Add tasking (No usermode support)

cpu/i386/cpu_init.c

@@ -1,10 +1,12 @@
 #include "gdt.h"
 #include "paging.h"
 #include "isr.h"
+#include "../tasking.h"
 
 void cpu_init() {
   gdt_init();
   isr_install();
   asm volatile("sti");
   paging_init();
+  tasking_init();
 }

cpu/i386/tasking.c

@@ -0,0 +1,99 @@
+#include "tasking_helpers.h"
+#include "tasking.h"
+#include "../tasking.h"
+#include "isr.h"
+#include "../../libc/stdlib.h"
+#include "../../libc/stdio.h"
+#include "memory.h"
+#include <stdint.h>
+#define STACK_PAGES 2
+
+uint32_t next_pid;
+
+static Task* currentTask;
+static Task* headTask;
+
+void tasking_init() {
+  currentTask=NULL;
+  next_pid=0;
+  headTask=createTask(NULL);
+  currentTask=headTask;
+}
+
+Task* createTaskEax(void* eip,uint32_t eax) {
+    Task* task=malloc(sizeof(Task));
+    task->regs.eax=eax;
+    task->regs.ebx=0;
+    task->regs.ecx=0;
+    task->regs.edx=0;
+    task->regs.esi=0;
+    task->regs.edi=0;
+    asm volatile("pushfl; movl (%%esp), %%eax; movl %%eax, %0; popfl;":"=m"(task->regs.eflags)::"%eax");
+    task->regs.eip=(uint32_t)eip;
+    asm volatile("movl %%cr3, %%eax; movl %%eax, %0;":"=m"(task->regs.cr3)::"%eax");
+    task->regs.esp=(uint32_t)alloc_memory(1);
+    task->regs.ebp=0;
+    task->msg_store=NULL;
+    task->rd=0;
+    task->wr=0;
+    task->next=NULL;
+    task->pid=next_pid;
+    next_pid++;
+    if (currentTask) {
+      currentTask->next=task;
+    }
+    return task;
+}
+
+Task* createTask(void* eip) {
+  return createTaskEax(eip,0);
+}
+
+void send_msg(uint32_t pid,char* msg) {
+  for (Task* task=headTask;task!=NULL;task=task->next) {
+    if (task->pid==pid) {
+      if (task->msg_store==NULL) {
+        task->msg_store=malloc(sizeof(char*)*256);
+        task->sender_store=malloc(sizeof(uint32_t)*256);
+      }
+      task->msg_store[task->wr]=msg;
+      task->sender_store[task->wr]=currentTask->pid;
+      task->wr++;
+      if (task->wr==task->rd) {
+        task->wr--;
+      }
+    }
+  }
+}
+
+char* get_msg(uint32_t* sender) {
+  if (!currentTask->msg_store) {
+    return NULL;
+  }
+  if (currentTask->msg_store[currentTask->rd]==NULL) {
+    currentTask->rd++;
+    if (currentTask->msg_store[currentTask->rd]==NULL) {
+      currentTask->rd--;
+      return NULL;
+    }
+  }
+  *sender=currentTask->sender_store[currentTask->rd];
+  char* data=currentTask->msg_store[currentTask->rd];
+  currentTask->msg_store[currentTask->rd]=NULL;
+  currentTask->sender_store[currentTask->rd]=0;
+  currentTask->rd++;
+  if (currentTask->rd>currentTask->wr) {
+    currentTask->rd=currentTask->wr-1;
+  }
+  return data;
+}
+
+void yield() {
+    Task* task=currentTask->next;
+    if (!task) {
+      task=headTask;
+    }
+    Task* oldCurr=currentTask;
+    currentTask=task;
+    switchTask(&oldCurr->regs, &currentTask->regs);
+}

cpu/i386/tasking.h

@@ -0,0 +1,22 @@
+#ifndef INT_TASKING_H
+#define INT_TASKING_H
+
+#include <stdint.h>
+
+typedef struct {
+    uint32_t eax, ebx, ecx, edx, esi, edi, esp, ebp, eip, eflags, cr3;
+} Registers;
+
+typedef struct Task {
+    Registers regs;
+    struct Task* next;
+    char** msg_store;
+    uint32_t* sender_store;
+    uint32_t msg_indx;
+    uint8_t rd;
+    uint8_t wr;
+    uint32_t pid;
+} Task;
+
+
+#endif

cpu/i386/tasking_helpers.h

@@ -0,0 +1,9 @@
+#ifndef TASKING_HELPERS_H
+#define TASKING_HELPERS_H
+
+#include "tasking.h"
+
+void switchTask(Registers *from, Registers *to);
+uint32_t readEip();
+
+#endif

