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TOMOYO Linux Cross Reference
Linux/arch/um/os-Linux/skas/process.c

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  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/wait.h>
 13 #include <asm/unistd.h>
 14 #include <as-layout.h>
 15 #include <init.h>
 16 #include <kern_util.h>
 17 #include <mem.h>
 18 #include <os.h>
 19 #include <proc_mm.h>
 20 #include <ptrace_user.h>
 21 #include <registers.h>
 22 #include <skas.h>
 23 #include <skas_ptrace.h>
 24 #include <sysdep/stub.h>
 25 
 26 int is_skas_winch(int pid, int fd, void *data)
 27 {
 28         return pid == getpgrp();
 29 }
 30 
 31 static int ptrace_dump_regs(int pid)
 32 {
 33         unsigned long regs[MAX_REG_NR];
 34         int i;
 35 
 36         if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
 37                 return -errno;
 38 
 39         printk(UM_KERN_ERR "Stub registers -\n");
 40         for (i = 0; i < ARRAY_SIZE(regs); i++)
 41                 printk(UM_KERN_ERR "\t%d - %lx\n", i, regs[i]);
 42 
 43         return 0;
 44 }
 45 
 46 /*
 47  * Signals that are OK to receive in the stub - we'll just continue it.
 48  * SIGWINCH will happen when UML is inside a detached screen.
 49  */
 50 #define STUB_SIG_MASK ((1 << SIGVTALRM) | (1 << SIGWINCH))
 51 
 52 /* Signals that the stub will finish with - anything else is an error */
 53 #define STUB_DONE_MASK (1 << SIGTRAP)
 54 
 55 void wait_stub_done(int pid)
 56 {
 57         int n, status, err, bad_stop = 0;
 58 
 59         while (1) {
 60                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
 61                 if ((n < 0) || !WIFSTOPPED(status))
 62                         goto bad_wait;
 63 
 64                 if (((1 << WSTOPSIG(status)) & STUB_SIG_MASK) == 0)
 65                         break;
 66 
 67                 err = ptrace(PTRACE_CONT, pid, 0, 0);
 68                 if (err) {
 69                         printk(UM_KERN_ERR "wait_stub_done : continue failed, "
 70                                "errno = %d\n", errno);
 71                         fatal_sigsegv();
 72                 }
 73         }
 74 
 75         if (((1 << WSTOPSIG(status)) & STUB_DONE_MASK) != 0)
 76                 return;
 77         else
 78                 bad_stop = 1;
 79 
 80 bad_wait:
 81         err = ptrace_dump_regs(pid);
 82         if (err)
 83                 printk(UM_KERN_ERR "Failed to get registers from stub, "
 84                        "errno = %d\n", -err);
 85         printk(UM_KERN_ERR "wait_stub_done : failed to wait for SIGTRAP, "
 86                "pid = %d, n = %d, errno = %d, status = 0x%x\n", pid, n, errno,
 87                status);
 88         if (bad_stop)
 89                 kill(pid, SIGKILL);
 90         else
 91                 fatal_sigsegv();
 92 }
 93 
 94 extern unsigned long current_stub_stack(void);
 95 
 96 static void get_skas_faultinfo(int pid, struct faultinfo *fi)
 97 {
 98         int err;
 99 
100         if (ptrace_faultinfo) {
101                 err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
102                 if (err) {
103                         printk(UM_KERN_ERR "get_skas_faultinfo - "
104                                "PTRACE_FAULTINFO failed, errno = %d\n", errno);
105                         fatal_sigsegv();
106                 }
107 
108                 /* Special handling for i386, which has different structs */
109                 if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
110                         memset((char *)fi + sizeof(struct ptrace_faultinfo), 0,
111                                sizeof(struct faultinfo) -
112                                sizeof(struct ptrace_faultinfo));
113         }
114         else {
115                 unsigned long fpregs[FP_SIZE];
116 
117                 err = get_fp_registers(pid, fpregs);
118                 if (err < 0) {
119                         printk(UM_KERN_ERR "save_fp_registers returned %d\n",
120                                err);
121                         fatal_sigsegv();
122                 }
123                 err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV);
124                 if (err) {
125                         printk(UM_KERN_ERR "Failed to continue stub, pid = %d, "
126                                "errno = %d\n", pid, errno);
127                         fatal_sigsegv();
128                 }
129                 wait_stub_done(pid);
130 
131                 /*
132                  * faultinfo is prepared by the stub-segv-handler at start of
133                  * the stub stack page. We just have to copy it.
