Merge branch 'virtex-for-2.6.25' of git://git.secretlab.ca/git/linux-2.6-virtex into...
[linux-2.6] / arch / um / os-Linux / skas / process.c
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
30 int 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
39 static 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)
59
60 /* Signals that the stub will finish with - anything else is an error */
61 #define STUB_DONE_MASK (1 << SIGTRAP)
62
63 void 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
86 bad_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
97 extern unsigned long current_stub_stack(void);
98
99 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                 err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV);
119                 if (err) {
120                         printk(UM_KERN_ERR "Failed to continue stub, pid = %d, "
121                                "errno = %d\n", pid, errno);
122                         fatal_sigsegv();
123                 }
124                 wait_stub_done(pid);
125
126                 /*
127                  * faultinfo is prepared by the stub-segv-handler at start of
128                  * the stub stack page. We just have to copy it.
129                  */
130                 memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
131         }
132 }
133
134 static void handle_segv(int pid, struct uml_pt_regs * regs)
135 {
136         get_skas_faultinfo(pid, &regs->faultinfo);
137         segv(regs->faultinfo, 0, 1, NULL);
138 }
139
140 /*
141  * To use the same value of using_sysemu as the caller, ask it that value
142  * (in local_using_sysemu
143  */
144 static void handle_trap(int pid, struct uml_pt_regs *regs,
145                         int local_using_sysemu)
146 {
147         int err, status;
148
149         if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
150                 fatal_sigsegv();
151
152         /* Mark this as a syscall */
153         UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
154
155         if (!local_using_sysemu)
156         {
157                 err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
158                              __NR_getpid);
159                 if (err < 0) {
160                         printk(UM_KERN_ERR "handle_trap - nullifying syscall "
161                                "failed, errno = %d\n", errno);
162                         fatal_sigsegv();
163                 }
164
165                 err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
166                 if (err < 0) {
167                         printk(UM_KERN_ERR "handle_trap - continuing to end of "
168                                "syscall failed, errno = %d\n", errno);
169                         fatal_sigsegv();
170                 }
171
172                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
173                 if ((err < 0) || !WIFSTOPPED(status) ||
174                     (WSTOPSIG(status) != SIGTRAP + 0x80)) {
175                         err = ptrace_dump_regs(pid);
176                         if (err)
177                                 printk(UM_KERN_ERR "Failed to get registers "
178                                        "from process, errno = %d\n", -err);
179                         printk(UM_KERN_ERR "handle_trap - failed to wait at "
180                                "end of syscall, errno = %d, status = %d\n",
181                                errno, status);
182                         fatal_sigsegv();
183                 }
184         }
185
186         handle_syscall(regs);
187 }
188
189 extern int __syscall_stub_start;
190
191 static int userspace_tramp(void *stack)
192 {
193         void *addr;
194         int err;
195
196         ptrace(PTRACE_TRACEME, 0, 0, 0);
197
198         signal(SIGTERM, SIG_DFL);
199         signal(SIGWINCH, SIG_IGN);
200         err = set_interval();
201         if (err) {
202                 printk(UM_KERN_ERR "userspace_tramp - setting timer failed, "
203                        "errno = %d\n", err);
204                 exit(1);
205         }
206
207         if (!proc_mm) {
208                 /*
209                  * This has a pte, but it can't be mapped in with the usual
210                  * tlb_flush mechanism because this is part of that mechanism
211                  */
212                 int fd;
213                 unsigned long long offset;
214                 fd = phys_mapping(to_phys(&__syscall_stub_start), &offset);
215                 addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE,
216                               PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
217                 if (addr == MAP_FAILED) {
218                         printk(UM_KERN_ERR "mapping mmap stub at 0x%lx failed, "
219                                "errno = %d\n", STUB_CODE, errno);
220                         exit(1);
221                 }
222
223                 if (stack != NULL) {
224                         fd = phys_mapping(to_phys(stack), &offset);
225                         addr = mmap((void *) STUB_DATA,
226                                     UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
