
+
+		#ifdef DEBUG
+		printf("Resource allocated %x of %i pages (%i bytes) for %i size.\n", tag, pages, pages * l_pageSize, size );
+
+		l_allocated += pages * l_pageSize;
+
+		printf("Total memory usage = %i KB\n",  (int)((l_allocated / (1024))) );
+		#endif
+		
+      return tag;
+}
+
+
+
+void *malloc(size_t size)
+{
+	int index;
+	void *ptr;
+	struct boundary_tag *tag = NULL;
+
+	liballoc_lock();
+
+		if ( l_initialized == 0 )
+		{
+			#ifdef DEBUG
+			printf("%s\n","liballoc initializing.");
+			#endif
+			for ( index = 0; index < MAXEXP; index++ )
+			{
+				l_freePages[index] = NULL;
+				l_completePages[index] = 0;
+			}
+			l_initialized = 1;
+		}
+
+		index = getexp( size ) + MODE;
+		if ( index < MINEXP ) index = MINEXP;
+		
+
+		// Find one big enough.
+			tag = l_freePages[ index ];				// Start at the front of the list.
+			while ( tag != NULL )
+			{
+					// If there's enough space in this tag.
+				if ( (tag->real_size - sizeof(struct boundary_tag))
+								>= (size + sizeof(struct boundary_tag) ) )
+				{
+					#ifdef DEBUG
+					printf("Tag search found %i >= %i\n",(tag->real_size - sizeof(struct boundary_tag)), (size + sizeof(struct boundary_tag) ) );
+					#endif
+					break;
+				}
+
+				tag = tag->next;
+			}
+
+		
+			// No page found. Make one.
+			if ( tag == NULL )
+			{	
+				if ( (tag = allocate_new_tag( size )) == NULL )
+				{
+					liballoc_unlock();
+					return NULL;
+				}
+				
+				index = getexp( tag->real_size - sizeof(struct boundary_tag) );
+			}
+			else
+			{
+				remove_tag( tag );
+
+				if ( (tag->split_left == NULL) && (tag->split_right == NULL) )
+					l_completePages[ index ] -= 1;
+			}
+		
+		// We have a free page.  Remove it from the free pages list.
+	
+		tag->size = size;
+
+		// Removed... see if we can re-use the excess space.
+
+		#ifdef DEBUG
+		printf("Found tag with %i bytes available (requested %i bytes, leaving %i), which has exponent: %i (%i bytes)\n", tag->real_size - sizeof(struct boundary_tag), size, tag->real_size - size - sizeof(struct boundary_tag), index, 1<<index );
+		#endif
+		
+		unsigned int remainder = tag->real_size - size - sizeof( struct boundary_tag ) * 2; // Support a new tag + remainder
+
+		if ( ((int)(remainder) > 0) /*&& ( (tag->real_size - remainder) >= (1<<MINEXP))*/ )
+		{
+			int childIndex = getexp( remainder );
+	
+			if ( childIndex >= 0 )
+			{
+				#ifdef DEBUG
+				printf("Seems to be splittable: %i >= 2^%i .. %i\n", remainder, childIndex, (1<<childIndex) );
+				#endif
+
+				struct boundary_tag *new_tag = split_tag( tag ); 
+
+        (void)new_tag;
+
+				#ifdef DEBUG
+				printf("Old tag has become %i bytes, new tag is now %i bytes (%i exp)\n", tag->real_size, new_tag->real_size, new_tag->index );
+				#endif
+			}	
+		}
+		
+		
+
+	ptr = (void*)((uintptr_t)tag + sizeof( struct boundary_tag ) );
+
+
+	
+	#ifdef DEBUG
+	l_inuse += size;
+	printf("malloc: %x,  %i, %i\n", ptr, (int)l_inuse / 1024, (int)l_allocated / 1024 );
+	dump_array();
+	#endif
+
+
+	liballoc_unlock();
+	return ptr;
+}
+
+
+
+
+
+void free(void *ptr)
+{