134                  */
135                 memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
136 
137                 err = put_fp_registers(pid, fpregs);
138                 if (err < 0) {
139                         printk(UM_KERN_ERR "put_fp_registers returned %d\n",
140                                err);
141                         fatal_sigsegv();
142                 }
143         }
144 }
145 
146 static void handle_segv(int pid, struct uml_pt_regs * regs)
147 {
148         get_skas_faultinfo(pid, &regs->faultinfo);
149         segv(regs->faultinfo, 0, 1, NULL);
150 }
151 
152 /*
153  * To use the same value of using_sysemu as the caller, ask it that value
154  * (in local_using_sysemu
155  */
156 static void handle_trap(int pid, struct uml_pt_regs *regs,
157                         int local_using_sysemu)
158 {
159         int err, status;
160 
161         if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
162                 fatal_sigsegv();
163 
164         /* Mark this as a syscall */
165         UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
166 
167         if (!local_using_sysemu)
168         {
169                 err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
170                              __NR_getpid);
171                 if (err < 0) {
172                         printk(UM_KERN_ERR "handle_trap - nullifying syscall "
173                                "failed, errno = %d\n", errno);
174                         fatal_sigsegv();
175                 }
176 
177                 err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
178                 if (err < 0) {
179                         printk(UM_KERN_ERR "handle_trap - continuing to end of "
180                                "syscall failed, errno = %d\n", errno);
181                         fatal_sigsegv();
182                 }
183 
184                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
185                 if ((err < 0) || !WIFSTOPPED(status) ||
186                     (WSTOPSIG(status) != SIGTRAP + 0x80)) {
187                         err = ptrace_dump_regs(pid);
188                         if (err)
189                                 printk(UM_KERN_ERR "Failed to get registers "
190                                        "from process, errno = %d\n", -err);
191                         printk(UM_KERN_ERR "handle_trap - failed to wait at "
192                                "end of syscall, errno = %d, status = %d\n",
193                                errno, status);
194                         fatal_sigsegv();
195                 }
196         }
197 
198         handle_syscall(regs);
199 }
200 
201 extern int __syscall_stub_start;
202 
203 static int userspace_tramp(void *stack)
204 {
205         void *addr;
206         int err;
207 
208         ptrace(PTRACE_TRACEME, 0, 0, 0);
209 
210         signal(SIGTERM, SIG_DFL);
211         signal(SIGWINCH, SIG_IGN);
212         err = set_interval();
213         if (err) {
214                 printk(UM_KERN_ERR "userspace_tramp - setting timer failed, "
215                        "errno = %d\n", err);
216                 exit(1);
217         }
218 
219         if (!proc_mm) {
220                 /*
221                  * This has a pte, but it can't be mapped in with the usual
222                  * tlb_flush mechanism because this is part of that mechanism
223                  */
224                 int fd;
225                 unsigned long long offset;
226                 fd = phys_mapping(to_phys(&__syscall_stub_start), &offset);
227                 addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE,
228                               PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
229                 if (addr == MAP_FAILED) {
230                         printk(UM_KERN_ERR "mapping mmap stub at 0x%lx failed, "
231                                "errno = %d\n", STUB_CODE, errno);
232                         exit(1);
233                 }
234 
235                 if (stack != NULL) {
236                         fd = phys_mapping(to_phys(stack), &offset);
237                         addr = mmap((void *) STUB_DATA,
238                                     UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
239                                     MAP_FIXED | MAP_SHARED, fd, offset);
240                         if (addr == MAP_FAILED) {
241                                 printk(UM_KERN_ERR "mapping segfault stack "
242                                        "at 0x%lx failed, errno = %d\n",
243                                        STUB_DATA, errno);
244                                 exit(1);
245                         }
246                 }
247         }
248         if (!ptrace_faultinfo && (stack != NULL)) {
249                 struct sigaction sa;
250 
