Physical memory manager

src/kernel/entry.asm

@@ -26,6 +26,7 @@ call_kmain:
     ; Enable interrupts
     sti
     ; Call kernel
+    push ebx ; pointer to multiboot info
     call kmain
     ; If on qemu, shutdown
     push 0x2000

src/kernel/lib/memory.c

@@ -1,27 +1,10 @@
-#include <stdbool.h>
-#include <stdint.h>
 #include "memory.h"
 
-static void *g_free_memory = ALLOC_START;
-
-void *kmalloc(size_t size){
-    void *ptr = g_free_memory;
-    g_free_memory += size;
-    return ptr;
+void memset(void *s, uint8_t c, size_t n){
+    uint8_t *p = s;
+    while(n--) *(p++) = c;
 }
 
-void *kcalloc(size_t count, size_t size){
-    void *ptr = g_free_memory;
-    size *= count;
-    g_free_memory += size;
-    for(int i = 0; i < size; i++){
-        ((uint8_t *)ptr)[i] = 0;
-    }
-    return ptr;
-}
-
-void memcpy(uint8_t *source, uint8_t *dest, size_t count){
-    for(size_t i = 0; i < count; i++){
-        dest[i] = source[i];
-    }
+void memcpy(void *dest, void *src, size_t n){
+    while(n--) ((uint8_t *)dest)[n] = ((uint8_t *)src)[n];
 }

src/kernel/lib/memory.h

@@ -3,10 +3,5 @@
 #include <stddef.h>
 #include <stdint.h>
 
-#define ALLOC_START (void *)0x1000
-
-void *kmalloc(size_t size);
-// TODO: void kfree(void *ptr);
-void *kcalloc(size_t count, size_t size);
-
-void memcpy(uint8_t *source, uint8_t *dest, size_t count);
+void memset(void *ptr, uint8_t val, size_t n);
+void memcpy(void *dest, void *src, size_t n);

src/kernel/main.c

@@ -5,14 +5,34 @@
 #include "drivers/keyboard.h"
 #include "drivers/serial.h"
 #include "fs/vfs.h"
+#include "mm/pmm.h"
+#include "multiboot.h"
 
-void __attribute__((cdecl)) kmain(uint64_t magic, uint64_t addr){
+extern uint8_t end; // Kernel end
+
+void __attribute__((cdecl)) kmain(multiboot_info_t *multiboot_info){
     // Clear screen
     clear_screen();
 
     // Initialize chip-specific hardware
     hal_initialize();
 
+    // Initialize physical memory manager
+    uint32_t mem_size = 1024 + multiboot_info->mem_lower + multiboot_info->mem_upper*64;
+
+    pmm_initialize(mem_size, (int)(&end));
+
+    for(int i = 0; i < multiboot_info->mmap_length; i += sizeof(multiboot_memory_map_t)){
+        multiboot_memory_map_t *memory_map = (multiboot_memory_map_t *)(multiboot_info->mmap_addr + i);
+        printf("Start Addr: 0x%x%x | Length: 0x%x%x | Size: 0x%x | Type: %i\n", memory_map->addr_h, memory_map->addr_l, memory_map->len_h, memory_map->len_l, memory_map->size, memory_map->type);
+    
+        if(memory_map->type == 1){
+            pmm_init_region(memory_map->addr_l, memory_map->len_l);
+        }
+    }
+
+    pmm_deinit_region(0x100000, (int)(&end) - 0x100000); // Deinit the section the kernel is in
+
     // Initialize drivers
     timer_initialize();
     keyboard_initialize();
@@ -20,5 +40,11 @@ void __attribute__((cdecl)) kmain(uint64_t magic, uint64_t addr){
     // Initialize FS
     vfs_initialize();
 
+    // PMM test code
+    uint32_t *p1 = (uint32_t *)pmm_alloc_block();
+    printf("Allocated p1 at: 0x%x\n", p1);
+    uint32_t *p2 = (uint32_t *)pmm_alloc_block();
+    printf("Allocated p2 at: 0x%x\n", p2);
+    
     for(;;);
 }

