src/kmain.c

@@ -82,6 +82,21 @@ struct boot_context boot_ctx;
 extern struct process_t* processes_list;
 extern struct process_t* current_process;
 
+void pedicel_main(void* arg)
+{
+	
+}
+
+void two_main(void* arg)
+{
+
+}
+
+void three_main(void* arg)
+{
+
+}
+
 // This is our entry point
 void kmain()
 {
@@ -118,13 +133,9 @@ void kmain()
 
 	vmm_init();
 	
-	struct process_t* pedicel = process_create();
-	struct process_t* two = process_create();
-	struct process_t* three = process_create();
-
-	process_add(&processes_list, pedicel);
-	process_add(&processes_list, two);
-	process_add(&processes_list, three);
+	struct process_t* pedicel = process_create("pedicel", (void*)pedicel_main, 0);
+	struct process_t* two = process_create("two", (void*)two_main, 0);
+	struct process_t* three = process_create("three", (void*)three_main, 0);
 	process_display_list(processes_list);
 
 	scheduler_init();

src/mem/heap/kheap.c

@@ -3,6 +3,7 @@
 #include "mem/paging/pmm.h"
 #include <stddef.h>
 #include <kernel.h>
+#include "sched/process.h"
 
 extern uint64_t kernel_phys_base;
 extern uint64_t kernel_virt_base;
@@ -103,4 +104,12 @@ void kfree(void* ptr)
     // Set it free!
     struct heap_block_t* block = (struct heap_block_t*)((uintptr_t)ptr - sizeof(struct heap_block_t));
     block->free = true;
+}
+
+// Should alloc enough for a stack (at least 64kb) to be used for a process.
+// Should return a pointer to top of the stack (as stack grows DOWNWARDS)
+void* kalloc_stack()
+{
+    void* ptr = kmalloc(PROCESS_STACK_SIZE);
+    return ptr+PROCESS_STACK_SIZE;
 }

src/mem/heap/kheap.h

@@ -22,5 +22,6 @@ struct heap_block_t
 void kheap_init();
 void* kmalloc(size_t size);
 void kfree(void* ptr);
+void* kalloc_stack();
 
 #endif

src/sched/process.c

@@ -2,10 +2,14 @@
 #include "process.h"
 #include "mem/heap/kheap.h"
 #include "kernel.h"
+#include "string/string.h"
+#include "mem/gdt/gdt.h"
 
 struct process_t* processes_list;
 struct process_t* current_process;
 
+size_t next_free_pid = 0;
+
 void process_init()
 {
     processes_list = NULL;
@@ -26,16 +30,35 @@ void process_display_list(struct process_t* processes_list)
     DEBUG("NULL");
 }
 
-struct process_t* process_create()
+struct process_t* process_create(char* name, void(*function)(void*), void* arg)
 {
+    CLEAR_INTERRUPTS;
     struct process_t* proc = (struct process_t*)kmalloc(sizeof(struct process_t));
     
+    struct cpu_status_t* ctx = (struct cpu_status_t*)kmalloc(sizeof(struct cpu_status_t));
+
+    // No more memory?
     if (!proc) return NULL;
+    if (!ctx) return NULL;
 
-    proc->context = NULL;
+    strncpy(proc->name, name, PROCESS_NAME_MAX);
+    proc->pid = next_free_pid++;
     proc->status = READY;
-    proc->next = NULL;
 
+    proc->context = ctx;
+    proc->context->iret_ss = KERNEL_DATA_SEGMENT; // process will live in kernel mode
+    proc->context->iret_rsp = (uint64_t)kalloc_stack();
+    proc->context->iret_flags = 0x202; //bit 2 and 9 set (Interrupt Flag)
+    proc->context->iret_cs = KERNEL_CODE_SEGMENT;
+    proc->context->iret_rip = (uint64_t)function; // beginning of executable code
+    proc->context->rdi = (uint64_t)arg; // 1st arg is in rdi (as per x64 calling convention)
+    proc->context->rbp = 0;
+
+    proc->next = 0;
+
+    process_add(&processes_list, proc);
+
+    SET_INTERRUPTS;
     return proc;
 }
 

src/sched/process.h

@@ -1,6 +1,8 @@
 #ifndef PROCESS_H
 #define PROCESS_H
 
+#include <stddef.h>
+
 typedef enum 
 {
     READY,
@@ -8,15 +10,21 @@ typedef enum
     DEAD
 } status_t;
 
+#define PROCESS_NAME_MAX 64
+#define PROCESS_STACK_SIZE 0x100 // 64kb
+
 struct process_t
 {
+    size_t pid;
+    char name[PROCESS_NAME_MAX];
+
     status_t status;
     struct cpu_status_t* context;
     struct process_t* next;
 };
 
 void process_init();
-struct process_t* process_create();
+struct process_t* process_create(char* name, void(*function)(void*), void* arg);
 void process_add(struct process_t** processes_list, struct process_t* process);
 void process_delete(struct process_t** processes_list, struct process_t* process);
 struct process_t* process_get_next(struct process_t* process);

src/sched/scheduler.c

@@ -4,32 +4,37 @@
 extern struct process_t* processes_list;
 extern struct process_t* current_process;
 
-// DEBUG: how many times we did schedule
-int scheduled = 0;
-
 void scheduler_init()
 {
     // Choose first process?
     current_process = processes_list;
 }
 
-void scheduler_schedule()
+struct cpu_status_t* scheduler_schedule(struct cpu_status_t* context)
 {
-    //DEBUG("Scheduler called!");
-    if (current_process->next != NULL)
-    {
-        current_process = current_process->next;
-    } else
-    {
-        current_process = processes_list;
-    }
-    scheduled++;
-    DEBUG("SCHEDULER CALLED: current_process=%p", current_process);
+    current_process->context = context;
+    current_process->status = READY;
 
-    // debug
-    /* if (scheduled == 5)
-    {
-        DEBUG("enough, halting");
-        hcf();
-    } */
+    for (;;) {
+        struct process_t* prev_process = current_process;
+        if (current_process->next != NULL)
+        {
+            current_process = current_process->next;
+        } else
+        {
+            current_process = processes_list;
+        }
+        
+        if (current_process != NULL && current_process->status == DEAD)
+        {
+            process_delete(&prev_process, current_process);
+        } else
+        {
+            current_process->status = RUNNING;
+            break;
+        }
+    }
+    
+    DEBUG("SCHEDULER CALLED: current_process=%p", current_process);
+    return current_process->context;
 }

src/string/string.c

@@ -16,4 +16,11 @@ char *strcat(char *dest, const char *src){
         dest[i+j] = src[j];
     dest[i+j] = '\0';
     return dest;
+}
+
+// https://stackoverflow.com/questions/14159625/implementation-of-strncpy
+void strncpy(char* dst, const char* src, size_t n)
+{
+   size_t i = 0;
+   while(i++ != n && (*dst++ = *src++));
 }

src/string/string.h

@@ -3,5 +3,6 @@
 
 char *strcpy(char *dest, const char *src);
 char *strcat(char *dest, const char *src);
+void strncpy(char* dst, const char* src, size_t n);
 
 #endif