Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
4 : * Copyright (C) 2002- 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
5 : */
6 :
7 : #include <stdlib.h>
8 : #include <stdbool.h>
9 : #include <unistd.h>
10 : #include <sched.h>
11 : #include <errno.h>
12 : #include <string.h>
13 : #include <sys/mman.h>
14 : #include <sys/wait.h>
15 : #include <asm/unistd.h>
16 : #include <as-layout.h>
17 : #include <init.h>
18 : #include <kern_util.h>
19 : #include <mem.h>
20 : #include <os.h>
21 : #include <ptrace_user.h>
22 : #include <registers.h>
23 : #include <skas.h>
24 : #include <sysdep/stub.h>
25 : #include <linux/threads.h>
26 :
27 0 : int is_skas_winch(int pid, int fd, void *data)
28 : {
29 0 : return pid == getpgrp();
30 : }
31 :
32 : static const char *ptrace_reg_name(int idx)
33 : {
34 : #define R(n) case HOST_##n: return #n
35 :
36 : switch (idx) {
37 : #ifdef __x86_64__
38 : R(BX);
39 : R(CX);
40 : R(DI);
41 : R(SI);
42 : R(DX);
43 : R(BP);
44 : R(AX);
45 : R(R8);
46 : R(R9);
47 : R(R10);
48 : R(R11);
49 : R(R12);
50 : R(R13);
51 : R(R14);
52 : R(R15);
53 : R(ORIG_AX);
54 : R(CS);
55 : R(SS);
56 : R(EFLAGS);
57 : #elif defined(__i386__)
58 : R(IP);
59 : R(SP);
60 : R(EFLAGS);
61 : R(AX);
62 : R(BX);
63 : R(CX);
64 : R(DX);
65 : R(SI);
66 : R(DI);
67 : R(BP);
68 : R(CS);
69 : R(SS);
70 : R(DS);
71 : R(FS);
72 : R(ES);
73 : R(GS);
74 : R(ORIG_AX);
75 : #endif
76 : }
77 : return "";
78 : }
79 :
80 0 : static int ptrace_dump_regs(int pid)
81 : {
82 : unsigned long regs[MAX_REG_NR];
83 : int i;
84 :
85 0 : if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
86 0 : return -errno;
87 :
88 0 : printk(UM_KERN_ERR "Stub registers -\n");
89 0 : for (i = 0; i < ARRAY_SIZE(regs); i++) {
90 0 : const char *regname = ptrace_reg_name(i);
91 :
92 0 : printk(UM_KERN_ERR "\t%s\t(%2d): %lx\n", regname, i, regs[i]);
93 : }
94 :
95 : return 0;
96 : }
97 :
98 : /*
99 : * Signals that are OK to receive in the stub - we'll just continue it.
100 : * SIGWINCH will happen when UML is inside a detached screen.