251                 unsigned long v = STUB_CODE +
252                                   (unsigned long) stub_segv_handler -
253                                   (unsigned long) &__syscall_stub_start;
254 
255                 set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
256                 sigemptyset(&sa.sa_mask);
257                 sa.sa_flags = SA_ONSTACK | SA_NODEFER | SA_SIGINFO;
258                 sa.sa_sigaction = (void *) v;
259                 sa.sa_restorer = NULL;
260                 if (sigaction(SIGSEGV, &sa, NULL) < 0) {
261                         printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV "
262                                "handler failed - errno = %d\n", errno);
263                         exit(1);
264                 }
265         }
266 
267         kill(os_getpid(), SIGSTOP);
268         return 0;
269 }
270 
271 /* Each element set once, and only accessed by a single processor anyway */
272 #undef NR_CPUS
273 #define NR_CPUS 1
274 int userspace_pid[NR_CPUS];
275 
276 int start_userspace(unsigned long stub_stack)
277 {
278         void *stack;
279         unsigned long sp;
280         int pid, status, n, flags, err;
281 
282         stack = mmap(NULL, UM_KERN_PAGE_SIZE,
283                      PROT_READ | PROT_WRITE | PROT_EXEC,
284                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
285         if (stack == MAP_FAILED) {
286                 err = -errno;
287                 printk(UM_KERN_ERR "start_userspace : mmap failed, "
288                        "errno = %d\n", errno);
289                 return err;
290         }
291 
292         sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
293 
294         flags = CLONE_FILES;
295         if (proc_mm)
296                 flags |= CLONE_VM;
297         else
298                 flags |= SIGCHLD;
299 
300         pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
301         if (pid < 0) {
302                 err = -errno;
303                 printk(UM_KERN_ERR "start_userspace : clone failed, "
304                        "errno = %d\n", errno);
305                 return err;
306         }
307 
308         do {
309                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
310                 if (n < 0) {
311                         err = -errno;
312                         printk(UM_KERN_ERR "start_userspace : wait failed, "
313                                "errno = %d\n", errno);
314                         goto out_kill;
315                 }
316         } while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
317 
318         if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) {
319                 err = -EINVAL;
320                 printk(UM_KERN_ERR "start_userspace : expected SIGSTOP, got "
321                        "status = %d\n", status);
322                 goto out_kill;
323         }
324 
325         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
326                    (void *) PTRACE_O_TRACESYSGOOD) < 0) {
327                 err = -errno;
328                 printk(UM_KERN_ERR "start_userspace : PTRACE_OLDSETOPTIONS "
329                        "failed, errno = %d\n", errno);
330                 goto out_kill;
331         }
332 
333         if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) {
334                 err = -errno;
335                 printk(UM_KERN_ERR "start_userspace : munmap failed, "
336                        "errno = %d\n", errno);
337                 goto out_kill;
338         }
339 
340         return pid;
341 
342  out_kill:
343         os_kill_ptraced_process(pid, 1);
344         return err;
345 }
346 
347 void userspace(struct uml_pt_regs *regs)
348 {
349         struct itimerval timer;
350         unsigned long long nsecs, now;
351         int err, status, op, pid = userspace_pid[0];
352         /* To prevent races if using_sysemu changes under us.*/
353         int local_using_sysemu;
354         siginfo_t si;
355 
356         /* Handle any immediate reschedules or signals */
357         interrupt_end();
358 
359         if (getitimer(ITIMER_VIRTUAL, &timer))
360                 printk(UM_KERN_ERR "Failed to get itimer, errno = %d\n", errno);
361         nsecs = timer.it_value.tv_sec * UM_NSEC_PER_SEC +
362                 timer.it_value.tv_usec * UM_NSEC_PER_USEC;
363         nsecs += os_nsecs();
364 
365         while (1) {
366                 /*
367                  * This can legitimately fail if the process loads a
368                  * bogus value into a segment register.  It will
369                  * segfault and PTRACE_GETREGS will read that value
370                  * out of the process.  However, PTRACE_SETREGS will
371                  * fail.  In this case, there is nothing to do but
372                  * just kill the process.
