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1/*
2 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
3 * Copyright (C) 2002- 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 * Licensed under the GPL
5 */
6
7#include <stdlib.h>
8#include <unistd.h>
9#include <sched.h>
10#include <errno.h>
11#include <string.h>
12#include <sys/mman.h>
13#include <sys/wait.h>
14#include <asm/unistd.h>
15#include <as-layout.h>
16#include <init.h>
17#include <kern_util.h>
18#include <mem.h>
19#include <os.h>
20#include <ptrace_user.h>
21#include <registers.h>
22#include <skas.h>
23#include <sysdep/stub.h>
24#include <linux/threads.h>
25
26int is_skas_winch(int pid, int fd, void *data)
27{
28 return pid == getpgrp();
29}
30
31static 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 << SIGALRM) | (1 << SIGWINCH))
51
52/* Signals that the stub will finish with - anything else is an error */
53#define STUB_DONE_MASK (1 << SIGTRAP)
54
55void wait_stub_done(int pid)
56{
57 int n, status, err;
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
78bad_wait:
79 err = ptrace_dump_regs(pid);
80 if (err)
81 printk(UM_KERN_ERR "Failed to get registers from stub, "
82 "errno = %d\n", -err);
83 printk(UM_KERN_ERR "wait_stub_done : failed to wait for SIGTRAP, "
84 "pid = %d, n = %d, errno = %d, status = 0x%x\n", pid, n, errno,
85 status);
86 fatal_sigsegv();
87}
88
89extern unsigned long current_stub_stack(void);
90
91static void get_skas_faultinfo(int pid, struct faultinfo *fi, unsigned long *aux_fp_regs)
92{
93 int err;
94
95 err = get_fp_registers(pid, aux_fp_regs);
96 if (err < 0) {
97 printk(UM_KERN_ERR "save_fp_registers returned %d\n",
98 err);
99 fatal_sigsegv();
100 }
101 err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV);
102 if (err) {
103 printk(UM_KERN_ERR "Failed to continue stub, pid = %d, "
104 "errno = %d\n", pid, errno);
105 fatal_sigsegv();
106 }
107 wait_stub_done(pid);
108
109 /*
110 * faultinfo is prepared by the stub_segv_handler at start of
111 * the stub stack page. We just have to copy it.
112 */
113 memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
114
115 err = put_fp_registers(pid, aux_fp_regs);
116 if (err < 0) {
117 printk(UM_KERN_ERR "put_fp_registers returned %d\n",
118 err);
119 fatal_sigsegv();
120 }
121}
122
123static void handle_segv(int pid, struct uml_pt_regs *regs, unsigned long *aux_fp_regs)
124{
125 get_skas_faultinfo(pid, ®s->faultinfo, aux_fp_regs);
126 segv(regs->faultinfo, 0, 1, NULL);
127}
128
129/*
130 * To use the same value of using_sysemu as the caller, ask it that value
131 * (in local_using_sysemu
132 */
133static void handle_trap(int pid, struct uml_pt_regs *regs,
134 int local_using_sysemu)
135{
136 int err, status;
137
138 if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
139 fatal_sigsegv();
140
141 if (!local_using_sysemu)
142 {
143 err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
144 __NR_getpid);
145 if (err < 0) {
146 printk(UM_KERN_ERR "handle_trap - nullifying syscall "
147 "failed, errno = %d\n", errno);
148 fatal_sigsegv();
149 }
150
151 err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
152 if (err < 0) {
153 printk(UM_KERN_ERR "handle_trap - continuing to end of "
154 "syscall failed, errno = %d\n", errno);
155 fatal_sigsegv();
156 }
157
158 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
159 if ((err < 0) || !WIFSTOPPED(status) ||
160 (WSTOPSIG(status) != SIGTRAP + 0x80)) {
161 err = ptrace_dump_regs(pid);
162 if (err)
163 printk(UM_KERN_ERR "Failed to get registers "
164 "from process, errno = %d\n", -err);
165 printk(UM_KERN_ERR "handle_trap - failed to wait at "
166 "end of syscall, errno = %d, status = %d\n",
167 errno, status);
168 fatal_sigsegv();
169 }
170 }
171
172 handle_syscall(regs);
173}
174
175extern char __syscall_stub_start[];
176
177/**
178 * userspace_tramp() - userspace trampoline
179 * @stack: pointer to the new userspace stack page, can be NULL, if? FIXME:
180 *
181 * The userspace trampoline is used to setup a new userspace process in start_userspace() after it was clone()'ed.