+	int index;
+	struct boundary_tag *tag;
+
+	if ( ptr == NULL ) return;
+
+	liballoc_lock();
+	
+
+		tag = (struct boundary_tag*)((uintptr_t)ptr - sizeof( struct boundary_tag ));
+	
+		if ( tag->magic != LIBALLOC_MAGIC ) 
+		{
+			liballoc_unlock();		// release the lock
+			return;
+		}
+
+
+
+		#ifdef DEBUG
+		l_inuse -= tag->size;
+		printf("free: %x, %i, %i\n", ptr, (int)l_inuse / 1024, (int)l_allocated / 1024 );
+		#endif
+		
+
+		// MELT LEFT...
+		while ( (tag->split_left != NULL) && (tag->split_left->index >= 0) )
+		{
+			#ifdef DEBUG
+			printf("Melting tag left into available memory. Left was %i, becomes %i (%i)\n", tag->split_left->real_size, tag->split_left->real_size + tag->real_size, tag->split_left->real_size );
+			#endif
+			tag = melt_left( tag );
+			remove_tag( tag );
+		}
+
+		// MELT RIGHT...
+		while ( (tag->split_right != NULL) && (tag->split_right->index >= 0) )
+		{
+			#ifdef DEBUG
+			printf("Melting tag right into available memory. This was was %i, becomes %i (%i)\n", tag->real_size, tag->split_right->real_size + tag->real_size, tag->split_right->real_size );
+			#endif
+			tag = absorb_right( tag );
+		}
+
+		
+		// Where is it going back to?
+		index = getexp( tag->real_size - sizeof(struct boundary_tag) );
+		if ( index < MINEXP ) index = MINEXP;
+		
+		// A whole, empty block?
+		if ( (tag->split_left == NULL) && (tag->split_right == NULL) )
+		{	
+
+			if ( l_completePages[ index ] == MAXCOMPLETE )
+			{
+				// Too many standing by to keep. Free this one.
+				unsigned int pages = tag->real_size / l_pageSize;
+
+				if ( (tag->real_size % l_pageSize) != 0 ) pages += 1;
+				if ( pages < (unsigned int)l_pageCount ) pages = l_pageCount;
+
+				liballoc_free( tag, pages );
+
+				#ifdef DEBUG
+				l_allocated -= pages * l_pageSize;
+				printf("Resource freeing %x of %i pages\n", tag, pages );
+				dump_array();
+				#endif
+
+				liballoc_unlock();
+				return;
+			}
+
+
+			l_completePages[ index ] += 1;	// Increase the count of complete pages.
+		}
+
+
+		// ..........
+
+
+		insert_tag( tag, index );
+
+	#ifdef DEBUG
+	printf("Returning tag with %i bytes (requested %i bytes), which has exponent: %i\n", tag->real_size, tag->size, index ); 
+	dump_array();
+	#endif
+
+	liballoc_unlock();
+}
+
+
+
+
+void* calloc(size_t nobj, size_t size)
+{
+       int real_size;
+       void *p;
+
+       real_size = nobj * size;
+       
+       p = malloc( real_size );
+
+       liballoc_memset( p, 0, real_size );
+
+       return p;
+}
+
+
+
+void*   realloc(void *p, size_t size)
+{
+	void *ptr;
+	struct boundary_tag *tag;
+	int real_size;
+	
+	if ( size == 0 )
+	{
+		free( p );
+		return NULL;
+	}
+	if ( p == NULL ) return malloc( size );
+
+	if ( &liballoc_lock != NULL ) liballoc_lock();		// lockit
+		tag = (struct boundary_tag*)((uintptr_t)p - sizeof( struct boundary_tag ));
+		real_size = tag->size;
+	if ( &liballoc_unlock != NULL ) liballoc_unlock();
+
+	if ( (size_t)real_size > size ) real_size = size;
+
+	ptr = malloc( size );
+	liballoc_memcpy( ptr, p, real_size );
+	free( p );
+
+	return ptr;
+}
+
+
+

