//---------------------------------------------------------------------- // // ProcessSchedule // // Schedule the next process to run. If there are no processes to // run, exit. This means that there should be an idle loop process // if you want to allow the system to "run" when there's no real // work to be done. // // NOTE: the scheduler should only be called from a trap or interrupt // handler. This way, interrupts are disabled. Also, it must be // called consistently, and because it might be called from an interrupt // handler (the timer interrupt), it must ALWAYS be called from a trap // or interrupt handler. // // Note that this procedure doesn't actually START the next process. // It only changes the currentPCB and other variables so the next // return from interrupt will restore a different context from that // which was saved. // //---------------------------------------------------------------------- void ProcessSchedule () { PCB *pcb=NULL; int i=0; Link *l=NULL; uint32 intrvals = 0; intrvals = DisableIntrs(); // The OS exits if there's no runnable process. This is a feature, not a // bug. An easy solution to allowing no runnable "user" processes is to // have an "idle" process that's simply an infinite loop. if (AQueueEmpty(&runQueue)) { if (!AQueueEmpty(&waitQueue)) { printf("FATAL ERROR: no runnable processes, but there are sleeping processes waiting!\n"); l = AQueueFirst(&waitQueue); while (l != NULL) { pcb = AQueueObject(l); printf("Sleeping process %d: ", i++); printf("PID = %d\n", (int)(pcb - pcbs)); l = AQueueNext(l); } exitsim(); } printf ("No runnable processes - exiting!\n"); exitsim (); // NEVER RETURNS } // Move the front of the queue to the end if currentPCB is not on sleep queue. // The running process was the one in front. if (currentPCB->flags & PROCESS_STATUS_RUNNABLE) { AQueueMoveAfter(&runQueue, AQueueLast(&runQueue), AQueueFirst(&runQueue)); } // Now, run the one at the head of the queue. pcb = (PCB *)AQueueObject(AQueueFirst(&runQueue)); currentPCB = pcb; dbprintf ('p',"About to switch to PCB 0x%x,flags=0x%x @ 0x%x\n", (int)pcb, pcb->flags, (int)(pcb->sysStackPtr[PROCESS_STACK_IAR])); // Clean up zombie processes here. This is done at interrupt time // because it can't be done while the process might still be running while (!AQueueEmpty(&zombieQueue)) { pcb = (PCB *)AQueueObject(AQueueFirst(&zombieQueue)); dbprintf ('p', "Freeing zombie PCB 0x%x.\n", (int)pcb); if (AQueueRemove(&(pcb->l)) != QUEUE_SUCCESS) { printf("FATAL ERROR: could not remove zombie process from zombieQueue in ProcessSchedule!\n"); exitsim(); } ProcessFreeResources(pcb); } RestoreIntrs(intrvals); }
//--------------------------------------------------------------------------- // CondHandleSignal // // This call wakes up exactly one process waiting on the condition // variable, if at least one is waiting. If there are no processes // waiting on the condition variable, it does nothing. In either case, // the calling process must have acquired the lock associated with // condition variable for this call to succeed, in which case it returns // 0. If the calling process does not own the lock, it returns 1, // indicating that the call was not successful. This function should be // written in such a way that the calling process should retain the // acquired lock even after the call completion (in other words, it // should not release the lock it has already acquired before the call). // // Note that the process woken up by this call tries to acquire the lock // associated with the condition variable as soon as it wakes up. Thus, // for such a process to run, the process invoking CondHandleSignal // must explicitly release the lock after the call is complete. //--------------------------------------------------------------------------- int CondSignal(Cond *c) { Link *l; int intrs; PCB *pcb; if (!c) return SYNC_FAIL; intrs = DisableIntrs (); dbprintf ('s', "CondSignal: Proc %d signalling cond %d.\n", GetCurrentPid(), (int)(c-conds)); if (c->lock->pid != GetCurrentPid()) { dbprintf('s', "CondSignal: Proc %d does not own cond %d.\n", GetCurrentPid(), (int)(c-conds)); return SYNC_FAIL; } if (!AQueueEmpty(&c->waiting)) { // there is a process to wake up l = AQueueFirst(&c->waiting); pcb = (PCB *)AQueueObject(l); if (AQueueRemove(&l) != QUEUE_SUCCESS) { printf("FATAL ERROR: could not remove link from cond queue in CondSignal!\n"); exitsim(); } dbprintf ('s', "CondSignal: Waking up PID %d, it still needs to acquire lock.\n", GetPidFromAddress(pcb)); ProcessWakeup (pcb); } else { dbprintf('s', "CondSignal: Proc %d signalled, but no processes were waiting.\n", GetCurrentPid()); } RestoreIntrs (intrs); return SYNC_SUCCESS; }
//--------------------------------------------------------------------------- // LockHandleRelease // // This procedure releases the unique lock described by the handle. It // first checks whether the lock is a valid lock. If not, it returns SYNC_FAIL. // If the lock is a valid lock, it should check whether the calling // process actually holds the lock. If not it returns SYNC_FAIL. Otherwise it // releases the lock, and returns SYNC_SUCCESS. //--------------------------------------------------------------------------- int LockRelease(Lock *k) { Link *l; int intrs; PCB *pcb; if (!k) return SYNC_FAIL; intrs = DisableIntrs (); dbprintf ('s', "LockRelease: Proc %d releasing lock %d.\n", GetCurrentPid(), (int)(k-locks)); if (k->pid != GetCurrentPid()) { dbprintf('s', "LockRelease: Proc %d does not own lock %d.\n", GetCurrentPid(), (int)(k-locks)); return SYNC_FAIL; } k->pid = -1; if (!AQueueEmpty(&k->waiting)) { // there is a process to wake up l = AQueueFirst(&k->waiting); pcb = (PCB *)AQueueObject(l); if (AQueueRemove(&l) != QUEUE_SUCCESS) { printf("FATAL ERROR: could not remove link from lock queue in LockRelease!\n"); exitsim(); } dbprintf ('s', "LockRelease: Waking up PID %d, assigning lock.\n", (int)(GetPidFromAddress(pcb))); k->pid = GetPidFromAddress(pcb); ProcessWakeup (pcb); } RestoreIntrs (intrs); return SYNC_SUCCESS; }
//---------------------------------------------------------------------- // // SemSignal // // Signal on a semaphore. Again, details are in Section 6.4 of // _OSC_. // //---------------------------------------------------------------------- int SemSignal (Sem *sem) { Link *l; int intrs; PCB *pcb; if (!sem) return SYNC_FAIL; intrs = DisableIntrs (); dbprintf ('s', "SemSignal: Process %d Signalling on sem %d, count=%d.\n", GetCurrentPid(), (int)(sem-sems), sem->count); // Increment internal counter before checking value sem->count++; if (sem->count > 0) { // check if there is a process to wake up if (!AQueueEmpty(&sem->waiting)) { // there is a process to wake up l = AQueueFirst(&sem->waiting); pcb = (PCB *)AQueueObject(l); if (AQueueRemove(&l) != QUEUE_SUCCESS) { printf("FATAL ERROR: could not remove link from semaphore queue in SemSignal!\n"); exitsim(); } dbprintf ('s', "SemSignal: Waking up PID %d.\n", (int)(GetPidFromAddress(pcb))); ProcessWakeup (pcb); // Decrement counter on behalf of woken up PCB sem->count--; } } RestoreIntrs (intrs); return SYNC_SUCCESS; }