182 * This function will run on a temporary stack page.
183 * It ptrace()'es itself, then
184 * Two pages are mapped into the userspace address space:
185 * - STUB_CODE (with EXEC), which contains the skas stub code
186 * - 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.
187 * Also for the userspace process a SIGSEGV handler is installed to catch pagefaults in the userspace process.
188 * And last the process stops itself to give control to the UML kernel for this userspace process.
189 *
190 * Return: Always zero, otherwise the current userspace process is ended with non null exit() call
191 */
192static int userspace_tramp(void *stack)
193{
194 void *addr;
195 int fd;
196 unsigned long long offset;
197
198 ptrace(PTRACE_TRACEME, 0, 0, 0);
199
200 signal(SIGTERM, SIG_DFL);
201 signal(SIGWINCH, SIG_IGN);
202
203 /*
204 * This has a pte, but it can't be mapped in with the usual
205 * tlb_flush mechanism because this is part of that mechanism
206 */
207 fd = phys_mapping(to_phys(__syscall_stub_start), &offset);
208 addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE,
209 PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
210 if (addr == MAP_FAILED) {
211 printk(UM_KERN_ERR "mapping mmap stub at 0x%lx failed, "
212 "errno = %d\n", STUB_CODE, errno);
213 exit(1);
214 }
215
216 if (stack != NULL) {
217 fd = phys_mapping(to_phys(stack), &offset);
218 addr = mmap((void *) STUB_DATA,
219 UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
220 MAP_FIXED | MAP_SHARED, fd, offset);
221 if (addr == MAP_FAILED) {
222 printk(UM_KERN_ERR "mapping segfault stack "
223 "at 0x%lx failed, errno = %d\n",
224 STUB_DATA, errno);
225 exit(1);
226 }
227 }
228 if (stack != NULL) {
229 struct sigaction sa;
230
231 unsigned long v = STUB_CODE +
232 (unsigned long) stub_segv_handler -
233 (unsigned long) __syscall_stub_start;
234
235 set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
236 sigemptyset(&sa.sa_mask);
237 sa.sa_flags = SA_ONSTACK | SA_NODEFER | SA_SIGINFO;
238 sa.sa_sigaction = (void *) v;
239 sa.sa_restorer = NULL;
240 if (sigaction(SIGSEGV, &sa, NULL) < 0) {
241 printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV "
242 "handler failed - errno = %d\n", errno);
243 exit(1);
244 }
245 }
246
247 kill(os_getpid(), SIGSTOP);
248 return 0;
249}
250
251int userspace_pid[NR_CPUS];
252
253/**
254 * start_userspace() - prepare a new userspace process
255 * @stub_stack: pointer to the stub stack. Can be NULL, if? FIXME:
256 *
257 * Setups a new temporary stack page that is used while userspace_tramp() runs
258 * Clones the kernel process into a new userspace process, with FDs only.
259 *
260 * Return: When positive: the process id of the new userspace process,
261 * when negative: an error number.
262 * FIXME: can PIDs become negative?!