kernel/mm/liballoc.h

@@ -0,0 +1,99 @@
+#ifndef _LIBALLOC_H
+#define _LIBALLOC_H
+
+#include <libk/std.h>
+
+// If we are told to not define our own size_t, then we
+// skip the define.
+#ifndef _ALLOC_SKIP_DEFINE
+
+#ifndef _HAVE_SIZE_T
+#define _HAVE_SIZE_T
+typedef	unsigned int	size_t;
+#endif
+
+
+#ifndef	NULL
+#define NULL		0
+#endif
+
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/** This is a boundary tag which is prepended to the
+ * page or section of a page which we have allocated. It is
+ * used to identify valid memory blocks that the
+ * application is trying to free.
+ */
+struct	boundary_tag
+{
+	unsigned int magic;			//< It's a kind of ...
+	unsigned int size; 			//< Requested size.
+	unsigned int real_size;		//< Actual size.
+	int index;					//< Location in the page table.
+
+	struct boundary_tag *split_left;	//< Linked-list info for broken pages.	
+	struct boundary_tag *split_right;	//< The same.
+	
+	struct boundary_tag *next;	//< Linked list info.
+	struct boundary_tag *prev;	//< Linked list info.
+};
+
+
+ 
+
+/** This function is supposed to lock the memory data structures. It
+ * could be as simple as disabling interrupts or acquiring a spinlock.
+ * It's up to you to decide. 
+ *
+ * \return 0 if the lock was acquired successfully. Anything else is
+ * failure.
+ */
+extern int liballoc_lock();
+
+/** This function unlocks what was previously locked by the liballoc_lock
+ * function.  If it disabled interrupts, it enables interrupts. If it
+ * had acquiried a spinlock, it releases the spinlock. etc.
+ *
+ * \return 0 if the lock was successfully released.
+ */
+extern int liballoc_unlock();
+
+/** This is the hook into the local system which allocates pages. It
+ * accepts an integer parameter which is the number of pages
+ * required.  The page size was set up in the liballoc_init function.
+ *
+ * \return NULL if the pages were not allocated.
+ * \return A pointer to the allocated memory.
+ */
+extern void* liballoc_alloc(int);
+
+/** This frees previously allocated memory. The void* parameter passed
+ * to the function is the exact same value returned from a previous
+ * liballoc_alloc call.
+ *
+ * The integer value is the number of pages to free.
+ *
+ * \return 0 if the memory was successfully freed.
+ */
+extern int liballoc_free(void*,int);
+
+       
+
+void     *malloc(size_t);				//< The standard function.
+void     *realloc(void *, size_t);		//< The standard function.
+void     *calloc(size_t, size_t);		//< The standard function.
+void      free(void *);					//< The standard function.
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+

