Celina's Git — CeDOS: 66ec18e54a0a707bfcd5dfd72f2b534985fac007

memory: Move to common The memory allocation algorithm can be used for kernel and user processes alike. To avoid code duplication, we move the code to common to reuse it in libcedos. To this end, we make the start and end addresses of the allocatable memory region flexible and set them as arguments in malloc_init.

Celina Sophie Kalus

hello@celinakalus.de

Wed, 29 Nov 2023 14:47:51 +0100

commit 66ec18e54a0a707bfcd5dfd72f2b534985fac007

parent f4e78a67b334d08f8c26bbe2496a8ee36ae04af6

11 files changed, 93 insertions(+), 59 deletions(-)

jump to

common/memory.h

kernel/drivers/ps2_keyboard.c

kernel/elf.c

kernel/fat.c

kernel/file.c

kernel/main.c

common/memory.c

kernel/sched/sched.c

libcedos/start.c

libcedos/stdlib.h

A common/memory.h

@@ -0,0 +1,34 @@
+/*! \file
+ * Provides functions for memory allocation.
+ */
+#ifndef MEMORY_H
+#define MEMORY_H
+
+#include <stdint.h>
+
+typedef uint32_t size_t;
+
+#define NULL (void*)(0)
+
+/*!
+ * Initialize memory allocator with predefined memory region.
+ * \param start Start of malloc memory region.
+ * \param end End of malloc memory region.
+ * \return Currently always 0.
+ */
+int malloc_init(void *start, void *end);
+
+/*!
+ * Allocates a block of \p size bytes of memory.
+ * \param size Size in bytes of the requested block of memory.
+ * \return Memory address to the new memory block
+ */
+void* malloc(size_t size);
+
+/*!
+ * Frees a previously allocated block of memory.
+ * \param ptr Pointer to the memory block to be freed.
+ */
+void free(void* ptr);
+
+#endif

M kernel/drivers/ps2_keyboard.c → kernel/drivers/ps2_keyboard.c

@@ -3,7 +3,7 @@ #include "interrupts.h"
 #include "pic.h"
 #include "core.h"
 #include "sched/sched.h"
-#include "mm/memory.h"
+#include "memory.h"
 #include "assembly.h"
 
 #define PS2_DATA				0x60
@@ -83,7 +83,7 @@ int ps2_kb_init(void) {
     buffer_head = 0;
     buffer_tail = 0;
 
-    buffer = os_kernel_malloc(BUFFER_LENGTH);
+    buffer = malloc(BUFFER_LENGTH);
 
     // clear incoming data
     inb(PS2_DATA);

M kernel/elf.c → kernel/elf.c

@@ -5,7 +5,7 @@
 #include "file.h"
 #include "sched/process.h"
 
-#include "mm/memory.h"
+#include "memory.h"
 
 #include "assert.h"
 
@@ -175,7 +175,7 @@ int section_size = header.sh_entry_size;
 
     SECT_HEADER *sect_names_sh = &sect_headers[header.sh_strndx];
     
-    char *sect_names = os_kernel_malloc(sect_names_sh->size);
+    char *sect_names = malloc(sect_names_sh->size);
 
     if (sect_names == NULL) {
         printk("Error while starting executable: Memory allocation failed.\n");

M kernel/fat.c → kernel/fat.c

@@ -4,7 +4,7 @@ #include "string.h"
 #include "assert.h"
 #include "core.h"
 
-#include "mm/memory.h"
+#include "memory.h"
 
 #include <stdint.h>
 
@@ -85,7 +85,7 @@ long root_dir_size = boot_sect->max_root_dir_entries * sizeof(DIR_ENTRY);
     data_lba = root_lba + (root_dir_size / boot_sect->bytes_per_sect);
     
     cluster_size = boot_sect->bytes_per_sect * boot_sect->sect_per_cluster;
-    cluster_buffer = os_kernel_malloc(cluster_size);
+    cluster_buffer = malloc(cluster_size);
 }
 
 void *FAT_read_sector_offset(uint32_t lba, uint32_t *offset) {

M kernel/file.c → kernel/file.c

@@ -5,7 +5,7 @@
 #include "drivers/tty.h"
 #include "core.h"
 
-#include "mm/memory.h"
+#include "memory.h"
 
 #include "sched/sched.h"
 #include "sched/process.h"
@@ -24,7 +24,7 @@
 int stdin, stdout, fat_root, pipe;
 
 int file_init() {
-    file_table = os_kernel_malloc(sizeof(file_t) * 512);
+    file_table = malloc(sizeof(file_t) * 512);
 
     file_table[next_free].fops = &tty_fops;
     file_table[next_free].stdio_id = 0;

M kernel/main.c → kernel/main.c

@@ -7,7 +7,7 @@ #include "sched/sched.h"
 #include "sched/process.h"
 
 #include "mm/paging.h"
-#include "mm/memory.h"
+#include "memory.h"
 