101 : */
102 : #define STUB_SIG_MASK ((1 << SIGALRM) | (1 << SIGWINCH))
103 :
104 : /* Signals that the stub will finish with - anything else is an error */
105 : #define STUB_DONE_MASK (1 << SIGTRAP)
106 :
107 0 : void wait_stub_done(int pid)
108 : {
109 : int n, status, err;
110 :
111 : while (1) {
112 0 : CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
113 0 : if ((n < 0) || !WIFSTOPPED(status))
114 : goto bad_wait;
115 :
116 0 : if (((1 << WSTOPSIG(status)) & STUB_SIG_MASK) == 0)
117 : break;
118 :
119 0 : err = ptrace(PTRACE_CONT, pid, 0, 0);
120 0 : if (err) {
121 0 : printk(UM_KERN_ERR "%s : continue failed, errno = %d\n",
122 : __func__, errno);
123 0 : fatal_sigsegv();
124 : }
125 : }
126 :
127 0 : if (((1 << WSTOPSIG(status)) & STUB_DONE_MASK) != 0)
128 0 : return;
129 :
130 : bad_wait:
131 0 : err = ptrace_dump_regs(pid);
132 0 : if (err)
133 0 : printk(UM_KERN_ERR "Failed to get registers from stub, errno = %d\n",
134 : -err);
135 0 : printk(UM_KERN_ERR "%s : failed to wait for SIGTRAP, pid = %d, n = %d, errno = %d, status = 0x%x\n",
136 : __func__, pid, n, errno, status);
137 0 : fatal_sigsegv();
138 : }
139 :
140 : extern unsigned long current_stub_stack(void);
141 :
142 0 : static void get_skas_faultinfo(int pid, struct faultinfo *fi, unsigned long *aux_fp_regs)
143 : {
144 : int err;
145 :
146 0 : err = get_fp_registers(pid, aux_fp_regs);
147 0 : if (err < 0) {
148 0 : printk(UM_KERN_ERR "save_fp_registers returned %d\n",
149 : err);
150 0 : fatal_sigsegv();
151 : }
152 0 : err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV);
153 0 : if (err) {
154 0 : printk(UM_KERN_ERR "Failed to continue stub, pid = %d, "
155 : "errno = %d\n", pid, errno);
156 0 : fatal_sigsegv();
157 : }
158 0 : wait_stub_done(pid);
159 :
160 : /*
161 : * faultinfo is prepared by the stub_segv_handler at start of
162 : * the stub stack page. We just have to copy it.
163 : */
164 0 : memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
165 :
166 0 : err = put_fp_registers(pid, aux_fp_regs);
167 0 : if (err < 0) {
168 0 : printk(UM_KERN_ERR "put_fp_registers returned %d\n",
169 : err);
170 0 : fatal_sigsegv();
171 : }
172 0 : }
173 :
174 : static void handle_segv(int pid, struct uml_pt_regs *regs, unsigned long *aux_fp_regs)
175 : {
176 : get_skas_faultinfo(pid, ®s->faultinfo, aux_fp_regs);
177 : segv(regs->faultinfo, 0, 1, NULL);
178 : }
179 :
180 : /*
181 : * To use the same value of using_sysemu as the caller, ask it that value
182 : * (in local_using_sysemu
183 : */
184 0 : static void handle_trap(int pid, struct uml_pt_regs *regs,
185 : int local_using_sysemu)
186 : {
187 : int err, status;
188 :
189 0 : if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
190 0 : fatal_sigsegv();
191 :
192 0 : if (!local_using_sysemu)
193 : {
194 0 : err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
195 : __NR_getpid);
196 0 : if (err < 0) {
197 0 : printk(UM_KERN_ERR "%s - nullifying syscall failed, errno = %d\n",
198 : __func__, errno);
199 0 : fatal_sigsegv();
200 : }
201 :
202 0 : err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
203 0 : if (err < 0) {
204 0 : printk(UM_KERN_ERR "%s - continuing to end of syscall failed, errno = %d\n",
205 : __func__, errno);
206 0 : fatal_sigsegv();
207 : }
208 :
209 0 : CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
210 0 : if ((err < 0) || !WIFSTOPPED(status) ||
211 0 : (WSTOPSIG(status) != SIGTRAP + 0x80)) {
212 0 : err = ptrace_dump_regs(pid);
213 0 : if (err)
214 0 : printk(UM_KERN_ERR "Failed to get registers from process, errno = %d\n",
215 : -err);
216 0 : printk(UM_KERN_ERR "%s - failed to wait at end of syscall, errno = %d, status = %d\n",
217 : __func__, errno, status);
218 0 : fatal_sigsegv();
219 : }
220 : }
221 :
222 0 : handle_syscall(regs);
223 0 : }
224 :
225 : extern char __syscall_stub_start[];
226 :
227 : /**
228 : * userspace_tramp() - userspace trampoline
229 : * @stack: pointer to the new userspace stack page, can be NULL, if? FIXME:
230 : *
231 : * The userspace trampoline is used to setup a new userspace process in start_userspace() after it was clone()'ed.
