os/kernel/tasking.c

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#include "tasking.h"
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#include <sys/types.h>
#include "kmalloc.h"
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#include "cpu/serial.h"
#include "cpu/halt.h"
#include "cpu/paging.h"
#include "cpu/tasking_helpers.h"
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#define MAX_PROCS 32768
#define HAS_UNBLOCKED_THREADS(proc) (proc->numThreads!=proc->numThreadsBlocked)
#define NUM_UNBLOCKED_THREADS(proc) (proc->numThreads-proc->numThreadsBlocked)
#define SAME_PROC(thread1,thread2) (thread1->process->pid==thread2->process->pid)
#define SAME_THREAD(thread1,thread2) (thread1->process->pid==thread2->process->pid&&thread1->tid==thread2->tid)
uint32_t next_pid=0;
uint32_t num_procs=0;
Process* processes[MAX_PROCS];
char proc_schedule_bmap[MAX_PROCS/8];
Thread* currentThread;
static Thread* readyToRunHead=NULL;
static Thread* readyToRunTail=NULL;
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static uint32_t* kstacks=(uint32_t*)KSTACKS_START;
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static char is_proc_scheduled(uint32_t index) {
uint32_t byte=index/8;
uint32_t bit=index%8;
char entry=proc_schedule_bmap[byte];
return (entry&(1<<bit))>0;
}
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static void mark_proc_scheduled(uint32_t index) {
if (is_proc_scheduled(index)) {
serial_printf("Attempt to schedule a thread in a process with a scheduled thread! (PID %d)\n",index);
halt();
}
uint32_t byte=index/8;
uint32_t bit=index%8;
proc_schedule_bmap[byte]=proc_schedule_bmap[byte]|(1<<bit);
}
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static void unmark_proc_scheduled(uint32_t index) {
uint32_t byte=index/8;
uint32_t bit=index%8;
proc_schedule_bmap[byte]=proc_schedule_bmap[byte]&(~(1<<bit));
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}
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void tasking_createTask(void* eip,void* cr3,char kmode,char param1_exists,uint32_t param1_arg,char param2_exists,uint32_t param2_arg,char isThread) {
if (next_pid>MAX_PROCS && !isThread) {
serial_printf("Failed to create a process, as 32k processes have been created already.\n");
halt(); //Cannot ever create more than 32k processes, as I don't currently reuse PIDs.
}
uint32_t param1;
if (param1_exists) {
param1=param1_arg;
} else {
param1=1;
}
uint32_t param2;
if (param2_exists) {
if (isThread) {
serial_printf("Param2 in Thread!\n");
halt();
}
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param2=param2_arg;
} else {
param2=2;
}
Process* proc;
Thread* thread=kmalloc(sizeof(Thread));
if (isThread) {
proc=processes[(pid_t)param2_arg];
proc->numThreads++;
thread->cr3=proc->firstThread->cr3;
} else {
proc=kmalloc(sizeof(Process));
if (currentThread) {
proc->priv=currentThread->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;
proc->numThreads=1;
proc->numThreadsBlocked=0;
proc->firstThread=thread;
processes[proc->pid]=proc;
thread->cr3=cr3;
}
thread->process=proc;
thread->errno=0;
thread->tid=proc->next_tid;
proc->next_tid++;
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void* old_cr3=get_cr3();
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uint32_t kstack_num=new_kstack();
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load_address_space(thread->cr3);
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if (kmode) {
uint32_t top_idx=(1024*(kstack_num+1));
thread->kernel_esp=((uint32_t)(&kstacks[top_idx-5]));
thread->kernel_esp_top=thread->kernel_esp;
kstacks[top_idx-1]=(uint32_t)eip;
} else {
uint32_t top_idx=(1024*(kstack_num+1));
thread->kernel_esp=((uint32_t)(&kstacks[top_idx-7]));
thread->kernel_esp_top=thread->kernel_esp;
kstacks[top_idx-3]=(uint32_t)task_init;
uint32_t* user_stack=(uint32_t*)(((uint32_t)alloc_pages(2))+0x2000);
int buffer_pg_num=(((uint32_t)user_stack)-0x2000)>>12;
make_protector(buffer_pg_num);
user_stack-=2;
user_stack[0]=param1;
user_stack[1]=param2;
kstacks[top_idx-2]=(uint32_t)user_stack;
kstacks[top_idx-1]=(uint32_t)eip;
}
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load_address_space(old_cr3);
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thread->prevReadyToRun=NULL;
thread->nextReadyToRun=NULL;
if (isThread) {
thread->nextThreadInProcess=proc->firstThread;
thread->prevThreadInProcess=NULL;
thread->state=THREAD_READY;
proc->firstThread->prevThreadInProcess=thread;
proc->firstThread=thread;
} else {
thread->nextThreadInProcess=NULL;
thread->prevThreadInProcess=NULL;
if (!is_proc_scheduled(proc->pid)) {
if (readyToRunTail) {
thread->state=THREAD_READY;
readyToRunTail->nextReadyToRun=thread;
