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/arch/um/os-Linux/skas/process.c

https://bitbucket.org/ndreys/linux-sunxi
C | 728 lines | 568 code | 96 blank | 64 comment | 86 complexity | f97ae5a70a5780682288b3401dcfd3fe MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
  1/*
  2 * Copyright (C) 2002- 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  3 * Licensed under the GPL
  4 */
  5
  6#include <stdlib.h>
  7#include <unistd.h>
  8#include <sched.h>
  9#include <errno.h>
 10#include <string.h>
 11#include <sys/mman.h>
 12#include <sys/ptrace.h>
 13#include <sys/wait.h>
 14#include <asm/unistd.h>
 15#include "as-layout.h"
 16#include "chan_user.h"
 17#include "kern_constants.h"
 18#include "kern_util.h"
 19#include "mem.h"
 20#include "os.h"
 21#include "process.h"
 22#include "proc_mm.h"
 23#include "ptrace_user.h"
 24#include "registers.h"
 25#include "skas.h"
 26#include "skas_ptrace.h"
 27#include "user.h"
 28#include "sysdep/stub.h"
 29
 30int is_skas_winch(int pid, int fd, void *data)
 31{
 32	if (pid != getpgrp())
 33		return 0;
 34
 35	register_winch_irq(-1, fd, -1, data, 0);
 36	return 1;
 37}
 38
 39static int ptrace_dump_regs(int pid)
 40{
 41	unsigned long regs[MAX_REG_NR];
 42	int i;
 43
 44	if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
 45		return -errno;
 46
 47	printk(UM_KERN_ERR "Stub registers -\n");
 48	for (i = 0; i < ARRAY_SIZE(regs); i++)
 49		printk(UM_KERN_ERR "\t%d - %lx\n", i, regs[i]);
 50
 51	return 0;
 52}
 53
 54/*
 55 * Signals that are OK to receive in the stub - we'll just continue it.
 56 * SIGWINCH will happen when UML is inside a detached screen.
 57 */
 58#define STUB_SIG_MASK ((1 << SIGVTALRM) | (1 << SIGWINCH))
 59
 60/* Signals that the stub will finish with - anything else is an error */
 61#define STUB_DONE_MASK (1 << SIGTRAP)
 62
 63void wait_stub_done(int pid)
 64{
 65	int n, status, err;
 66
 67	while (1) {
 68		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
 69		if ((n < 0) || !WIFSTOPPED(status))
 70			goto bad_wait;
 71
 72		if (((1 << WSTOPSIG(status)) & STUB_SIG_MASK) == 0)
 73			break;
 74
 75		err = ptrace(PTRACE_CONT, pid, 0, 0);
 76		if (err) {
 77			printk(UM_KERN_ERR "wait_stub_done : continue failed, "
 78			       "errno = %d\n", errno);
 79			fatal_sigsegv();
 80		}
 81	}
 82
 83	if (((1 << WSTOPSIG(status)) & STUB_DONE_MASK) != 0)
 84		return;
 85
 86bad_wait:
 87	err = ptrace_dump_regs(pid);
 88	if (err)
 89		printk(UM_KERN_ERR "Failed to get registers from stub, "
 90		       "errno = %d\n", -err);
 91	printk(UM_KERN_ERR "wait_stub_done : failed to wait for SIGTRAP, "
 92	       "pid = %d, n = %d, errno = %d, status = 0x%x\n", pid, n, errno,
 93	       status);
 94	fatal_sigsegv();
 95}
 96
 97extern unsigned long current_stub_stack(void);
 98
 99static void get_skas_faultinfo(int pid, struct faultinfo *fi)
100{
101	int err;
102
103	if (ptrace_faultinfo) {
104		err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
105		if (err) {
106			printk(UM_KERN_ERR "get_skas_faultinfo - "
107			       "PTRACE_FAULTINFO failed, errno = %d\n", errno);
108			fatal_sigsegv();
109		}
110
111		/* Special handling for i386, which has different structs */
112		if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
113			memset((char *)fi + sizeof(struct ptrace_faultinfo), 0,
114			       sizeof(struct faultinfo) -
115			       sizeof(struct ptrace_faultinfo));
116	}
117	else {
118		unsigned long fpregs[FP_SIZE];
119
120		err = get_fp_registers(pid, fpregs);
121		if (err < 0) {
122			printk(UM_KERN_ERR "save_fp_registers returned %d\n",
123			       err);
124			fatal_sigsegv();
125		}
126		err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV);
127		if (err) {
128			printk(UM_KERN_ERR "Failed to continue stub, pid = %d, "
129			       "errno = %d\n", pid, errno);
130			fatal_sigsegv();
131		}
132		wait_stub_done(pid);
133
134		/*
135		 * faultinfo is prepared by the stub-segv-handler at start of
136		 * the stub stack page. We just have to copy it.
