feat: introduced tasking, added paging (no vm), moved malloc, added

syscalls, other stuff

CMakeLists.txt

@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.15)
 project(new_kernel C ASM)
 #set(CMAKE_VERBOSE_MAKEFILE ON)
-set(CMAKE_C_FLAGS "-I/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include -g -ffreestanding -Wall -Wextra -fno-exceptions -fno-stack-protector -nostdinc -nostdlib -fno-pie -m32")
+set(CMAKE_C_FLAGS "-I/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include -mno-sse -g -ffreestanding -Wall -Wextra -fno-exceptions -fno-stack-protector -nostdinc -nostdlib -fno-pie -m32")
 #set(CMAKE_ASM_NASM_OBJECT_FORMAT "elf")
 set(CMAKE_ASM_FLAGS --32)
 #set(CMAKE_ASM-ATT_FLAGS --32)

boot/boot.S

@@ -92,6 +92,11 @@ _start:
 	*/
 	cli
     lgdt (gdtr)
+    movw $0x10,%ax # kernel data segment descriptor
+    movw %ax,%ds
+    movw %ax,%es
+    movw %ax,%fs
+    movw %ax,%gs
     ljmp $0x8, $continue_boot
 
 continue_boot:

kernel/attributes.h

@@ -0,0 +1,16 @@
+//
+// Created by rick on 24-02-21.
+//
+
+#ifndef NEW_KERNEL_ATTRIBUTES_H
+#define NEW_KERNEL_ATTRIBUTES_H
+
+// function
+#define noreturn __attribute((noreturn))
+#define cdecl __attribute((cdecl))
+// structure
+#define packed __attribute((packed))
+// field
+#define at_aligned(size) __attribute((aligned(size)))
+
+#endif //NEW_KERNEL_ATTRIBUTES_H

kernel/command.c

@@ -0,0 +1,144 @@
+//
+// Created by rick on 23-02-21.
+//
+
+#include "command.h"
+#include "kprint.h"
+#include "libk.h"
+#include <types.h>
+#include <libc/kprintf.h>
+#include <stdbool.h>
+#include <libc/string.h>
+#include <mem/mem.h>
+#include <mem/malloc.h>
+#include <cpu/timer.h>
+#include <drivers/pci.h>
+#include <drivers/ide.h>
+#include <fs/blockdev.h>
+#include <fs/mbr.h>
+#include <libc/readline.h>
+#include <libc/libc.h>
+#include <attributes.h>
+
+#define BOOTLOADER_NAME_MAX_LENGTH 64
+#define CMDLINE_MAX_LENGTH 256
+
+char bootloader_name[BOOTLOADER_NAME_MAX_LENGTH];
+char cmdline[CMDLINE_MAX_LENGTH];
+
+typedef void (*cmd_handler_func)(const char *);
+
+typedef struct {
+    char *cmd;
+    cmd_handler_func handler;
+} cmd_handler;
+
+void print(const char *arg);
+
+void ide(const char *arg);
+
+void echo(const char *arg);
+
+void help(const char *arg);
+
+cmd_handler cmd_handlers[] = {
+        {"help",  help},
+        {"echo",  echo},
+        {"print", print},
+        {"ide",   ide},
+        {NULL, NULL},
+};
+
+void print_bootinfo() {
+    printf("Bootloader name: %s\n"
+           "cmdline: %s\n",
+           (bootloader_name[0] == 0 ? "NULL" : bootloader_name),
+           (cmdline[0] == 0 ? "NULL" : cmdline));
+}
+
+
+void help(const char *arg) {
+    kprint("Available commands:\n");
+    int index = 0;
+    while (true) {
+        if (cmd_handlers[index].cmd == NULL) {
+            break;
+        }
+        printf("%s\n", cmd_handlers[index].cmd);
+        index += 1;
+    }
+
+}
+
+void echo(const char *arg) {
+    printf("%s\n", arg);
+}
+
+void print(const char *arg) {
+    if (strcmp(arg, "mmap") == 0) {
+        print_mmap_info();
+    } else if (strcmp(arg, "malloc") == 0) {
+        print_malloc_info();
+    } else if (strcmp(arg, "tick") == 0) {
+        print_current_tick();
+    } else if (strcmp(arg, "bootinfo") == 0) {
+        print_bootinfo();
+    } else if (strcmp(arg, "pci") == 0) {
+        pci_print_info();
+    } else if (strcmp(arg, "ide") == 0) {
+        ide_print_devices();
+    } else {
+        printf("Unknown print %s\n", arg);
+    }
+}
+
+void ide(const char *arg) {
+    if (strcmp(arg, "block_devices") == 0) {
+        block_dev_print_info();
+    } else if (strcmp(arg, "ide_devices") == 0) {
+        ide_print_devices();
+    } else if (strcmp(arg, "mbr") == 0) {
+        mbr_read_from_ide(0);
+    } else {
+        printf("Unknown print %s\n", arg);
+    }
+}
+
+void store_bootloader_info(multiboot_info_t *multiboot_info) {
+    // get bootloader and cmdline
+    if (multiboot_info->flags & MULTIBOOT_INFO_CMDLINE) {
+        int cmdline_length = strlen((const char *) multiboot_info->cmdline);
+        if (cmdline_length > CMDLINE_MAX_LENGTH) {
+            k_panics("cmdline to long!\n");
+        }
+        memcpy(cmdline, (char *) multiboot_info->cmdline, cmdline_length);
+    }
+    if (multiboot_info->flags & MULTIBOOT_INFO_BOOT_LOADER_NAME) {
+        int bootloader_length = strlen((const char *) multiboot_info->boot_loader_name);
+        if (bootloader_length > BOOTLOADER_NAME_MAX_LENGTH) {
+            k_panics("bootloader name to long!\n");
+        }
+        memcpy(bootloader_name, (char *) multiboot_info->boot_loader_name, bootloader_length);
+    }
+}
+
+void noreturn main_loop(void* data) {
+    while (true) {
+        char *msg = readline(NULL);
+        char *args = strchr(msg, ' ') + 1;
+        args[-1] = 0;
+        int test_index = 0;
+        while (true) {
+            if (cmd_handlers[test_index].cmd == 0) {
+                printf("Unknown command: %s\n", msg);
+                break;
+            }
+            if (strcmp(cmd_handlers[test_index].cmd, msg) == 0) {
+                cmd_handlers[test_index].handler(args);
+                break;
+            }
+            test_index++;
+        }
+        free(msg);
+    }
+}

kernel/command.h

@@ -0,0 +1,14 @@
+//
+// Created by rick on 23-02-21.
+//
+
+#ifndef NEW_KERNEL_COMMAND_H
+#define NEW_KERNEL_COMMAND_H
+
+#include "multiboot.h"
+
+void store_bootloader_info(multiboot_info_t *multiboot_info);
+
+void main_loop(void* data);
+
+#endif //NEW_KERNEL_COMMAND_H

kernel/cpu/cpu.h

@@ -0,0 +1,20 @@
+//
+// Created by rick on 22-02-21.
+//
+
+#ifndef NEW_KERNEL_CPU_H
+#define NEW_KERNEL_CPU_H
+#include <types.h>
+
+typedef struct {
+    uint32_t edi, esi, ebx, ebp, eip;
+} task_registers_t;
+
+typedef struct {
+    uint32_t ds; // pushed in common handler
+    uint32_t edi, esi, ebp, esp, ebx, edx, ecx, eax; // pusha/popa
+    uint32_t int_no, err_code; // pushed by handlers
+    uint32_t eip, cs, eflags, useresp, ss; // isr/iret
+} isr_registers_t;
+
+#endif //NEW_KERNEL_CPU_H

kernel/cpu/cpuidx.c

@@ -4,3 +4,30 @@
 
 #include "cpuidx.h"
 
