358 lines
13 KiB
C
358 lines
13 KiB
C
/**
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* \file
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*/
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#include "cpu/halt.h"
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#include "cpu/paging.h"
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#include "cpu/serial.h"
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#include "cpu/tasking_helpers.h"
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#include "kmalloc.h"
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#include "tasking.h"
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#include <sys/types.h>
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#define MAX_PROCS 32768 //!< Maximum number of processes that can be running at a time
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#define HAS_UNBLOCKED_THREADS(proc) (proc->num_threads!=proc->num_threads_blocked) //!< Macro to check whethe a process has unblocked threads
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#define NUM_UNBLOCKED_THREADS(proc) (proc->num_threads-proc->num_threads_blocked) //!< Macro to get the number of unblocked threads for a process
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#define SAME_PROC(thread1,thread2) (thread1->process->pid==thread2->process->pid) //!< Macro to check whether two threads have the same PID
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#define SAME_THREAD(thread1,thread2) (thread1->process->pid==thread2->process->pid&&thread1->tid==thread2->tid) //!< Macro to check whether two threads have the same PID and TID
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pid_t next_pid=0; //!< PID to use for the next created process
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size_t num_procs=0; //!< Number of non-exited processes
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Process processes[MAX_PROCS]; //!< Array pf processes by PID
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char proc_schedule_bmap[MAX_PROCS/8]; //!< Bitmap of what processes are scheduled
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Thread* current_thread; //!< Currently running thread
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static Thread* ready_to_run_head=NULL; //!< Head of the linked list of ready to run threads
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static Thread* ready_to_run_tail=NULL; //!< Tail of the linked list of ready to run threads
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/**
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* Check whether a process is scheduled
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* \param index The PID to check
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* \return whether the process is scheduled
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*/
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static char is_proc_scheduled(pid_t index) {
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size_t byte=index/8;
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size_t bit=index%8;
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char entry=proc_schedule_bmap[byte];
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return (entry&(1<<bit))>0;
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}
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/**
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* Mark a process as scheduled
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* \param index The PID to mark
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*/
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static void mark_proc_scheduled(pid_t index) {
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if (is_proc_scheduled(index)) {
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serial_printf("Attempt to schedule a thread in a process with a scheduled thread! (PID %d)\n",index);
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halt();
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}
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size_t byte=index/8;
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size_t bit=index%8;
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proc_schedule_bmap[byte]=proc_schedule_bmap[byte]|(1<<bit);
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}
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/**
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* Unmark a process as scheduled
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* \param index The PID to unmark
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*/
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static void unmark_proc_scheduled(pid_t index) {
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size_t byte=index/8;
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size_t bit=index%8;
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proc_schedule_bmap[byte]=proc_schedule_bmap[byte]&(~(1<<bit));
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}
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void tasking_create_task(void* eip,void* cr3,char kmode,char param1_exists,void* param1_arg,char param2_exists,void* param2_arg,char isThread) {
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if (next_pid>MAX_PROCS && !isThread) {
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serial_printf("Failed to create a process, as 32k processes have been created already.\n");
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halt(); //Cannot ever create more than 32k processes, as I don't currently reuse PIDs.
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}
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void* param1;
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if (param1_exists) {
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param1=param1_arg;
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} else {
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param1=NULL;
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}
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void* param2;
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if (param2_exists) {
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if (isThread) {
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serial_printf("Param2 in Thread!\n");
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halt();
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}
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param2=param2_arg;
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} else {
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param2=NULL;
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}
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Process* proc=&processes[(pid_t)param2_arg];
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Thread* thread=kmalloc(sizeof(Thread));
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if (isThread) {
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proc->num_threads++;
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thread->cr3=proc->first_thread->cr3;
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} else {
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proc=kmalloc(sizeof(Process));
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if (current_thread) {
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proc->priv=current_thread->process->priv;
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} else {
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proc->priv=1;
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}
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proc->pid=next_pid;
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next_pid++;
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proc->next_tid=0;
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proc->num_threads=1;
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proc->num_threads_blocked=0;
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proc->first_thread=thread;
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thread->cr3=cr3;
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}
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thread->process=proc;
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thread->errno=0;
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thread->tid=proc->next_tid;
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proc->next_tid++;
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setup_kstack(thread,param1,param2,kmode,eip);
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thread->prev_ready_to_run=NULL;
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thread->next_ready_to_run=NULL;
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if (isThread) {
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thread->next_thread_in_process=proc->first_thread;
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thread->prev_thread_in_process=NULL;
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thread->state=THREAD_READY;
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proc->first_thread->prev_thread_in_process=thread;
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proc->first_thread=thread;
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} else {
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thread->next_thread_in_process=NULL;
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thread->prev_thread_in_process=NULL;
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if (!is_proc_scheduled(proc->pid)) {
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if (ready_to_run_tail) {
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thread->state=THREAD_READY;
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ready_to_run_tail->next_ready_to_run=thread;
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thread->prev_ready_to_run=ready_to_run_tail;
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ready_to_run_tail=thread;
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mark_proc_scheduled(proc->pid);
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} else if (current_thread) {
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thread->state=THREAD_READY;
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ready_to_run_head=thread;
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ready_to_run_tail=thread;
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mark_proc_scheduled(proc->pid);
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} else {
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thread->state=THREAD_RUNNING;
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current_thread=thread;
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}
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}
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}
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if (!isThread) {
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num_procs++;
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}
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serial_printf("Created thread with PID %d and TID %d.\n",proc->pid,thread->tid);
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}
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void tasking_init() {
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for (size_t i = 0; i < MAX_PROCS; i++) {
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processes[i].num_threads=0;
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}
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tasking_create_task(NULL,get_cr3(),1,0,0,0,0,0);
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}
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char tasking_is_privleged() {
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return current_thread->process->priv;
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}
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pid_t tasking_get_PID() {
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return current_thread->process->pid;
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}
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int* tasking_get_errno_address() {
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return ¤t_thread->errno;
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}
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pid_t tasking_new_thread(void* start,pid_t pid,char param_exists,void* param_arg) {
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tasking_create_task(start,NULL,0,param_exists,param_arg,0,(void*)pid,1);
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return processes[pid].first_thread->tid;
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}
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/**
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* Switch to a thread and schedule the next ready thread in the current process, if there is one.