137		 */
138		memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
139
140		err = put_fp_registers(pid, fpregs);
141		if (err < 0) {
142			printk(UM_KERN_ERR "put_fp_registers returned %d\n",
143			       err);
144			fatal_sigsegv();
145		}
146	}
147}
148
149static void handle_segv(int pid, struct uml_pt_regs * regs)
150{
151	get_skas_faultinfo(pid, &regs->faultinfo);
152	segv(regs->faultinfo, 0, 1, NULL);
153}
154
155/*
156 * To use the same value of using_sysemu as the caller, ask it that value
157 * (in local_using_sysemu
158 */
159static void handle_trap(int pid, struct uml_pt_regs *regs,
160			int local_using_sysemu)
161{
162	int err, status;
163
164	if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
165		fatal_sigsegv();
166
167	/* Mark this as a syscall */
168	UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
169
170	if (!local_using_sysemu)
171	{
172		err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
173			     __NR_getpid);
174		if (err < 0) {
175			printk(UM_KERN_ERR "handle_trap - nullifying syscall "
176			       "failed, errno = %d\n", errno);
177			fatal_sigsegv();
178		}
179
180		err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
181		if (err < 0) {
182			printk(UM_KERN_ERR "handle_trap - continuing to end of "
183			       "syscall failed, errno = %d\n", errno);
184			fatal_sigsegv();
185		}
186
187		CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
188		if ((err < 0) || !WIFSTOPPED(status) ||
189		    (WSTOPSIG(status) != SIGTRAP + 0x80)) {
190			err = ptrace_dump_regs(pid);
191			if (err)
192				printk(UM_KERN_ERR "Failed to get registers "
193				       "from process, errno = %d\n", -err);
194			printk(UM_KERN_ERR "handle_trap - failed to wait at "
195			       "end of syscall, errno = %d, status = %d\n",
196			       errno, status);
197			fatal_sigsegv();
198		}
199	}
200
201	handle_syscall(regs);
202}
203
204extern int __syscall_stub_start;
205
206static int userspace_tramp(void *stack)
207{
208	void *addr;
209	int err;
210
211	ptrace(PTRACE_TRACEME, 0, 0, 0);
212
213	signal(SIGTERM, SIG_DFL);
214	signal(SIGWINCH, SIG_IGN);
215	err = set_interval();
216	if (err) {
217		printk(UM_KERN_ERR "userspace_tramp - setting timer failed, "
218		       "errno = %d\n", err);
219		exit(1);
220	}
221
222	if (!proc_mm) {
223		/*
224		 * This has a pte, but it can't be mapped in with the usual
225		 * tlb_flush mechanism because this is part of that mechanism
226		 */
227		int fd;
228		unsigned long long offset;
229		fd = phys_mapping(to_phys(&__syscall_stub_start), &offset);
230		addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE,
231			      PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
232		if (addr == MAP_FAILED) {
233			printk(UM_KERN_ERR "mapping mmap stub at 0x%lx failed, "
234			       "errno = %d\n", STUB_CODE, errno);
235			exit(1);
236		}
237
238		if (stack != NULL) {
239			fd = phys_mapping(to_phys(stack), &offset);
240			addr = mmap((void *) STUB_DATA,
241				    UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
242				    MAP_FIXED | MAP_SHARED, fd, offset);
243			if (addr == MAP_FAILED) {
244				printk(UM_KERN_ERR "mapping segfault stack "
245				       "at 0x%lx failed, errno = %d\n",
246				       STUB_DATA, errno);
247				exit(1);
248			}
249		}
250	}
251	if (!ptrace_faultinfo && (stack != NULL)) {
252		struct sigaction sa;
253
254		unsigned long v = STUB_CODE +
255				  (unsigned long) stub_segv_handler -