373                  */
374                 if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp))
375                         fatal_sigsegv();
376 
377                 if (put_fp_registers(pid, regs->fp))
378                         fatal_sigsegv();
379 
380                 /* Now we set local_using_sysemu to be used for one loop */
381                 local_using_sysemu = get_using_sysemu();
382 
383                 op = SELECT_PTRACE_OPERATION(local_using_sysemu,
384                                              singlestepping(NULL));
385 
386                 if (ptrace(op, pid, 0, 0)) {
387                         printk(UM_KERN_ERR "userspace - ptrace continue "
388                                "failed, op = %d, errno = %d\n", op, errno);
389                         fatal_sigsegv();
390                 }
391 
392                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
393                 if (err < 0) {
394                         printk(UM_KERN_ERR "userspace - wait failed, "
395                                "errno = %d\n", errno);
396                         fatal_sigsegv();
397                 }
398 
399                 regs->is_user = 1;
400                 if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) {
401                         printk(UM_KERN_ERR "userspace - PTRACE_GETREGS failed, "
402                                "errno = %d\n", errno);
403                         fatal_sigsegv();
404                 }
405 
406                 if (get_fp_registers(pid, regs->fp)) {
407                         printk(UM_KERN_ERR "userspace -  get_fp_registers failed, "
408                                "errno = %d\n", errno);
409                         fatal_sigsegv();
410                 }
411 
412                 UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
413 
414                 if (WIFSTOPPED(status)) {
415                         int sig = WSTOPSIG(status);
416 
417                         ptrace(PTRACE_GETSIGINFO, pid, 0, (struct siginfo *)&si);
418 
419                         switch (sig) {
420                         case SIGSEGV:
421                                 if (PTRACE_FULL_FAULTINFO ||
422                                     !ptrace_faultinfo) {
423                                         get_skas_faultinfo(pid,
424                                                            &regs->faultinfo);
425                                         (*sig_info[SIGSEGV])(SIGSEGV, (struct siginfo *)&si,
426                                                              regs);
427                                 }
428                                 else handle_segv(pid, regs);
429                                 break;
430                         case SIGTRAP + 0x80:
431                                 handle_trap(pid, regs, local_using_sysemu);
432                                 break;
433                         case SIGTRAP:
434                                 relay_signal(SIGTRAP, (struct siginfo *)&si, regs);
435                                 break;
436                         case SIGVTALRM:
437                                 now = os_nsecs();
438                                 if (now < nsecs)
439                                         break;
440                                 block_signals();
441                                 (*sig_info[sig])(sig, (struct siginfo *)&si, regs);
442                                 unblock_signals();
443                                 nsecs = timer.it_value.tv_sec *
444                                         UM_NSEC_PER_SEC +
445                                         timer.it_value.tv_usec *
446                                         UM_NSEC_PER_USEC;
447                                 nsecs += os_nsecs();
448                                 break;
449                         case SIGIO:
450                         case SIGILL:
451                         case SIGBUS:
452                         case SIGFPE:
453                         case SIGWINCH:
454                                 block_signals();
455                                 (*sig_info[sig])(sig, (struct siginfo *)&si, regs);
456                                 unblock_signals();
457                                 break;
458                         default:
459                                 printk(UM_KERN_ERR "userspace - child stopped "
460                                        "with signal %d\n", sig);
461                                 fatal_sigsegv();
462                         }
463                         pid = userspace_pid[0];
464                         interrupt_end();
465 
466                         /* Avoid -ERESTARTSYS handling in host */
467                         if (PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
468                                 PT_SYSCALL_NR(regs->gp) = -1;
469                 }
470         }
471 }
472 
473 static unsigned long thread_regs[MAX_REG_NR];
474 static unsigned long thread_fp_regs[FP_SIZE];
475 
476 static int __init init_thread_regs(void)
477 {
478         get_safe_registers(thread_regs, thread_fp_regs);
479         /* Set parent's instruction pointer to start of clone-stub */