//------------------------------------------------------- // // int MboxClose(mbox_t); // // Close the mailbox for use to the current process. // If the number of processes using the given mailbox // is zero, then disable the mailbox structure and // return it to the set of available mboxes. // // Returns MBOX_FAIL on failure. // Returns MBOX_SUCCESS on success. // //------------------------------------------------------- int MboxClose(mbox_t handle) { int i; int length; Link *l; if(!&mboxs[handle]) return MBOX_FAIL; if(!AQueueEmpty(&mboxs[handle].pids)){ length = AQueueLength(&mboxs[handle].pids); l = AQueueFirst(&mboxs[handle].pids); for(i=0; i < length; i++){ if((int)AQueueObject(l) == GetCurrentPid()){ AQueueRemove(&l); break; } l = AQueueNext(l); } } if(AQueueEmpty(&mboxs[handle].pids)){ while(!AQueueEmpty(&mboxs[handle].messages)){ l = AQueueFirst(&mboxs[handle].messages); AQueueRemove(&l); } mboxs[handle].inuse = 0; } return MBOX_SUCCESS; }
//--------------------------------------------------------------------------- // CondHandleBroadcast // // This function is very similar to CondHandleSignal. But instead of // waking only one process, it wakes up all the processes waiting on the // condition variable. For this call to succeed, the calling process must // have acquired the lock associated with the condition variable. This // function should be written in such a way that the calling process // should retain the lock even after call completion. // // Note that the process woken up by this call tries to acquire the lock // associated with the condition variable as soon as it wakes up. Thus, // for such a process to run, the process invoking CondHandleBroadcast // must explicitly release the lock after the call completion. //--------------------------------------------------------------------------- int CondBroadcast(Cond *c) { if (!c) return SYNC_FAIL; if (c->lock->pid != GetCurrentPid()) { dbprintf('s', "CondBroadcast: Proc %d tried to broadcast, but it doesn't own cond %d\n", GetCurrentPid(), (int)(c-conds)); return SYNC_FAIL; } while (!AQueueEmpty(&c->waiting)) { if (CondSignal(c) != SYNC_SUCCESS) { dbprintf('s', "CondBroadcast: Proc %d failed in signalling cond %d\n", GetCurrentPid(), (int)(c-conds)); return SYNC_FAIL; } } dbprintf('s', "CondBroadcast: Proc %d successful broadcast on cond %d, still needs to release lock\n", GetCurrentPid(), (int)(c-conds)); return SYNC_SUCCESS; }
////////////////////////////////////////////////////////////////// // Inserts link "l" before link "before" in queue "q" ////////////////////////////////////////////////////////////////// int AQueueInsertBefore(Queue *q, Link *before, Link *l) { if (!l) return QUEUE_FAIL; if (!q) return QUEUE_FAIL; if (before) { // If before is not NULL, then before must be on the queue q if (before->queue != q) return QUEUE_FAIL; } else { // Otherwise before is NULL, so the list has to be empty if (AQueueFirst(q) != NULL) return QUEUE_FAIL; if (AQueueLast(q) != NULL) return QUEUE_FAIL; if (!AQueueEmpty(q)) return QUEUE_FAIL; } // Save the queue inside the link for simplicity l->queue = q; // Set next and previous on the link itself l->next = before; if (before) l->prev = before->prev; else l->prev = NULL; // Fix the list around l if (before) before->prev = l; if (l->prev) l->prev->next = l; // Update the queue accordingly for this new node if (!before) { q->first = l; q->last = l; q->nitems = 1; } else { // Note: don't need to worry about if "before" was last item, because // we're inserting before it, not after it if (q->first == before) q->first = l; q->nitems++; } return QUEUE_SUCCESS; }
///////////////////////////////////////////////////////////////// // Inserts link "l" after link "after" in queue "q" ///////////////////////////////////////////////////////////////// int AQueueInsertAfter (Queue *q, Link *after, Link *l) { if (!l) return QUEUE_FAIL; if (!q) return QUEUE_FAIL; if (after) { // If after is not NULL, then after must be on the queue q if (after->queue != q) return QUEUE_FAIL; } else { // Otherwise after is NULL, so the list has to be empty if (q->first != NULL) return QUEUE_FAIL; if (q->last != NULL) return QUEUE_FAIL; if (!AQueueEmpty(q)) return QUEUE_FAIL; } // Save the queue inside the link for simplicity l->queue = q; // Set next and previous on the link itself l->prev = after; if (after) l->next = after->next; else l->next = NULL; // Fix the list around l if (after) after->next = l; if (l->next) l->next->prev = l; // Update the queue accordingly for this new node if (!after) { q->first = l; q->last = l; q->nitems = 1; } else { // Note: don't need to worry about if "after" was first item, because // we're inserting after it, not before it if (q->last == after) q->last = l; q->nitems++; } return QUEUE_SUCCESS; }
/////////////////////////////////////////////////////// // Gets an empty link structure from the global queue // of empty links. /////////////////////////////////////////////////////// Link *AQueueAllocLink (void *obj_to_store) { extern Queue freeLinks; Link *l=NULL; dbprintf('q', "AQueueAllocLink: allocating link\n"); if (AQueueEmpty(&freeLinks)) { dbprintf('q', "AQueueAllocLink: no free links!\n"); return NULL; } l = AQueueFirst(&freeLinks); if (!l) { dbprintf('q', "AQueueAllocLink: first link in freeLinks is NULL!\n"); return NULL; } // Can't use QueueRemove because it puts the link back onto // the list of free links. Therefore, we must remove it // manually. // First fix freeLinks structure if (freeLinks.first == l) freeLinks.first = l->next; if (freeLinks.last == l) freeLinks.last = l->prev; freeLinks.nitems--; // Next, fix list around l if (l->prev) l->prev->next = l->next; if (l->next) l->next->prev = l->prev; // Finally, reset l's internal pointers to NULL for safety l->next = NULL; l->prev = NULL; l->queue = NULL; l->object = obj_to_store; return l; }
//---------------------------------------------------------------------- // // ProcessFork // // Create a new process and make it runnable. This involves the // following steps: // * Allocate resources for the process (PCB, memory, etc.) // * Initialize the resources // * Place the PCB on the runnable queue // // NOTE: This code has been tested for system processes, but not // for user processes. // //---------------------------------------------------------------------- int ProcessFork (VoidFunc func, uint32 param, char *name, int isUser) { int i,j; // Loop index variable int fd, n; // Used for reading code from files. int start, codeS, codeL; // Used for reading code from files. int dataS, dataL; // Used for reading code from files. int addr = 0; // Used for reading code from files. unsigned char buf[100]; // Used for reading code from files. uint32 *stackframe; // Stores address of current stack frame. PCB *pcb; // Holds pcb while we build it for this process. int intrs; // Stores previous interrupt settings. uint32 initial_user_params[MAX_ARGS+2]; // Initial memory for user parameters (argc, argv) // initial_user_params[0] = argc // initial_user_params[1] = argv, points to initial_user_params[2] // initial_user_params[2] = address of string for argv[0] // initial_user_params[3] = address of string for argv[1] // ... uint32 argc=0; // running counter for number of arguments uint32 offset; // Used in parsing command line argument strings, holds offset (in bytes) from // beginning of the string to the current argument. uint32 initial_user_params_bytes; // total number of bytes in initial user parameters array int newpage; int index; int *p; intrs = DisableIntrs (); dbprintf ('I', "ProcessFork-Old interrupt value was 0x%x.\n", intrs); dbprintf ('p', "ProcessFork-Entering ProcessFork args=0x%x 0x%x %s %d\n", (int)func, param, name, isUser); // Get a free PCB for the new process if (AQueueEmpty(&freepcbs)) { printf ("ProcessFork-FATAL error: no free processes!