227                                     MAP_FIXED | MAP_SHARED, fd, offset);
228                         if (addr == MAP_FAILED) {
229                                 printk(UM_KERN_ERR "mapping segfault stack "
230                                        "at 0x%lx failed, errno = %d\n",
231                                        STUB_DATA, errno);
232                                 exit(1);
233                         }
234                 }
235         }
236         if (!ptrace_faultinfo && (stack != NULL)) {
237                 struct sigaction sa;
238
239                 unsigned long v = STUB_CODE +
240                                   (unsigned long) stub_segv_handler -
241                                   (unsigned long) &__syscall_stub_start;
242
243                 set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
244                 sigemptyset(&sa.sa_mask);
245                 sa.sa_flags = SA_ONSTACK | SA_NODEFER;
246                 sa.sa_handler = (void *) v;
247                 sa.sa_restorer = NULL;
248                 if (sigaction(SIGSEGV, &sa, NULL) < 0) {
249                         printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV "
250                                "handler failed - errno = %d\n", errno);
251                         exit(1);
252                 }
253         }
254
255         kill(os_getpid(), SIGSTOP);
256         return 0;
257 }
258
259 /* Each element set once, and only accessed by a single processor anyway */
260 #undef NR_CPUS
261 #define NR_CPUS 1
262 int userspace_pid[NR_CPUS];
263
264 int start_userspace(unsigned long stub_stack)
265 {
266         void *stack;
267         unsigned long sp;
268         int pid, status, n, flags, err;
269
270         stack = mmap(NULL, UM_KERN_PAGE_SIZE,
271                      PROT_READ | PROT_WRITE | PROT_EXEC,
272                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
273         if (stack == MAP_FAILED) {
274                 err = -errno;
275                 printk(UM_KERN_ERR "start_userspace : mmap failed, "
276                        "errno = %d\n", errno);
277                 return err;
278         }
279
280         sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
281
282         flags = CLONE_FILES;
283         if (proc_mm)
284                 flags |= CLONE_VM;
285         else
286                 flags |= SIGCHLD;
287
288         pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
289         if (pid < 0) {
290                 err = -errno;
291                 printk(UM_KERN_ERR "start_userspace : clone failed, "
292                        "errno = %d\n", errno);
293                 return err;
294         }
295
296         do {
297                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
298                 if (n < 0) {
299                         err = -errno;
300                         printk(UM_KERN_ERR "start_userspace : wait failed, "
301                                "errno = %d\n", errno);
302                         goto out_kill;
303                 }
304         } while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
305
306         if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) {
307                 err = -EINVAL;
308                 printk(UM_KERN_ERR "start_userspace : expected SIGSTOP, got "
309                        "status = %d\n", status);
310                 goto out_kill;
311         }
312
313         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
314                    (void *) PTRACE_O_TRACESYSGOOD) < 0) {
315                 err = -errno;
316                 printk(UM_KERN_ERR "start_userspace : PTRACE_OLDSETOPTIONS "
317                        "failed, errno = %d\n", errno);
318                 goto out_kill;
319         }
320
321         if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) {
322                 err = -errno;
323                 printk(UM_KERN_ERR "start_userspace : munmap failed, "
324                        "errno = %d\n", errno);
325                 goto out_kill;
326         }
327
328         return pid;
329
330  out_kill:
331         os_kill_ptraced_process(pid, 1);
332         return err;
333 }
334
335 void userspace(struct uml_pt_regs *regs)
336 {
337         struct itimerval timer;
338         unsigned long long nsecs, now;
339         int err, status, op, pid = userspace_pid[0];
340         /* To prevent races if using_sysemu changes under us.*/
341         int local_using_sysemu;
342
343         if (getitimer(ITIMER_VIRTUAL, &timer))
344                 printk("Failed to get itimer, errno = %d\n", errno);
345         nsecs = timer.it_value.tv_sec * UM_NSEC_PER_SEC +
346                 timer.it_value.tv_usec * UM_NSEC_PER_USEC;
347         nsecs += os_nsecs();
348
349         while (1) {
350                 /*
351                  * This can legitimately fail if the process loads a
352                  * bogus value into a segment register.  It will
353                  * segfault and PTRACE_GETREGS will read that value
354                  * out of the process.  However, PTRACE_SETREGS will
355                  * fail.  In this case, there is nothing to do but
356                  * just kill the process.