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* \param thread The thread to switch to
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*/
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void switch_to_thread(Thread* thread) {
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// Unlink the thread from the list of ready-to-run threads
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if (thread!=ready_to_run_head) {
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thread->prev_ready_to_run->next_ready_to_run=thread->next_ready_to_run;
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if (thread->next_ready_to_run) {
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thread->next_ready_to_run->prev_ready_to_run=thread->prev_ready_to_run;
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}
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} else {
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ready_to_run_head=thread->next_ready_to_run;
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if (ready_to_run_head==NULL) {
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ready_to_run_tail=NULL;
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}
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}
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unmark_proc_scheduled(thread->process->pid);
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thread->prev_ready_to_run=NULL;
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thread->next_ready_to_run=NULL;
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if (current_thread->state==THREAD_RUNNING) {
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current_thread->state=THREAD_READY;
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}
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Thread* current_thread_next_ready=current_thread->next_thread_in_process;
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while ((current_thread_next_ready&¤t_thread_next_ready->state!=THREAD_READY)||(current_thread_next_ready&&SAME_THREAD(thread,current_thread_next_ready))) {
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current_thread_next_ready=current_thread_next_ready->next_thread_in_process;
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}
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if (!current_thread_next_ready) {
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current_thread_next_ready=current_thread->process->first_thread;
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while ((current_thread_next_ready&¤t_thread_next_ready->state!=THREAD_READY)||(current_thread_next_ready&&SAME_THREAD(thread,current_thread_next_ready))) {
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current_thread_next_ready=current_thread_next_ready->next_thread_in_process;
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}
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}
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if (!current_thread_next_ready) {
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//This process is fully blocked, try the process of the thread we're yielding to
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current_thread_next_ready=thread->next_thread_in_process;
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while ((current_thread_next_ready&¤t_thread_next_ready->state!=THREAD_READY)||(current_thread_next_ready&&SAME_THREAD(thread,current_thread_next_ready))) {
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current_thread_next_ready=current_thread_next_ready->next_thread_in_process;
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}
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if (!current_thread_next_ready) {
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current_thread_next_ready=thread->process->first_thread;
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while ((current_thread_next_ready&¤t_thread_next_ready->state!=THREAD_READY)||(current_thread_next_ready&&SAME_THREAD(thread,current_thread_next_ready))) {
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current_thread_next_ready=current_thread_next_ready->next_thread_in_process;
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}
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}
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}
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if (current_thread_next_ready && !is_proc_scheduled(current_thread->process->pid)) {
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// Link the thread onto the list of ready to run threads
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if (ready_to_run_tail) {
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current_thread_next_ready->prev_ready_to_run=ready_to_run_tail;
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ready_to_run_tail->next_ready_to_run=current_thread_next_ready;
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ready_to_run_tail=current_thread_next_ready;
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} else {
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ready_to_run_head=current_thread_next_ready;
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ready_to_run_tail=current_thread_next_ready;
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}
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mark_proc_scheduled(current_thread->process->pid);
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}
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serial_printf("Switching to PID %d TID %d.\n",thread->process->pid,thread->tid);
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switch_to_thread_asm(thread);
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}
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void tasking_yield() {
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serial_printf("Attempting to yield\n");
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if (ready_to_run_head) {
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serial_printf("Attempting to switch to PID %d TID %d\n",ready_to_run_head->process->pid,ready_to_run_head->tid);
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switch_to_thread(ready_to_run_head);
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} else {
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if (NUM_UNBLOCKED_THREADS(current_thread->process)>1) {
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serial_printf("The ready to run list is empty, and the current process has other unblocked threads? This is an invalid state! Halting!\n");
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halt();
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} else if (NUM_UNBLOCKED_THREADS(current_thread->process)==1) {
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serial_printf("Yield failed, no other ready processes\n");
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return;
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} else {
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if (num_procs==0) {
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serial_printf("All processes exited, halting\n");
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halt();
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} else {
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serial_printf("All threads in all processes blocked, waiting for an IRQ which unblocks a thread\n");
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// All threads in all processes blocked, so wait for an IRQ whose handler unblocks a thread.