\n"); exitsim (); // NEVER RETURNS! } pcb = (PCB *)AQueueObject(AQueueFirst (&freepcbs)); dbprintf ('p', "ProcessFork-Got a link @ 0x%x\n", (int)(pcb->l)); if (AQueueRemove (&(pcb->l)) != QUEUE_SUCCESS) { printf("ProcessFork-FATAL ERROR: could not remove link from freepcbsQueue in ProcessFork!\n"); exitsim(); } // This prevents someone else from grabbing this process ProcessSetStatus (pcb, PROCESS_STATUS_RUNNABLE); // At this point, the PCB is allocated and nobody else can get it. // However, it's not in the run queue, so it won't be run. Thus, we // can turn on interrupts here. RestoreIntrs (intrs); // Copy the process name into the PCB. dstrcpy(pcb->name, name); //---------------------------------------------------------------------- // This section initializes the memory for this process //---------------------------------------------------------------------- // Allocate 1 page for system stack, 1 page for user stack (at top of // virtual address space), and 4 pages for user code and global data. //--------------------------------------------------------- // STUDENT: allocate pages for a new process here. The // code below assumes that you set the "stackframe" variable // equal to the last 4-byte-aligned address in physical page // for the system stack. //--------------------------------------------------------- //////////////////////////////////////////////////////////////// // JSM, allocate 6 physical pages for new process // First, get L2 Page Table for index 0 of L1 Page Table index = MemoryAllocateL2PT(); if (index == -1) { printf ("ProcessFork-FATAL: couldn't allocate L2 Page Table for index 0 of L1 Page Table - no free page tables!\n"); exitsim (); // NEVER RETURNS! } // Assign L1 entry to address of start of L2 Page Table pcb->pagetable[0] = (uint32)&level2_pt_block[index]; p = (uint32 *)pcb->pagetable[0];//L2 // Allocate 4 pages for code and data for(i = 0; i < 4; i++) { newpage = MemoryAllocatePage(); if (newpage == 0) { printf ("ProcessFork-FATAL: couldn't allocate memory - no free pages!\n"); exitsim (); // NEVER RETURNS! } dbprintf('p', "ProcessFork-Allocating physical page #%d (Address 0x%.8X) for process virtual page #%d (data/code)\n", newpage, (newpage*MEM_PAGE_SIZE), i); *(p+i) = ((newpage*MEM_PAGE_SIZE) | MEM_PTE_VALID); dbprintf('p', "Contents at 0x%.8X: 0x%.8X\n\n", (int)(p+i), *(p+i)); } ///////////////////////////////////////////////////// //YF ADDED allocate page for heap // First, initialize the heapfree map for (j=0; j<MEM_MAX_HEAP_FREEMAP; j++){ pcb->HeapFreeMap[j] = 0; } for (j =0; j<MEM_MAX_HEAP_POINTER_ARRAY; j++){ pcb->HeapPtrSizes[j] = 0; } index = MemoryAllocateL2PT(); if (index == -1) { printf ("ProcessFork-FATAL: couldn't allocate L2 Page Table for index 0 of L1 Page Table - no free page tables!\n"); exitsim (); // NEVER RETURNS! } // Assign L1 entry to address of start of L2 Page Table pcb->pagetable[0] = (uint32)&level2_pt_block[index]; p = (uint32 *)pcb->pagetable[0]; newpage = MemoryAllocatePage(); if (newpage == 0) { printf ("ProcessFork-FATAL: couldn't allocate memory - no free pages!\n"); exitsim (); // NEVER RETURNS! } dbprintf('p', "ProcessFork-Allocating physical page #%d (Address 0x%.8X) for process virtual page #%d (Heap Allocation)\n", newpage, (newpage*MEM_PAGE_SIZE), i); //address for catch in Memory translate. UserHeap Address =0x4000 = *(p+i) = ((newpage*MEM_PAGE_SIZE) | MEM_PTE_VALID | MEM_PTE_HEAP); //TODO ProcessFork: marked as a heap. pcb->userHeapArea = (uint32 *)(newpage*MEM_PAGE_SIZE); dbprintf('p', "Heap area is at physical address:0x%.8X L2 Address: 0x%.8X\n", (int)(newpage*MEM_PAGE_SIZE), *(p+i)); dbprintf('p', "Contents at 0x%.8X: 0x%.8X\n\n", (int)(p+i), *(p+i)); //Done with Heap allocation /////////////////////////////////////////////////////////////////////////////////////////////////// // Allocate page for user stack // First, get L2 Page Table for index 15 of L1 Page Table index = MemoryAllocateL2PT(); if (index == -1) { printf ("ProcessFork-FATAL: couldn't allocate L2 Page Table for index 0 of L1 Page Table - no free page tables!\n"); exitsim (); // NEVER RETURNS! } // Assign L1 entry to address of start of L2 Page Table pcb->pagetable[MEM_L1_PAGE_TABLE_SIZE-1] = (uint32)&level2_pt_block[index]; p = (uint32 *)pcb->pagetable[MEM_L1_PAGE_TABLE_SIZE-1]; newpage = MemoryAllocatePage(); if (newpage == 0) { printf ("ProcessFork-FATAL: couldn't allocate memory - no free pages!\n"); exitsim (); // NEVER RETURNS! } dbprintf('p', "ProcessFork-Allocating physical page #%d (Address 0x%.8X) for process virtual page #%d (user stack)\n\n", newpage, (newpage*MEM_PAGE_SIZE), (MEM_L1_PAGE_TABLE_SIZE*MEM_L2_PAGE_TABLE_SIZE)-1); *(p+(MEM_L2_PAGE_TABLE_SIZE-1)) = ((newpage*MEM_PAGE_SIZE) | MEM_PTE_VALID); dbprintf('p', "Contents at 0x%.8X: 0x%.8X\n\n", (int)(p+(MEM_L2_PAGE_TABLE_SIZE-1)), *(p+(MEM_L2_PAGE_TABLE_SIZE-1))); // Allocate page for system stack newpage = MemoryAllocatePage(); if (newpage == 0) { printf ("ProcessFork-FATAL: couldn't allocate memory - no free pages!\n"); exitsim (); // NEVER RETURNS! } dbprintf('p', "ProcessFork-Allocating physical page #%d (Address 0x%.8X) for process system stack\n\n", newpage, (newpage*MEM_PAGE_SIZE)); pcb->sysStackArea = newpage * MEM_PAGE_SIZE; stackframe = (uint32 *)(pcb->sysStackArea + (MEM_PAGE_SIZE-4)); dbprintf('p', "ProcessFork-Initializing system stack pointer to 0x%.8X\n\n", (uint32)stackframe); //////////////////////////////////////////////////////////////// // Now that the stack frame points at the bottom of the system stack memory area, we need to // move it up (decrement it) by one stack frame size because we're about to fill in the // initial stack frame that will be loaded for this PCB when it gets switched in by // ProcessSchedule the first time. stackframe -= PROCESS_STACK_FRAME_SIZE; // The system stack pointer is set to the base of the current interrupt stack frame. pcb->sysStackPtr = stackframe; // The current stack frame pointer is set to the same thing. pcb->currentSavedFrame = stackframe; //---------------------------------------------------------------------- // This section sets up the stack frame for the process. This is done // so that the frame looks to the interrupt handler like the process // was "suspended" right before it began execution. The standard // mechanism of swapping in the registers and returning to the place // where it was "interrupted" will then work. //---------------------------------------------------------------------- // The previous stack frame pointer is set to 0, meaning there is no // previous frame. dbprintf('m', "ProcessFork-ProcessFork: stackframe = 0x%x\n", (int)stackframe); stackframe[PROCESS_STACK_PREV_FRAME] = 0; //---------------------------------------------------------------------- // STUDENT: setup the PTBASE, PTBITS, and PTSIZE here on the current // stack frame. //---------------------------------------------------------------------- // JSM added PTBASE, PTBITS, and PTSIZE on stack frame ////////////////////////////////////////////////////////// stackframe[PROCESS_STACK_PTBASE] = (uint32)&(pcb->pagetable[0]); dbprintf('p', "ProcessFork-PTBASE: 0x%.8X\n\n", (uint32)&(pcb->pagetable[0])); stackframe[PROCESS_STACK_PTSIZE] = MEM_L1_PAGE_TABLE_SIZE; dbprintf('p', "ProcessFork-PTSIZE: 0x%.8X\n\n", MEM_L1_PAGE_TABLE_SIZE); stackframe[PROCESS_STACK_PTBITS] = (MEM_L2FIELD_FIRST_BITNUM << 16) | MEM_L1FIELD_FIRST_BITNUM; dbprintf('p', "ProcessFork-PTBITS: 0x%.8X\n\n", (MEM_L2FIELD_FIRST_BITNUM << 16) | MEM_L1FIELD_FIRST_BITNUM); ////////////////////////////////////////////////////////// if (isUser) {//user prog .dlx.obj dbprintf ('p', "ProcessFork-About to load %s\n", name); fd = ProcessGetCodeInfo (name, &start, &codeS, &codeL, &dataS, &dataL); if (fd < 0) { // Free newpage and pcb so we don't run out... ProcessFreeResources (pcb); return (-1); } dbprintf ('p', "ProcessFork-File %s -> start=0x%08x\n", name, start); dbprintf ('p', "ProcessFork-File %s -> code @ 0x%08x (size=0x%08x)\n", name, codeS, codeL); dbprintf ('p', "ProcessFork-File %s -> data @ 0x%08x (size=0x%08x)\n", name, dataS, dataL); while ((n = ProcessGetFromFile (fd, buf, &addr, sizeof (buf))) > 0) { dbprintf ('p', "ProcessFork-Placing %d bytes at vaddr %08x.