256				  (unsigned long) &__syscall_stub_start;
257
258		set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
259		sigemptyset(&sa.sa_mask);
260		sa.sa_flags = SA_ONSTACK | SA_NODEFER;
261		sa.sa_handler = (void *) v;
262		sa.sa_restorer = NULL;
263		if (sigaction(SIGSEGV, &sa, NULL) < 0) {
264			printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV "
265			       "handler failed - errno = %d\n", errno);
266			exit(1);
267		}
268	}
269
270	kill(os_getpid(), SIGSTOP);
271	return 0;
272}
273
274/* Each element set once, and only accessed by a single processor anyway */
275#undef NR_CPUS
276#define NR_CPUS 1
277int userspace_pid[NR_CPUS];
278
279int start_userspace(unsigned long stub_stack)
280{
281	void *stack;
282	unsigned long sp;
283	int pid, status, n, flags, err;
284
285	stack = mmap(NULL, UM_KERN_PAGE_SIZE,
286		     PROT_READ | PROT_WRITE | PROT_EXEC,
287		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
288	if (stack == MAP_FAILED) {
289		err = -errno;
290		printk(UM_KERN_ERR "start_userspace : mmap failed, "
291		       "errno = %d\n", errno);
292		return err;
293	}
294
295	sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
296
297	flags = CLONE_FILES;
298	if (proc_mm)
299		flags |= CLONE_VM;
300	else
301		flags |= SIGCHLD;
302
303	pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
304	if (pid < 0) {
305		err = -errno;
306		printk(UM_KERN_ERR "start_userspace : clone failed, "
307		       "errno = %d\n", errno);
308		return err;
309	}
310
311	do {
312		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
313		if (n < 0) {
314			err = -errno;
315			printk(UM_KERN_ERR "start_userspace : wait failed, "
316			       "errno = %d\n", errno);
317			goto out_kill;
318		}
319	} while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
320
321	if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) {
322		err = -EINVAL;
323		printk(UM_KERN_ERR "start_userspace : expected SIGSTOP, got "
324		       "status = %d\n", status);
325		goto out_kill;
326	}
327
328	if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
329		   (void *) PTRACE_O_TRACESYSGOOD) < 0) {
330		err = -errno;
331		printk(UM_KERN_ERR "start_userspace : PTRACE_OLDSETOPTIONS "
332		       "failed, errno = %d\n", errno);
333		goto out_kill;
334	}
335
336	if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) {
337		err = -errno;
338		printk(UM_KERN_ERR "start_userspace : munmap failed, "
339		       "errno = %d\n", errno);
340		goto out_kill;
341	}
342
343	return pid;
344
345 out_kill:
346	os_kill_ptraced_process(pid, 1);
347	return err;
348}
349
350void userspace(struct uml_pt_regs *regs)
351{
352	struct itimerval timer;
353	unsigned long long nsecs, now;
354	int err, status, op, pid = userspace_pid[0];
355	/* To prevent races if using_sysemu changes under us.*/
356	int local_using_sysemu;
357
358	if (getitimer(ITIMER_VIRTUAL, &timer))
359		printk(UM_KERN_ERR "Failed to get itimer, errno = %d\n", errno);
360	nsecs = timer.it_value.tv_sec * UM_NSEC_PER_SEC +
361		timer.it_value.tv_usec * UM_NSEC_PER_USEC;
362	nsecs += os_nsecs();
363
364	while (1) {
365		/*
366		 * This can legitimately fail if the process loads a
367		 * bogus value into a segment register.  It will
368		 * segfault and PTRACE_GETREGS will read that value
369		 * out of the process.  However, PTRACE_SETREGS will
370		 * fail.  In this case, there is nothing to do but
371		 * just kill the process.