357                  */
358                 if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp))
359                         fatal_sigsegv();
360
361                 /* Now we set local_using_sysemu to be used for one loop */
362                 local_using_sysemu = get_using_sysemu();
363
364                 op = SELECT_PTRACE_OPERATION(local_using_sysemu,
365                                              singlestepping(NULL));
366
367                 if (ptrace(op, pid, 0, 0)) {
368                         printk(UM_KERN_ERR "userspace - ptrace continue "
369                                "failed, op = %d, errno = %d\n", op, errno);
370                         fatal_sigsegv();
371                 }
372
373                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
374                 if (err < 0) {
375                         printk(UM_KERN_ERR "userspace - wait failed, "
376                                "errno = %d\n", errno);
377                         fatal_sigsegv();
378                 }
379
380                 regs->is_user = 1;
381                 if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) {
382                         printk(UM_KERN_ERR "userspace - PTRACE_GETREGS failed, "
383                                "errno = %d\n", errno);
384                         fatal_sigsegv();
385                 }
386
387                 UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
388
389                 if (WIFSTOPPED(status)) {
390                         int sig = WSTOPSIG(status);
391                         switch(sig) {
392                         case SIGSEGV:
393                                 if (PTRACE_FULL_FAULTINFO ||
394                                     !ptrace_faultinfo) {
395                                         get_skas_faultinfo(pid,
396                                                            &regs->faultinfo);
397                                         (*sig_info[SIGSEGV])(SIGSEGV, regs);
398                                 }
399                                 else handle_segv(pid, regs);
400                                 break;
401                         case SIGTRAP + 0x80:
402                                 handle_trap(pid, regs, local_using_sysemu);
403                                 break;
404                         case SIGTRAP:
405                                 relay_signal(SIGTRAP, regs);
406                                 break;
407                         case SIGVTALRM:
408                                 now = os_nsecs();
409                                 if (now < nsecs)
410                                         break;
411                                 block_signals();
412                                 (*sig_info[sig])(sig, regs);
413                                 unblock_signals();
414                                 nsecs = timer.it_value.tv_sec *
415                                         UM_NSEC_PER_SEC +
416                                         timer.it_value.tv_usec *
417                                         UM_NSEC_PER_USEC;
418                                 nsecs += os_nsecs();
419                                 break;
420                         case SIGIO:
421                         case SIGILL:
422                         case SIGBUS:
423                         case SIGFPE:
424                         case SIGWINCH:
425                                 block_signals();
426                                 (*sig_info[sig])(sig, regs);
427                                 unblock_signals();
428                                 break;
429                         default:
430                                 printk(UM_KERN_ERR "userspace - child stopped "
431                                        "with signal %d\n", sig);
432                                 fatal_sigsegv();
433                         }
434                         pid = userspace_pid[0];
435                         interrupt_end();
436
437                         /* Avoid -ERESTARTSYS handling in host */
438                         if (PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
439                                 PT_SYSCALL_NR(regs->gp) = -1;
440                 }
441         }
442 }
443
444 static unsigned long thread_regs[MAX_REG_NR];
445
446 static int __init init_thread_regs(void)
447 {
448         get_safe_registers(thread_regs);
449         /* Set parent's instruction pointer to start of clone-stub */
450         thread_regs[REGS_IP_INDEX] = STUB_CODE +
451                                 (unsigned long) stub_clone_handler -
452                                 (unsigned long) &__syscall_stub_start;
453         thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
454                 sizeof(void *);
455 #ifdef __SIGNAL_FRAMESIZE
456         thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
457 #endif
458         return 0;
459 }
460
461 __initcall(init_thread_regs);
462
463 int copy_context_skas0(unsigned long new_stack, int pid)
464 {
465         struct timeval tv = { .tv_sec = 0, .tv_usec = UM_USEC_PER_SEC / UM_HZ };
466         int err;
467         unsigned long current_stack = current_stub_stack();
468         struct stub_data *data = (struct stub_data *) current_stack;
469         struct stub_data *child_data = (struct stub_data *) new_stack;
470         unsigned long long new_offset;
471         int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
472
473         /*
474          * prepare offset and fd of child's stack as argument for parent's
475          * and child's mmap2 calls
476          */
477         *data = ((struct stub_data) { .offset   = MMAP_OFFSET(new_offset),
478                                       .fd       = new_fd,
479                                       .timer    = ((struct itimerval)
480                                                    { .it_value = tv,
481                                                      .it_interval = tv }) });
482
483         err = ptrace_setregs(pid, thread_regs);
484         if (err < 0) {
485                 err = -errno;
486                 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_SETREGS "
487                        "failed, pid = %d, errno = %d\n", pid, -err);
488                 return err;
489         }
490
491         /* set a well known return code for detection of child write failure */
492         child_data->err = 12345678;
493
494         /*
495          * Wait, until parent has finished its work: read child's pid from
496          * parent's stack, and check, if bad result.