\n", n, addr - n); // Copy the data to user memory. Note that the user memory needs to // have enough space so that this copy will succeed! MemoryCopySystemToUser (pcb, buf, (char *)(addr - n), n); } FsClose (fd); stackframe[PROCESS_STACK_ISR] = PROCESS_INIT_ISR_USER; //---------------------------------------------------------------------- // STUDENT: setup the initial user stack pointer here as the top // of the process's virtual address space (4-byte aligned). //---------------------------------------------------------------------- // JSM initialized user stack pointer ////////////////////////////////////////////////////////// stackframe[PROCESS_STACK_USER_STACKPOINTER] = (MEM_MAX_VIRTUAL_ADDRESS-3); dbprintf('p', "ProcessFork-USER_STACKPOINTER: 0x%.8X\n\n", stackframe[PROCESS_STACK_USER_STACKPOINTER]); ////////////////////////////////////////////////////////// //-------------------------------------------------------------------- // This part is setting up the initial user stack with argc and argv. //-------------------------------------------------------------------- // Copy the entire set of strings of command line parameters onto the user stack. // The "param" variable is a pointer to the start of a sequenial set of strings, // each ending with its own '\0' character. The final "string" of the sequence // must be an empty string to indicate that the sequence is done. Since we // can't figure out how long the set of strings actually is in this scenario, // we have to copy the maximum possible string length and parse things manually. stackframe[PROCESS_STACK_USER_STACKPOINTER] -= SIZE_ARG_BUFF; MemoryCopySystemToUser (pcb, (char *)param, (char *)stackframe[PROCESS_STACK_USER_STACKPOINTER], SIZE_ARG_BUFF); // Now that the main string is copied into the user space, we need to setup // argv as an array of pointers into that string, and argc as the total // number of arguments found in the string. The first call to get_argument // should return 0 as the offset of the first string. offset = get_argument((char *)param); // Compute the addresses in user space of where each string for the command line arguments // begins. These addresses make up the argv array. for(argc=0; argc < MAX_ARGS; argc++) { // The "+2" is because initial_user_params[0] is argc, and initial_user_params[1] is argv. // The address can be found as the current stack pointer (which points to the start of // the params list) plus the byte offset of the parameter from the beginning of // the list of parameters. initial_user_params[argc+2] = stackframe[PROCESS_STACK_USER_STACKPOINTER] + offset; offset = get_argument(NULL); if (offset == 0) { initial_user_params[argc+2+1] = 0; // last entry should be a null value break; } } // argc is currently the index of the last command line argument. We need it to instead // be the number of command line arguments, so we increment it by 1. argc++; // Now argc can be stored properly initial_user_params[0] = argc; // Compute where initial_user_params[3] will be copied in user space as the // base of the array of string addresses. The entire initial_user_params array // of uint32's will be copied onto the stack. We'll move the stack pointer by // the necessary amount, then start copying the array. Therefore, initial_user_params[3] // will reside at the current stack pointer value minus the number of command line // arguments (argc). initial_user_params[1] = stackframe[PROCESS_STACK_USER_STACKPOINTER] - (argc*sizeof(uint32)); // Now copy the actual memory. Remember that stacks grow down from the top of memory, so // we need to move the stack pointer first, then do the copy. The "+2", as before, is // because initial_user_params[0] is argc, and initial_user_params[1] is argv. initial_user_params_bytes = (argc + 2) * sizeof(uint32); stackframe[PROCESS_STACK_USER_STACKPOINTER] -= initial_user_params_bytes; MemoryCopySystemToUser (pcb, (char *)initial_user_params, (char *)(stackframe[PROCESS_STACK_USER_STACKPOINTER]), initial_user_params_bytes); // Set the correct address at which to execute a user process. stackframe[PROCESS_STACK_IAR] = (uint32)start; // Flag this as a user process pcb->flags |= PROCESS_TYPE_USER; } else { // Don't worry about messing with any code here for kernel processes because // there aren't any kernel processes in DLXOS. // Set r31 to ProcessExit(). This will only be called for a system // process; user processes do an exit() trap. stackframe[PROCESS_STACK_IREG+31] = (uint32)ProcessExit; // Set the stack register to the base of the system stack. //stackframe[PROCESS_STACK_IREG+29]=pcb->sysStackArea + MEM_PAGESIZE; // Set the initial parameter properly by placing it on the stack frame // at the location pointed to by the "saved" stack pointer (r29). *((uint32 *)(stackframe[PROCESS_STACK_IREG+29])) = param; // Set up the initial address at which to execute. This is done by // placing the address into the IAR slot of the stack frame. stackframe[PROCESS_STACK_IAR] = (uint32)func; // Set the initial value for the interrupt status register stackframe[PROCESS_STACK_ISR] = PROCESS_INIT_ISR_SYS; // Mark this as a system process. pcb->flags |= PROCESS_TYPE_SYSTEM; } // Place the PCB onto the run queue. intrs = DisableIntrs (); if ((pcb->l = AQueueAllocLink(pcb)) == NULL) { printf("FATAL ERROR: could not get link for forked PCB in ProcessFork!\n"); exitsim(); } if (AQueueInsertLast(&runQueue, pcb->l) != QUEUE_SUCCESS) { printf("FATAL ERROR: could not insert link into runQueue in ProcessFork!\n"); exitsim(); } RestoreIntrs (intrs); // If this is the first process, make it the current one if (currentPCB == NULL) { dbprintf ('p', "Setting currentPCB=0x%x, stackframe=0x%x\n", (int)pcb, (int)(pcb->currentSavedFrame)); currentPCB = pcb; } dbprintf ('p', "Leaving ProcessFork (%s)\n", name); // Return the process number (found by subtracting the PCB number // from the base of the PCB array). return (pcb - pcbs); }