263 */
264int start_userspace(unsigned long stub_stack)
265{
266 void *stack;
267 unsigned long sp;
268 int pid, status, n, flags, err;
269
270 /* setup a temporary stack page */
271 stack = mmap(NULL, UM_KERN_PAGE_SIZE,
272 PROT_READ | PROT_WRITE | PROT_EXEC,
273 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
274 if (stack == MAP_FAILED) {
275 err = -errno;
276 printk(UM_KERN_ERR "start_userspace : mmap failed, "
277 "errno = %d\n", errno);
278 return err;
279 }
280
281 /* set stack pointer to the end of the stack page, so it can grow downwards */
282 sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
283
284 flags = CLONE_FILES | SIGCHLD;
285
286 /* clone into new userspace process */
287 pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
288 if (pid < 0) {
289 err = -errno;
290 printk(UM_KERN_ERR "start_userspace : clone failed, "
291 "errno = %d\n", errno);
292 return err;
293 }
294
295 do {
296 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
297 if (n < 0) {
298 err = -errno;
299 printk(UM_KERN_ERR "start_userspace : wait failed, "
300 "errno = %d\n", errno);
301 goto out_kill;
302 }
303 } while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGALRM));
304
305 if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) {
306 err = -EINVAL;
307 printk(UM_KERN_ERR "start_userspace : expected SIGSTOP, got "
308 "status = %d\n", status);
309 goto out_kill;
310 }
311
312 if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
313 (void *) PTRACE_O_TRACESYSGOOD) < 0) {
314 err = -errno;
315 printk(UM_KERN_ERR "start_userspace : PTRACE_OLDSETOPTIONS "
316 "failed, errno = %d\n", errno);
317 goto out_kill;
318 }
319
320 if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) {
321 err = -errno;
322 printk(UM_KERN_ERR "start_userspace : munmap failed, "
323 "errno = %d\n", errno);
324 goto out_kill;
325 }
326
327 return pid;
328
329 out_kill:
330 os_kill_ptraced_process(pid, 1);
331 return err;
332}
333
334void userspace(struct uml_pt_regs *regs, unsigned long *aux_fp_regs)
335{
336 int err, status, op, pid = userspace_pid[0];
337 /* To prevent races if using_sysemu changes under us.*/
338 int local_using_sysemu;
339 siginfo_t si;
340
341 /* Handle any immediate reschedules or signals */
342 interrupt_end();
343
344 while (1) {
345
346 /*
347 * This can legitimately fail if the process loads a
348 * bogus value into a segment register. It will
349 * segfault and PTRACE_GETREGS will read that value
350 * out of the process. However, PTRACE_SETREGS will
351 * fail. In this case, there is nothing to do but
352 * just kill the process.
353 */
354 if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp)) {
355 printk(UM_KERN_ERR "userspace - ptrace set regs "
356 "failed, errno = %d\n", errno);
357 fatal_sigsegv();
358 }
359
360 if (put_fp_registers(pid, regs->fp)) {
361 printk(UM_KERN_ERR "userspace - ptrace set fp regs "
362 "failed, errno = %d\n", errno);
363 fatal_sigsegv();
364 }
365
366 /* Now we set local_using_sysemu to be used for one loop */
367 local_using_sysemu = get_using_sysemu();
368
369 op = SELECT_PTRACE_OPERATION(local_using_sysemu,
370 singlestepping(NULL));
371
372 if (ptrace(op, pid, 0, 0)) {
373 printk(UM_KERN_ERR "userspace - ptrace continue "
374 "failed, op = %d, errno = %d\n", op, errno);
375 fatal_sigsegv();
376 }
377
378 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
379 if (err < 0) {
380 printk(UM_KERN_ERR "userspace - wait failed, "
381 "errno = %d\n", errno);