kernel/mm/pmm.c

@@ -0,0 +1,151 @@
+#include <libk/std.h>
+#include <libk/bm.h>
+#include <libk/string.h>
+#include <libk/align.h>
+#include <sys/mm.h>
+#include <sys/debug.h>
+#include <sync/spin_lock.h>
+#include <mm/types.h>
+#include <mm/pmm.h>
+#include <limine/limine.h>
+#include <limine/requests.h>
+
+static struct pmm pmm;
+
+void pmm_init(void) {
+  memset(&pmm, 0, sizeof(pmm));
+
+  struct limine_memmap_response *memmap = limine_memmap_request.response;
+  struct limine_hhdm_response *hhdm = limine_hhdm_request.response;
+
+  size_t region = 0;
+  for (size_t i = 0; i < memmap->entry_count; i++) {
+    struct limine_memmap_entry *entry = memmap->entries[i];
+    static const char *entry_strings[] = {
+      "usable", "reserved", "acpi reclaimable", "acpi nvs",
+      "bad memory", "bootloader reclaimable", "executable and modules",
+      "framebuffer", "acpi tables"
+    };
+
+    DEBUG("memmap entry: %-25s %p (%zu bytes)\n", entry_strings[entry->type], entry->base, entry->length);
+
+    if (entry->type == LIMINE_MEMMAP_USABLE && region < PMM_REGIONS_MAX) {
+      struct pmm_region *pmm_region = &pmm.regions[region];
+
+      /*
+       * We need to calculate sizes for the pmm region and the bitmap. The bitmap MUSTN'T include it's
+       * own region within the bit range.
+       * */
+
+      size_t size = align_down(entry->length, PAGE_SIZE);
+      physaddr_t start = align_up(entry->base, PAGE_SIZE);
+
+      size_t max_pages = (size * 8) / (PAGE_SIZE * 8 + 1);
+
+      size_t bm_nbits = max_pages;
+      size_t bm_size = align_up(bm_nbits, 8) / 8;
+
+      physaddr_t bm_base = start;
+      physaddr_t data_base = align_up(bm_base + bm_size, PAGE_SIZE);
+
+      if (bm_base + bm_size >= start + size)
+        continue;
+
+      size_t available = (start + size) - data_base;
+
+      size_t final_pages = available / PAGE_SIZE;
+
+      if (final_pages < max_pages) {
+        bm_nbits = final_pages;
+        bm_size = align_up(bm_nbits, 8) / 8;
+        data_base = align_up(bm_base + bm_size, PAGE_SIZE);
+      }
+
+      size_t managed_size = final_pages * PAGE_SIZE;
+
+      uint8_t *bm_base1 = (uint8_t *)(bm_base + hhdm->offset);
+
+      /* Init the pm region. */
+      pmm_region->lock = SPIN_LOCK_INIT;
+      pmm_region->membase = data_base;
+      pmm_region->size = managed_size;
+      bm_init(&pmm_region->bm, bm_base1, bm_nbits);
+      bm_clear_region(&pmm_region->bm, 0, bm_nbits);
+      pmm_region->flags |= PMM_REGION_ACTIVE; /* mark as active */
+      
+      region++;
+    }
+  }
+}
+
+/*
+ * Find free space for a block range. For every bit of the bitmap, we test nblks bits forward.
+ * bm_test_region helps us out, because it automatically does range checks. See comments there.
+ */
+static size_t pmm_find_free_space(struct pmm_region *pmm_region, size_t nblks) {
+  for (size_t bit = 0; bit < pmm_region->bm.nbits; bit++) {
+    if (bm_test_region(&pmm_region->bm, bit, nblks)) {
+      continue;
+    }
+
+    return bit;
+  }
+
+  return (size_t)-1;
+}
+
+physaddr_t pmm_alloc(size_t nblks) {
+  for (size_t region = 0; region < PMM_REGIONS_MAX; region++) {
+    struct pmm_region *pmm_region = &pmm.regions[region];
+
+    /* Inactive region, so don't bother with it. */
+    if (!(pmm_region->flags & PMM_REGION_ACTIVE))
+      continue;
+
+    spin_lock(&pmm_region->lock);
+
+    /* Find starting bit of the free bit range */
+    size_t bit = pmm_find_free_space(pmm_region, nblks);
+
+    /* Found a free range? */
+    if (bit != (size_t)-1) {
+      /* Mark it */
+      bm_set_region(&pmm_region->bm, bit, nblks);
+      spin_unlock(&pmm_region->lock);
+
+      return pmm_region->membase + bit * PAGE_SIZE;
+    }
+
+    spin_unlock(&pmm_region->lock);
+  }
+
+  return PMM_ALLOC_ERR;
+}
+
+void pmm_free(physaddr_t p_addr, size_t nblks) {
+  /* Round down to nearest page boundary */
+  physaddr_t aligned_p_addr = align_down(p_addr, PAGE_SIZE);
+
+  for (size_t region = 0; region < PMM_REGIONS_MAX; region++) {
+    struct pmm_region *pmm_region = &pmm.regions[region];
+
+    /* Inactive region, so don't bother with it. */
+    if (!(pmm_region->flags & PMM_REGION_ACTIVE))
+      continue;
+
+    /* If aligned_p_addr is within the range if this region, it belongs to it. */
+    if (aligned_p_addr >= pmm_region->membase && aligned_p_addr < pmm_region->size) {
+      physaddr_t addr = aligned_p_addr - pmm_region->membase;
+
+      size_t bit = div_align_up(addr, PAGE_SIZE);
+
+      spin_lock(&pmm_region->lock);
+      
+      bm_clear_region(&pmm_region->bm, bit, nblks);
+
+      spin_unlock(&pmm_region->lock);
+
+      break;
+    }
+  }
+}