+#include <types.h>
+#include <cpuid.h>
+#include <libc/kprintf.h>
+
+union cpu_name {
+    uint32_t parts[3];
+    struct {
+        char name[12];
+        char end;
+    };
+};
+
+
+void cpuidx_print_info() {
+    union cpu_name name;
+    __get_cpuid(0, NULL, &name.parts[0], &name.parts[2], &name.parts[1]);
+    name.end = 0;
+    printf("CPU: %s\n", &name.name);
+
+    cpu_features_ecx features_ecx;
+    cpu_features_edx features_edx;
+    __get_cpuid(1, NULL, NULL, (uint32_t *) &features_ecx, (uint32_t *) &features_edx);
+
+    printf("");
+
+
+}

kernel/cpu/cpuidx.h

@@ -5,10 +5,76 @@
 #ifndef NEW_KERNEL_CPUIDX_H
 #define NEW_KERNEL_CPUIDX_H
 
-#include <cpuid.h>
+#include <stdbool.h>
-#include <stdint.h>
 
-enum {
+typedef struct {
+    bool sse3: 1;
+    bool pclmul: 1;
+    bool dtes64: 1;
+    bool monitor: 1;
+    bool ds_cpl: 1;
+    bool vmx: 1;
+    bool smx: 1;
+    bool est: 1;
+    bool tm2: 1;
+    bool ssse3: 1;
+    bool cid: 1;
+    bool reserved: 1;
+    bool fma: 1;
+    bool cx16: 1;
+    bool etprd: 1;
+    bool pdcm: 1;
+    bool pcide: 1;
+    bool dca: 1;
+    bool sse4_1: 1;
+    bool sse4_2: 1;
+    bool x2APIC: 1;
+    bool movbe: 1;
+    bool popcnt: 1;
+    bool reserved2: 1;
+    bool aes: 1;
+    bool xsave: 1;
+    bool osxsave: 1;
+    bool avx: 1;
+} cpu_features_ecx ;
+
+typedef struct {
+    bool fpu: 1;
+    bool vme: 1;
+    bool de: 1;
+    bool pse: 1;
+    bool tsc: 1;
+    bool msr: 1;
+    bool pae: 1;
+    bool mce: 1;
+    bool cx8: 1;
+    bool apic: 1;
+    bool reserved: 1;
+    bool sep: 1;
+    bool mtrr: 1;
+    bool pge: 1;
+    bool mca: 1;
+    bool cmov: 1;
+    bool pat: 1;
+    bool pse36: 1;
+    bool psn: 1;
+    bool clf: 1;
+    bool reserved2: 1;
+    bool dtes: 1;
+    bool acpi: 1;
+    bool mmx: 1;
+    bool fxsr: 1;
+    bool sse: 1;
+    bool sse2: 1;
+    bool ss: 1;
+    bool htt: 1;
+    bool tm1: 1;
+    bool ia64: 1;
+    bool pbe: 1;
+
+} cpu_features_edx ;
+
+enum cpu_features {
     CPUID_FEAT_ECX_SSE3 = 1 << 0,
     CPUID_FEAT_ECX_PCLMUL = 1 << 1,
     CPUID_FEAT_ECX_DTES64 = 1 << 2,
@@ -68,16 +134,6 @@ enum {
     CPUID_FEAT_EDX_PBE = 1 << 31
 };
 
-static inline void cpuid(int code, uint32_t *a, uint32_t *d) {
+void cpuidx_print_info();
-    asm volatile("cpuid":"=a"(*a), "=d"(*d):"a"(code):"ecx", "ebx");
-}
-
-/** issue a complete request, storing general registers output as a string
- */
-static inline int cpuid_string(int code, uint32_t where[4]) {
-    asm volatile("cpuid":"=a"(*where), "=b"(*(where + 1)),
-    "=c"(*(where + 2)), "=d"(*(where + 3)):"a"(code));
-    return (int) where[0];
-}
 
 #endif //NEW_KERNEL_CPUIDX_H

kernel/cpu/idt.h

@@ -5,6 +5,8 @@
 
 #ifndef MY_KERNEL_IDT_H
 #define MY_KERNEL_IDT_H
+#include <attributes.h>
+
 #define KERNEL_CS 0x08
 
 /* How every interrupt gate (handler) is defined */
@@ -19,12 +21,12 @@ typedef struct {
      * Bits 3-0: bits 1110 = decimal 14 = "32 bit interrupt gate" */
     uint8_t flags;
     uint16_t high_offset; /* Higher 16 bits of handler function address */
-} __attribute__((packed)) idt_gate_t;
+} packed idt_gate_t;
 
 typedef struct {
     uint16_t limit;
     uint32_t base;
-} __attribute__((packed)) idt_register_t;
+} packed idt_register_t;
 
 #define IDT_REGISTERS 256
 

kernel/cpu/interrupt.S

@@ -109,6 +109,8 @@ irq_common_stub:
 .global irq14
 .global irq15
 
+.global isr128
+
 # 0: Divide By Zero Exception
 isr0: 
     cli
@@ -424,3 +426,9 @@ irq15:
         push $47
         jmp irq_common_stub
 
+# Syscall
+isr128:
+    cli
+    push $0
+    push $128
+    jmp isr_common_stub

kernel/cpu/isr.c

@@ -5,9 +5,11 @@
 #include "isr.h"
 
 #include <cpu/idt.h>
+#include <cpu/syscall_handler.h>
 #include <libc/libc.h>
 #include <drivers/ports.h>
 #include <libc/kprintf.h>
+#include <libk.h>
 
 #define PIC_END_OF_INTERRUPT 0x20
 
@@ -48,6 +50,7 @@ void isr_install() {
     set_idt_gate(31, (uint32_t) isr31);
 
     // Remap the PIC
+    // todo make readable
     port_byte_out(0x20, 0x11);
     port_byte_out(0xA0, 0x11);
     port_byte_out(0x21, 0x20);
@@ -77,6 +80,8 @@ void isr_install() {
     set_idt_gate(46, (uint32_t) irq14);
     set_idt_gate(47, (uint32_t) irq15);
 
+    set_idt_gate(128, (uint32_t) isr128);
+
     set_idt(); // Load with ASM
 }
 
@@ -118,15 +123,20 @@ char *exception_messages[] = {
         "Reserved"
 };
 
