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