4d8335ad75
This is a pretty big commit, so let's run through it in parts: - All of the userspace changes are to switch away from syscall_wait Mostly, this is to waitpid; some things were tweaked to do things "properly" instead of waiting for particular processes. Init has been fixed to do a proper spin wait. - syscall_wait is gone - as are its uses. newlib bindings have been using just waitpid for a while now. - waitpid now performs like a Unix waitpid - process reaping is no longer a "do this on next change thing": it happens when a process is waited on, like it should (That means we can have real zombies: terminated processes that have not yet been waited on) - Reparenting of children to init has been implemented, so you can fork-daemonize! Overall, this is pretty big... So I hope it doesn't break everything.
574 lines
15 KiB
C
574 lines
15 KiB
C
/* vim: tabstop=4 shiftwidth=4 noexpandtab
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*
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* Task Switching and Management Functions
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*
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*/
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#include <system.h>
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#include <process.h>
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#include <logging.h>
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#include <shm.h>
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#include <mem.h>
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#define TASK_MAGIC 0xDEADBEEF
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uint32_t next_pid = 0;
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#define PUSH(stack, type, item) stack -= sizeof(type); \
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*((type *) stack) = item
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page_directory_t *kernel_directory;
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page_directory_t *current_directory;
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/*
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* Clone a page directory and its contents.
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* (If you do not intend to clone the contents, do it yourself!)
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*
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* @param src Pointer to source directory to clone from.
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* @return A pointer to a new directory.
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*/
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page_directory_t *
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clone_directory(
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page_directory_t * src
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) {
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/* Allocate a new page directory */
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uintptr_t phys;
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page_directory_t * dir = (page_directory_t *)kvmalloc_p(sizeof(page_directory_t), &phys);
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/* Clear it out */
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memset(dir, 0, sizeof(page_directory_t));
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dir->ref_count = 1;
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/* And store it... */
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dir->physical_address = phys;
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uint32_t i;
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for (i = 0; i < 1024; ++i) {
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/* Copy each table */
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if (!src->tables[i] || (uintptr_t)src->tables[i] == (uintptr_t)0xFFFFFFFF) {
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continue;
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}
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if (kernel_directory->tables[i] == src->tables[i]) {
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/* Kernel tables are simply linked together */
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dir->tables[i] = src->tables[i];
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dir->physical_tables[i] = src->physical_tables[i];
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} else {
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if (i * 0x1000 * 1024 < SHM_START) {
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/* User tables must be cloned */
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uintptr_t phys;
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dir->tables[i] = clone_table(src->tables[i], &phys);
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dir->physical_tables[i] = phys | 0x07;
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}
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}
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}
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return dir;
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}
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/*
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* Free a directory and its tables
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*/
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void release_directory(page_directory_t * dir) {
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dir->ref_count--;
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if (dir->ref_count < 1) {
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uint32_t i;
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for (i = 0; i < 1024; ++i) {
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if (!dir->tables[i] || (uintptr_t)dir->tables[i] == (uintptr_t)0xFFFFFFFF) {
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continue;
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}
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if (kernel_directory->tables[i] != dir->tables[i]) {
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if (i * 0x1000 * 1024 < SHM_START) {
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for (uint32_t j = 0; j < 1024; ++j) {
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if (dir->tables[i]->pages[j].frame) {
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free_frame(&(dir->tables[i]->pages[j]));
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}
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}
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}
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free(dir->tables[i]);
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}
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}
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free(dir);
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}
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}
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void release_directory_for_exec(page_directory_t * dir) {
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uint32_t i;
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/* This better be the only owner of this directory... */
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for (i = 0; i < 1024; ++i) {
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if (!dir->tables[i] || (uintptr_t)dir->tables[i] == (uintptr_t)0xFFFFFFFF) {
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continue;
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}
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if (kernel_directory->tables[i] != dir->tables[i]) {
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if (i * 0x1000 * 1024 < USER_STACK_BOTTOM) {
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for (uint32_t j = 0; j < 1024; ++j) {
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if (dir->tables[i]->pages[j].frame) {
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free_frame(&(dir->tables[i]->pages[j]));
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}
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}
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dir->physical_tables[i] = 0;
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free(dir->tables[i]);
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dir->tables[i] = 0;
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}
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}
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}
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}
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extern char * default_name;
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/*
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* Clone a page table
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*
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* @param src Pointer to a page table to clone.