-void isr_handler(registers_t r) {
+void isr_handler(isr_registers_t r) {
+    if (r.int_no == 128) {
+        syscall_handle(&r);
+        return;
+    }
     printf("Received interrupt: %d - %s\n", r.int_no, exception_messages[r.int_no]);
+    k_panic();
 }
 
 void register_interrupt_handler(uint8_t n, isr_t handler) {
     interrupt_handlers[n] = handler;
 }
 
-void irq_handler(registers_t r) {
+void irq_handler(isr_registers_t r) {
     /* After every interrupt we need to send an EOI to the PICs
      * or they will not send another interrupt again */
     if (r.int_no >= 40) port_byte_out(PORT_PIC_SLAVE_COMMAND, PIC_END_OF_INTERRUPT); /* slave */
@@ -135,6 +145,6 @@ void irq_handler(registers_t r) {
     /* Handle the interrupt in a more modular way */
     if (interrupt_handlers[r.int_no] != NULL) {
         isr_t handler = interrupt_handlers[r.int_no];
-        handler(r);
+        handler(&r);
     }
 }

kernel/cpu/isr.h

@@ -7,6 +7,8 @@
 #ifndef MY_KERNEL_ISR_H
 #define MY_KERNEL_ISR_H
 
+#include <cpu/cpu.h>
+
 /* ISRs reserved for CPU exceptions */
 extern void isr0();
 
@@ -105,6 +107,8 @@ extern void irq14();
 
 extern void irq15();
 
+extern void isr128();
+
 #define IRQ0 32
 #define IRQ1 33
 #define IRQ2 34
@@ -122,19 +126,12 @@ extern void irq15();
 #define IRQ14 46
 #define IRQ15 47
 
-typedef struct {
+typedef void (*isr_t)(isr_registers_t*);
-    uint32_t ds;
-    uint32_t edi, esi, ebp, esp, ebx, edx, ecx, eax;
-    uint32_t int_no, err_code;
-    uint32_t eip, cs, eflags, useresp, ss;
-} registers_t;
-
-typedef void (*isr_t)(registers_t);
 
 void register_interrupt_handler(uint8_t n, isr_t handler);
 
 void isr_install();
 
-void isr_handler(registers_t r);
+void isr_handler(isr_registers_t r);
 
 #endif //MY_KERNEL_ISR_H

kernel/cpu/syscall_handler.c

@@ -0,0 +1,20 @@
+//
+// Created by rick on 24-02-21.
+//
+
+#include "syscall_handler.h"
+#include <syscall.h>
+#include <tasks/task.h>
+
+void syscall_handle(isr_registers_t *registers) {
+    switch (registers->eax) {
+        case SYSCALL_START_SCHEDULER:
+            task_start_first();
+            break;
+        case SYSCALL_YIELD_JOB:
+            task_switch_next();
+            break;
+        default:
+            break;
+    }
+}

kernel/cpu/syscall_handler.h

@@ -0,0 +1,11 @@
+//
+// Created by rick on 24-02-21.
+//
+
+#ifndef NEW_KERNEL_SYSCALL_HANDLER_H
+#define NEW_KERNEL_SYSCALL_HANDLER_H
+#include <cpu/cpu.h>
+
+void syscall_handle(isr_registers_t *registers);
+
+#endif //NEW_KERNEL_SYSCALL_HANDLER_H

kernel/cpu/timer.c

@@ -9,6 +9,7 @@
 #include <libc/libc.h>
 #include <libk.h>
 #include <kprint.h>
+#include <tasks/task.h>
 
 // https://wiki.osdev.org/PIT
 #define PIT_MODE_BIN_BCD                            (1 << 0)
@@ -34,8 +35,13 @@
 
 uint32_t tick = 0;
 
-static void timer_callback(registers_t regs) {
+static void timer_callback(isr_registers_t *regs) {
     tick++;
+    task_switch_next();
+}
+
+uint32_t timer_get_tick() {
+    return tick;
 }
 
 void sleep(uint32_t milliseconds) {

kernel/cpu/timer.h

@@ -11,6 +11,8 @@ int init_timer(uint32_t freq);
 
 void print_current_tick();
 
+uint32_t timer_get_tick();
+
 void sleep(uint32_t milliseconds);
 
 #endif //MY_KERNEL_TIMER_H

kernel/drivers/ide.c

@@ -13,7 +13,7 @@
 #include <cpu/timer.h>
 #include <libc/kprintf.h>
 #include <fs/blockdev.h>
-#include <mem/mem.h>
+#include <mem/malloc.h>
 
 #define ATA_SR_BSY     0x80    // Busy
 #define ATA_SR_DRDY    0x40    // Drive ready

kernel/drivers/keyboard.c

@@ -6,8 +6,8 @@
 #include <drivers/ports.h>
 #include <cpu/isr.h>
 #include <libc/ringqueue.h>
-#include <mem/mem.h>
 #include <libk.h>
+#include <mem/malloc.h>
 
 
 const char scancode_map_lowercase[] = {
@@ -119,7 +119,7 @@ void publish_key_event(unsigned char scan_code) {
     ring_buffer_put(keyboard_event_buffer, &event);
 }
 
-static void keyboard_callback(registers_t regs) {
+static void keyboard_callback(isr_registers_t *regs) {
     unsigned char status = port_byte_in(PORT_PS2_STATUS);
     // check if data available
     if ((status & 0b00000001) == 0) {

kernel/fs/blockdev.c

@@ -4,8 +4,8 @@
 
 #include <libc/libc.h>
 #include <libk.h>
-#include <mem/mem.h>
 #include <libc/kprintf.h>
+#include <mem/malloc.h>
 #include "blockdev.h"
 
 #define MAX_BLOCK_DEVS 64
@@ -21,7 +21,7 @@ uint8_t block_dev_register_driver(block_dev_driver *driver) {
         return BLOCK_DEV_REGISTER_DRIVER_FULL;
     }
 
-    memcpy((uint8_t *) &block_dev_drivers[last_block_driver++], (const uint8_t *) driver, sizeof(block_dev_drivers));
+    memcpy((uint8_t *) &block_dev_drivers[last_block_driver++], (const uint8_t *) driver, sizeof(block_dev_driver));
     return BLOCK_DEV_REGISTER_DRIVER_OK;
 }
 

kernel/fs/fat.c

@@ -8,7 +8,8 @@
 #include <types.h>
 #include <libc/libc.h>
 #include <libc/kprintf.h>
-#include <mem/mem.h>
+#include <mem/malloc.h>
+#include <attributes.h>
 