382 fatal_sigsegv();
383 }
384
385 regs->is_user = 1;
386 if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) {
387 printk(UM_KERN_ERR "userspace - PTRACE_GETREGS failed, "
388 "errno = %d\n", errno);
389 fatal_sigsegv();
390 }
391
392 if (get_fp_registers(pid, regs->fp)) {
393 printk(UM_KERN_ERR "userspace - get_fp_registers failed, "
394 "errno = %d\n", errno);
395 fatal_sigsegv();
396 }
397
398 UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
399
400 if (WIFSTOPPED(status)) {
401 int sig = WSTOPSIG(status);
402
403 ptrace(PTRACE_GETSIGINFO, pid, 0, (struct siginfo *)&si);
404
405 switch (sig) {
406 case SIGSEGV:
407 if (PTRACE_FULL_FAULTINFO) {
408 get_skas_faultinfo(pid,
409 ®s->faultinfo, aux_fp_regs);
410 (*sig_info[SIGSEGV])(SIGSEGV, (struct siginfo *)&si,
411 regs);
412 }
413 else handle_segv(pid, regs, aux_fp_regs);
414 break;
415 case SIGTRAP + 0x80:
416 handle_trap(pid, regs, local_using_sysemu);
417 break;
418 case SIGTRAP:
419 relay_signal(SIGTRAP, (struct siginfo *)&si, regs);
420 break;
421 case SIGALRM:
422 break;
423 case SIGIO:
424 case SIGILL:
425 case SIGBUS:
426 case SIGFPE:
427 case SIGWINCH:
428 block_signals();
429 (*sig_info[sig])(sig, (struct siginfo *)&si, regs);
430 unblock_signals();
431 break;
432 default:
433 printk(UM_KERN_ERR "userspace - child stopped "
434 "with signal %d\n", sig);
435 fatal_sigsegv();
436 }
437 pid = userspace_pid[0];
438 interrupt_end();
439
440 /* Avoid -ERESTARTSYS handling in host */
441 if (PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
442 PT_SYSCALL_NR(regs->gp) = -1;
443 }
444 }
445}
446
447static unsigned long thread_regs[MAX_REG_NR];
448static unsigned long thread_fp_regs[FP_SIZE];
449
450static int __init init_thread_regs(void)
451{
452 get_safe_registers(thread_regs, thread_fp_regs);
453 /* Set parent's instruction pointer to start of clone-stub */
454 thread_regs[REGS_IP_INDEX] = STUB_CODE +
455 (unsigned long) stub_clone_handler -
456 (unsigned long) __syscall_stub_start;
457 thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
458 sizeof(void *);
459#ifdef __SIGNAL_FRAMESIZE
460 thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
461#endif
462 return 0;
463}
464
465__initcall(init_thread_regs);
466
467int copy_context_skas0(unsigned long new_stack, int pid)
468{
469 int err;
470 unsigned long current_stack = current_stub_stack();
471 struct stub_data *data = (struct stub_data *) current_stack;
472 struct stub_data *child_data = (struct stub_data *) new_stack;
473 unsigned long long new_offset;
474 int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
475
476 /*
477 * prepare offset and fd of child's stack as argument for parent's
478 * and child's mmap2 calls
479 */
480 *data = ((struct stub_data) {
481 .offset = MMAP_OFFSET(new_offset),
482 .fd = new_fd
483 });
484
485 err = ptrace_setregs(pid, thread_regs);
486 if (err < 0) {
487 err = -errno;
488 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_SETREGS "
489 "failed, pid = %d, errno = %d\n", pid, -err);
490 return err;
491 }
492
493 err = put_fp_registers(pid, thread_fp_regs);
494 if (err < 0) {
495 printk(UM_KERN_ERR "copy_context_skas0 : put_fp_registers "
496 "failed, pid = %d, err = %d\n", pid, err);
497 return err;
498 }
499
500 /* set a well known return code for detection of child write failure */
501 child_data->err = 12345678;
502
503 /*
504 * Wait, until parent has finished its work: read child's pid from
505 * parent's stack, and check, if bad result.