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* @param physAddr [out] Pointer to the physical address of the new page table
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* @return A pointer to a new page table.
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*/
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page_table_t *
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clone_table(
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page_table_t * src,
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uintptr_t * physAddr
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) {
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/* Allocate a new page table */
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page_table_t * table = (page_table_t *)kvmalloc_p(sizeof(page_table_t), physAddr);
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memset(table, 0, sizeof(page_table_t));
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uint32_t i;
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for (i = 0; i < 1024; ++i) {
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/* For each frame in the table... */
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if (!src->pages[i].frame) {
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continue;
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}
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/* Allocate a new frame */
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alloc_frame(&table->pages[i], 0, 0);
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/* Set the correct access bit */
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if (src->pages[i].present) table->pages[i].present = 1;
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if (src->pages[i].rw) table->pages[i].rw = 1;
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if (src->pages[i].user) table->pages[i].user = 1;
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if (src->pages[i].accessed) table->pages[i].accessed = 1;
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if (src->pages[i].dirty) table->pages[i].dirty = 1;
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/* Copy the contents of the page from the old table to the new one */
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copy_page_physical(src->pages[i].frame * 0x1000, table->pages[i].frame * 0x1000);
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}
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return table;
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}
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uintptr_t frozen_stack = 0;
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/*
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* Install multitasking functionality.
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*/
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void tasking_install(void) {
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IRQ_OFF; /* Disable interrupts */
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debug_print(NOTICE, "Initializing multitasking");
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/* Initialize the process tree */
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initialize_process_tree();
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/* Spawn the initial process */
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current_process = spawn_init();
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kernel_idle_task = spawn_kidle();
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/* Initialize the paging environment */
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#if 0
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set_process_environment((process_t *)current_process, current_directory);
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#endif
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/* Switch to the kernel directory */
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switch_page_directory(current_process->thread.page_directory);
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frozen_stack = (uintptr_t)valloc(KERNEL_STACK_SIZE);
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/* Reenable interrupts */
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IRQ_RES;
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}
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/*
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* Fork.
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*
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* @return To the parent: PID of the child; to the child: 0
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*/
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uint32_t fork(void) {
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IRQ_OFF;
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uintptr_t esp, ebp;
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current_process->syscall_registers->eax = 0;
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/* Make a pointer to the parent process (us) on the stack */
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process_t * parent = (process_t *)current_process;
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assert(parent && "Forked from nothing??");
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/* Clone the current process' page directory */
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page_directory_t * directory = clone_directory(current_directory);
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assert(directory && "Could not allocate a new page directory!");
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/* Spawn a new process from this one */
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debug_print(INFO,"\033[1;32mALLOC {\033[0m");
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process_t * new_proc = spawn_process(current_process);
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debug_print(INFO,"\033[1;32m}\033[0m");
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assert(new_proc && "Could not allocate a new process!");
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/* Set the new process' page directory to clone */
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set_process_environment(new_proc, directory);
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struct regs r;
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memcpy(&r, current_process->syscall_registers, sizeof(struct regs));