 #define FAT_TYPE_12 1
 #define FAT_TYPE_16 2
@@ -31,7 +32,7 @@ typedef struct {
         uint16_t heads_sides;
         uint32_t hidden_sectors;
         uint32_t large_total_sectors;
-    } __attribute((packed)) bpb;
+    } packed bpb;
     union {
         struct {
             uint8_t drive_number;
@@ -40,7 +41,7 @@ typedef struct {
             uint32_t serial;
             uint8_t label[11];
             uint8_t system_id[8];
-        } __attribute((packed)) ebr_12_16;
+        } packed ebr_12_16;
         struct {
             uint32_t sectors_per_fat;
             uint16_t flags;
@@ -55,21 +56,21 @@ typedef struct {
             uint32_t serial;
             uint8_t label[11];
             uint8_t system_id[8];
-        } __attribute((packed)) ebr_32;
+        } packed ebr_32;
     };
-} __attribute((packed)) fat_bpb;
+} packed fat_bpb;
 
 typedef struct {
     uint8_t hours: 5;
     uint8_t minutes: 6;
     uint8_t seconds: 5;
-} __attribute((packed)) time_83;
+} packed time_83;
 
 typedef struct {
     uint8_t hours: 5;
     uint8_t minutes: 6;
     uint8_t seconds: 5;
-} __attribute((packed)) date_83;
+} packed date_83;
 
 typedef struct {
     union {
@@ -86,7 +87,7 @@ typedef struct {
             date_83 last_mod_date;
             uint16_t low_first_cluster;
             uint32_t file_size;
-        } __attribute((packed)) name_83;
+        } packed name_83;
         struct {
             uint8_t order;
             uint16_t text_1[5];
@@ -96,9 +97,9 @@ typedef struct {
             uint16_t text_2[6];
             uint16_t reserved;
             uint16_t text_3[2];
-        } __attribute((packed)) long_name;
+        } packed long_name;
     };
-} __attribute((packed)) fat_directory_entry;
+} packed fat_directory_entry;
 
 uint8_t fat_check_device(const block_device *device, uint8_t *first_sector);
 
@@ -128,7 +129,8 @@ uint8_t fat_check_device(const block_device *device, uint8_t *first_sector) {
 
     uint32_t total_sectors = bpb.bpb.total_sectors == 0 ? bpb.bpb.large_total_sectors : bpb.bpb.total_sectors;
     uint32_t fat_size = bpb.bpb.sectors_per_fat == 0 ? bpb.ebr_32.sectors_per_fat : bpb.bpb.sectors_per_fat;
-    uint32_t root_dir_sectors = ((bpb.bpb.directories * 32) + (bpb.bpb.bytes_per_sector - 1)) / bpb.bpb.bytes_per_sector;
+    uint32_t root_dir_sectors =
+            ((bpb.bpb.directories * 32) + (bpb.bpb.bytes_per_sector - 1)) / bpb.bpb.bytes_per_sector;
     uint32_t first_data_sector = bpb.bpb.reserved_sectors + (bpb.bpb.fats * fat_size) + root_dir_sectors;
     uint32_t first_fat_sector = bpb.bpb.reserved_sectors;
     uint32_t data_sectors = total_sectors - (bpb.bpb.reserved_sectors + (bpb.bpb.fats * fat_size) + root_dir_sectors);
@@ -163,7 +165,8 @@ typedef struct {
 } table_result;
 
 table_result
-get_fat_table_value(uint8_t fat_type, const uint8_t *fat_table, uint32_t active_cluster, uint32_t first_fat_cluster, uint32_t sector_size) {
+get_fat_table_value(uint8_t fat_type, const uint8_t *fat_table, uint32_t active_cluster, uint32_t first_fat_cluster,
+                    uint32_t sector_size) {
     uint32_t fat_offset;
     table_result result = {
             .value = 0,

kernel/fs/mbr.c

@@ -5,10 +5,11 @@
 #include "mbr.h"
 #include <types.h>
 #include <drivers/ide.h>
-#include <mem/mem.h>
 #include <libc/kprintf.h>
 #include <fs/blockdev.h>
 #include <libc/libc.h>
+#include <mem/malloc.h>
+#include <attributes.h>
 
 typedef struct {
     uint8_t bootable;
@@ -21,14 +22,14 @@ typedef struct {
     uint16_t ending_cylinder: 10;
     uint32_t start_lba;
     uint32_t num_lbas;
-}  __attribute((packed)) mbr_partition_table_entry;
+}  packed mbr_partition_table_entry;
 
 typedef struct {
     uint32_t unique_id;
     uint16_t reserved;
     mbr_partition_table_entry entries[4];
     uint8_t signature[2];
-} __attribute((packed)) mbr_table;
+} packed mbr_table;
 
 typedef struct {
     const block_device *device;

kernel/kernel.c

@@ -1,6 +1,4 @@
-#include <drivers/ports.h>
 #include <drivers/vgascreen.h>
-#include <libc/libc.h>
 #include <cpu/isr.h>
 #include <cpu/timer.h>
 #include <drivers/keyboard.h>
@@ -8,8 +6,6 @@
 #include <multiboot.h>
 #include <drivers/serial.h>
 #include <kprint.h>
-#include <libc/readline.h>
-#include <libc/string.h>
 #include <libk.h>
 #include <drivers/pci.h>
 #include <drivers/ide.h>
@@ -18,118 +14,22 @@
 #include <fs/blockdev.h>
 #include <fs/fat.h>
 #include <stdbool.h>
-
+#include <cpu/cpuidx.h>
-#define BOOTLOADER_NAME_MAX_LENGTH 64
+#include <mem/malloc.h>
-#define CMDLINE_MAX_LENGTH 256
+#include <tasks/task.h>
+#include <syscall.h>
+#include <command.h>
+#include <attributes.h>
 
 const int version_major = 0,
         version_minor = 0,
         version_patch = 1;
 
-char bootloader_name[BOOTLOADER_NAME_MAX_LENGTH];
-char cmdline[CMDLINE_MAX_LENGTH];
-
-typedef void (*cmd_handler_func)(const char *);
-
-typedef struct {
-    char *cmd;
-    cmd_handler_func handler;
-} cmd_handler;
-
-void print(const char *arg);
-
-void ide(const char *arg);
-
-void echo(const char *arg);
-
-void help(const char *arg);
-
-cmd_handler cmd_handlers[] = {
-        {"help",  help},
-        {"echo",  echo},
-        {"print", print},
-        {"ide",   ide},
-        {NULL, NULL},
-};
-
-void print_bootinfo() {
-    printf("Bootloader name: %s\n"
-           "cmdline: %s\n",
-           (bootloader_name[0] == 0 ? "NULL" : bootloader_name),
-           (cmdline[0] == 0 ? "NULL" : cmdline));
-}
-
-void help(const char *arg) {
-    kprint("Available commands:\n");
-    int index = 0;
-    while (true) {
-        if (cmd_handlers[index].cmd == NULL) {
-            break;
-        }
-        printf("%s\n", cmd_handlers[index].cmd);
-        index += 1;
-    }
-
-}
-
-void echo(const char *arg) {
-    printf("%s\n", arg);
-}
-
-void print(const char *arg) {
-    if (strcmp(arg, "mmap") == 0) {
-        print_mmap_info();
-    } else if (strcmp(arg, "malloc") == 0) {
-        print_malloc_info();
-    } else if (strcmp(arg, "tick") == 0) {
-        print_current_tick();
-    } else if (strcmp(arg, "bootinfo") == 0) {
-        print_bootinfo();
-    } else if (strcmp(arg, "pci") == 0) {
-        pci_print_info();
-    } else if (strcmp(arg, "ide") == 0) {
-        ide_print_devices();
-    } else {
-        printf("Unknown print %s\n", arg);
-    }
-}
-
-void ide(const char *arg) {
-    if (strcmp(arg, "block_devices") == 0) {
-        block_dev_print_info();
-    } else if (strcmp(arg, "ide_devices") == 0) {
-        ide_print_devices();
-    } else if (strcmp(arg, "mbr") == 0) {
-        mbr_read_from_ide(0);
-    } else {
-        printf("Unknown print %s\n", arg);
-    }
-}
-
-void main_loop();
-
-void store_bootloader_info(multiboot_info_t *multiboot_info) {
-    // get bootloader and cmdline
-    if (multiboot_info->flags & MULTIBOOT_INFO_CMDLINE) {
-        int cmdline_length = strlen((const char *) multiboot_info->cmdline);
-        if (cmdline_length > CMDLINE_MAX_LENGTH) {
-            k_panics("cmdline to long!\n");
-        }
-        memcpy(cmdline, (char *) multiboot_info->cmdline, cmdline_length);
-    }
-    if (multiboot_info->flags & MULTIBOOT_INFO_BOOT_LOADER_NAME) {
-        int bootloader_length = strlen((const char *) multiboot_info->boot_loader_name);
-        if (bootloader_length > BOOTLOADER_NAME_MAX_LENGTH) {
-            k_panics("bootloader name to long!\n");
-        }
-        memcpy(bootloader_name, (char *) multiboot_info->boot_loader_name, bootloader_length);
-    }
-}
-
 void init_mmap(multiboot_info_t *multiboot_info) {
     if (multiboot_info->flags & (1 << 6)) {
-        init_mmap_multiboot((struct multiboot_mmap_entry *) multiboot_info->mmap_addr,
+        mmap_init_multiboot((struct multiboot_mmap_entry *) multiboot_info->mmap_addr,
                             multiboot_info->mmap_length / sizeof(struct multiboot_mmap_entry));
+        malloc_init();
         // todo fallback on other mechanisms?
     } else {
         k_panics("mmap invalid!\n");
@@ -156,7 +56,7 @@ void init_block_devices() {
     block_dev_scan_repeat();
 }
 