 #include "interrupts.h"
 #include "syscall.h"
@@ -56,7 +56,7 @@ sti();
     printk("done.\n");
 
     printk("Initiallizing malloc...");
-    malloc_init();
+    malloc_init(0xC0400000u, 0xC0800000u);
     printk("done.\n");
 
     printk("Installing syscalls...");

M kernel/mm/memory.c → common/memory.c

@@ -1,4 +1,4 @@
-#include "mm/memory.h"
+#include "memory.h"
 
 #include "assert.h"
 
@@ -9,9 +9,9 @@ };
 
 volatile struct memblock volatile *malloc_first, *malloc_last, *malloc_next_free;
 
-int malloc_init() {
-    uint32_t mem_start = 0xC0400000u;
-    uint32_t mem_end = 0xC0800000u;
+int malloc_init(void *start, void *end) {
+    uint32_t mem_start = (uint32_t)(start);
+    uint32_t mem_end = (uint32_t)(end);
 
     malloc_first = (volatile struct memblock*)(mem_start);
     malloc_last = (volatile struct memblock*)(mem_end - sizeof(struct memblock));
@@ -22,6 +22,8 @@ malloc_first->next = malloc_last;
 
     malloc_last->size = 0;
     malloc_last->next = NULL;
+
+    return 0;
 }
 
 /*!
@@ -29,7 +31,7 @@ * Allocates a block of \p size bytes of memory. (KERNEL MODE)
  * \param size Size in bytes of the requested block of memory.
  * \return Memory address to the new memory block
  */
-void* os_kernel_malloc(size_t size) {
+void* malloc(size_t size) {
     // size == 0 means the block is free
     assert(malloc_next_free->size == 0);
 
@@ -61,7 +63,7 @@ /*!
  * Frees a previously allocated block of memory. (KERNEL MODE)
  * \param ptr Pointer to the memory block to be freed.
  */
-void os_kernel_free(void* ptr) {
+void free(void* ptr) {
     
 }

D kernel/mm/memory.h

@@ -1,41 +0,0 @@
-/*! \file
- * Provides functions for memory allocation.
- */
-#ifndef MEMORY_H
-#define MEMORY_H
-
-#include <stdint.h>
-
-typedef uint32_t size_t;
-
-#define NULL (void*)(0)
-
-int malloc_init();
-
-/*!
- * Allocates a block of \p size bytes of memory. (KERNEL MODE)
- * \param size Size in bytes of the requested block of memory.
- * \return Memory address to the new memory block
- */
-void* os_kernel_malloc(size_t size);
-
-/*!
- * Frees a previously allocated block of memory. (KERNEL MODE)
- * \param ptr Pointer to the memory block to be freed.
- */
-void os_kernel_free(void* ptr);
-
-/*!
- * Allocates a block of \p size bytes of memory. (USER MODE)
- * \param size Size in bytes of the requested block of memory.
- * \return Memory address to the new memory block
- */
-void* os_user_malloc(size_t size);
-
-/*!
- * Frees a previously allocated block of memory. (USER MODE)
- * \param ptr Pointer to the memory block to be freed.
- */
-void os_user_free(void* ptr);
-
-#endif

M kernel/sched/sched.c → kernel/sched/sched.c

@@ -3,7 +3,7 @@ #include "sched/process.h"
 #include "sched/sched_strats.h"
 
 #include "mm/paging.h"
-#include "mm/memory.h"
+#include "memory.h"
 
 #include "drivers/console.h"
 #include "drivers/speaker.h"
@@ -30,7 +30,7 @@ #define PRINT_DBG(...) {}
 #endif
 
 PROCESS* get_slot(void) {
-    PROCESS *new_process = (PROCESS*)os_kernel_malloc(sizeof(PROCESS));
+    PROCESS *new_process = (PROCESS*)malloc(sizeof(PROCESS));
     return new_process;
 }

M libcedos/start.c → libcedos/start.c

@@ -2,8 +2,12 @@ #include "assembly.h"
 
 #include <stdint.h>
 
+#include "memory.h"
+
 extern void main(char *args);
 
 int _start(char *args) {
+    malloc_init(0x20000000, 0x30000000);
+    
     main(args);
 }

A libcedos/stdlib.h

@@ -0,0 +1,35 @@
+/*! \file
+ * Provides functions for memory allocation.
+ */
+#ifndef MEMORY_H
+#define MEMORY_H
+
+#include <stdint.h>
+
+typedef uint32_t size_t;
+
+#define NULL (void*)(0)
+
+/*!
+ * Initialize memory allocator with predefined memory region.
+ * \param start Start of malloc memory region.
+ * \param end End of malloc memory region.
+ * \return Currently always 0.
+ */
+int malloc_init(void *start, void *end);
+
+/*!
+ * Allocates a block of \p size bytes of memory.
+ * \param size Size in bytes of the requested block of memory.
+ * \return Memory address to the new memory block
+ */
+void* malloc(size_t size);
+
+/*!
+ * Frees a previously allocated block of memory.
+ * \param ptr Pointer to the memory block to be freed.
+ */
+void free(void* ptr);
+
+
+#endif