372		 */
373		if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp))
374			fatal_sigsegv();
375
376		/* Now we set local_using_sysemu to be used for one loop */
377		local_using_sysemu = get_using_sysemu();
378
379		op = SELECT_PTRACE_OPERATION(local_using_sysemu,
380					     singlestepping(NULL));
381
382		if (ptrace(op, pid, 0, 0)) {
383			printk(UM_KERN_ERR "userspace - ptrace continue "
384			       "failed, op = %d, errno = %d\n", op, errno);
385			fatal_sigsegv();
386		}
387
388		CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
389		if (err < 0) {
390			printk(UM_KERN_ERR "userspace - wait failed, "
391			       "errno = %d\n", errno);
392			fatal_sigsegv();
393		}
394
395		regs->is_user = 1;
396		if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) {
397			printk(UM_KERN_ERR "userspace - PTRACE_GETREGS failed, "
398			       "errno = %d\n", errno);
399			fatal_sigsegv();
400		}
401
402		UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
403
404		if (WIFSTOPPED(status)) {
405			int sig = WSTOPSIG(status);
406			switch (sig) {
407			case SIGSEGV:
408				if (PTRACE_FULL_FAULTINFO ||
409				    !ptrace_faultinfo) {
410					get_skas_faultinfo(pid,
411							   &regs->faultinfo);
412					(*sig_info[SIGSEGV])(SIGSEGV, regs);
413				}
414				else handle_segv(pid, regs);
415				break;
416			case SIGTRAP + 0x80:
417			        handle_trap(pid, regs, local_using_sysemu);
418				break;
419			case SIGTRAP:
420				relay_signal(SIGTRAP, regs);
421				break;
422			case SIGVTALRM:
423				now = os_nsecs();
424				if (now < nsecs)
425					break;
426				block_signals();
427				(*sig_info[sig])(sig, regs);
428				unblock_signals();
429				nsecs = timer.it_value.tv_sec *
430					UM_NSEC_PER_SEC +
431					timer.it_value.tv_usec *
432					UM_NSEC_PER_USEC;
433				nsecs += os_nsecs();
434				break;
435			case SIGIO:
436			case SIGILL:
437			case SIGBUS:
438			case SIGFPE:
439			case SIGWINCH:
440				block_signals();
441				(*sig_info[sig])(sig, regs);
442				unblock_signals();
443				break;
444			default:
445				printk(UM_KERN_ERR "userspace - child stopped "
446				       "with signal %d\n", sig);
447				fatal_sigsegv();
448			}
449			pid = userspace_pid[0];
450			interrupt_end();
451
452			/* Avoid -ERESTARTSYS handling in host */
453			if (PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
454				PT_SYSCALL_NR(regs->gp) = -1;
455		}
456	}
457}
458
459static unsigned long thread_regs[MAX_REG_NR];
460
461static int __init init_thread_regs(void)
462{
463	get_safe_registers(thread_regs);
464	/* Set parent's instruction pointer to start of clone-stub */
465	thread_regs[REGS_IP_INDEX] = STUB_CODE +
466				(unsigned long) stub_clone_handler -
467				(unsigned long) &__syscall_stub_start;
468	thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
469		sizeof(void *);
470#ifdef __SIGNAL_FRAMESIZE
471	thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
472#endif
473	return 0;
474}
475
476__initcall(init_thread_regs);
477
478int copy_context_skas0(unsigned long new_stack, int pid)
479{
480	struct timeval tv = { .tv_sec = 0, .tv_usec = UM_USEC_PER_SEC / UM_HZ };
481	int err;
482	unsigned long current_stack = current_stub_stack();
483	struct stub_data *data = (struct stub_data *) current_stack;
484	struct stub_data *child_data = (struct stub_data *) new_stack;
485	unsigned long long new_offset;
486	int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