480         thread_regs[REGS_IP_INDEX] = STUB_CODE +
481                                 (unsigned long) stub_clone_handler -
482                                 (unsigned long) &__syscall_stub_start;
483         thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
484                 sizeof(void *);
485 #ifdef __SIGNAL_FRAMESIZE
486         thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
487 #endif
488         return 0;
489 }
490 
491 __initcall(init_thread_regs);
492 
493 int copy_context_skas0(unsigned long new_stack, int pid)
494 {
495         struct timeval tv = { .tv_sec = 0, .tv_usec = UM_USEC_PER_SEC / UM_HZ };
496         int err;
497         unsigned long current_stack = current_stub_stack();
498         struct stub_data *data = (struct stub_data *) current_stack;
499         struct stub_data *child_data = (struct stub_data *) new_stack;
500         unsigned long long new_offset;
501         int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
502 
503         /*
504          * prepare offset and fd of child's stack as argument for parent's
505          * and child's mmap2 calls
506          */
507         *data = ((struct stub_data) { .offset   = MMAP_OFFSET(new_offset),
508                                       .fd       = new_fd,
509                                       .timer    = ((struct itimerval)
510                                                    { .it_value = tv,
511                                                      .it_interval = tv }) });
512 
513         err = ptrace_setregs(pid, thread_regs);
514         if (err < 0) {
515                 err = -errno;
516                 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_SETREGS "
517                        "failed, pid = %d, errno = %d\n", pid, -err);
518                 return err;
519         }
520 
521         err = put_fp_registers(pid, thread_fp_regs);
522         if (err < 0) {
523                 printk(UM_KERN_ERR "copy_context_skas0 : put_fp_registers "
524                        "failed, pid = %d, err = %d\n", pid, err);
525                 return err;
526         }
527 
528         /* set a well known return code for detection of child write failure */
529         child_data->err = 12345678;
530 
531         /*
532          * Wait, until parent has finished its work: read child's pid from
533          * parent's stack, and check, if bad result.
534          */
535         err = ptrace(PTRACE_CONT, pid, 0, 0);
536         if (err) {
537                 err = -errno;
538                 printk(UM_KERN_ERR "Failed to continue new process, pid = %d, "
539                        "errno = %d\n", pid, errno);
540                 return err;
541         }
542 
543         wait_stub_done(pid);
544 
545         pid = data->err;
546         if (pid < 0) {
547                 printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports "
548                        "error %d\n", -pid);
549                 return pid;
550         }
551 
552         /*
553          * Wait, until child has finished too: read child's result from
554          * child's stack and check it.
555          */
556         wait_stub_done(pid);
557         if (child_data->err != STUB_DATA) {
558                 printk(UM_KERN_ERR "copy_context_skas0 - stub-child reports "
559                        "error %ld\n", child_data->err);
560                 err = child_data->err;
561                 goto out_kill;
562         }
563 
564         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
565                    (void *)PTRACE_O_TRACESYSGOOD) < 0) {
566                 err = -errno;
567                 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_OLDSETOPTIONS "
568                        "failed, errno = %d\n", errno);
569                 goto out_kill;
570         }
571 
572         return pid;
573 
574  out_kill:
575         os_kill_ptraced_process(pid, 1);
576         return err;
577 }
578 
579 /*
580  * This is used only, if stub pages are needed, while proc_mm is
581  * available. Opening /proc/mm creates a new mm_context, which lacks
582  * the stub-pages. Thus, we map them using /proc/mm-fd
583  */
584 int map_stub_pages(int fd, unsigned long code, unsigned long data,
585                    unsigned long stack)
586 {
587         struct proc_mm_op mmop;
588         int n;
589         unsigned long long code_offset;
590         int code_fd = phys_mapping(to_phys((void *) &__syscall_stub_start),
591                                    &code_offset);
592 
593         mmop = ((struct proc_mm_op) { .op        = MM_MMAP,
594                                       .u         =
595                                       { .mmap    =
596                                         { .addr    = code,
597                                           .len     = UM_KERN_PAGE_SIZE,
598                                           .prot    = PROT_EXEC,
599                                           .flags   = MAP_FIXED | MAP_PRIVATE,
600                                           .fd      = code_fd,
601                                           .offset  = code_offset
602         } } });
603         CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
604         if (n != sizeof(mmop)) {