232 : * This function will run on a temporary stack page.
233 : * It ptrace()'es itself, then
234 : * Two pages are mapped into the userspace address space:
235 : * - STUB_CODE (with EXEC), which contains the skas stub code
236 : * - STUB_DATA (with R/W), which contains a data page that is used to transfer certain data between the UML userspace process and the UML kernel.
237 : * Also for the userspace process a SIGSEGV handler is installed to catch pagefaults in the userspace process.
238 : * And last the process stops itself to give control to the UML kernel for this userspace process.
239 : *
240 : * Return: Always zero, otherwise the current userspace process is ended with non null exit() call
241 : */
242 0 : static int userspace_tramp(void *stack)
243 : {
244 : void *addr;
245 : int fd;
246 : unsigned long long offset;
247 :
248 0 : ptrace(PTRACE_TRACEME, 0, 0, 0);
249 :
250 0 : signal(SIGTERM, SIG_DFL);
251 0 : signal(SIGWINCH, SIG_IGN);
252 :
253 0 : fd = phys_mapping(uml_to_phys(__syscall_stub_start), &offset);
254 0 : addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE,
255 : PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
256 0 : if (addr == MAP_FAILED) {
257 0 : printk(UM_KERN_ERR "mapping mmap stub at 0x%lx failed, errno = %d\n",
258 : STUB_CODE, errno);
259 0 : exit(1);
260 : }
261 :
262 0 : if (stack != NULL) {
263 0 : fd = phys_mapping(uml_to_phys(stack), &offset);
264 0 : addr = mmap((void *) STUB_DATA,
265 : UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
266 : MAP_FIXED | MAP_SHARED, fd, offset);
267 0 : if (addr == MAP_FAILED) {
268 0 : printk(UM_KERN_ERR "mapping segfault stack at 0x%lx failed, errno = %d\n",
269 : STUB_DATA, errno);
270 0 : exit(1);
271 : }
272 : }
273 0 : if (stack != NULL) {
274 : struct sigaction sa;
275 :
276 0 : unsigned long v = STUB_CODE +
277 0 : (unsigned long) stub_segv_handler -
278 : (unsigned long) __syscall_stub_start;
279 :
280 0 : set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
281 0 : sigemptyset(&sa.sa_mask);
282 0 : sa.sa_flags = SA_ONSTACK | SA_NODEFER | SA_SIGINFO;
283 0 : sa.sa_sigaction = (void *) v;
284 0 : sa.sa_restorer = NULL;
285 0 : if (sigaction(SIGSEGV, &sa, NULL) < 0) {
286 0 : printk(UM_KERN_ERR "%s - setting SIGSEGV handler failed - errno = %d\n",
287 : __func__, errno);
288 0 : exit(1);
289 : }
290 : }
291 :
292 0 : kill(os_getpid(), SIGSTOP);
293 0 : return 0;
294 : }
295 :
296 : int userspace_pid[NR_CPUS];
297 : int kill_userspace_mm[NR_CPUS];
298 :
299 : /**
300 : * start_userspace() - prepare a new userspace process
301 : * @stub_stack: pointer to the stub stack. Can be NULL, if? FIXME:
302 : *
303 : * Setups a new temporary stack page that is used while userspace_tramp() runs
304 : * Clones the kernel process into a new userspace process, with FDs only.
305 : *
306 : * Return: When positive: the process id of the new userspace process,
307 : * when negative: an error number.
308 : * FIXME: can PIDs become negative?!