//---------------------------------------------------------------------- // // ProcessFork // // Create a new process and make it runnable. This involves the // following steps: // * Allocate resources for the process (PCB, memory, etc.) // * Initialize the resources // * Place the PCB on the runnable queue // // NOTE: This code has been tested for system processes, but not // for user processes. // //---------------------------------------------------------------------- int ProcessFork (VoidFunc func, uint32 param, char *name, int isUser) { int i; // Loop index variable int fd, n; // Used for reading code from files. int start, codeS, codeL; // Used for reading code from files. int dataS, dataL; // Used for reading code from files. int addr = 0; // Used for reading code from files. unsigned char buf[100]; // Used for reading code from files. uint32 *stackframe; // Stores address of current stack frame. PCB *pcb; // Holds pcb while we build it for this process. int intrs; // Stores previous interrupt settings. uint32 initial_user_params[MAX_ARGS+2]; // Initial memory for user parameters (argc, argv) // initial_user_params[0] = argc // initial_user_params[1] = argv, points to initial_user_params[2] // initial_user_params[2] = address of string for argv[0] // initial_user_params[3] = address of string for argv[1] // ... uint32 argc=0; // running counter for number of arguments uint32 offset; // Used in parsing command line argument strings, holds offset (in bytes) from // beginning of the string to the current argument. uint32 initial_user_params_bytes; // total number of bytes in initial user parameters array int newPage; intrs = DisableIntrs (); dbprintf ('I', "Old interrupt value was 0x%x.\n", intrs); dbprintf ('p', "Entering ProcessFork args=0x%x 0x%x %s %d\n", (int)func, param, name, isUser); // Get a free PCB for the new process if (AQueueEmpty(&freepcbs)) { printf ("FATAL error: no free processes!\n"); exitsim (); // NEVER RETURNS! } pcb = (PCB *)AQueueObject(AQueueFirst (&freepcbs)); dbprintf ('p', "Got a link @ 0x%x\n", (int)(pcb->l)); if (AQueueRemove (&(pcb->l)) != QUEUE_SUCCESS) { printf("FATAL ERROR: could not remove link from freepcbsQueue in ProcessFork!\n"); exitsim(); } // This prevents someone else from grabbing this process ProcessSetStatus (pcb, PROCESS_STATUS_RUNNABLE); // At this point, the PCB is allocated and nobody else can get it. // However, it's not in the run queue, so it won't be run. Thus, we // can turn on interrupts here. RestoreIntrs (intrs); // Copy the process name into the PCB. dstrcpy(pcb->name, name); //---------------------------------------------------------------------- // This section initializes the memory for this process //---------------------------------------------------------------------- // Allocate 1 page for system stack, 1 page for user stack (at top of // virtual address space), and 4 pages for user code and global data. //--------------------------------------------------------- // STUDENT: allocate pages for a new process here. The // code below assumes that you set the "stackframe" variable // equal to the last 4-byte-aligned address in physical page // for the system stack. //--------------------------------------------------------- // Pages for code and global data and Heap pcb->npages = 5; for(i = 0; i < pcb->npages; i++) { newPage = MemoryAllocPage(); if(newPage == MEM_FAIL) { printf ("FATAL: couldn't allocate memory - no free pages!\n"); ProcessFreeResources (pcb); return PROCESS_FORK_FAIL; } pcb->pagetable[i] = MemorySetupPte (newPage); } // Initialize nodes in pool for (i = 1; i <= MEM_HEAP_MAX_NODES; i++) { pcb->htree_array[i].parent = NULL; pcb->htree_array[i].cleft = NULL; pcb->htree_array[i].crght = NULL; pcb->htree_array[i].index = i; pcb->htree_array[i].size = -1; pcb->htree_array[i].addr = -1; pcb->htree_array[i].inuse = 0; pcb->htree_array[i].order = -1; } // Initialize Heap tree pcb->htree_array[1].size = MEM_PAGESIZE; pcb->htree_array[1].addr = 0; pcb->htree_array[1].order = 7; // user stack pcb->npages += 1; newPage = MemoryAllocPage(); if(newPage == MEM_FAIL) { printf ("FATAL: couldn't allocate user stack - no free pages!\n"); ProcessFreeResources (pcb); return PROCESS_FORK_FAIL; } pcb->pagetable[MEM_ADDRESS_TO_PAGE(MEM_MAX_VIRTUAL_ADDRESS)] = MemorySetupPte (newPage); // for system stack newPage = MemoryAllocPage (); if(newPage == MEM_FAIL) { printf ("FATAL: couldn't allocate system stack - no free pages!\n"); ProcessFreeResources (pcb); return PROCESS_FORK_FAIL; } pcb->sysStackArea = newPage * MEM_PAGESIZE; //---------------------------------------------------------------------- // Stacks grow down from the top. The current system stack pointer has // to be set to the bottom of the interrupt stack frame, which is at the // high end (address-wise) of the system stack. stackframe = (uint32 *)(pcb->sysStackArea + MEM_PAGESIZE - 4); dbprintf('p', "ProcessFork: SystemStack page=%d sysstackarea=0x%x\n", newPage, pcb->sysStackArea); // Now that the stack frame points at the bottom of the system stack memory area, we need to // move it up (decrement it) by one stack frame size because we're about to fill in the // initial stack frame that will be loaded for this PCB when it gets switched in by // ProcessSchedule the first time. stackframe -= PROCESS_STACK_FRAME_SIZE; // The system stack pointer is set to the base of the current interrupt stack frame. pcb->sysStackPtr = stackframe; // The current stack frame pointer is set to the same thing. pcb->currentSavedFrame = stackframe; dbprintf ('p', "Setting up PCB @ 0x%x (sys stack=0x%x, mem=0x%x, size=0x%x)\n", (int)pcb, pcb->sysStackArea, pcb->pagetable[0], pcb->npages * MEM_PAGESIZE); //---------------------------------------------------------------------- // This section sets up the stack frame for the process. This is done // so that the frame looks to the interrupt handler like the process // was "suspended" right before it began execution. The standard // mechanism of swapping in the registers and returning to the place // where it was "interrupted" will then work. //---------------------------------------------------------------------- // The previous stack frame pointer is set to 0, meaning there is no // previous frame. dbprintf('p', "ProcessFork: stackframe = 0x%x\n", (int)stackframe); stackframe[PROCESS_STACK_PREV_FRAME] = 0; //---------------------------------------------------------------------- // STUDENT: setup the PTBASE, PTBITS, and PTSIZE here on the current // stack frame. //---------------------------------------------------------------------- // Set the base of the level 1 page table. If there's only one page // table level, this is it. For 2-level page tables, put the address // of the level 1 page table here. For 2-level page tables, we'll also // have to build up the necessary tables.... stackframe[PROCESS_STACK_PTBASE] = (uint32)(&(pcb->pagetable[0])); // Set the size (maximum number of entries) of the level 1 page table. // In our case, it's just one page, but it could be larger. stackframe[PROCESS_STACK_PTSIZE] = MEM_PAGE_TBL_SIZE; // Set the number of bits for both the level 1 and level 2 page tables. // This can be changed on a per-process basis if desired. For now, // though, it's fixed. stackframe[PROCESS_STACK_PTBITS] = (MEM_L1FIELD_FIRST_BITNUM << 16) + MEM_L1FIELD_FIRST_BITNUM; if (isUser) { dbprintf ('p', "About to load %s\n", name); fd = ProcessGetCodeInfo (name, &start, &codeS, &codeL, &dataS, &dataL); if (fd < 0) { // Free newPage and pcb so we don't run out... ProcessFreeResources (pcb); return (-1); } dbprintf ('p', "File %s -> start=0x%08x\n", name, start); dbprintf ('p', "File %s -> code @ 0x%08x (size=0x%08x)\n", name, codeS, codeL); dbprintf ('p', "File %s -> data @ 0x%08x (size=0x%08x)\n", name, dataS, dataL); while ((n = ProcessGetFromFile (fd, buf, &addr, sizeof (buf))) > 0) { dbprintf ('i', "Placing %d bytes at vaddr %08x.