497          */
498         err = ptrace(PTRACE_CONT, pid, 0, 0);
499         if (err) {
500                 err = -errno;
501                 printk(UM_KERN_ERR "Failed to continue new process, pid = %d, "
502                        "errno = %d\n", pid, errno);
503                 return err;
504         }
505
506         wait_stub_done(pid);
507
508         pid = data->err;
509         if (pid < 0) {
510                 printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports "
511                        "error %d\n", -pid);
512                 return pid;
513         }
514
515         /*
516          * Wait, until child has finished too: read child's result from
517          * child's stack and check it.
518          */
519         wait_stub_done(pid);
520         if (child_data->err != STUB_DATA) {
521                 printk(UM_KERN_ERR "copy_context_skas0 - stub-child reports "
522                        "error %ld\n", child_data->err);
523                 err = child_data->err;
524                 goto out_kill;
525         }
526
527         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
528                    (void *)PTRACE_O_TRACESYSGOOD) < 0) {
529                 err = -errno;
530                 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_OLDSETOPTIONS "
531                        "failed, errno = %d\n", errno);
532                 goto out_kill;
533         }
534
535         return pid;
536
537  out_kill:
538         os_kill_ptraced_process(pid, 1);
539         return err;
540 }
541
542 /*
543  * This is used only, if stub pages are needed, while proc_mm is
544  * available. Opening /proc/mm creates a new mm_context, which lacks
545  * the stub-pages. Thus, we map them using /proc/mm-fd
546  */
547 int map_stub_pages(int fd, unsigned long code, unsigned long data,
548                    unsigned long stack)
549 {
550         struct proc_mm_op mmop;
551         int n;
552         unsigned long long code_offset;
553         int code_fd = phys_mapping(to_phys((void *) &__syscall_stub_start),
554                                    &code_offset);
555
556         mmop = ((struct proc_mm_op) { .op        = MM_MMAP,
557                                       .u         =
558                                       { .mmap    =
559                                         { .addr    = code,
560                                           .len     = UM_KERN_PAGE_SIZE,
561                                           .prot    = PROT_EXEC,
562                                           .flags   = MAP_FIXED | MAP_PRIVATE,
563                                           .fd      = code_fd,
564                                           .offset  = code_offset
565         } } });
566         CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
567         if (n != sizeof(mmop)) {
568                 n = errno;
569                 printk(UM_KERN_ERR "mmap args - addr = 0x%lx, fd = %d, "
570                        "offset = %llx\n", code, code_fd,
571                        (unsigned long long) code_offset);
572                 printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for code "
573                        "failed, err = %d\n", n);
574                 return -n;
575         }
576
577         if (stack) {
578                 unsigned long long map_offset;
579                 int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
580                 mmop = ((struct proc_mm_op)
581                                 { .op        = MM_MMAP,
582                                   .u         =
583                                   { .mmap    =
584                                     { .addr    = data,
585                                       .len     = UM_KERN_PAGE_SIZE,
586                                       .prot    = PROT_READ | PROT_WRITE,
587                                       .flags   = MAP_FIXED | MAP_SHARED,
588                                       .fd      = map_fd,
589                                       .offset  = map_offset
590                 } } });