-void kmain(multiboot_info_t *multiboot_info) {
+void noreturn kmain(multiboot_info_t *multiboot_info) {
     isr_install();
     vga_clear_screen();
     vga_clear_screen(' ', VGA_WHITE | (VGA_GRAY << VGA_SHIFT_BG));
@@ -164,6 +64,8 @@ void kmain(multiboot_info_t *multiboot_info) {
     serial_init();
     kprint_register(serial_kprint);
 
+    cpuidx_print_info();
+
     store_bootloader_info(multiboot_info);
     init_mmap(multiboot_info);
 
@@ -176,27 +78,6 @@ void kmain(multiboot_info_t *multiboot_info) {
 
     printf("Booted successfully v%d.%d.%d\n", version_major, version_minor, version_patch);
 
-    // enter main loop
+    task_spawn(main_loop, NULL);
-    while (true) {
+    syscall_start_scheduler();
-        main_loop();
-    }
-}
-
-void main_loop() {
-    char *msg = readline(NULL);
-    char *args = strchr(msg, ' ') + 1;
-    args[-1] = 0;
-    int test_index = 0;
-    while (true) {
-        if (cmd_handlers[test_index].cmd == 0) {
-            printf("Unknown command: %s\n", msg);
-            break;
-        }
-        if (strcmp(cmd_handlers[test_index].cmd, msg) == 0) {
-            cmd_handlers[test_index].handler(args);
-            break;
-        }
-        test_index++;
-    }
-    free(msg);
 }

kernel/libc/libc.c

@@ -15,7 +15,7 @@ int memcpy(uint8_t *dst, const uint8_t *src, int amount) {
     return 0;
 }
 
-int memset(char *dst, char data, int amount) {
+int memset(uint8_t *dst, char data, int amount) {
     for (int i = 0; i < amount; ++i) {
         dst[i] = data;
     }

kernel/libc/libc.h

@@ -12,7 +12,7 @@
 
 int memcpy(uint8_t *dst, const uint8_t *src, int amount);
 
-int memset(char *dst, char data, int amount);
+int memset(uint8_t *dst, char data, int amount);
 
 char *itoa(int value, char *buffer, int base);
 

kernel/libc/readline.c

@@ -6,8 +6,8 @@
 #include <libc/libc.h>
 #include <types.h>
 #include <kprint.h>
-#include <mem/mem.h>
 #include <drivers/keyboard.h>
+#include <mem/malloc.h>
 
 #define RESULT_SIZE 256
 

kernel/libc/ringqueue.c

@@ -4,7 +4,7 @@
 
 #include "ringqueue.h"
 #include <libc/libc.h>
-#include <mem/mem.h>
+#include <mem/malloc.h>
 
 #define calc_pos(buffer, index) ((buffer->object_size) * (index))
 

kernel/libc/string.c

@@ -52,7 +52,7 @@ int strncmp(const char *s1, const char *s2, int n) {
         if (s1[i] > s2[i]) {
             return -1;
         }
-        if (s2[i] < s1[i]) {
+        if (s1[i] < s2[i]) {
             return 1;
         }
     }

kernel/libk.c

@@ -2,9 +2,14 @@
 // Created by rick on 02-02-21.
 //
 
+#include <stdbool.h>
 #include "libk.h"
 #include "kprint.h"
 
+bool k_addr_in_kspace(void* addr) {
+    return addr > kernel_start && addr < kernel_end;
+}
+
 void k_wait_for_interrupt() {
     __asm__ __volatile__("hlt;");
 }

kernel/libk.h

@@ -4,6 +4,14 @@
 
 #ifndef NEW_KERNEL_LIBK_H
 #define NEW_KERNEL_LIBK_H
+#include <stdbool.h>
+
+extern void* _kernel_start;
+extern void* _kernel_end;
+#define kernel_start ((uint32_t)(&_kernel_start))
+#define kernel_end ((uint32_t)(&_kernel_end))
+
+bool k_addr_in_kspace(void *addr);
 
 void k_wait_for_interrupt();
 