\n", n, addr - n); // Copy the data to user memory. Note that the user memory needs to // have enough space so that this copy will succeed! MemoryCopySystemToUser (pcb, buf, (char *)(addr - n), n); } FsClose (fd); stackframe[PROCESS_STACK_ISR] = PROCESS_INIT_ISR_USER; //---------------------------------------------------------------------- // STUDENT: setup the initial user stack pointer here as the top // of the process's virtual address space (4-byte aligned). //---------------------------------------------------------------------- stackframe[PROCESS_STACK_USER_STACKPOINTER] = MEM_MAX_VIRTUAL_ADDRESS - 3; dbprintf('p', "ProcessFork: UserStack usrsp=0x%x\n", stackframe[PROCESS_STACK_USER_STACKPOINTER]); //-------------------------------------------------------------------- // This part is setting up the initial user stack with argc and argv. //-------------------------------------------------------------------- // Copy the entire set of strings of command line parameters onto the user stack. // The "param" variable is a pointer to the start of a sequenial set of strings, // each ending with its own '\0' character. The final "string" of the sequence // must be an empty string to indicate that the sequence is done. Since we // can't figure out how long the set of strings actually is in this scenario, // we have to copy the maximum possible string length and parse things manually. stackframe[PROCESS_STACK_USER_STACKPOINTER] -= SIZE_ARG_BUFF; MemoryCopySystemToUser (pcb, (char *)param, (char *)stackframe[PROCESS_STACK_USER_STACKPOINTER], SIZE_ARG_BUFF); // Now that the main string is copied into the user space, we need to setup // argv as an array of pointers into that string, and argc as the total // number of arguments found in the string. The first call to get_argument // should return 0 as the offset of the first string. offset = get_argument((char *)param); // Compute the addresses in user space of where each string for the command line arguments // begins. These addresses make up the argv array. for(argc=0; argc < MAX_ARGS; argc++) { // The "+2" is because initial_user_params[0] is argc, and initial_user_params[1] is argv. // The address can be found as the current stack pointer (which points to the start of // the params list) plus the byte offset of the parameter from the beginning of // the list of parameters. initial_user_params[argc+2] = stackframe[PROCESS_STACK_USER_STACKPOINTER] + offset; offset = get_argument(NULL); if (offset == 0) { initial_user_params[argc+2+1] = 0; // last entry should be a null value break; } } // argc is currently the index of the last command line argument. We need it to instead // be the number of command line arguments, so we increment it by 1. argc++; // Now argc can be stored properly initial_user_params[0] = argc; // Compute where initial_user_params[3] will be copied in user space as the // base of the array of string addresses. The entire initial_user_params array // of uint32's will be copied onto the stack. We'll move the stack pointer by // the necessary amount, then start copying the array. Therefore, initial_user_params[3] // will reside at the current stack pointer value minus the number of command line // arguments (argc). initial_user_params[1] = stackframe[PROCESS_STACK_USER_STACKPOINTER] - (argc*sizeof(uint32)); // Now copy the actual memory. Remember that stacks grow down from the top of memory, so // we need to move the stack pointer first, then do the copy. The "+2", as before, is // because initial_user_params[0] is argc, and initial_user_params[1] is argv. initial_user_params_bytes = (argc + 2) * sizeof(uint32); stackframe[PROCESS_STACK_USER_STACKPOINTER] -= initial_user_params_bytes; MemoryCopySystemToUser (pcb, (char *)initial_user_params, (char *)(stackframe[PROCESS_STACK_USER_STACKPOINTER]), initial_user_params_bytes); // Set the correct address at which to execute a user process. stackframe[PROCESS_STACK_IAR] = (uint32)start; // Flag this as a user process pcb->flags |= PROCESS_TYPE_USER; } else { // Don't worry about messing with any code here for kernel processes because // there aren't any kernel processes in DLXOS. // Set r31 to ProcessExit(). This will only be called for a system // process; user processes do an exit() trap. stackframe[PROCESS_STACK_IREG+31] = (uint32)ProcessExit; // Set the stack register to the base of the system stack. //stackframe[PROCESS_STACK_IREG+29]=pcb->sysStackArea + MEM_PAGESIZE; // Set the initial parameter properly by placing it on the stack frame // at the location pointed to by the "saved" stack pointer (r29). *((uint32 *)(stackframe[PROCESS_STACK_IREG+29])) = param; // Set up the initial address at which to execute. This is done by // placing the address into the IAR slot of the stack frame. stackframe[PROCESS_STACK_IAR] = (uint32)func; // Set the initial value for the interrupt status register stackframe[PROCESS_STACK_ISR] = PROCESS_INIT_ISR_SYS; // Mark this as a system process. pcb->flags |= PROCESS_TYPE_SYSTEM; } // Place the PCB onto the run queue. intrs = DisableIntrs (); if ((pcb->l = AQueueAllocLink(pcb)) == NULL) { printf("FATAL ERROR: could not get link for forked PCB in ProcessFork!\n"); exitsim(); } if (AQueueInsertLast(&runQueue, pcb->l) != QUEUE_SUCCESS) { printf("FATAL ERROR: could not insert link into runQueue in ProcessFork!\n"); exitsim(); } RestoreIntrs (intrs); // If this is the first process, make it the current one if (currentPCB == NULL) { dbprintf ('p', "Setting currentPCB=0x%x, stackframe=0x%x\n", (int)pcb, (int)(pcb->currentSavedFrame)); currentPCB = pcb; } dbprintf ('p', "Leaving ProcessFork (%s)\n", name); // Return the process number (found by subtracting the PCB number // from the base of the PCB array). return (pcb - pcbs); }
int ProcessRealFork (PCB* ppcb) { PCB *cpcb; // Holds pcb while we build it for this process. int intrs; // Stores previous interrupt settings. int newPage; int i; uint32 *stackframe; intrs = DisableIntrs (); dbprintf ('I', "Old interrupt value was 0x%x.\n", intrs); dbprintf ('p', "Entering ProcessRealFork ppcb=%d\n", GetPidFromAddress(ppcb)); // Get a free PCB for the new process if (AQueueEmpty(&freepcbs)) { printf ("FATAL error: no free processes!\n"); exitsim (); // NEVER RETURNS! } cpcb = (PCB *)AQueueObject(AQueueFirst (&freepcbs)); dbprintf ('p', "Got a link @ 0x%x\n", (int)(cpcb->l)); if (AQueueRemove (&(cpcb->l)) != QUEUE_SUCCESS) { printf("FATAL ERROR: could not remove link from freepcbsQueue in ProcessFork!\n"); exitsim(); } // This prevents someone else from grabbing this process ProcessSetStatus (cpcb, PROCESS_STATUS_RUNNABLE); // cpcb shares code and global data with ppcb for(i = 0; i < 4; i++) { ppcb->pagetable[i] |= MEM_PTE_READONLY; MemorySharePage(ppcb->pagetable[i]); } // user stack is also shared at first ppcb->pagetable[MEM_ADDRESS_TO_PAGE(MEM_MAX_VIRTUAL_ADDRESS)] |= MEM_PTE_READONLY; MemorySharePage(ppcb->pagetable[MEM_ADDRESS_TO_PAGE(MEM_MAX_VIRTUAL_ADDRESS)]); // copy parent pcb to child pcb bcopy((char *)ppcb, (char *)cpcb, sizeof(PCB)); // At this point, the PCB is allocated and nobody else can get it. // However, it's not in the run queue, so it won't be run. Thus, we // can turn on interrupts here. RestoreIntrs (intrs); // for system stack newPage = MemoryAllocPage (); if(newPage == MEM_FAIL) { printf ("FATAL: couldn't allocate system stack - no free pages!