506 */
507 err = ptrace(PTRACE_CONT, pid, 0, 0);
508 if (err) {
509 err = -errno;
510 printk(UM_KERN_ERR "Failed to continue new process, pid = %d, "
511 "errno = %d\n", pid, errno);
512 return err;
513 }
514
515 wait_stub_done(pid);
516
517 pid = data->err;
518 if (pid < 0) {
519 printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports "
520 "error %d\n", -pid);
521 return pid;
522 }
523
524 /*
525 * Wait, until child has finished too: read child's result from
526 * child's stack and check it.
527 */
528 wait_stub_done(pid);
529 if (child_data->err != STUB_DATA) {
530 printk(UM_KERN_ERR "copy_context_skas0 - stub-child reports "
531 "error %ld\n", child_data->err);
532 err = child_data->err;
533 goto out_kill;
534 }
535
536 if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
537 (void *)PTRACE_O_TRACESYSGOOD) < 0) {
538 err = -errno;
539 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_OLDSETOPTIONS "
540 "failed, errno = %d\n", errno);
541 goto out_kill;
542 }
543
544 return pid;
545
546 out_kill:
547 os_kill_ptraced_process(pid, 1);
548 return err;
549}
550
551void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
552{
553 (*buf)[0].JB_IP = (unsigned long) handler;
554 (*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE -
555 sizeof(void *);
556}
557
558#define INIT_JMP_NEW_THREAD 0
559#define INIT_JMP_CALLBACK 1
560#define INIT_JMP_HALT 2
561#define INIT_JMP_REBOOT 3
562
563void switch_threads(jmp_buf *me, jmp_buf *you)
564{
565 if (UML_SETJMP(me) == 0)
566 UML_LONGJMP(you, 1);
567}
568
569static jmp_buf initial_jmpbuf;
570
571/* XXX Make these percpu */
572static void (*cb_proc)(void *arg);
573static void *cb_arg;
574static jmp_buf *cb_back;
575
576int start_idle_thread(void *stack, jmp_buf *switch_buf)
577{
578 int n;
579
580 set_handler(SIGWINCH);
581
582 /*
583 * Can't use UML_SETJMP or UML_LONGJMP here because they save
584 * and restore signals, with the possible side-effect of
585 * trying to handle any signals which came when they were
586 * blocked, which can't be done on this stack.
587 * Signals must be blocked when jumping back here and restored
588 * after returning to the jumper.
589 */
590 n = setjmp(initial_jmpbuf);
591 switch (n) {
592 case INIT_JMP_NEW_THREAD:
593 (*switch_buf)[0].JB_IP = (unsigned long) uml_finishsetup;
594 (*switch_buf)[0].JB_SP = (unsigned long) stack +
595 UM_THREAD_SIZE - sizeof(void *);
596 break;
597 case INIT_JMP_CALLBACK:
598 (*cb_proc)(cb_arg);
599 longjmp(*cb_back, 1);
600 break;
601 case INIT_JMP_HALT:
602 kmalloc_ok = 0;
603 return 0;
604 case INIT_JMP_REBOOT:
605 kmalloc_ok = 0;
606 return 1;
607 default:
608 printk(UM_KERN_ERR "Bad sigsetjmp return in "
609 "start_idle_thread - %d\n", n);
610 fatal_sigsegv();
611 }
612 longjmp(*switch_buf, 1);
613}
614
615void initial_thread_cb_skas(void (*proc)(void *), void *arg)
616{
617 jmp_buf here;
618
619 cb_proc = proc;
620 cb_arg = arg;
621 cb_back = &here;
622
623 block_signals();
624 if (UML_SETJMP(&here) == 0)
625 UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
626 unblock_signals();
627
628 cb_proc = NULL;
629 cb_arg = NULL;
630 cb_back = NULL;
631}
