示例#1
0
int
execv(const char *path, char *const argv[])
{
	// We'll build the new program in child 0,
	// which never represents a forked child since 0 is an invalid pid.
	// First clear out the new program's entire address space.
	sys_put(SYS_ZERO, 0, NULL, NULL, (void*)VM_USERLO, VM_USERHI-VM_USERLO);

	// Load the ELF executable into child 0.
	if (exec_readelf(path) < 0)
		return -1;

	// Setup child 0's stack with the argument array.
	intptr_t esp = exec_copyargs(argv);

	// Copy our Unix file system and process state into the child.
	sys_put(SYS_COPY, 0, NULL, (void*)VM_FILELO, (void*)VM_FILELO,
		VM_FILEHI-VM_FILELO);

	// Copy child 0's entire memory state onto ours
	// and start the new program.  See lib/entry.S for details.
	exec_start(esp);
}
示例#2
0
intptr_t
exec_copyargs(char *const argv[])
{
	// Give the process a nice big 4MB, zero-filled stack.
	sys_get(SYS_ZERO | SYS_PERM | SYS_READ | SYS_WRITE, 0, NULL,
		NULL, (void*)VM_SCRATCHLO, PTSIZE);

#if SOL >= 4
	// How many arguments?
	int argc;
	for (argc = 0; argv[argc] != NULL; argc++)
		;

	// Make room for the argv array
	intptr_t esp = VM_STACKHI;
	intptr_t scratchofs = VM_SCRATCHLO - (VM_STACKHI-PTSIZE);
	esp -= (argc+1) * sizeof(intptr_t);	// room for arguments plus NULL
	intptr_t dargv = esp;

	// Copy the argument strings
	int i;
	for (i = 0; i < argc; i++) {
		int len = strlen(argv[i]);
		esp -= len+1;
		strcpy((void*)esp + scratchofs, argv[i]);
		((intptr_t*)(dargv + scratchofs))[i] = esp;
	}
	esp &= ~3;	// get esp word-aligned again

	// Push the arguments to main()
	esp -= 4;	*(intptr_t*)(esp + scratchofs) = dargv;
	esp -= 4;	*(intptr_t*)(esp + scratchofs) = argc;
#else // ! SOL >= 4
	// Lab 4: insert your code here to copy our command-line arguments
	// onto the new process's stack, taking into account the fact that
	// the stack area is mapped at VM_SCRATCHLO to VM_SCRATCHLO+PTSIZE
	// in _our_ address space while we're copying the arguments,
	// but the pointers we're writing into this space will be
	// interpreted by the newly executed process,
	// where the stack will be mapped from VM_STACKHI-PTSIZE to VM_STACKHI.
	warn("exec_copyargs not implemented yet");
	intptr_t esp = VM_STACKHI;	// no arguments - fix this.
#endif // ! SOL >= 4

	// Copy the stack into its correct position in child 0.
	sys_put(SYS_COPY, 0, NULL, (void*)VM_SCRATCHLO,
		(void*)VM_STACKHI-PTSIZE, PTSIZE);

	return esp;
}
示例#3
0
文件: proc.c 项目: britodouglas/tp3
void
proc_check(void)
{
	// Spawn 2 child processes, executing on statically allocated stacks.

	cprintf("in proc_check()\n");
	int i;
	for (i = 0; i < 4; i++) {
		// Setup register state for child
		uint32_t *esp = (uint32_t*) &child_stack[i][PAGESIZE];
		*--esp = i;	// push argument to child() function
		*--esp = 0;	// fake return address
		child_state.tf.eip = (uint32_t) child;
		child_state.tf.esp = (uint32_t) esp;

		// Use PUT syscall to create each child,
		// but only start the first 2 children for now.
		cprintf("spawning child %d\n", i);
		sys_put(SYS_REGS | (i < 2 ? SYS_START : 0), i, &child_state,
			NULL, NULL, 0);
	}
	cprintf("proc_check() created childs\n");


	// Wait for both children to complete.
	// This should complete without preemptive scheduling
	// when we're running on a 2-processor machine.
	for (i = 0; i < 2; i++) {
		cprintf("waiting for child %d\n", i);
		sys_get(SYS_REGS, i, &child_state, NULL, NULL, 0);
	}
	cprintf("proc_check() 2-child test succeeded\n");

	// (Re)start all four children, and wait for them.
	// This will require preemptive scheduling to complete
	// if we have less than 4 CPUs.
	cprintf("proc_check: spawning 4 children\n");
	for (i = 0; i < 4; i++) {
		cprintf("spawning child %d\n", i);
		sys_put(SYS_START, i, NULL, NULL, NULL, 0);
	}