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do { wait_for_unblocked_thread_asm(); } while (ready_to_run_head==NULL);
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}
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serial_printf("Attempting to switch to PID %d TID %d\n",ready_to_run_head->process->pid,ready_to_run_head->tid);
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switch_to_thread(ready_to_run_head);
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}
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}
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}
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void tasking_block(thread_state newstate) {
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if (ready_to_run_head&&SAME_THREAD(ready_to_run_head,current_thread)) {
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ready_to_run_head=ready_to_run_head->next_ready_to_run;
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if (ready_to_run_head==NULL) {
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ready_to_run_tail=NULL;
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}
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}
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if (ready_to_run_tail&&SAME_THREAD(ready_to_run_tail,current_thread)) {
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ready_to_run_tail=ready_to_run_tail->prev_ready_to_run;
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if (ready_to_run_tail==NULL) {
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ready_to_run_head=NULL;
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}
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}
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if (ready_to_run_head&&ready_to_run_head->next_ready_to_run) {
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for (Thread* thread=ready_to_run_head->next_ready_to_run;thread!=NULL;thread=thread->next_ready_to_run) {
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if (SAME_THREAD(thread,current_thread)) {
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thread->prev_ready_to_run->next_ready_to_run=thread->next_ready_to_run;
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if (thread->next_ready_to_run) {
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thread->next_ready_to_run->prev_ready_to_run=thread->prev_ready_to_run;
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}
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break;
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}
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}
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}
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for (Thread* thread=current_thread->process->first_thread;thread!=NULL;thread=thread->next_thread_in_process) {
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if (thread->tid==current_thread->tid) {
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thread->state=newstate;
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}
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}
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}
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void tasking_unblock(pid_t pid,pid_t tid) {
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serial_printf("Unblocking PID %d TID %d\n",pid,tid);
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if (processes[pid].num_threads==0) {
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serial_printf("PID %d does not exist!\n",pid);
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}
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Thread* thread=processes[pid].first_thread;
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for (;thread!=NULL;thread=thread->next_thread_in_process) {
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if (thread->tid==tid) {
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break;
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}
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}
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if (!thread) {
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serial_printf("PID %d TID %d does not exist!\n",pid,thread);
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}
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if (thread->tid!=tid) {
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serial_printf("Error! Got wrong thread! (Wanted TID %d, got TID %d)\n",tid,thread->tid);
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halt();
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}
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if (thread->state==THREAD_EXITED||thread->state==THREAD_READY||thread->state==THREAD_RUNNING) {
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serial_printf("Tried to unblock an exited/ready/running thread!\n");
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return;
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}
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thread->state=THREAD_READY;
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if (!is_proc_scheduled(thread->process->pid)) {
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// Link the thread onto the list of ready to run threads
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if (ready_to_run_tail) {
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thread->prev_ready_to_run=ready_to_run_tail;
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ready_to_run_tail->next_thread_in_process=thread;
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ready_to_run_tail=thread;
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} else {
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ready_to_run_head=thread;
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ready_to_run_tail=thread;
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}
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mark_proc_scheduled(thread->process->pid);
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}
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}
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void tasking_exit(int code) {
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serial_printf("PID %d is exiting with code %d.\n",current_thread->process->pid,code);
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if (ready_to_run_head&&SAME_PROC(ready_to_run_head,current_thread)) {
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ready_to_run_head=ready_to_run_head->next_ready_to_run;
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if (ready_to_run_head==NULL) {
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ready_to_run_tail=NULL;
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}
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}
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if (ready_to_run_tail&&SAME_PROC(ready_to_run_tail,current_thread)) {
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ready_to_run_tail=ready_to_run_tail->prev_ready_to_run;
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if (ready_to_run_tail==NULL) {
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ready_to_run_head=NULL;
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}
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}
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if (ready_to_run_head&&ready_to_run_head->next_ready_to_run) {
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for (Thread* thread=ready_to_run_head->next_ready_to_run;thread!=NULL;thread=thread->next_ready_to_run) {
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if (SAME_PROC(thread,current_thread)) {
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thread->prev_ready_to_run->next_ready_to_run=thread->next_ready_to_run;
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if (thread->next_ready_to_run) {
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thread->next_ready_to_run->prev_ready_to_run=thread->prev_ready_to_run;
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}
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break;
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}
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}
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}
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unmark_proc_scheduled(current_thread->process->pid);
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for (Thread* thread=current_thread->process->first_thread;thread!=NULL;thread=thread->next_thread_in_process) {
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thread->state=THREAD_EXITED;
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}
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current_thread->process->num_threads_blocked=current_thread->process->num_threads;
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num_procs--;
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tasking_yield();
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}
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