632
633void halt_skas(void)
634{
635 block_signals();
636 UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
637}
638
639void reboot_skas(void)
640{
641 block_signals();
642 UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
643}
644
645void __switch_mm(struct mm_id *mm_idp)
646{
647 userspace_pid[0] = mm_idp->u.pid;
648}
1/*
2 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
3 * Copyright (C) 2002- 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 * Licensed under the GPL
5 */
6
7#include <stdlib.h>
8#include <unistd.h>
9#include <sched.h>
10#include <errno.h>
11#include <string.h>
12#include <sys/mman.h>
13#include <sys/wait.h>
14#include <asm/unistd.h>
15#include <as-layout.h>
16#include <init.h>
17#include <kern_util.h>
18#include <mem.h>
19#include <os.h>
20#include <ptrace_user.h>
21#include <registers.h>
22#include <skas.h>
23#include <sysdep/stub.h>
24
25int is_skas_winch(int pid, int fd, void *data)
26{
27 return pid == getpgrp();
28}
29
30static int ptrace_dump_regs(int pid)
31{
32 unsigned long regs[MAX_REG_NR];
33 int i;
34
35 if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
36 return -errno;
37
38 printk(UM_KERN_ERR "Stub registers -\n");
39 for (i = 0; i < ARRAY_SIZE(regs); i++)
40 printk(UM_KERN_ERR "\t%d - %lx\n", i, regs[i]);
41
42 return 0;
43}
44
45/*
46 * Signals that are OK to receive in the stub - we'll just continue it.
47 * SIGWINCH will happen when UML is inside a detached screen.
48 */
49#define STUB_SIG_MASK ((1 << SIGALRM) | (1 << SIGWINCH))
50
51/* Signals that the stub will finish with - anything else is an error */
52#define STUB_DONE_MASK (1 << SIGTRAP)
53
54void wait_stub_done(int pid)
55{
56 int n, status, err;
57
58 while (1) {
59 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
60 if ((n < 0) || !WIFSTOPPED(status))
61 goto bad_wait;
62
63 if (((1 << WSTOPSIG(status)) & STUB_SIG_MASK) == 0)
64 break;
65
66 err = ptrace(PTRACE_CONT, pid, 0, 0);
67 if (err) {
68 printk(UM_KERN_ERR "wait_stub_done : continue failed, "
69 "errno = %d\n", errno);
70 fatal_sigsegv();
71 }
72 }
73
74 if (((1 << WSTOPSIG(status)) & STUB_DONE_MASK) != 0)
75 return;
76
77bad_wait:
78 err = ptrace_dump_regs(pid);
79 if (err)
80 printk(UM_KERN_ERR "Failed to get registers from stub, "
81 "errno = %d\n", -err);
82 printk(UM_KERN_ERR "wait_stub_done : failed to wait for SIGTRAP, "
83 "pid = %d, n = %d, errno = %d, status = 0x%x\n", pid, n, errno,
84 status);
85 fatal_sigsegv();
86}
87
88extern unsigned long current_stub_stack(void);
89
90static void get_skas_faultinfo(int pid, struct faultinfo *fi)
91{
92 int err;
93 unsigned long fpregs[FP_SIZE];
94
95 err = get_fp_registers(pid, fpregs);
96 if (err < 0) {
97 printk(UM_KERN_ERR "save_fp_registers returned %d\n",
98 err);
99 fatal_sigsegv();
100 }
101 err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV);
102 if (err) {
103 printk(UM_KERN_ERR "Failed to continue stub, pid = %d, "
104 "errno = %d\n", pid, errno);
105 fatal_sigsegv();
106 }
107 wait_stub_done(pid);
108
109 /*
110 * faultinfo is prepared by the stub-segv-handler at start of
111 * the stub stack page. We just have to copy it.