309 : */
310 0 : int start_userspace(unsigned long stub_stack)
311 : {
312 : void *stack;
313 : unsigned long sp;
314 : int pid, status, n, flags, err;
315 :
316 : /* setup a temporary stack page */
317 0 : stack = mmap(NULL, UM_KERN_PAGE_SIZE,
318 : PROT_READ | PROT_WRITE | PROT_EXEC,
319 : MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
320 0 : if (stack == MAP_FAILED) {
321 0 : err = -errno;
322 0 : printk(UM_KERN_ERR "%s : mmap failed, errno = %d\n",
323 : __func__, errno);
324 0 : return err;
325 : }
326 :
327 : /* set stack pointer to the end of the stack page, so it can grow downwards */
328 0 : sp = (unsigned long)stack + UM_KERN_PAGE_SIZE;
329 :
330 0 : flags = CLONE_FILES | SIGCHLD;
331 :
332 : /* clone into new userspace process */
333 0 : pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
334 0 : if (pid < 0) {
335 0 : err = -errno;
336 0 : printk(UM_KERN_ERR "%s : clone failed, errno = %d\n",
337 : __func__, errno);
338 0 : return err;
339 : }
340 :
341 : do {
342 0 : CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
343 0 : if (n < 0) {
344 0 : err = -errno;
345 0 : printk(UM_KERN_ERR "%s : wait failed, errno = %d\n",
346 : __func__, errno);
347 0 : goto out_kill;
348 : }
349 0 : } while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGALRM));
350 :
351 0 : if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) {
352 0 : err = -EINVAL;
353 0 : printk(UM_KERN_ERR "%s : expected SIGSTOP, got status = %d\n",
354 : __func__, status);
355 0 : goto out_kill;
356 : }
357 :
358 0 : if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
359 : (void *) PTRACE_O_TRACESYSGOOD) < 0) {
360 0 : err = -errno;
361 0 : printk(UM_KERN_ERR "%s : PTRACE_OLDSETOPTIONS failed, errno = %d\n",
362 : __func__, errno);
363 0 : goto out_kill;
364 : }
365 :
366 0 : if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) {
367 0 : err = -errno;
368 0 : printk(UM_KERN_ERR "%s : munmap failed, errno = %d\n",
369 : __func__, errno);
370 0 : goto out_kill;
371 : }
372 :
373 : return pid;
374 :
375 : out_kill:
376 0 : os_kill_ptraced_process(pid, 1);
377 0 : return err;
378 : }
379 :
380 0 : void userspace(struct uml_pt_regs *regs, unsigned long *aux_fp_regs)
381 : {
382 0 : int err, status, op, pid = userspace_pid[0];
383 : /* To prevent races if using_sysemu changes under us.*/
384 : int local_using_sysemu;
385 : siginfo_t si;
386 :
387 : /* Handle any immediate reschedules or signals */
388 0 : interrupt_end();
389 :
390 : while (1) {
391 0 : if (kill_userspace_mm[0])
392 0 : fatal_sigsegv();
393 :
394 : /*
395 : * This can legitimately fail if the process loads a
396 : * bogus value into a segment register. It will
397 : * segfault and PTRACE_GETREGS will read that value
398 : * out of the process. However, PTRACE_SETREGS will
399 : * fail. In this case, there is nothing to do but
400 : * just kill the process.