605                 n = errno;
606                 printk(UM_KERN_ERR "mmap args - addr = 0x%lx, fd = %d, "
607                        "offset = %llx\n", code, code_fd,
608                        (unsigned long long) code_offset);
609                 printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for code "
610                        "failed, err = %d\n", n);
611                 return -n;
612         }
613 
614         if (stack) {
615                 unsigned long long map_offset;
616                 int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
617                 mmop = ((struct proc_mm_op)
618                                 { .op        = MM_MMAP,
619                                   .u         =
620                                   { .mmap    =
621                                     { .addr    = data,
622                                       .len     = UM_KERN_PAGE_SIZE,
623                                       .prot    = PROT_READ | PROT_WRITE,
624                                       .flags   = MAP_FIXED | MAP_SHARED,
625                                       .fd      = map_fd,
626                                       .offset  = map_offset
627                 } } });
628                 CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
629                 if (n != sizeof(mmop)) {
630                         n = errno;
631                         printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for "
632                                "data failed, err = %d\n", n);
633                         return -n;
634                 }
635         }
636 
637         return 0;
638 }
639 
640 void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
641 {
642         (*buf)[0].JB_IP = (unsigned long) handler;
643         (*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE -
644                 sizeof(void *);
645 }
646 
647 #define INIT_JMP_NEW_THREAD 0
648 #define INIT_JMP_CALLBACK 1
649 #define INIT_JMP_HALT 2
650 #define INIT_JMP_REBOOT 3
651 
652 void switch_threads(jmp_buf *me, jmp_buf *you)
653 {
654         if (UML_SETJMP(me) == 0)
655                 UML_LONGJMP(you, 1);
656 }
657 
658 static jmp_buf initial_jmpbuf;
659 
660 /* XXX Make these percpu */
661 static void (*cb_proc)(void *arg);
662 static void *cb_arg;
663 static jmp_buf *cb_back;
664 
665 int start_idle_thread(void *stack, jmp_buf *switch_buf)
666 {
667         int n;
668 
669         set_handler(SIGWINCH);
670 
671         /*
672          * Can't use UML_SETJMP or UML_LONGJMP here because they save
673          * and restore signals, with the possible side-effect of
674          * trying to handle any signals which came when they were
675          * blocked, which can't be done on this stack.
676          * Signals must be blocked when jumping back here and restored
677          * after returning to the jumper.
678          */
679         n = setjmp(initial_jmpbuf);
680         switch (n) {
681         case INIT_JMP_NEW_THREAD:
682                 (*switch_buf)[0].JB_IP = (unsigned long) new_thread_handler;
683                 (*switch_buf)[0].JB_SP = (unsigned long) stack +
684                         UM_THREAD_SIZE - sizeof(void *);
685                 break;
686         case INIT_JMP_CALLBACK:
687                 (*cb_proc)(cb_arg);
688                 longjmp(*cb_back, 1);
689                 break;
690         case INIT_JMP_HALT:
691                 kmalloc_ok = 0;
692                 return 0;
693         case INIT_JMP_REBOOT:
694                 kmalloc_ok = 0;
695                 return 1;
696         default:
697                 printk(UM_KERN_ERR "Bad sigsetjmp return in "
698                        "start_idle_thread - %d\n", n);
699                 fatal_sigsegv();
700         }
701         longjmp(*switch_buf, 1);
702 }
703 
704 void initial_thread_cb_skas(void (*proc)(void *), void *arg)
705 {
706         jmp_buf here;
707 
708         cb_proc = proc;
709         cb_arg = arg;
710         cb_back = &here;
711 
712         block_signals();
713         if (UML_SETJMP(&here) == 0)
714                 UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
715         unblock_signals();
716 
717         cb_proc = NULL;
718         cb_arg = NULL;
719         cb_back = NULL;
720 }
721 
722 void halt_skas(void)
723 {
724         block_signals();
725         UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
726 }
727 
728 void reboot_skas(void)
729 {
730         block_signals();
731         UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
732 }
733 
734 void __switch_mm(struct mm_id *mm_idp)
735 {
736         int err;
737 
738         /* FIXME: need cpu pid in __switch_mm */
739         if (proc_mm) {
740                 err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
741                              mm_idp->u.mm_fd);
742                 if (err) {
743                         printk(UM_KERN_ERR "__switch_mm - PTRACE_SWITCH_MM "
744                                "failed, errno = %d\n", errno);
745                         fatal_sigsegv();
746                 }
747         }
748         else userspace_pid[0] = mm_idp->u.pid;
749 }
750 

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