112 */
113 memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
114
115 err = put_fp_registers(pid, fpregs);
116 if (err < 0) {
117 printk(UM_KERN_ERR "put_fp_registers returned %d\n",
118 err);
119 fatal_sigsegv();
120 }
121}
122
123static void handle_segv(int pid, struct uml_pt_regs * regs)
124{
125 get_skas_faultinfo(pid, ®s->faultinfo);
126 segv(regs->faultinfo, 0, 1, NULL);
127}
128
129/*
130 * To use the same value of using_sysemu as the caller, ask it that value
131 * (in local_using_sysemu
132 */
133static void handle_trap(int pid, struct uml_pt_regs *regs,
134 int local_using_sysemu)
135{
136 int err, status;
137
138 if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
139 fatal_sigsegv();
140
141 if (!local_using_sysemu)
142 {
143 err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
144 __NR_getpid);
145 if (err < 0) {
146 printk(UM_KERN_ERR "handle_trap - nullifying syscall "
147 "failed, errno = %d\n", errno);
148 fatal_sigsegv();
149 }
150
151 err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
152 if (err < 0) {
153 printk(UM_KERN_ERR "handle_trap - continuing to end of "
154 "syscall failed, errno = %d\n", errno);
155 fatal_sigsegv();
156 }
157
158 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
159 if ((err < 0) || !WIFSTOPPED(status) ||
160 (WSTOPSIG(status) != SIGTRAP + 0x80)) {
161 err = ptrace_dump_regs(pid);
162 if (err)
163 printk(UM_KERN_ERR "Failed to get registers "
164 "from process, errno = %d\n", -err);
165 printk(UM_KERN_ERR "handle_trap - failed to wait at "
166 "end of syscall, errno = %d, status = %d\n",
167 errno, status);
168 fatal_sigsegv();
169 }
170 }
171
172 handle_syscall(regs);
173}
174
175extern char __syscall_stub_start[];
176
177static int userspace_tramp(void *stack)
178{
179 void *addr;
180 int fd;
181 unsigned long long offset;
182
183 ptrace(PTRACE_TRACEME, 0, 0, 0);
184
185 signal(SIGTERM, SIG_DFL);
186 signal(SIGWINCH, SIG_IGN);
187
188 /*
189 * This has a pte, but it can't be mapped in with the usual
190 * tlb_flush mechanism because this is part of that mechanism
191 */
192 fd = phys_mapping(to_phys(__syscall_stub_start), &offset);
193 addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE,
194 PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
195 if (addr == MAP_FAILED) {
196 printk(UM_KERN_ERR "mapping mmap stub at 0x%lx failed, "
197 "errno = %d\n", STUB_CODE, errno);
198 exit(1);
199 }
200
201 if (stack != NULL) {
202 fd = phys_mapping(to_phys(stack), &offset);
203 addr = mmap((void *) STUB_DATA,
204 UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
205 MAP_FIXED | MAP_SHARED, fd, offset);
206 if (addr == MAP_FAILED) {
207 printk(UM_KERN_ERR "mapping segfault stack "
208 "at 0x%lx failed, errno = %d\n",
209 STUB_DATA, errno);
210 exit(1);
211 }
212 }
213 if (stack != NULL) {
214 struct sigaction sa;
215
216 unsigned long v = STUB_CODE +
217 (unsigned long) stub_segv_handler -
218 (unsigned long) __syscall_stub_start;
219
220 set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
221 sigemptyset(&sa.sa_mask);
222 sa.sa_flags = SA_ONSTACK | SA_NODEFER | SA_SIGINFO;
223 sa.sa_sigaction = (void *) v;
224 sa.sa_restorer = NULL;
225 if (sigaction(SIGSEGV, &sa, NULL) < 0) {
226 printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV "
227 "handler failed - errno = %d\n", errno);
228 exit(1);
229 }
230 }
231
232 kill(os_getpid(), SIGSTOP);
233 return 0;
234}
235
236/* Each element set once, and only accessed by a single processor anyway */
237#undef NR_CPUS
238#define NR_CPUS 1
239int userspace_pid[NR_CPUS];
240