401 : */
402 0 : if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp)) {
403 0 : printk(UM_KERN_ERR "%s - ptrace set regs failed, errno = %d\n",
404 : __func__, errno);
405 0 : fatal_sigsegv();
406 : }
407 :
408 0 : if (put_fp_registers(pid, regs->fp)) {
409 0 : printk(UM_KERN_ERR "%s - ptrace set fp regs failed, errno = %d\n",
410 : __func__, errno);
411 0 : fatal_sigsegv();
412 : }
413 :
414 : /* Now we set local_using_sysemu to be used for one loop */
415 0 : local_using_sysemu = get_using_sysemu();
416 :
417 0 : op = SELECT_PTRACE_OPERATION(local_using_sysemu,
418 : singlestepping(NULL));
419 :
420 0 : if (ptrace(op, pid, 0, 0)) {
421 0 : printk(UM_KERN_ERR "%s - ptrace continue failed, op = %d, errno = %d\n",
422 : __func__, op, errno);
423 0 : fatal_sigsegv();
424 : }
425 :
426 0 : CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
427 0 : if (err < 0) {
428 0 : printk(UM_KERN_ERR "%s - wait failed, errno = %d\n",
429 : __func__, errno);
430 0 : fatal_sigsegv();
431 : }
432 :
433 0 : regs->is_user = 1;
434 0 : if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) {
435 0 : printk(UM_KERN_ERR "%s - PTRACE_GETREGS failed, errno = %d\n",
436 : __func__, errno);
437 0 : fatal_sigsegv();
438 : }
439 :
440 0 : if (get_fp_registers(pid, regs->fp)) {
441 0 : printk(UM_KERN_ERR "%s - get_fp_registers failed, errno = %d\n",
442 : __func__, errno);
443 0 : fatal_sigsegv();
444 : }
445 :
446 0 : UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
447 :
448 0 : if (WIFSTOPPED(status)) {
449 0 : int sig = WSTOPSIG(status);
450 :
451 : /* These signal handlers need the si argument.
452 : * The SIGIO and SIGALARM handlers which constitute the
453 : * majority of invocations, do not use it.
454 : */
455 : switch (sig) {
456 : case SIGSEGV:
457 : case SIGTRAP:
458 : case SIGILL:
459 : case SIGBUS:
460 : case SIGFPE:
461 : case SIGWINCH:
462 0 : ptrace(PTRACE_GETSIGINFO, pid, 0, (struct siginfo *)&si);
463 0 : break;
464 : }
465 :
466 0 : switch (sig) {
467 : case SIGSEGV:
468 : if (PTRACE_FULL_FAULTINFO) {
469 0 : get_skas_faultinfo(pid,
470 : ®s->faultinfo, aux_fp_regs);
471 0 : (*sig_info[SIGSEGV])(SIGSEGV, (struct siginfo *)&si,
472 : regs);
473 : }
474 : else handle_segv(pid, regs, aux_fp_regs);
475 0 : break;
476 : case SIGTRAP + 0x80:
477 0 : handle_trap(pid, regs, local_using_sysemu);
478 0 : break;
479 : case SIGTRAP:
480 0 : relay_signal(SIGTRAP, (struct siginfo *)&si, regs);
481 0 : break;
482 : case SIGALRM:
483 : break;
484 : case SIGIO:
485 : case SIGILL:
486 : case SIGBUS:
487 : case SIGFPE:
488 : case SIGWINCH:
489 0 : block_signals_trace();
490 0 : (*sig_info[sig])(sig, (struct siginfo *)&si, regs);
491 0 : unblock_signals_trace();
492 0 : break;
493 : default:
494 0 : printk(UM_KERN_ERR "%s - child stopped with signal %d\n",
495 : __func__, sig);
496 0 : fatal_sigsegv();
497 : }
498 0 : pid = userspace_pid[0];
499 0 : interrupt_end();
500 :
501 : /* Avoid -ERESTARTSYS handling in host */
502 : if (PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
503 0 : PT_SYSCALL_NR(regs->gp) = -1;
504 : }
505 : }
506 : }
507 :
508 : static unsigned long thread_regs[MAX_REG_NR];
509 : static unsigned long thread_fp_regs[FP_SIZE];
510 :
511 1 : static int __init init_thread_regs(void)
512 : {
513 1 : get_safe_registers(thread_regs, thread_fp_regs);
514 : /* Set parent's instruction pointer to start of clone-stub */
515 1 : thread_regs[REGS_IP_INDEX] = STUB_CODE +
516 1 : (unsigned long) stub_clone_handler -
517 : (unsigned long) __syscall_stub_start;
518 1 : thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
519 : sizeof(void *);
520 : #ifdef __SIGNAL_FRAMESIZE
521 : thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
522 : #endif
523 1 : return 0;