	// Wait for all 4 children to complete.
	for (i = 0; i < 4; i++)
		sys_get(0, i, NULL, NULL, NULL, 0);
	cprintf("proc_check() 4-child test succeeded\n");

	// Now do a trap handling test using all 4 children -
	// but they'll _think_ they're all child 0!
	// (We'll lose the register state of the other children.)
	i = 0;
	sys_get(SYS_REGS, i, &child_state, NULL, NULL, 0);
		// get child 0's state
	assert(recovargs == NULL);
	do {
		sys_put(SYS_REGS | SYS_START, i, &child_state, NULL, NULL, 0);
		sys_get(SYS_REGS, i, &child_state, NULL, NULL, 0);
		if (recovargs) {	// trap recovery needed
			trap_check_args *args = recovargs;
			cprintf("recover from trap %d\n",
				child_state.tf.trapno);
			child_state.tf.eip = (uint32_t) args->reip;
			args->trapno = child_state.tf.trapno;
		} else
			assert(child_state.tf.trapno == T_SYSCALL);
		i = (i+1) % 4;	// rotate to next child proc
	} while (child_state.tf.trapno != T_SYSCALL);
	assert(recovargs == NULL);

	cprintf("proc_check() trap reflection test succeeded\n");

	cprintf("proc_check() succeeded!\n");
}
示例#4
0
int
exec_readelf(const char *path)
{
	// We'll load the ELF image into a scratch area in our address space.
	sys_get(SYS_ZERO, 0, NULL, NULL, (void*)VM_SCRATCHLO, EXEMAX);

	// Open the ELF image to load.
	filedesc *fd = filedesc_open(NULL, path, O_RDONLY, 0);
	if (fd == NULL)
		return -1;
	void *imgdata = FILEDATA(fd->ino);
	size_t imgsize = files->fi[fd->ino].size;

	// Make sure it looks like an ELF image.
	elfhdr *eh = imgdata;
	if (imgsize < sizeof(*eh) || eh->e_magic != ELF_MAGIC) {
		warn("exec_readelf: ELF header not found");
		goto err;
	}

	// Load each program segment into the scratch area
	proghdr *ph = imgdata + eh->e_phoff;
	proghdr *eph = ph + eh->e_phnum;
	if (imgsize < (void*)eph - imgdata) {
		warn("exec_readelf: ELF program header truncated");
		goto err;
	}
	for (; ph < eph; ph++) {
		if (ph->p_type != ELF_PROG_LOAD)
			continue;

		// The executable should fit in the first 4MB of user space.
		intptr_t valo = ph->p_va;
		intptr_t vahi = valo + ph->p_memsz;
		if (valo < VM_USERLO || valo > VM_USERLO+EXEMAX ||
				vahi < valo || vahi > VM_USERLO+EXEMAX) {
			warn("exec_readelf: executable image too large "
				"(%d bytes > %d max)", vahi-valo, EXEMAX);
			goto err;
		}

		// Map all pages the segment touches in our scratch region.
		// They've already been zeroed by the SYS_ZERO above.
		intptr_t scratchofs = VM_SCRATCHLO - VM_USERLO;
		intptr_t pagelo = ROUNDDOWN(valo, PAGESIZE);
		intptr_t pagehi = ROUNDUP(vahi, PAGESIZE);
		sys_get(SYS_PERM | SYS_READ | SYS_WRITE, 0, NULL, NULL,
			(void*)pagelo + scratchofs, pagehi - pagelo);

		// Initialize the file-loaded part of the ELF image.
		// (We could use copy-on-write if SYS_COPY
		// supports copying at arbitrary page boundaries.)
		intptr_t filelo = ph->p_offset;
		intptr_t filehi = filelo + ph->p_filesz;
		if (filelo < 0 || filelo > imgsize
				|| filehi < filelo || filehi > imgsize) {
			warn("exec_readelf: loaded section out of bounds");
			goto err;
		}
		memcpy((void*)valo + scratchofs, imgdata + filelo,
			filehi - filelo);

		// Finally, remove write permissions on read-only segments.
		if (!(ph->p_flags & ELF_PROG_FLAG_WRITE))
			sys_get(SYS_PERM | SYS_READ, 0, NULL, NULL,
				(void*)pagelo + scratchofs, pagehi - pagelo);
	}

	// Copy the ELF image into its correct position in child 0.
	sys_put(SYS_COPY, 0, NULL, (void*)VM_SCRATCHLO,
		(void*)VM_USERLO, EXEMAX);

	// The new program should have the same entrypoint as we do!
	if (eh->e_entry != (intptr_t)start) {
		warn("exec_readelf: executable has a different start address");
		goto err;
	}

	filedesc_close(fd);	// Done with the ELF file
	return 0;

err:
	filedesc_close(fd);
	return -1;
}