kernel/mm/pmm.h

@@ -0,0 +1,31 @@
+#ifndef _KERNEL_MM_PMM_H
+#define _KERNEL_MM_PMM_H
+
+#include <libk/std.h>
+#include <libk/bm.h>
+#include <sync/spin_lock.h>
+#include <mm/types.h>
+
+#define PMM_ALLOC_ERR ((physaddr_t)-1)
+
+#define PMM_REGIONS_MAX 32
+
+#define PMM_REGION_ACTIVE     (1 << 0)
+
+struct pmm_region {
+  spin_lock_t lock;
+  struct bm bm;
+  physaddr_t membase;
+  size_t size;
+  uint32_t flags;
+};
+
+struct pmm {
+  struct pmm_region regions[PMM_REGIONS_MAX];
+};
+
+void pmm_init(void);
+physaddr_t pmm_alloc(size_t nblks);
+void pmm_free(physaddr_t p_addr, size_t nblks);
+
+#endif // _KERNEL_MM_PMM_H

kernel/mm/src.mk

@@ -0,0 +1,5 @@
+c += mm/pmm.c \
+		 mm/liballoc.c
+
+o += mm/pmm.o \
+		 mm/liballoc.o

kernel/mm/types.h

@@ -0,0 +1,8 @@
+#ifndef _KERNEL_MM_TYPES_H
+#define _KERNEL_MM_TYPES_H
+
+#include <libk/std.h>
+
+typedef uintptr_t physaddr_t;
+
+#endif // _KERNEL_MM_TYPES_H

kernel/src.mk

@@ -0,0 +1,5 @@
+include $(platform)/src.mk
+include libk/src.mk
+include sync/src.mk
+include mm/src.mk
+include limine/src.mk

kernel/sync/.gitignore

@@ -0,0 +1 @@
+*.o

kernel/sync/spin_lock.c

@@ -0,0 +1,12 @@
+#include <libk/std.h>
+#include <sys/spin_lock.h>
+#include <sync/spin_lock.h>
+
+void spin_lock(spin_lock_t *sl) {
+  while (atomic_flag_test_and_set_explicit(sl, memory_order_acquire))
+    spin_lock_relax();
+}
+
+void spin_unlock(spin_lock_t *sl) {
+  atomic_flag_clear_explicit(sl, memory_order_release);
+}

kernel/sync/spin_lock.h

@@ -0,0 +1,13 @@
+#ifndef _KERNEL_SYNC_SPIN_LOCK_H
+#define _KERNEL_SYNC_SPIN_LOCK_H
+
+#include <libk/std.h>
+
+#define SPIN_LOCK_INIT  ATOMIC_FLAG_INIT
+
+typedef atomic_flag spin_lock_t;
+
+void spin_lock(spin_lock_t *sl);
+void spin_unlock(spin_lock_t *sl);
+
+#endif // _KERNEL_SYNC_SPIN_LOCK_H

kernel/sync/src.mk

@@ -0,0 +1,3 @@
+c += sync/spin_lock.c
+
+o += sync/spin_lock.o

kernel/sys/debug.h

@@ -4,7 +4,7 @@
 void debugprintf(const char *fmt, ...);
 
 #define DEBUG(fmt, ...) do {                                      \
-    debugprintf("%s: " fmt, __PRETTY_FUNCTION__, ##__VA_ARGS__);  \
+    debugprintf("%s: " fmt, __func__, ##__VA_ARGS__);  \
   } while(0)
 
 #endif // _KERNEL_SYS_DEBUG_H

kernel/sys/mm.h

@@ -0,0 +1,8 @@
+#ifndef _KERNEL_SYS_MM_H
+#define _KERNEL_SYS_MM_H
+
+#if defined(__x86_64__)
+  #include <amd64/mm.h>
+#endif
+
+#endif // _KERNEL_SYS_MM_H

kernel/sys/spin_lock.h

@@ -0,0 +1,6 @@
+#ifndef _KERNEL_SYS_SPIN_LOCK_H
+#define _KERNEL_SYS_SPIN_LOCK_H
+
+void spin_lock_relax(void);
+
+#endif // _KERNEL_SYS_SPIN_LOCK_H