524 : }
525 :
526 : __initcall(init_thread_regs);
527 :
528 0 : int copy_context_skas0(unsigned long new_stack, int pid)
529 : {
530 : int err;
531 0 : unsigned long current_stack = current_stub_stack();
532 0 : struct stub_data *data = (struct stub_data *) current_stack;
533 0 : struct stub_data *child_data = (struct stub_data *) new_stack;
534 : unsigned long long new_offset;
535 0 : int new_fd = phys_mapping(uml_to_phys((void *)new_stack), &new_offset);
536 :
537 : /*
538 : * prepare offset and fd of child's stack as argument for parent's
539 : * and child's mmap2 calls
540 : */
541 0 : *data = ((struct stub_data) {
542 : .offset = MMAP_OFFSET(new_offset),
543 : .fd = new_fd,
544 : .parent_err = -ESRCH,
545 : .child_err = 0,
546 : });
547 :
548 0 : *child_data = ((struct stub_data) {
549 : .child_err = -ESRCH,
550 : });
551 :
552 0 : err = ptrace_setregs(pid, thread_regs);
553 0 : if (err < 0) {
554 0 : err = -errno;
555 0 : printk(UM_KERN_ERR "%s : PTRACE_SETREGS failed, pid = %d, errno = %d\n",
556 : __func__, pid, -err);
557 0 : return err;
558 : }
559 :
560 0 : err = put_fp_registers(pid, thread_fp_regs);
561 0 : if (err < 0) {
562 0 : printk(UM_KERN_ERR "%s : put_fp_registers failed, pid = %d, err = %d\n",
563 : __func__, pid, err);
564 0 : return err;
565 : }
566 :
567 : /*
568 : * Wait, until parent has finished its work: read child's pid from
569 : * parent's stack, and check, if bad result.
570 : */
571 0 : err = ptrace(PTRACE_CONT, pid, 0, 0);
572 0 : if (err) {
573 0 : err = -errno;
574 0 : printk(UM_KERN_ERR "Failed to continue new process, pid = %d, errno = %d\n",
575 : pid, errno);
576 0 : return err;
577 : }
578 :
579 0 : wait_stub_done(pid);
580 :
581 0 : pid = data->parent_err;
582 0 : if (pid < 0) {
583 0 : printk(UM_KERN_ERR "%s - stub-parent reports error %d\n",
584 : __func__, -pid);
585 0 : return pid;
586 : }
587 :
588 : /*
589 : * Wait, until child has finished too: read child's result from
590 : * child's stack and check it.
591 : */
592 0 : wait_stub_done(pid);
593 0 : if (child_data->child_err != STUB_DATA) {
594 0 : printk(UM_KERN_ERR "%s - stub-child %d reports error %ld\n",
595 : __func__, pid, data->child_err);
596 0 : err = data->child_err;
597 0 : goto out_kill;
598 : }
599 :
600 0 : if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
601 : (void *)PTRACE_O_TRACESYSGOOD) < 0) {
602 0 : err = -errno;
603 0 : printk(UM_KERN_ERR "%s : PTRACE_OLDSETOPTIONS failed, errno = %d\n",
604 : __func__, errno);
605 0 : goto out_kill;
606 : }
607 :
608 : return pid;
609 :
610 : out_kill:
611 0 : os_kill_ptraced_process(pid, 1);
612 0 : return err;
613 : }
614 :
615 340 : void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
616 : {
617 340 : (*buf)[0].JB_IP = (unsigned long) handler;
618 340 : (*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE -
619 : sizeof(void *);
620 340 : }
621 :
622 : #define INIT_JMP_NEW_THREAD 0
623 : #define INIT_JMP_CALLBACK 1
624 : #define INIT_JMP_HALT 2
625 : #define INIT_JMP_REBOOT 3
626 :
627 2210 : void switch_threads(jmp_buf *me, jmp_buf *you)
628 : {
629 2210 : if (UML_SETJMP(me) == 0)
630 2210 : UML_LONGJMP(you, 1);
631 1870 : }
632 :
633 : static jmp_buf initial_jmpbuf;
634 :
635 : /* XXX Make these percpu */
636 : static void (*cb_proc)(void *arg);
637 : static void *cb_arg;
638 : static jmp_buf *cb_back;
639 :
640 1 : int start_idle_thread(void *stack, jmp_buf *switch_buf)
641 : {
642 : int n;
643 :
644 1 : set_handler(SIGWINCH);
645 :
646 : /*
647 : * Can't use UML_SETJMP or UML_LONGJMP here because they save
648 : * and restore signals, with the possible side-effect of
649 : * trying to handle any signals which came when they were
650 : * blocked, which can't be done on this stack.