kernel/mem/malloc.c

@@ -0,0 +1,90 @@
+//
+// Created by rick on 23-02-21.
+//
+
+#include <libc/kprintf.h>
+#include <tasks/task.h>
+#include "malloc.h"
+#include "pmm.h"
+
+#define MALLOC_TYPE_FREE 0
+#define MALLOC_TYPE_USED 1
+
+int malloc_entries = 0;
+int malloc_used = 0;
+
+typedef struct malloc_map {
+    struct malloc_map *next;
+    struct malloc_map *prev;
+    uint32_t size;
+    int type;
+} malloc_map;
+
+malloc_map *first_malloc_entry;
+
+void malloc_init() {
+    first_malloc_entry = pmm_get_pages(16);
+    first_malloc_entry->next = first_malloc_entry;
+    first_malloc_entry->prev = first_malloc_entry;
+    first_malloc_entry->size = PAGE_SIZE * 16;
+    first_malloc_entry->type = MALLOC_TYPE_FREE;
+    malloc_entries++;
+}
+
+void split_malloc_map(malloc_map *entry, unsigned int size) {
+    malloc_entries++;
+    malloc_map *new_entry = entry + sizeof(malloc_map) + size;
+    new_entry->size = entry->size - size - sizeof(malloc_map);
+    new_entry->next = entry->next;
+    new_entry->prev = entry;
+    new_entry->type = MALLOC_TYPE_FREE;
+    entry->next->prev = new_entry;
+    entry->next = new_entry;
+    entry->size = size;
+}
+
+void *malloc(size_t size) {
+    // todo replace this horrible mess!
+    // this lacks any page alignment and what so ever
+    void* result = NULL;
+    task_lock_acquire();
+    malloc_map *current_map = first_malloc_entry;
+    // iterate through maps
+    do {
+        if (current_map->type == MALLOC_TYPE_USED) {
+            goto malloc_find_next;
+        }
+        if ((unsigned int) current_map->size < size) {
+            goto malloc_find_next;
+        }
+        if ((unsigned int) current_map->size > (size + sizeof(malloc_map))) {
+            // big enough to split
+            split_malloc_map(current_map, size);
+        }
+        malloc_used++;
+        current_map->type = MALLOC_TYPE_USED;
+        result = ((void *) current_map) + sizeof(malloc_map);
+        break;
+
+        malloc_find_next:
+        current_map = current_map->next;
+    } while (current_map != first_malloc_entry);
+    task_lock_free();
+    return result;
+}
+
+void free(void *mem) {
+    if (mem == NULL) {
+        return;
+    }
+    malloc_used--;
+    malloc_map *map = (mem - sizeof(malloc_map));
+    map->type = MALLOC_TYPE_FREE;
+};
+
+
+void print_malloc_info() {
+    printf("Malloc avail entries: %d\n"
+           "Malloc used entries: %d\n", malloc_entries, malloc_used);
+}
+

kernel/mem/malloc.h

@@ -0,0 +1,17 @@
+//
+// Created by rick on 23-02-21.
+//
+
+#ifndef NEW_KERNEL_MALLOC_H
+#define NEW_KERNEL_MALLOC_H
+#include <types.h>
+
+void malloc_init();
+
+void print_malloc_info();
+
+void *malloc(size_t size);
+
+void free(void *mem);
+
+#endif //NEW_KERNEL_MALLOC_H

kernel/mem/mem.c

@@ -2,9 +2,12 @@
 // Created by rick on 22-04-20.
 //
 
+#include "pmm.h"
 #include <types.h>
 #include <mem/mem.h>
 #include <libc/kprintf.h>
+#include <libk.h>
+#include <attributes.h>
 
 #define MEMMAP_ENTRIES 16
 
@@ -15,26 +18,13 @@
 #define MMAP_TYPE_NVS               4
 #define MMAP_TYPE_BADRAM            5
 #define MMAP_TYPE_KERNEL            6
-#define MMAP_TYPE_MALLOC            7
+#define MMAP_TYPE_PAGING            7
-
-#define MALLOC_TYPE_FREE 0
-#define MALLOC_TYPE_USED 1
-
-#define kilobyte (1024)
-//#define kernel_start (one_meg)
-#define kernel_size (32 * kilobyte)
-#define kernel_end (kernel_start + kernel_size)
-extern void *kernel_start;
-//extern void *kernel_end;
 
 typedef struct {
-    void *address;
+    uint32_t address;
     uint32_t length;
     uint32_t type;
-} __attribute((packed)) mmap_entry;
+} packed mmap_entry;
-
-int malloc_entries = 0;
-int malloc_used = 0;
 
 int last_memmap_entry = 0;
 mmap_entry memmap[MEMMAP_ENTRIES] = {
@@ -56,114 +46,51 @@ mmap_entry memmap[MEMMAP_ENTRIES] = {
         {0, 0, 0},
 };
 
-typedef struct malloc_map {
-    struct malloc_map *next;
-    struct malloc_map *pref;
-    uint32_t size;
-    int type;
-} malloc_map;
-
 void use_mmap_entry(struct multiboot_mmap_entry *entry) {
     mmap_entry *mm_entry = &memmap[last_memmap_entry++];
     mm_entry->address = (void *) entry->addr;
     mm_entry->length = entry->len;
     mm_entry->type = entry->type;
-    if (last_memmap_entry == 1) {
-        // not using first map entry for now
-        return;
-    }
     // check if the entry overlaps with the kernel address space
     if (kernel_start >= mm_entry->address && kernel_start <= mm_entry->address + mm_entry->length) {
+        uint32_t page_after_kernel = kernel_end + PAGE_SIZE & ~(PAGE_SIZE - 1);
+        uint32_t kernel_size_full_pages = page_after_kernel - mm_entry->address;
         // todo make this something proper
         struct multiboot_mmap_entry extra_entry;
         extra_entry.size = entry->size;
         extra_entry.type = entry->type;
-        extra_entry.addr = entry->addr + kernel_size;
+        extra_entry.addr = page_after_kernel;
-        extra_entry.len = entry->size - kernel_size;
+        extra_entry.len = entry->size - kernel_size_full_pages;
         use_mmap_entry(&extra_entry);
 
-        mm_entry->length = kernel_size;
+        mm_entry->length = kernel_size_full_pages;
         mm_entry->type = MMAP_TYPE_KERNEL;
     }
-    if (mm_entry->type == MMAP_TYPE_AVAILABLE && (unsigned int) mm_entry->length > sizeof(malloc_map)) {
-        mm_entry->type = MMAP_TYPE_MALLOC;
-        malloc_map *map = (malloc_map *) mm_entry->address;
-        map->type = MALLOC_TYPE_FREE;
-        map->size = mm_entry->length - sizeof(malloc_map);
-        map->pref = map;
-        map->next = map;
-        malloc_entries++;
-    }
 }
 
-void init_mmap_multiboot(struct multiboot_mmap_entry *entries, uint32_t count) {
+void mmap_init_multiboot(struct multiboot_mmap_entry *entries, uint32_t count) {
     for (uint32_t i = 0; i < count; ++i) {
         use_mmap_entry(&entries[i]);
     }
-}
 
-void split_malloc_map(malloc_map *entry, unsigned int size) {
+    // init page manager
-    malloc_entries++;
+    for (int i = 0; i < last_memmap_entry; ++i) {
-    malloc_map *new_entry = entry + sizeof(malloc_map) + size;
+        mmap_entry *entry = &memmap[i];
-    new_entry->size = entry->size - size - sizeof(malloc_map);
+        if (entry->type != MMAP_TYPE_AVAILABLE) {
-    new_entry->next = entry->next;
-    new_entry->pref = entry;
-    new_entry->type = MALLOC_TYPE_FREE;
-    entry->next->pref = new_entry;
-    entry->next = new_entry;
-    entry->size = size;
-}
-
-void *malloc(size_t size) {
-    // todo replace this horrible mess!
-    // this lacks any page alignment and what so ever
-    for (int i = 0; i < MEMMAP_ENTRIES; ++i) {
-        if (memmap[i].type != MMAP_TYPE_MALLOC) {
             continue;
         }
-        // get first first_map of address
+        if (entry->address < kernel_start) {
-        malloc_map *first_map = (malloc_map *) memmap[i].address;
+            continue; // skip for now
-        malloc_map *current_map = first_map;
-        // iterate through maps
-        do {
-            if (current_map->type == MALLOC_TYPE_USED) {
-                goto malloc_find_next;
-            }
-            if ((unsigned int) current_map->size < size) {
-                goto malloc_find_next;
-            }
-            if ((unsigned int) current_map->size > (size + sizeof(malloc_map))) {
-                // big enough to split
-                split_malloc_map(current_map, size);
-            }
-            malloc_used++;
-            current_map->type = MALLOC_TYPE_USED;
-            return ((void *) current_map) + sizeof(malloc_map);
-
-            malloc_find_next:
-            current_map = current_map->next;
-        } while (current_map != first_map);
-    }
-    return NULL;
         }
 