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new_proc->syscall_registers = &r;
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esp = new_proc->image.stack;
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ebp = esp;
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new_proc->syscall_registers->eax = 0;
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PUSH(esp, struct regs, r);
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new_proc->thread.esp = esp;
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new_proc->thread.ebp = ebp;
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new_proc->is_tasklet = parent->is_tasklet;
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new_proc->thread.eip = (uintptr_t)&return_to_userspace;
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/* Clear page table tie-ins for shared memory mappings */
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#if 0
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assert((new_proc->shm_mappings->length == 0) && "Spawned process had shared memory mappings!");
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foreach (n, current_process->shm_mappings) {
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shm_mapping_t * mapping = (shm_mapping_t *)n->value;
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for (uint32_t i = 0; i < mapping->num_vaddrs; i++) {
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/* Get the vpage address (it's the same for the cloned directory)... */
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uintptr_t vpage = mapping->vaddrs[i];
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assert(!(vpage & 0xFFF) && "shm_mapping_t contained a ptr to the middle of a page (bad)");
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/* ...and from that, the cloned dir's page entry... */
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page_t * page = get_page(vpage, 0, new_proc->thread.page_directory);
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assert(test_frame(page->frame * 0x1000) && "ptr wasn't mapped in?");
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/* ...which refers to a bogus frame that we don't want. */
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clear_frame(page->frame * 0x1000);
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memset(page, 0, sizeof(page_t));
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}
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}
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#endif
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/* Add the new process to the ready queue */
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make_process_ready(new_proc);
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IRQ_RES;
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/* Return the child PID */
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return new_proc->id;
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}
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int create_kernel_tasklet(tasklet_t tasklet, char * name, void * argp) {
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IRQ_OFF;
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uintptr_t esp, ebp;
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if (current_process->syscall_registers) {
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current_process->syscall_registers->eax = 0;
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}
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page_directory_t * directory = kernel_directory;
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/* Spawn a new process from this one */
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process_t * new_proc = spawn_process(current_process);
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assert(new_proc && "Could not allocate a new process!");
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/* Set the new process' page directory to the original process' */
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set_process_environment(new_proc, directory);
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directory->ref_count++;
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/* Read the instruction pointer */
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if (current_process->syscall_registers) {
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struct regs r;
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memcpy(&r, current_process->syscall_registers, sizeof(struct regs));
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new_proc->syscall_registers = &r;
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}
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esp = new_proc->image.stack;
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ebp = esp;
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if (current_process->syscall_registers) {
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new_proc->syscall_registers->eax = 0;
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}
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new_proc->is_tasklet = 1;
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new_proc->name = name;
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PUSH(esp, uintptr_t, (uintptr_t)name);
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PUSH(esp, uintptr_t, (uintptr_t)argp);
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PUSH(esp, uintptr_t, (uintptr_t)&task_exit);
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new_proc->thread.esp = esp;
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new_proc->thread.ebp = ebp;
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new_proc->thread.eip = (uintptr_t)tasklet;
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/* Add the new process to the ready queue */
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make_process_ready(new_proc);
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IRQ_RES;
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/* Return the child PID */
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return new_proc->id;
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}
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/*
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* clone the current thread and create a new one in the same
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* memory space with the given pointer as its new stack.