src/kernel/mm/pmm.c

@@ -0,0 +1,153 @@
+#include <stdint.h>
+#include "pmm.h"
+#include "../lib/memory.h"
+
+static uint32_t g_pmm_memory_size = 0;
+static uint32_t g_pmm_used_blocks = 0;
+static uint32_t g_pmm_max_blocks = 0;
+static uint32_t *g_pmm_memory_map = 0;
+
+static inline void pmm_map_set(int bit){
+    g_pmm_memory_map[bit / 32] |= (1 << (bit % 32));
+}
+
+static inline void pmm_map_unset(int bit){
+    g_pmm_memory_map[bit / 32] &= ~(1 << (bit % 32));
+}
+
+static inline bool pmm_map_get(int bit){
+    return g_pmm_memory_map[bit / 32] & (1 << (bit % 32));
+}
+
+int pmm_map_first_free(){
+    for(uint32_t i = 0; i < pmm_get_block_count() / 32; i++){
+        if(g_pmm_memory_map[i] != 0xffffffff){
+            for(int j = 0; j < 32; j++){
+                if(!(g_pmm_memory_map[i] & (1 << j))){
+                    return i*4*8+j;
+                }
+            }
+        }
+    }
+    return -1;
+}
+
+int pmm_map_first_free_s(size_t size){
+    if(size == 0) return -1;
+    if(size == 1) return pmm_map_first_free();
+
+    for(uint32_t i = 0; i < pmm_get_block_count() / 32; i++){
+        if(g_pmm_memory_map[i] != 0xffffffff){
+            for(int j = 0; j < 32; j++){
+                int bit = 1 << j;
+                if(!(g_pmm_memory_map[i] & bit)){
+                    int start_bit = i*32;
+                    start_bit+=bit;
+
+                    uint32_t free = 0;
+                    for(uint32_t count = 0; count <= size; count++){
+                        if(!pmm_map_get(start_bit+count)) free++;
+                        if(free == size) return i*4*8+j;
+                    }
+                }
+            }
+        }
+    }
+    return -1;
+}
+
+void pmm_initialize(size_t mem_size, phys_addr bitmap){
+    g_pmm_memory_size = mem_size;
+    g_pmm_memory_map = (uint32_t *)bitmap;
+    g_pmm_max_blocks = (pmm_get_memory_size()*1024) / PMM_BLOCK_SIZE;
+    g_pmm_used_blocks = g_pmm_max_blocks;
+
+    // FIXME
+    memset(g_pmm_memory_map, 0xFF, pmm_get_block_count() / PMM_BLOCKS_PER_BYTE);
+}
+
+void pmm_init_region(phys_addr base, size_t size){
+    int align = base / PMM_BLOCK_SIZE;
+    int blocks = size / PMM_BLOCK_SIZE;
+
+    for(; blocks >= 0; blocks--){
+        pmm_map_unset(align++);
+        g_pmm_used_blocks--;
+    }
+
+    pmm_map_set(0); // First block always set
+}
+
+void pmm_deinit_region(phys_addr base, size_t size){
+    int align = base / PMM_BLOCK_SIZE;
+    int blocks = size / PMM_BLOCK_SIZE;
+
+    for(; blocks >= 0; blocks--){
+        pmm_map_set(align++);
+        g_pmm_used_blocks++;
+    }
+
+    pmm_map_set(0); // First block always set
+}
+
+void *pmm_alloc_block(){
+    if(pmm_get_free_block_count() <= 0) return 0; // Out of memory
+
+    int frame = pmm_map_first_free();
+    if(frame == -1) return 0; // Out of memory
+
+    pmm_map_set(frame);
+
+    phys_addr addr = frame * PMM_BLOCK_SIZE;
+    g_pmm_used_blocks++;
+    
+    return (void *)addr;
+}
+
+void pmm_free_block(void *p){
+    phys_addr addr = (phys_addr)p;
+    int frame = addr / PMM_BLOCK_SIZE;
+
+    pmm_map_unset(frame);
+
+    g_pmm_used_blocks--;
+}
+
+void *pmm_alloc_blocks(size_t size){
+    if(pmm_get_free_block_count() <= size) return 0; // Out of memory
+
+    int frame = pmm_map_first_free_s(size);
+    if(frame == -1) return 0; // Out of memory
+
+    for(uint32_t i = 0; i < size; i++) pmm_map_set(frame+i);
+
+    phys_addr addr = frame * PMM_BLOCK_SIZE;
+    g_pmm_used_blocks += size;
+    
+    return (void *)addr;
+}
+
+void pmm_free_blocks(void *p, size_t size){
+    phys_addr addr = (phys_addr)p;
+    int frame = addr / PMM_BLOCK_SIZE;
+
+    for(uint32_t i = 0; i < size; i++) pmm_map_unset(frame+i);
+
+    g_pmm_used_blocks -= size;
+}
+
+size_t pmm_get_memory_size(){
+    return g_pmm_memory_size;
+}
+
+uint32_t pmm_get_block_count(){
+    return g_pmm_max_blocks;
+}
+
+uint32_t pmm_get_used_block_count(){
+    return g_pmm_used_blocks;
+}
+
+uint32_t pmm_get_free_block_count(){
+    return g_pmm_max_blocks - g_pmm_used_blocks;
+}