487
488	/*
489	 * prepare offset and fd of child's stack as argument for parent's
490	 * and child's mmap2 calls
491	 */
492	*data = ((struct stub_data) { .offset	= MMAP_OFFSET(new_offset),
493				      .fd	= new_fd,
494				      .timer    = ((struct itimerval)
495					           { .it_value = tv,
496						     .it_interval = tv }) });
497
498	err = ptrace_setregs(pid, thread_regs);
499	if (err < 0) {
500		err = -errno;
501		printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_SETREGS "
502		       "failed, pid = %d, errno = %d\n", pid, -err);
503		return err;
504	}
505
506	/* set a well known return code for detection of child write failure */
507	child_data->err = 12345678;
508
509	/*
510	 * Wait, until parent has finished its work: read child's pid from
511	 * parent's stack, and check, if bad result.
512	 */
513	err = ptrace(PTRACE_CONT, pid, 0, 0);
514	if (err) {
515		err = -errno;
516		printk(UM_KERN_ERR "Failed to continue new process, pid = %d, "
517		       "errno = %d\n", pid, errno);
518		return err;
519	}
520
521	wait_stub_done(pid);
522
523	pid = data->err;
524	if (pid < 0) {
525		printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports "
526		       "error %d\n", -pid);
527		return pid;
528	}
529
530	/*
531	 * Wait, until child has finished too: read child's result from
532	 * child's stack and check it.
533	 */
534	wait_stub_done(pid);
535	if (child_data->err != STUB_DATA) {
536		printk(UM_KERN_ERR "copy_context_skas0 - stub-child reports "
537		       "error %ld\n", child_data->err);
538		err = child_data->err;
539		goto out_kill;
540	}
541
542	if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
543		   (void *)PTRACE_O_TRACESYSGOOD) < 0) {
544		err = -errno;
545		printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_OLDSETOPTIONS "
546		       "failed, errno = %d\n", errno);
547		goto out_kill;
548	}
549
550	return pid;
551
552 out_kill:
553	os_kill_ptraced_process(pid, 1);
554	return err;
555}
556
557/*
558 * This is used only, if stub pages are needed, while proc_mm is
559 * available. Opening /proc/mm creates a new mm_context, which lacks
560 * the stub-pages. Thus, we map them using /proc/mm-fd
561 */
562int map_stub_pages(int fd, unsigned long code, unsigned long data,
563		   unsigned long stack)
564{
565	struct proc_mm_op mmop;
566	int n;
567	unsigned long long code_offset;
568	int code_fd = phys_mapping(to_phys((void *) &__syscall_stub_start),
569				   &code_offset);
570
571	mmop = ((struct proc_mm_op) { .op        = MM_MMAP,
572				      .u         =
573				      { .mmap    =
574					{ .addr    = code,
575					  .len     = UM_KERN_PAGE_SIZE,
576					  .prot    = PROT_EXEC,
577					  .flags   = MAP_FIXED | MAP_PRIVATE,
578					  .fd      = code_fd,
579					  .offset  = code_offset
580	} } });
581	CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
582	if (n != sizeof(mmop)) {
583		n = errno;
584		printk(UM_KERN_ERR "mmap args - addr = 0x%lx, fd = %d, "
585		       "offset = %llx\n", code, code_fd,
586		       (unsigned long long) code_offset);
587		printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for code "
588		       "failed, err = %d\n", n);
589		return -n;
590	}
591
592	if (stack) {
593		unsigned long long map_offset;
594		int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
595		mmop = ((struct proc_mm_op)
596				{ .op        = MM_MMAP,
597				  .u         =