cpu/i386/tasking_helpers.s

@@ -0,0 +1,53 @@
+.section .text
+.global switchTask
+switchTask:
+    pusha
+    pushf
+    mov %cr3, %eax #Push CR3
+    push %eax
+    mov 44(%esp), %eax #The first argument, where to save
+    mov %ebx, 4(%eax)
+    mov %ecx, 8(%eax)
+    mov %edx, 12(%eax)
+    mov %esi, 16(%eax)
+    mov %edi, 20(%eax)
+    mov 36(%esp), %ebx #EAX
+    mov 40(%esp), %ecx #IP
+    mov 20(%esp), %edx #ESP
+    add $4, %edx #Remove the return value ;)
+    mov 16(%esp), %esi #EBP
+    mov 4(%esp), %edi #EFLAGS
+    mov %ebx, (%eax)
+    mov %edx, 24(%eax)
+    mov %esi, 28(%eax)
+    mov %ecx, 32(%eax)
+    mov %edi, 36(%eax)
+    pop %ebx #CR3
+    mov %ebx, 40(%eax)
+    push %ebx #Goodbye again ;)
+    mov 48(%esp), %eax #Now it is the new object
+    mov 4(%eax), %ebx #EBX
+    mov 8(%eax), %ecx #ECX
+    mov 12(%eax), %edx #EDX
+    mov 16(%eax), %esi #ESI
+    mov 20(%eax), %edi #EDI
+    mov 28(%eax), %ebp #EBP
+    push %eax
+    mov 36(%eax), %eax #EFLAGS
+    push %eax
+    popf
+    pop %eax
+    mov 24(%eax), %esp #ESP
+    push %eax
+    mov 40(%eax), %eax #CR3
+    mov %eax, %cr3
+    pop %eax
+    push %eax
+    mov 32(%eax), %eax #EIP
+    xchg (%esp), %eax #We do not have any more registers to use as tmp storage
+    mov (%eax), %eax #EAX
+    ret #This ends all!
+.global readEip
+readEip:
+  pop %eax
+  jmp %eax

cpu/tasking.h

@@ -0,0 +1,10 @@
+#ifndef TASKING_H
+#define TASKING_H
+#include "i386/tasking.h"
+
+void tasking_init();
+void yield();
+Task* createTask(void* eip);
+void send_msg(uint32_t pid,char* msg);
+char* get_msg(uint32_t* sender);
+#endif

kernel/kernel.c

@@ -1,10 +1,18 @@
 #include "../cpu/cpu_init.h"
 #include "../cpu/i386/ports.h"
+#include "../cpu/i386/tasking.h"
 #include "../drivers/vga.h"
 #include <grub/text_fb_info.h>
 #include <stdlib.h>
 #include "multiboot.h"
 
+void task() {
+  vga_write_string("TASK!\n");
+  for (;;) {
+    yield();
+  }
+}
+
 void kmain(multiboot_info_t* header) {
   cpu_init();
   text_fb_info info;
@@ -19,26 +27,26 @@ void kmain(multiboot_info_t* header) {
   }
   vga_init(info);
   vga_write_string("Hello\n");
-  asm volatile("  \
-    cli; \
-    mov $0x23, %ax; \
-    mov %ax, %ds; \
-    mov %ax, %es; \
-    mov %ax, %fs; \
-    mov %ax, %gs; \
-                  \
-    mov %esp, %eax; \
-    pushl $0x23; \
-    pushl %eax; \
-    pushf; \
-    pop %eax; \
-    or $0x200,%eax; \
-    push %eax; \
-    pushl $0x1B; \
-    push $1f; \
-    iret; \
-  1: \
-    ");
+  // asm volatile("  \
+  //   cli; \
+  //   mov $0x23, %ax; \
+  //   mov %ax, %ds; \
+  //   mov %ax, %es; \
+  //   mov %ax, %fs; \
+  //   mov %ax, %gs; \
+  //                 \
+  //   mov %esp, %eax; \
+  //   pushl $0x23; \
+  //   pushl %eax; \
+  //   pushf; \
+  //   pop %eax; \
+  //   or $0x200,%eax; \
+  //   push %eax; \
+  //   pushl $0x1B; \
+  //   push $1f; \
+  //   iret; \
+  // 1: \
+  //   ");
   vga_write_string("UMODE!\n");
   port_byte_out(0xe9,'U');
   port_byte_out(0xe9,'M');
@@ -47,4 +55,9 @@ void kmain(multiboot_info_t* header) {
   port_byte_out(0xe9,'E');
   port_byte_out(0xe9,'!');
   port_byte_out(0xe9,'\n');
+  vga_write_string("Task create\n");
+  createTask(task);
+  vga_write_string("Task switch\n");
+  yield();
+  vga_write_string("Back in main\n");
 }

psinfo/i386/o.txt

@@ -1,4 +1,5 @@
 cpu/i386/interrupt.o
 cpu/i386/paging_helpers.o
 cpu/i386/seg_upd.o
+cpu/i386/tasking_helpers.o
 kernel/boot.o