src/kernel/mm/pmm.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+
+#define PMM_BLOCKS_PER_BYTE 8
+#define PMM_BLOCK_SIZE 4096
+#define PMM_BLOCK_ALIGN PMM_BLOCK_SIZE
+
+typedef uint32_t phys_addr;
+
+int pmm_map_first_free();
+int pmm_map_first_free_s(size_t size);
+void pmm_initialize(size_t mem_size, phys_addr bitmap);
+void pmm_init_region(phys_addr base, size_t size);
+void pmm_deinit_region(phys_addr base, size_t size);
+void *pmm_alloc_block();
+void pmm_free_block(void *p);
+void *pmm_alloc_blocks(size_t size);
+void pmm_free_blocks(void *p, size_t size);
+size_t pmm_get_memory_size();
+uint32_t pmm_get_block_count();
+uint32_t pmm_get_used_block_count();
+uint32_t pmm_get_free_block_count();

src/kernel/multiboot.h

@@ -0,0 +1,96 @@
+#pragma once
+
+#include <stdint.h>
+
+typedef struct{
+    uint32_t size;
+    uint32_t addr_l;
+    uint32_t addr_h;
+    uint32_t len_l;
+    uint32_t len_h;
+    uint32_t type;
+} __attribute__((packed)) multiboot_memory_map_t;
+
+typedef struct{
+    uint32_t tabsize;
+    uint32_t strsize;
+    uint32_t addr;
+    uint32_t reserved;
+} multiboot_aout_symbol_table_t;
+
+typedef struct{
+    uint32_t num;
+    uint32_t size;
+    uint32_t addr;
+    uint32_t shndx;
+} multiboot_elf_section_header_table_t;
+
+typedef struct{
+    /* Multiboot info version number */
+    uint32_t flags;
+
+    /* Available memory from BIOS */
+    uint32_t mem_lower;
+    uint32_t mem_upper;
+
+    /* "root" partition */
+    uint32_t boot_device;
+
+    /* Kernel command line */
+    uint32_t cmdline;
+
+    /* Boot-Module list */
+    uint32_t mods_count;
+    uint32_t mods_addr;
+
+    union{
+        multiboot_aout_symbol_table_t aout_sym;
+        multiboot_elf_section_header_table_t elf_sec;
+    } u;
+
+    /* Memory Mapping buffer */
+    uint32_t mmap_length;
+    uint32_t mmap_addr;
+
+    /* Drive Info buffer */
+    uint32_t drives_length;
+    uint32_t drives_addr;
+
+    /* ROM configuration table */
+    uint32_t config_table;
+
+    /* Boot Loader Name */
+    uint32_t boot_loader_name;
+
+    /* APM table */
+    uint32_t apm_table;
+
+    /* Video */
+    uint32_t vbe_control_info;
+    uint32_t vbe_mode_info;
+    uint16_t vbe_mode;
+    uint16_t vbe_interface_seg;
+    uint16_t vbe_interface_off;
+    uint16_t vbe_interface_len;
+
+    uint64_t framebuffer_addr; // FIXME: This may fail, as we are not in 64 bit (long) mode
+    uint32_t framebuffer_pitch;
+    uint32_t framebuffer_width;
+    uint32_t framebuffer_height;
+    uint8_t framebuffer_bpp;
+    uint8_t framebuffer_type;
+    union{
+        struct{
+            uint32_t framebuffer_palette_addr;
+            uint16_t framebuffer_palette_num_colors;
+        };
+        struct{
+            uint8_t framebuffer_red_field_position;
+            uint8_t framebuffer_red_mask_size;
+            uint8_t framebuffer_green_field_position;
+            uint8_t framebuffer_green_mask_size;
+            uint8_t framebuffer_blue_field_position;
+            uint8_t framebuffer_blue_mask_size;
+        };
+    };
+} __attribute__((packed)) multiboot_info_t;

src/kernel/shell.c

@@ -14,12 +14,6 @@ int shell_run(char *cmd){
     else if(!strcmp(cmd, "version")){
         printf("%s\n", OS_VERSION);
     }
-    else if(!strcmp(cmd, "malloc")){
-        printf("Allocated 10 bytes:\n%x\n", kmalloc(10));
-    }
-    else if(!strcmp(cmd, "calloc")){
-        printf("Allocated and zeroed 10 chars:\n%x\n", kcalloc(10, sizeof(char)));
-    }
     else if(!strcmp(cmd, "clear")){
         clear_screen();
     }