\n"); ProcessFreeResources (cpcb); return PROCESS_FORK_FAIL; } cpcb->sysStackArea = newPage * MEM_PAGESIZE; // copy system stack from ppcb to cpcb bcopy((char *)(ppcb->sysStackArea), (char *)(cpcb->sysStackArea), MEM_PAGESIZE); dbprintf('p', "ProcessRealFork: SystemStack page=%d sysstackarea=0x%x\n", newPage, cpcb->sysStackArea); // printf("ProcessRealFork: parent_sysstackarea=0x%x child_sysstackarea=0x%x\n", ppcb->sysStackArea, cpcb->sysStackArea); //---------------------------------------------------------------------- // Stacks grow down from the top. The current system stack pointer has // to be set to the bottom of the interrupt stack frame, which is at the // high end (address-wise) of the system stack. stackframe = (uint32 *)(cpcb->sysStackArea + MEM_PAGESIZE - 4); // Now that the stack frame points at the bottom of the system stack memory area, we need to // move it up (decrement it) by one stack frame size because we're about to fill in the // initial stack frame that will be loaded for this PCB when it gets switched in by // ProcessSchedule the first time. stackframe -= PROCESS_STACK_FRAME_SIZE; // The system stack pointer is set to the base of the current interrupt stack frame. cpcb->sysStackPtr = stackframe; // The current stack frame pointer is set to the same thing. cpcb->currentSavedFrame = stackframe; dbprintf ('p', "Setting up PCB @ 0x%x (sys stack=0x%x, mem=0x%x, size=0x%x)\n", (int)cpcb, cpcb->sysStackArea, cpcb->pagetable[0], cpcb->npages * MEM_PAGESIZE); //---------------------------------------------------------------------- // STUDENT: setup the PTBASE, PTBITS, and PTSIZE here on the current // stack frame. //---------------------------------------------------------------------- // Set the base of the level 1 page table. If there's only one page // table level, this is it. For 2-level page tables, put the address // of the level 1 page table here. For 2-level page tables, we'll also // have to build up the necessary tables.... stackframe[PROCESS_STACK_PTBASE] = (uint32)(&(cpcb->pagetable[0])); // Place the PCB onto the run queue. intrs = DisableIntrs (); if ((cpcb->l = AQueueAllocLink(cpcb)) == NULL) { printf("FATAL ERROR: could not get link for forked PCB in ProcessFork!\n"); exitsim(); } if (AQueueInsertLast(&runQueue, cpcb->l) != QUEUE_SUCCESS) { printf("FATAL ERROR: could not insert link into runQueue in ProcessFork!\n"); exitsim(); } RestoreIntrs (intrs); ProcessSetResult(cpcb, 0); ProcessSetResult(ppcb, GetPidFromAddress(cpcb)); // TEST PRINTS printf("\nIn ProcessRealFork:\n"); printf("----- Page table of parent process PID:%d -----\n", GetPidFromAddress(ppcb)); ProcessForkTestPrints(ppcb); printf("\n----- Page table of child process PID: %d -----\n", GetPidFromAddress(cpcb)); ProcessForkTestPrints(cpcb); dbprintf ('p', "Leaving ProcessRealFork cpcbid=%d\n", GetPidFromAddress(cpcb)); return PROCESS_FORK_SUCCESS; }
//------------------------------------------------------- // // int MboxRecv(mbox_t handle, int maxlength, void* message); // // Receive a message from the specified mailbox. The call // blocks when there is no message in the buffer. Maxlength // should indicate the maximum number of bytes that can be // copied from the buffer into the address of "message". // An error occurs if the message is larger than maxlength. // Note that the calling process must have opened the mailbox // via MboxOpen. // // Returns MBOX_FAIL on failure. // Returns number of bytes written into message on success. // //------------------------------------------------------- int MboxRecv(mbox_t handle, int maxlength, void* message) { int i; int qlen; Link *l; int exists = 0; mbox_message *m; //check if mailbox is real if(!&mboxs[handle]) return MBOX_FAIL; //check if pid opened this mailbox if(!AQueueEmpty(&mboxs[handle].pids ) ){ qlen = AQueueLength(&mboxs[handle].pids); l = AQueueFirst(&mboxs[handle].pids); for(i=0; i < qlen; i++){ if((int)AQueueObject(l) == GetCurrentPid()){ exists = 1; break; } l = AQueueNext(l); } //actualy checks if pid exists if(exists == 0){ return MBOX_FAIL; } //wait until queue has something in it if(SemHandleWait(mboxs[handle].s_msg_full) == SYNC_FAIL){ printf("bad sem handle wait in mbox recv\n"); exitsim(); } //lock if(LockHandleAcquire(mboxs[handle].l) != SYNC_SUCCESS){ printf("FATAL ERROR: could not get lock in Mbox send!\n"); exitsim(); } l = AQueueFirst(&mboxs[handle].messages); m = (mbox_message *) l->object; //check if message longer than max length if(m->length > maxlength) { return MBOX_FAIL; } //copy message to local variable dstrncpy(message,(void*) m->message, m->length); //reset structure for use elsewhere m->inuse =0; //delete link AQueueRemove(&l); //unlock if(LockHandleRelease(mboxs[handle].l) != SYNC_SUCCESS){ printf("FATAL ERROR: could not release lock in Mbox send!\n"); exitsim(); } if(SemHandleSignal(mboxs[handle].s_msg_empty) == SYNC_FAIL){ printf("bad sem handle signal in mbox recv\n"); exitsim(); } }else{ return MBOX_FAIL; } return MBOX_SUCCESS; }
//------------------------------------------------------- // // int MboxSend(mbox_t handle,int length, void* message); // // Send a message (pointed to by "message") of length // "length" bytes to the specified mailbox. Messages of // length 0 are allowed. The call // blocks when there is not enough space in the mailbox. // Messages cannot be longer than MBOX_MAX_MESSAGE_LENGTH. // Note that the calling process must have opened the // mailbox via MboxOpen. // // Returns MBOX_FAIL on failure. // Returns MBOX_SUCCESS on success. // //------------------------------------------------------- int MboxSend(mbox_t handle, int length, void* message) { int i; int qlen; Link *l; int exists = 0; //check if mailbox is real if(!&mboxs[handle]) return MBOX_FAIL; //check if pid opened this mailbox if(!AQueueEmpty(&mboxs[handle].pids ) ){ qlen = AQueueLength(&mboxs[handle].pids); l = AQueueFirst(&mboxs[handle].pids); for(i=0; i < qlen; i++){ if((int)AQueueObject(l) == GetCurrentPid()){ exists = 1; break; } l = AQueueNext(l); } //actuall checks if pid exists if(exists == 0){ return MBOX_FAIL; } //check if message longer than max length if(length > MBOX_MAX_MESSAGE_LENGTH) { return MBOX_FAIL; } //check for space in mailbox if((SemHandleWait(mboxs[handle].s_msg_empty)) == SYNC_FAIL ){ printf("bad sem handle wait in mbox send\n"); exitsim(); } //lock if(LockHandleAcquire(mboxs[handle].l) != SYNC_SUCCESS){ printf("FATAL ERROR: could not get lock in Mbox send!\n"); exitsim(); } for(i=0; i<MBOX_NUM_BUFFERS; i++){ if(mbox_messages[i].inuse == 0){ mbox_messages[i].inuse = 1; break; } } //creating mbox_message structure dstrncpy(mbox_messages[i].message, (char *) message, length); mbox_messages[i].length = length; if ((l = AQueueAllocLink(&mbox_messages[i])) == NULL) { printf("FATAL ERROR: could not allocate link for pid queue in Mbox Open!\n"); exitsim(); } //add message to end of queue AQueueInsertLast(&mboxs[handle].messages, l); //unlock if(LockHandleRelease(mboxs[handle].l) != SYNC_SUCCESS){ printf("FATAL ERROR: could not release lock in Mbox send!\n"); exitsim(); } if(SemHandleSignal(mboxs[handle].s_msg_full) == SYNC_FAIL){ printf("bad sem handle signal in mbox send\n"); exitsim(); } }else{ return MBOX_FAIL; } return MBOX_SUCCESS; }