598				  { .mmap    =
599				    { .addr    = data,
600				      .len     = UM_KERN_PAGE_SIZE,
601				      .prot    = PROT_READ | PROT_WRITE,
602				      .flags   = MAP_FIXED | MAP_SHARED,
603				      .fd      = map_fd,
604				      .offset  = map_offset
605		} } });
606		CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
607		if (n != sizeof(mmop)) {
608			n = errno;
609			printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for "
610			       "data failed, err = %d\n", n);
611			return -n;
612		}
613	}
614
615	return 0;
616}
617
618void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
619{
620	(*buf)[0].JB_IP = (unsigned long) handler;
621	(*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE -
622		sizeof(void *);
623}
624
625#define INIT_JMP_NEW_THREAD 0
626#define INIT_JMP_CALLBACK 1
627#define INIT_JMP_HALT 2
628#define INIT_JMP_REBOOT 3
629
630void switch_threads(jmp_buf *me, jmp_buf *you)
631{
632	if (UML_SETJMP(me) == 0)
633		UML_LONGJMP(you, 1);
634}
635
636static jmp_buf initial_jmpbuf;
637
638/* XXX Make these percpu */
639static void (*cb_proc)(void *arg);
640static void *cb_arg;
641static jmp_buf *cb_back;
642
643int start_idle_thread(void *stack, jmp_buf *switch_buf)
644{
645	int n;
646
647	set_handler(SIGWINCH, (__sighandler_t) sig_handler,
648		    SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGVTALRM, -1);
649
650	/*
651	 * Can't use UML_SETJMP or UML_LONGJMP here because they save
652	 * and restore signals, with the possible side-effect of
653	 * trying to handle any signals which came when they were
654	 * blocked, which can't be done on this stack.
655	 * Signals must be blocked when jumping back here and restored
656	 * after returning to the jumper.
657	 */
658	n = setjmp(initial_jmpbuf);
659	switch (n) {
660	case INIT_JMP_NEW_THREAD:
661		(*switch_buf)[0].JB_IP = (unsigned long) new_thread_handler;
662		(*switch_buf)[0].JB_SP = (unsigned long) stack +
663			UM_THREAD_SIZE - sizeof(void *);
664		break;
665	case INIT_JMP_CALLBACK:
666		(*cb_proc)(cb_arg);
667		longjmp(*cb_back, 1);
668		break;
669	case INIT_JMP_HALT:
670		kmalloc_ok = 0;
671		return 0;
672	case INIT_JMP_REBOOT:
673		kmalloc_ok = 0;
674		return 1;
675	default:
676		printk(UM_KERN_ERR "Bad sigsetjmp return in "
677		       "start_idle_thread - %d\n", n);
678		fatal_sigsegv();
679	}
680	longjmp(*switch_buf, 1);
681}
682
683void initial_thread_cb_skas(void (*proc)(void *), void *arg)
684{
685	jmp_buf here;
686
687	cb_proc = proc;
688	cb_arg = arg;
689	cb_back = &here;
690
691	block_signals();
692	if (UML_SETJMP(&here) == 0)
693		UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
694	unblock_signals();
695
696	cb_proc = NULL;
697	cb_arg = NULL;
698	cb_back = NULL;
699}
700
701void halt_skas(void)
702{
703	block_signals();
704	UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
705}
706
707void reboot_skas(void)
708{
709	block_signals();
710	UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
711}
712
713void __switch_mm(struct mm_id *mm_idp)
714{
715	int err;
716
717	/* FIXME: need cpu pid in __switch_mm */
718	if (proc_mm) {
719		err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
720			     mm_idp->u.mm_fd);
721		if (err) {
722			printk(UM_KERN_ERR "__switch_mm - PTRACE_SWITCH_MM "
723			       "failed, errno = %d\n", errno);
724			fatal_sigsegv();
725		}
726	}
727	else userspace_pid[0] = mm_idp->u.pid;
728}