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*/
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uint32_t
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clone(uintptr_t new_stack, uintptr_t thread_func, uintptr_t arg) {
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uintptr_t esp, ebp;
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IRQ_OFF;
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current_process->syscall_registers->eax = 0;
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/* Make a pointer to the parent process (us) on the stack */
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process_t * parent = (process_t *)current_process;
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assert(parent && "Cloned from nothing??");
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page_directory_t * directory = current_directory;
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/* Spawn a new process from this one */
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process_t * new_proc = spawn_process(current_process);
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assert(new_proc && "Could not allocate a new process!");
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/* Set the new process' page directory to the original process' */
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set_process_environment(new_proc, directory);
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directory->ref_count++;
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/* Read the instruction pointer */
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struct regs r;
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memcpy(&r, current_process->syscall_registers, sizeof(struct regs));
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new_proc->syscall_registers = &r;
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esp = new_proc->image.stack;
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ebp = esp;
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/* Set the gid */
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if (current_process->group) {
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new_proc->group = current_process->group;
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} else {
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/* We are the session leader */
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new_proc->group = current_process->id;
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}
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new_proc->syscall_registers->ebp = new_stack;
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new_proc->syscall_registers->eip = thread_func;
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/* Push arg, bogus return address onto the new thread's stack */
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new_stack -= sizeof(uintptr_t);
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*((uintptr_t *)new_stack) = arg;
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new_stack -= sizeof(uintptr_t);
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*((uintptr_t *)new_stack) = THREAD_RETURN;
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/* Set esp, ebp, and eip for the new thread */
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new_proc->syscall_registers->esp = new_stack;
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new_proc->syscall_registers->useresp = new_stack;
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PUSH(esp, struct regs, r);
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new_proc->thread.esp = esp;
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new_proc->thread.ebp = ebp;
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new_proc->is_tasklet = parent->is_tasklet;
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free(new_proc->fds);
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new_proc->fds = current_process->fds;
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new_proc->fds->refs++;
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new_proc->thread.eip = (uintptr_t)&return_to_userspace;
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/* Add the new process to the ready queue */
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make_process_ready(new_proc);
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IRQ_RES;
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/* Return the child PID */
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return new_proc->id;
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}
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/*
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* Get the process ID of the current process.
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*
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* @return The PID of the current process.
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*/
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uint32_t getpid(void) {
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/* Fairly self-explanatory. */
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return current_process->id;
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}
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/*
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* Switch to the next ready task.
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*
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* This is called from the interrupt handler for the interval timer to
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* perform standard task switching.
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*/
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void switch_task(uint8_t reschedule) {
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if (!current_process) {
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/* Tasking is not yet installed. */
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return;
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}
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if (!current_process->running) {
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switch_next();
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}
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/* Collect the current kernel stack and instruction pointers */
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uintptr_t esp, ebp, eip;
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asm volatile ("mov %%esp, %0" : "=r" (esp));
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asm volatile ("mov %%ebp, %0" : "=r" (ebp));
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eip = read_eip();
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if (eip == 0x10000) {
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/* Returned from EIP after task switch, we have
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* finished switching. */
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fix_signal_stacks();
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/* XXX: Signals */
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if (!current_process->finished) {
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if (current_process->signal_queue->length > 0) {
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node_t * node = list_dequeue(current_process->signal_queue);
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signal_t * sig = node->value;
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free(node);
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handle_signal((process_t *)current_process, sig);
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}
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}
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return;
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}
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/* Remember this process' ESP/EBP/EIP */
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current_process->thread.eip = eip;
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current_process->thread.esp = esp;
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current_process->thread.ebp = ebp;
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current_process->running = 0;
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/* Save floating point state */
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switch_fpu();
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if (reschedule && current_process != kernel_idle_task) {
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/* And reinsert it into the ready queue */
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make_process_ready((process_t *)current_process);
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}
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/* Switch to the next task */
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switch_next();
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}
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/*
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* Immediately switch to the next task.
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*
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* Does not store the ESP/EBP/EIP of the current thread.