thread->prevReadyToRun=readyToRunTail;
readyToRunTail=thread;
mark_proc_scheduled(proc->pid);
} else if (currentThread) {
thread->state=THREAD_READY;
readyToRunHead=thread;
readyToRunTail=thread;
mark_proc_scheduled(proc->pid);
} else {
thread->state=THREAD_RUNNING;
currentThread=thread;
}
}
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}
if (!isThread) {
num_procs++;
}
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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tasking_createTask(NULL,get_cr3(),1,0,0,0,0,0);
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}
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char tasking_isPrivleged() {
return currentThread->process->priv;
}
pid_t tasking_getPID() {
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return currentThread->process->pid;
}
int* tasking_get_errno_address() {
return &currentThread->errno;
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}
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uint32_t tasking_new_thread(void* start,pid_t pid,char param_exists,uint32_t param_arg) {
tasking_createTask(start,NULL,0,param_exists,param_arg,0,pid,1);
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return processes[pid]->firstThread->tid;
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}
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void switch_to_thread(Thread* thread) {
// Unlink the thread from the list of ready-to-run threads
if (thread!=readyToRunHead) {
thread->prevReadyToRun->nextReadyToRun=thread->nextReadyToRun;
if (thread->nextReadyToRun) {
thread->nextReadyToRun->prevReadyToRun=thread->prevReadyToRun;
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}
} else {
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readyToRunHead=thread->nextReadyToRun;
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if (readyToRunHead==NULL) {
readyToRunTail=NULL;
}
}
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unmark_proc_scheduled(thread->process->pid);
thread->prevReadyToRun=NULL;
thread->nextReadyToRun=NULL;
if (currentThread->state==THREAD_RUNNING) {
currentThread->state=THREAD_READY;
}
Thread* currentThreadNextReady=currentThread->nextThreadInProcess;
while ((currentThreadNextReady&&currentThreadNextReady->state!=THREAD_READY)||(currentThreadNextReady&&SAME_THREAD(thread,currentThreadNextReady))) {
currentThreadNextReady=currentThreadNextReady->nextThreadInProcess;
}
if (!currentThreadNextReady) {
currentThreadNextReady=currentThread->process->firstThread;
while ((currentThreadNextReady&&currentThreadNextReady->state!=THREAD_READY)||(currentThreadNextReady&&SAME_THREAD(thread,currentThreadNextReady))) {
currentThreadNextReady=currentThreadNextReady->nextThreadInProcess;
}
}
if (!currentThreadNextReady) {
//This process is fully blocked, try the process of the thread we're yielding to
currentThreadNextReady=thread->nextThreadInProcess;
while ((currentThreadNextReady&&currentThreadNextReady->state!=THREAD_READY)||(currentThreadNextReady&&SAME_THREAD(thread,currentThreadNextReady))) {
currentThreadNextReady=currentThreadNextReady->nextThreadInProcess;
}
if (!currentThreadNextReady) {
currentThreadNextReady=thread->process->firstThread;
while ((currentThreadNextReady&&currentThreadNextReady->state!=THREAD_READY)||(currentThreadNextReady&&SAME_THREAD(thread,currentThreadNextReady))) {
currentThreadNextReady=currentThreadNextReady->nextThreadInProcess;
}
}
}
if (currentThreadNextReady && !is_proc_scheduled(currentThread->process->pid)) {
// Link the thread onto the list of ready to run threads
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if (readyToRunTail) {
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currentThreadNextReady->prevReadyToRun=readyToRunTail;
readyToRunTail->nextThreadInProcess=currentThreadNextReady;
readyToRunTail=currentThreadNextReady;
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} else {
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readyToRunHead=currentThreadNextReady;
readyToRunTail=currentThreadNextReady;
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}
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mark_proc_scheduled(currentThread->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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load_smap(thread->cr3);
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switch_to_thread_asm(thread);
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}
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void tasking_yield() {
serial_printf("Attempting to yield\n");
if (readyToRunHead) {
serial_printf("Attempting to switch to PID %d TID %d\n",readyToRunHead->process->pid,readyToRunHead->tid);