-void free(void *mem) {
+        pmm_init((void *) entry->address, entry->length);
-    if (mem == NULL) {
+        entry->type = MMAP_TYPE_PAGING;
-        return;
     }
-    malloc_used--;
-    malloc_map *map = (mem - sizeof(malloc_map));
-    map->type = MALLOC_TYPE_FREE;
-};
-
-
-void print_malloc_info() {
-    printf("Malloc avail entries: %d\n"
-           "Malloc used entries: %d\n", malloc_entries, malloc_used);
 }
 
-
 void print_mmap_info() {
+    printf("Kernel start: %8x\n"
+           "Kernel end:   %8x\n", kernel_start, kernel_end);
     for (int i = 0; i < 16; ++i) {
         if (memmap[i].type == 0) {
             break;

kernel/mem/mem.h

@@ -7,14 +7,8 @@
 
 #include <multiboot.h>
 
-void init_mmap_multiboot(struct multiboot_mmap_entry *entries, uint32_t count);
+void mmap_init_multiboot(struct multiboot_mmap_entry *entries, uint32_t count);
-
-void print_malloc_info();
 
 void print_mmap_info();
 
-void *malloc(size_t size);
-
-void free(void *mem);
-
 #endif //NEW_KERNEL_MEM_H

kernel/mem/pmm.c

@@ -0,0 +1,98 @@
+//
+// Created by rick on 23-02-21.
+//
+
+#include <stdbool.h>
+#include <libc/libc.h>
+#include <libk.h>
+#include "pmm.h"
+
+#define NUM_PAGING_INFOS 16
+
+#define BLOCK_USED 1
+#define BLOCK_FREE 0
+
+#define bitmap_block_byte(block) ((block) / 8)
+#define bitmap_block_bit(block) ((block) % 8)
+
+#define bitmap_set(addr, block) (addr)[bitmap_block_byte(block)] = ((addr)[bitmap_block_byte(block)] | (1 << (bitmap_block_bit(block))))
+#define bitmap_unset(addr, block) (addr)[bitmap_block_byte(block)] = ((addr)[bitmap_block_byte(block)] & ~(1 << (bitmap_block_bit(block))))
+
+#define bitmap_get(addr, block) ((addr)[bitmap_block_byte(block)] >> bitmap_block_bit(block))
+
+#define page_to_addr(base_addr, block) ((base_addr) + ((block) * PAGE_SIZE))
+#define addr_to_page(base_addr, addr) (((addr) - (base_addr)) / PAGE_SIZE)
+
+typedef struct {
+    union {
+        uint8_t *page_bitmap;
+        void *first_page;
+    };
+    uint32_t num_pages;
+    size_t size;
+    struct {
+        bool present: 1;
+    } flags;
+} paging_info;
+
+uint8_t last_paging_info = 0;
+paging_info paging_infos[NUM_PAGING_INFOS];
+
+void pmm_init(void *start_addr, size_t size) {
+    uint32_t num_pages = size / PAGE_SIZE;
+    uint32_t bitmap_size = num_pages / 8;
+    uint32_t bitmap_pages = bitmap_size / PAGE_SIZE;
+    paging_infos[last_paging_info].page_bitmap = start_addr;
+    paging_infos[last_paging_info].num_pages = num_pages;
+    paging_infos[last_paging_info].size = size;
+    paging_infos[last_paging_info].flags.present = true;
+
+    memset(start_addr, BLOCK_FREE, bitmap_pages);
+    for (uint32_t i = 0; i < bitmap_pages; ++i) {
+        bitmap_set((uint8_t *) start_addr, i);
+    }
+    last_paging_info++;
+}
+
+void *pmm_get_pages(uint32_t num_pages) {
+    for (int i = 0; i < last_paging_info; ++i) {
+        paging_info *info = &paging_infos[i];
+        if (!info->flags.present) continue;
+
+        for (uint32_t j = 0; j < info->num_pages; ++j) {
+            if (bitmap_get(info->page_bitmap, j) == BLOCK_FREE) {
+                uint32_t k;
+                bool usable = true;
+                for (k = j + 1; k < j + num_pages; ++k) {
+                    if (bitmap_get(info->page_bitmap, k) == BLOCK_USED) {
+                        usable = false;
+                        j = k; // skip ahead
+                        break;
+                    }
+                }
+                if (!usable) break;
+                for (k = j; k < j + num_pages; ++k) {
+                    bitmap_set(info->page_bitmap, k);
+                }
+                return page_to_addr(info->first_page, j);
+            }
+        }
+    }
+    k_panics("No page found!");
+    return NULL;
+}
+
+void pmm_free_pages(void *page, uint32_t num_pages) {
+    for (int i = 0; i < last_paging_info; ++i) {
+        paging_info *info = &paging_infos[i];
+        if (!info->flags.present) continue;
+        // check if page is in memory area
+        if (page < info->first_page || page > (info->first_page + info->size)) continue;
+
+        // free page
+        uint32_t first_page = addr_to_page(info->first_page, page);
+        for (uint32_t current_page = first_page; current_page < first_page + num_pages; ++current_page) {
+            bitmap_unset(info->page_bitmap, current_page);
+        }
+    }
+}

kernel/mem/pmm.h

@@ -0,0 +1,16 @@
+//
+// Created by rick on 23-02-21.
+//
+
+#ifndef NEW_KERNEL_PMM_H
+#define NEW_KERNEL_PMM_H
+#include <types.h>
+
+// 4k blocks
+#define PAGE_SIZE 4096
+
+void pmm_init(void* start_addr, size_t size);
+void *pmm_get_pages(uint32_t num_pages);
+void pmm_free_pages(void* page, uint32_t num_pages);
+
+#endif //NEW_KERNEL_PMM_H

kernel/syscall.c

@@ -0,0 +1,22 @@
+//
+// Created by rick on 22-02-21.
+//
+
+#include "syscall.h"
+#include <types.h>
+#include <attributes.h>
+
+void syscall1(uint32_t arg1) {
+    __asm__("int $0x80"
+    :
+    : "a"(arg1));
+}
+
+void syscall_yield_job() {
+    syscall1(SYSCALL_YIELD_JOB);
+}
+
+void noreturn syscall_start_scheduler() {
+    syscall1(SYSCALL_START_SCHEDULER);
+    while (1) { __asm__("hlt"); };
+}