591                 CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
592                 if (n != sizeof(mmop)) {
593                         n = errno;
594                         printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for "
595                                "data failed, err = %d\n", n);
596                         return -n;
597                 }
598         }
599
600         return 0;
601 }
602
603 void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
604 {
605         (*buf)[0].JB_IP = (unsigned long) handler;
606         (*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE -
607                 sizeof(void *);
608 }
609
610 #define INIT_JMP_NEW_THREAD 0
611 #define INIT_JMP_CALLBACK 1
612 #define INIT_JMP_HALT 2
613 #define INIT_JMP_REBOOT 3
614
615 void switch_threads(jmp_buf *me, jmp_buf *you)
616 {
617         if (UML_SETJMP(me) == 0)
618                 UML_LONGJMP(you, 1);
619 }
620
621 static jmp_buf initial_jmpbuf;
622
623 /* XXX Make these percpu */
624 static void (*cb_proc)(void *arg);
625 static void *cb_arg;
626 static jmp_buf *cb_back;
627
628 int start_idle_thread(void *stack, jmp_buf *switch_buf)
629 {
630         int n;
631
632         set_handler(SIGWINCH, (__sighandler_t) sig_handler,
633                     SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGVTALRM, -1);
634
635         /*
636          * Can't use UML_SETJMP or UML_LONGJMP here because they save
637          * and restore signals, with the possible side-effect of
638          * trying to handle any signals which came when they were
639          * blocked, which can't be done on this stack.
640          * Signals must be blocked when jumping back here and restored
641          * after returning to the jumper.
642          */
643         n = setjmp(initial_jmpbuf);
644         switch(n) {
645         case INIT_JMP_NEW_THREAD:
646                 (*switch_buf)[0].JB_IP = (unsigned long) new_thread_handler;
647                 (*switch_buf)[0].JB_SP = (unsigned long) stack +
648                         UM_THREAD_SIZE - sizeof(void *);
649                 break;
650         case INIT_JMP_CALLBACK:
651                 (*cb_proc)(cb_arg);
652                 longjmp(*cb_back, 1);
653                 break;
654         case INIT_JMP_HALT:
655                 kmalloc_ok = 0;
656                 return 0;
657         case INIT_JMP_REBOOT:
658                 kmalloc_ok = 0;
659                 return 1;
660         default:
661                 printk(UM_KERN_ERR "Bad sigsetjmp return in "
662                        "start_idle_thread - %d\n", n);
663                 fatal_sigsegv();
664         }
665         longjmp(*switch_buf, 1);
666 }
667
668 void initial_thread_cb_skas(void (*proc)(void *), void *arg)
669 {
670         jmp_buf here;
671
672         cb_proc = proc;
673         cb_arg = arg;
674         cb_back = &here;
675
676         block_signals();
677         if (UML_SETJMP(&here) == 0)
678                 UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
679         unblock_signals();
680
681         cb_proc = NULL;
682         cb_arg = NULL;
683         cb_back = NULL;
684 }
685
686 void halt_skas(void)
687 {
688         block_signals();
689         UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
690 }
691
692 void reboot_skas(void)
693 {
694         block_signals();
695         UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
696 }
697
698 void __switch_mm(struct mm_id *mm_idp)
699 {
700         int err;
701
702         /* FIXME: need cpu pid in __switch_mm */
703         if (proc_mm) {
704                 err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
705                              mm_idp->u.mm_fd);
706                 if (err) {
707                         printk(UM_KERN_ERR "__switch_mm - PTRACE_SWITCH_MM "
708                                "failed, errno = %d\n", errno);
709                         fatal_sigsegv();
710                 }
711         }
712         else userspace_pid[0] = mm_idp->u.pid;
713 }