651 : * Signals must be blocked when jumping back here and restored
652 : * after returning to the jumper.
653 : */
654 1 : n = setjmp(initial_jmpbuf);
655 3 : switch (n) {
656 : case INIT_JMP_NEW_THREAD:
657 1 : (*switch_buf)[0].JB_IP = (unsigned long) uml_finishsetup;
658 2 : (*switch_buf)[0].JB_SP = (unsigned long) stack +
659 1 : UM_THREAD_SIZE - sizeof(void *);
660 1 : break;
661 : case INIT_JMP_CALLBACK:
662 1 : (*cb_proc)(cb_arg);
663 1 : longjmp(*cb_back, 1);
664 0 : break;
665 : case INIT_JMP_HALT:
666 1 : kmalloc_ok = 0;
667 1 : return 0;
668 : case INIT_JMP_REBOOT:
669 0 : kmalloc_ok = 0;
670 0 : return 1;
671 : default:
672 0 : printk(UM_KERN_ERR "Bad sigsetjmp return in %s - %d\n",
673 : __func__, n);
674 0 : fatal_sigsegv();
675 : }
676 1 : longjmp(*switch_buf, 1);
677 :
678 : /* unreachable */
679 0 : printk(UM_KERN_ERR "impossible long jump!");
680 0 : fatal_sigsegv();
681 : return 0;
682 : }
683 :
684 1 : void initial_thread_cb_skas(void (*proc)(void *), void *arg)
685 : {
686 : jmp_buf here;
687 :
688 1 : cb_proc = proc;
689 1 : cb_arg = arg;
690 1 : cb_back = &here;
691 :
692 1 : block_signals_trace();
693 1 : if (UML_SETJMP(&here) == 0)
694 1 : UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
695 1 : unblock_signals_trace();
696 :
697 1 : cb_proc = NULL;
698 1 : cb_arg = NULL;
699 1 : cb_back = NULL;
700 1 : }
701 :
702 1 : void halt_skas(void)
703 : {
704 1 : block_signals_trace();
705 1 : UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
706 0 : }
707 :
708 : static bool noreboot;
709 :
710 0 : static int __init noreboot_cmd_param(char *str, int *add)
711 : {
712 0 : noreboot = true;
713 0 : return 0;
714 : }
715 :
716 : __uml_setup("noreboot", noreboot_cmd_param,
717 : "noreboot\n"
718 : " Rather than rebooting, exit always, akin to QEMU's -no-reboot option.\n"
719 : " This is useful if you're using CONFIG_PANIC_TIMEOUT in order to catch\n"
720 : " crashes in CI\n");
721 :
722 0 : void reboot_skas(void)
723 : {
724 0 : block_signals_trace();
725 0 : UML_LONGJMP(&initial_jmpbuf, noreboot ? INIT_JMP_HALT : INIT_JMP_REBOOT);
726 0 : }
727 :
728 0 : void __switch_mm(struct mm_id *mm_idp)
729 : {
730 0 : userspace_pid[0] = mm_idp->u.pid;
731 0 : kill_userspace_mm[0] = mm_idp->kill;
732 0 : }
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