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*/
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void switch_next(void) {
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uintptr_t esp, ebp, eip;
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/* Get the next available process */
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current_process = next_ready_process();
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/* Retreive the ESP/EBP/EIP */
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eip = current_process->thread.eip;
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esp = current_process->thread.esp;
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ebp = current_process->thread.ebp;
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/* Validate */
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if ((eip < (uintptr_t)&code) || (eip > (uintptr_t)heap_end)) {
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debug_print(WARNING, "Skipping broken process %d! [eip=0x%x <0x%x or >0x%x]", current_process->id, eip, &code, &end);
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switch_next();
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}
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if (current_process->finished) {
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debug_print(WARNING, "Tried to switch to process %d, but it claims it is finished.", current_process->id);
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switch_next();
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}
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/* Set the page directory */
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current_directory = current_process->thread.page_directory;
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switch_page_directory(current_directory);
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/* Set the kernel stack in the TSS */
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set_kernel_stack(current_process->image.stack);
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if (current_process->started) {
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if (!current_process->signal_kstack) {
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if (current_process->signal_queue->length > 0) {
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current_process->signal_kstack = malloc(KERNEL_STACK_SIZE);
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current_process->signal_state.esp = current_process->thread.esp;
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current_process->signal_state.eip = current_process->thread.eip;
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current_process->signal_state.ebp = current_process->thread.ebp;
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memcpy(current_process->signal_kstack, (void *)(current_process->image.stack - KERNEL_STACK_SIZE), KERNEL_STACK_SIZE);
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}
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}
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} else {
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current_process->started = 1;
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}
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current_process->running = 1;
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/* Jump, baby, jump */
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asm volatile (
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"mov %0, %%ebx\n"
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"mov %1, %%esp\n"
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"mov %2, %%ebp\n"
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"mov %3, %%cr3\n"
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"mov $0x10000, %%eax\n" /* read_eip() will return 0x10000 */
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"jmp *%%ebx"
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: : "r" (eip), "r" (esp), "r" (ebp), "r" (current_directory->physical_address)
|
|
: "%ebx", "%esp", "%eax");
|
|
|
|
}
|
|
|
|
/*
|
|
* Enter ring 3 and jump to `location`.
|
|
*
|
|
* @param location Address to jump to in user space
|
|
* @param argc Argument count
|
|
* @param argv Argument pointers
|
|
* @param stack Userspace stack address
|
|
*/
|
|
void
|
|
enter_user_jmp(uintptr_t location, int argc, char ** argv, uintptr_t stack) {
|
|
IRQ_OFF;
|
|
set_kernel_stack(current_process->image.stack);
|
|
|
|
PUSH(stack, uintptr_t, (uintptr_t)argv);
|
|
PUSH(stack, int, argc);
|
|
|
|
asm volatile(
|
|
"mov %1, %%esp\n"
|
|
"pushl $0xDECADE21\n" /* Magic */
|
|
"mov $0x23, %%ax\n" /* Segment selector */
|
|
"mov %%ax, %%ds\n"
|
|
"mov %%ax, %%es\n"
|
|
"mov %%ax, %%fs\n"
|
|
"mov %%ax, %%gs\n"
|
|
"mov %%esp, %%eax\n" /* Stack -> EAX */
|
|
"pushl $0x23\n" /* Segment selector again */
|
|
"pushl %%eax\n"
|
|
"pushf\n" /* Push flags */
|
|
"popl %%eax\n" /* Fix the Interrupt flag */
|
|
"orl $0x200, %%eax\n"
|
|
"pushl %%eax\n"
|
|
"pushl $0x1B\n"
|
|
"pushl %0\n" /* Push the entry point */
|
|
"iret\n"
|
|
: : "m"(location), "r"(stack) : "%ax", "%esp", "%eax");
|
|
}
|
|
|
|
/*
|
|
* Dequeue the current task and set it as finished
|
|
*
|
|
* @param retval Set the return value to this.
|
|
*/
|
|
void task_exit(int retval) {
|
|
/* Free the image memory */
|
|
if (__builtin_expect(current_process->id == 0,0)) {
|
|
/* This is probably bad... */
|
|
switch_next();
|
|
return;
|
|
}
|
|
current_process->status = retval;
|
|
current_process->finished = 1;
|
|
process_t * parent = process_get_parent((process_t *)current_process);
|
|
|
|
if (parent) {
|
|
wakeup_queue(parent->wait_queue);
|
|
}
|
|
|
|
switch_next();
|
|
}
|
|
|
|
/*
|
|
* Call task_exit() and immediately STOP if we can't.
|
|
*/
|
|
void kexit(int retval) {
|
|
task_exit(retval);
|
|
debug_print(CRITICAL, "Process returned from task_exit! Environment is definitely unclean. Stopping.");
|
|
STOP;
|
|
}
|