switch_to_thread(readyToRunHead);
} else {
if (NUM_UNBLOCKED_THREADS(currentThread->process)>1) {
serial_printf("The ready to run list is empty, and the current process has other unblocked threads? This is an invalid state! Halting!\n");
halt();
} else if (NUM_UNBLOCKED_THREADS(currentThread->process)==1) {
serial_printf("Yield failed, no other ready processes\n");
return;
} else {
if (num_procs==0) {
serial_printf("All processes exited, halting\n");
halt();
} else {
serial_printf("All threads in all processes blocked, waiting for an IRQ which unblocks a thread\n");
// 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 (readyToRunHead==NULL);
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}
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serial_printf("Attempting to switch to PID %d TID %d\n",readyToRunHead->process->pid,readyToRunHead->tid);
switch_to_thread(readyToRunHead);
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}
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}
}
void tasking_block(ThreadState newstate) {
if (readyToRunHead&&SAME_THREAD(readyToRunHead,currentThread)) {
readyToRunHead=readyToRunHead->nextReadyToRun;
if (readyToRunHead==NULL) {
readyToRunTail=NULL;
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}
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}
if (readyToRunTail&&SAME_THREAD(readyToRunTail,currentThread)) {
readyToRunTail=readyToRunTail->prevReadyToRun;
if (readyToRunTail==NULL) {
readyToRunHead=NULL;
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}
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}
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if (readyToRunHead&&readyToRunHead->nextReadyToRun) {
for (Thread* thread=readyToRunHead->nextReadyToRun;thread!=NULL;thread=thread->nextReadyToRun) {
if (SAME_THREAD(thread,currentThread)) {
thread->prevReadyToRun->nextReadyToRun=thread->nextReadyToRun;
if (thread->nextReadyToRun) {
thread->nextReadyToRun->prevReadyToRun=thread->prevReadyToRun;
}
break;
}
}
}
for (Thread* thread=currentThread->process->firstThread;thread!=NULL;thread=thread->nextThreadInProcess) {
if (thread->tid==currentThread->tid) {
thread->state=newstate;
}
}
}
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void tasking_unblock(pid_t pid,uint32_t tid) {
serial_printf("Unblocking PID %d TID %d\n",pid,tid);
if (!processes[pid]) {
serial_printf("PID %d does not exist!\n",pid);
}
Thread* thread=processes[pid]->firstThread;
for (;thread!=NULL;thread=thread->nextThreadInProcess) {
if (thread->tid==tid) {
break;
}
}
if (!thread) {
serial_printf("PID %d TID %d does not exist!\n",pid,thread);
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}
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if (thread->tid!=tid) {
serial_printf("Error! Got wrong thread! (Wanted TID %d, got TID %d)\n",tid,thread->tid);
halt();
}
thread->state=THREAD_READY;
if (!is_proc_scheduled(thread->process->pid)) {
// Link the thread onto the list of ready to run threads
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if (readyToRunTail) {
thread->prevReadyToRun=readyToRunTail;
readyToRunTail->nextThreadInProcess=thread;
readyToRunTail=thread;
} else {
readyToRunHead=thread;
readyToRunTail=thread;
}
mark_proc_scheduled(thread->process->pid);
}
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}
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void tasking_exit(uint8_t code) {
serial_printf("PID %d is exiting with code %d.\n",currentThread->process->pid,code);
if (readyToRunHead&&SAME_PROC(readyToRunHead,currentThread)) {
readyToRunHead=readyToRunHead->nextReadyToRun;
if (readyToRunHead==NULL) {
readyToRunTail=NULL;
}
}
if (readyToRunTail&&SAME_PROC(readyToRunTail,currentThread)) {
readyToRunTail=readyToRunTail->prevReadyToRun;
if (readyToRunTail==NULL) {
readyToRunHead=NULL;
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}
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}
if (readyToRunHead&&readyToRunHead->nextReadyToRun) {
for (Thread* thread=readyToRunHead->nextReadyToRun;thread!=NULL;thread=thread->nextReadyToRun) {
if (SAME_PROC(thread,currentThread)) {
thread->prevReadyToRun->nextReadyToRun=thread->nextReadyToRun;
if (thread->nextReadyToRun) {
thread->nextReadyToRun->prevReadyToRun=thread->prevReadyToRun;
}
break;
}
}
}
unmark_proc_scheduled(currentThread->process->pid);
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for (Thread* thread=currentThread->process->firstThread;thread!=NULL;thread=thread->nextThreadInProcess) {
thread->state=THREAD_EXITED;
}
currentThread->process->numThreadsBlocked=currentThread->process->numThreads;
num_procs--;
tasking_yield();
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}