//---------------------------------------------------------------------- // // ProcessFork // // Create a new process and make it runnable. This involves the // following steps: // * Allocate resources for the process (PCB, memory, etc.) // * Initialize the resources // * Place the PCB on the runnable queue // // NOTE: This code has been tested for system processes, but not // for user processes. // //---------------------------------------------------------------------- int ProcessFork (VoidFunc func, uint32 param, char *name, int isUser) { int fd, n; int start, codeS, codeL, dataS, dataL; uint32 *stackframe; int newPage; PCB *pcb; int addr = 0; int intrs; unsigned char buf[100]; uint32 dum[MAX_ARGS+8], count, offset; char *str; dbprintf ('p', "ProcessFork (%d): function started\n", GetCurrentPid()); intrs = DisableIntrs (); dbprintf ('I', "Old interrupt value was 0x%x.\n", intrs); dbprintf ('p', "Entering ProcessFork args=0x%x 0x%x %s %d\n", (int)func, param, name, isUser); // Get a free PCB for the new process if (AQueueEmpty(&freepcbs)) { printf ("FATAL error: no free processes!\n"); GracefulExit (); // NEVER RETURNS! } pcb = (PCB *)AQueueObject(AQueueFirst (&freepcbs)); dbprintf ('p', "Got a link @ 0x%x\n", (int)(pcb->l)); if (AQueueRemove (&(pcb->l)) != QUEUE_SUCCESS) { printf("FATAL ERROR: could not remove link from freepcbsQueue in ProcessFork!\n"); GracefulExit(); } // This prevents someone else from grabbing this process ProcessSetStatus (pcb, PROCESS_STATUS_RUNNABLE); // At this point, the PCB is allocated and nobody else can get it. // However, it's not in the run queue, so it won't be run. Thus, we // can turn on interrupts here. dbprintf ('I', "Before restore interrupt value is 0x%x.\n", (int)CurrentIntrs()); RestoreIntrs (intrs); dbprintf ('I', "New interrupt value is 0x%x.\n", (int)CurrentIntrs()); // Copy the process name into the PCB. dbprintf('p', "ProcessFork: Copying process name (%s) to pcb\n", name); dstrcpy(pcb->name, name); //---------------------------------------------------------------------- // This section initializes the memory for this process //---------------------------------------------------------------------- // For now, we'll use one user page and a page for the system stack. // For system processes, though, all pages must be contiguous. // Of course, system processes probably need just a single page for // their stack, and don't need any code or data pages allocated for them. pcb->npages = 1; newPage = MemoryAllocPage (); if (newPage == 0) { printf ("aFATAL: couldn't allocate memory - no free pages!\n"); GracefulExit (); // NEVER RETURNS! } pcb->pagetable[0] = MemorySetupPte (newPage); newPage = MemoryAllocPage (); if (newPage == 0) { printf ("bFATAL: couldn't allocate system stack - no free pages!\n"); GracefulExit (); // NEVER RETURNS! } pcb->sysStackArea = newPage * MEMORY_PAGE_SIZE; //---------------------------------------------------------------------- // Stacks grow down from the top. The current system stack pointer has // to be set to the bottom of the interrupt stack frame, which is at the // high end (address-wise) of the system stack. stackframe = ((uint32 *)(pcb->sysStackArea + MEMORY_PAGE_SIZE)) - (PROCESS_STACK_FRAME_SIZE + 8); // The system stack pointer is set to the base of the current interrupt // stack frame. pcb->sysStackPtr = stackframe; // The current stack frame pointer is set to the same thing. pcb->currentSavedFrame = stackframe; dbprintf ('p', "Setting up PCB @ 0x%x (sys stack=0x%x, mem=0x%x, size=0x%x)\n", (int)pcb, pcb->sysStackArea, pcb->pagetable[0], pcb->npages * MEMORY_PAGE_SIZE); //---------------------------------------------------------------------- // This section sets up the stack frame for the process. This is done // so that the frame looks to the interrupt handler like the process // was "suspended" right before it began execution. The standard // mechanism of swapping in the registers and returning to the place // where it was "interrupted" will then work. //---------------------------------------------------------------------- // The previous stack frame pointer is set to 0, meaning there is no // previous frame. stackframe[PROCESS_STACK_PREV_FRAME] = 0; // Set the base of the level 1 page table. If there's only one page // table level, this is it. For 2-level page tables, put the address // of the level 1 page table here. For 2-level page tables, we'll also // have to build up the necessary tables.... stackframe[PROCESS_STACK_PTBASE] = (uint32)&(pcb->pagetable[0]); // Set the size (maximum number of entries) of the level 1 page table. // In our case, it's just one page, but it could be larger. stackframe[PROCESS_STACK_PTSIZE] = pcb->npages; // Set the number of bits for both the level 1 and level 2 page tables. // This can be changed on a per-process basis if desired. For now, // though, it's fixed. stackframe[PROCESS_STACK_PTBITS] = (MEMORY_L1_PAGE_SIZE_BITS + (MEMORY_L2_PAGE_SIZE_BITS << 16)); if (isUser) { dbprintf ('p', "About to load %s\n", name); fd = ProcessGetCodeInfo (name, &start, &codeS, &codeL, &dataS, &dataL); if (fd < 0) { // Free newpage and pcb so we don't run out... ProcessFreeResources (pcb); return (-1); } dbprintf ('p', "File %s -> start=0x%08x\n", name, start); dbprintf ('p', "File %s -> code @ 0x%08x (size=0x%08x)\n", name, codeS, codeL); dbprintf ('p', "File %s -> data @ 0x%08x (size=0x%08x)\n", name, dataS, dataL); while ((n = ProcessGetFromFile (fd, buf, &addr, sizeof (buf))) > 0) { dbprintf ('p', "Placing %d bytes at vaddr %08x.\n", n, addr - n); // Copy the data to user memory. Note that the user memory needs to // have enough space so that this copy will succeed! MemoryCopySystemToUser (pcb, buf, addr - n, n); } FsClose (fd); stackframe[PROCESS_STACK_ISR] = PROCESS_INIT_ISR_USER; // Set the initial stack pointer correctly. Currently, it's just set // to the top of the (single) user address space allocated to this // process. str = (char *)param; stackframe[PROCESS_STACK_IREG+29] = MEMORY_PAGE_SIZE - SIZE_ARG_BUFF; // Copy the initial parameter to the top of stack MemoryCopySystemToUser (pcb, (char *)str, (char *)stackframe[PROCESS_STACK_IREG+29], SIZE_ARG_BUFF-32); offset = get_argument((char *)param); dum[2] = MEMORY_PAGE_SIZE - SIZE_ARG_BUFF + offset; for(count=3;;count++) { offset=get_argument(NULL); dum[count] = MEMORY_PAGE_SIZE - SIZE_ARG_BUFF + offset; if(offset==0) { break; } } dum[0] = count-2; dum[1] = MEMORY_PAGE_SIZE - SIZE_ARG_BUFF - (count-2)*4; MemoryCopySystemToUser (pcb, (char *)dum, (char *)(stackframe[PROCESS_STACK_IREG+29]-count*4), (count)*sizeof(uint32)); stackframe[PROCESS_STACK_IREG+29] -= 4*count; // Set the correct address at which to execute a user process. stackframe[PROCESS_STACK_IAR] = (uint32)start; pcb->flags |= PROCESS_TYPE_USER; } else { // Set r31 to ProcessExit(). This will only be called for a system // process; user processes do an exit() trap. stackframe[PROCESS_STACK_IREG+31] = (uint32)ProcessExit; // Set the stack register to the base of the system stack. stackframe[PROCESS_STACK_IREG+29]=pcb->sysStackArea + MEMORY_PAGE_SIZE-32; // Set the initial parameter properly by placing it on the stack frame // at the location pointed to by the "saved" stack pointer (r29). *((uint32 *)(stackframe[PROCESS_STACK_IREG+29])) = param; // Set up the initial address at which to execute. This is done by // placing the address into the IAR slot of the stack frame. stackframe[PROCESS_STACK_IAR] = (uint32)func; // Set the initial value for the interrupt status register stackframe[PROCESS_STACK_ISR] = PROCESS_INIT_ISR_SYS; // Mark this as a system process. pcb->flags |= PROCESS_TYPE_SYSTEM; } // Place PCB onto run queue intrs = DisableIntrs (); if ((pcb->l = AQueueAllocLink(pcb)) == NULL) { printf("FATAL ERROR: could not get link for forked PCB in ProcessFork!\n"); GracefulExit(); } if (AQueueInsertLast(&runQueue, pcb->l) != QUEUE_SUCCESS) { printf("FATAL ERROR: could not insert link into runQueue in ProcessFork!\n"); GracefulExit(); } RestoreIntrs (intrs); // If this is the first process, make it the current one if (currentPCB == NULL) { dbprintf ('p', "Setting currentPCB=0x%x, stackframe=0x%x\n", (int)pcb, (int)(pcb->currentSavedFrame)); currentPCB = pcb; } dbprintf ('p', "Leaving ProcessFork (%s)\n", name); // Return the process number (found by subtracting the PCB number // from the base of the PCB array). dbprintf ('p', "ProcessFork (%d): function complete\n", GetCurrentPid()); return (pcb - pcbs); }