kernel/syscall.h

@@ -0,0 +1,17 @@
+//
+// Created by rick on 22-02-21.
+//
+
+#ifndef NEW_KERNEL_SYSCALL_H
+#define NEW_KERNEL_SYSCALL_H
+
+#include <attributes.h>
+
+#define SYSCALL_START_SCHEDULER 0x01
+#define SYSCALL_YIELD_JOB       0x02
+
+void syscall_yield_job();
+
+void noreturn syscall_start_scheduler();
+
+#endif //NEW_KERNEL_SYSCALL_H

kernel/tasks/task.S

@@ -0,0 +1,42 @@
+.code32
+
+.global __task_entry_point
+__task_entry_point:
+    # Load segments
+    popl %eax
+    movw %ax,%ds
+    movw %ax,%es
+    movw %ax,%fs
+    movw %ax,%gs
+    # pop isr_registers
+    popa
+    # Remove errono etc.
+    addl $8,%esp # Cleans up the pushed error code and pushed ISR number
+    sti
+    # return to program
+    iret # pops 5 things at once: CS, EIP, EFLAGS, SS, and ESP
+.global __task_entry_point_inner
+__task_entry_point_inner:
+    add $8, %esp # Remove useresp and ss (only exists in user space)
+    call task_entry_point
+.global switch_task
+switch_task:
+    movl 4(%esp), %eax
+    movl 8(%esp), %edx
+    test %eax, %eax
+    jz _st_no_store
+    pushl %ebp
+    pushl %ebx
+    pushl %esi
+    pushl %edi
+    movl %esp, (%eax)
+    _st_no_store:
+    movl %edx, %esp
+    popl %edi
+    popl %esi
+    popl %ebx
+    popl %ebp
+    ret
+
+
+

kernel/tasks/task.c

@@ -0,0 +1,131 @@
+//
+// Created by rick on 22-02-21.
+//
+
+#include "task.h"
+#include <cpu/cpu.h>
+#include <stdbool.h>
+#include <libc/libc.h>
+#include <mem/malloc.h>
+#include <mem/pmm.h>
+
+#include <attributes.h>
+
+#define stack_end(task) ((task)->stack + ((task)->stack_page_count * PAGE_SIZE))
+
+typedef struct task {
+    bool present: 1;
+    uint8_t wait_irq: 4;
+
+    uint32_t tid;
+
+    struct task *next;
+
+    void* stack;
+    uint32_t stack_page_count;
+
+    task_registers_t *task_registers;
+} task_t;
+
+typedef struct {
+    task_registers_t task_registers;
+    isr_registers_t isr_registers;
+    task_entrypoint entrypoint;
+    void *entry_data;
+    char alignment[4];
+} packed task_stack_start;
+
+bool task_locked = false;
+
+task_t *first_task = NULL;
+task_t *last_task = NULL;
+task_t *current_task = NULL;
+
+uint32_t last_tid = 0;
+
+extern switch_task(task_registers_t**, task_registers_t*);
+extern cdecl noreturn void __task_entry_point();
+extern noreturn void __task_entry_point_inner();
+// explicit cdecl calling convention
+void cdecl noreturn task_entry_point(task_entrypoint entrypoint, void *entry_data) {
+    entrypoint(entry_data);
+//    task_end_self();
+    while (true); // halt
+}
+
+void task_lock_acquire() {
+    task_locked = true;
+}
+
+void task_lock_free() {
+    task_locked = false;
+}
+
+void task_switch_next_inner(task_t *next_task) {
+    if (task_locked) {
+        return; // don't switch while the task is locked
+    }
+    if (next_task == current_task) {
+        return;
+    }
+    task_t *previous_task = current_task;
+    current_task = next_task;
+    // switch task
+    switch_task(previous_task == NULL ? NULL : &previous_task->task_registers, current_task->task_registers);
+}
+
+void task_start_first() {
+    task_switch_next_inner(first_task);
+}
+
+void task_switch_next() {
+    if (current_task == NULL) {
+        return;
+    }
+    task_switch_next_inner(current_task->next == NULL ? first_task : current_task->next);
+}
+
+uint32_t task_spawn(task_entrypoint entrypoint, void *entry_data) {
+    task_t *new_task = malloc(sizeof(task_t));
+    memset((uint8_t *) new_task, 0, sizeof(task_t));
+    new_task->tid = last_tid++;
+
+    new_task->stack = pmm_get_pages(16);
+    new_task->stack_page_count = 16;
+    // todo check for null
+
+
+    if (first_task == NULL) {
+        // first task
+        first_task = new_task;
+    } else {
+        last_task->next = new_task;
+    }
+    last_task = new_task;
+
+    // prepare stack
+    // cdecl format
+    task_stack_start* stack = (task_stack_start *) (stack_end(new_task) - sizeof(task_stack_start));
+    memset((uint8_t *) stack, 0, sizeof(task_stack_start));
+    // setup isr return frame
+    stack->isr_registers.cs = 0x08; // todo proper gdt setup
+    stack->isr_registers.ds = 0x10; // todo
+//    stack->isr_registers.ss = 0x10; // todo
+
+    stack->isr_registers.eip = (uint32_t) __task_entry_point_inner;
+    stack->isr_registers.eflags = 0x200;
+    // setup task switch frame
+    stack->task_registers.eip = (uint32_t) __task_entry_point;
+    stack->task_registers.ebp = (uint32_t) stack_end(new_task);
+    // setup entrypoint
+    stack->entrypoint = entrypoint;
+    stack->entry_data = entry_data;
+
+    new_task->task_registers = &stack->task_registers;
+
+    new_task->present = true;
+    return new_task->tid;
+}
+
+void task_end(uint32_t pid) {
+}

kernel/tasks/task.h

@@ -0,0 +1,24 @@
+//
+// Created by rick on 22-02-21.
+//
+
+#ifndef NEW_KERNEL_TASK_H
+#define NEW_KERNEL_TASK_H
+
+#include <cpu/cpu.h>
+
+typedef void (*task_entrypoint)(void *entry_data);
+
+void task_start_first();
+
+void task_switch_next();
+
+uint32_t task_spawn(task_entrypoint, void *entry_data);
+
+void task_end(uint32_t pid);
+
+void task_lock_acquire();
+
+void task_lock_free();
+
+#endif //NEW_KERNEL_TASK_H

linker.ld

@@ -9,7 +9,7 @@ SECTIONS
 	/* Begin putting sections at 1 MiB, a conventional place for kernels to be
 	   loaded at by the bootloader. */
 	. = 1M;
-	kernel_start = .;
+	_kernel_start = .;
 
 	/* First put the multiboot header, as it is required to be put very early
 	   early in the image or the bootloader won't recognize the file format.
@@ -38,6 +38,7 @@ SECTIONS
 		*(COMMON)
 		*(.bss)
 	}
+	_kernel_end = .;
 
 	/DISCARD/ : {
 	    *(.eh_frame);

qemu-debug.sh

@@ -1,3 +1,3 @@
 #!/bin/bash
-nohup qemu-system-i386 -S -s -kernel cmake-build-debug/my-kernel.bin -hda tmp.img -d guest_errors,int -m 1G > /dev/null &
+nohup qemu-system-i386 -cpu max -S -s -kernel cmake-build-debug/my-kernel.bin -hda tmp.img -d guest_errors,int -m 1G > /dev/null &
 disown