241int start_userspace(unsigned long stub_stack)
242{
243 void *stack;
244 unsigned long sp;
245 int pid, status, n, flags, err;
246
247 stack = mmap(NULL, UM_KERN_PAGE_SIZE,
248 PROT_READ | PROT_WRITE | PROT_EXEC,
249 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
250 if (stack == MAP_FAILED) {
251 err = -errno;
252 printk(UM_KERN_ERR "start_userspace : mmap failed, "
253 "errno = %d\n", errno);
254 return err;
255 }
256
257 sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
258
259 flags = CLONE_FILES | SIGCHLD;
260
261 pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
262 if (pid < 0) {
263 err = -errno;
264 printk(UM_KERN_ERR "start_userspace : clone failed, "
265 "errno = %d\n", errno);
266 return err;
267 }
268
269 do {
270 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
271 if (n < 0) {
272 err = -errno;
273 printk(UM_KERN_ERR "start_userspace : wait failed, "
274 "errno = %d\n", errno);
275 goto out_kill;
276 }
277 } while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGALRM));
278
279 if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) {
280 err = -EINVAL;
281 printk(UM_KERN_ERR "start_userspace : expected SIGSTOP, got "
282 "status = %d\n", status);
283 goto out_kill;
284 }
285
286 if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
287 (void *) PTRACE_O_TRACESYSGOOD) < 0) {
288 err = -errno;
289 printk(UM_KERN_ERR "start_userspace : PTRACE_OLDSETOPTIONS "
290 "failed, errno = %d\n", errno);
291 goto out_kill;
292 }
293
294 if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) {
295 err = -errno;
296 printk(UM_KERN_ERR "start_userspace : munmap failed, "
297 "errno = %d\n", errno);
298 goto out_kill;
299 }
300
301 return pid;
302
303 out_kill:
304 os_kill_ptraced_process(pid, 1);
305 return err;
306}
307
308void userspace(struct uml_pt_regs *regs)
309{
310 int err, status, op, pid = userspace_pid[0];
311 /* To prevent races if using_sysemu changes under us.*/
312 int local_using_sysemu;
313 siginfo_t si;
314
315 /* Handle any immediate reschedules or signals */
316 interrupt_end();
317
318 while (1) {
319
320 /*
321 * This can legitimately fail if the process loads a
322 * bogus value into a segment register. It will
323 * segfault and PTRACE_GETREGS will read that value
324 * out of the process. However, PTRACE_SETREGS will
325 * fail. In this case, there is nothing to do but
326 * just kill the process.
327 */
328 if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp))
329 fatal_sigsegv();
330
331 if (put_fp_registers(pid, regs->fp))
332 fatal_sigsegv();
333
334 /* Now we set local_using_sysemu to be used for one loop */
335 local_using_sysemu = get_using_sysemu();
336
337 op = SELECT_PTRACE_OPERATION(local_using_sysemu,
338 singlestepping(NULL));
339
340 if (ptrace(op, pid, 0, 0)) {
341 printk(UM_KERN_ERR "userspace - ptrace continue "
342 "failed, op = %d, errno = %d\n", op, errno);
343 fatal_sigsegv();
344 }
345
346 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
347 if (err < 0) {
348 printk(UM_KERN_ERR "userspace - wait failed, "
349 "errno = %d\n", errno);
350 fatal_sigsegv();
351 }
352
353 regs->is_user = 1;
354 if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) {
355 printk(UM_KERN_ERR "userspace - PTRACE_GETREGS failed, "
356 "errno = %d\n", errno);
357 fatal_sigsegv();
358 }
359
360 if (get_fp_registers(pid, regs->fp)) {
361 printk(UM_KERN_ERR "userspace - get_fp_registers failed, "
362 "errno = %d\n", errno);
363 fatal_sigsegv();
364 }
365
366 UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
367
368 if (WIFSTOPPED(status)) {
369 int sig = WSTOPSIG(status);
370
371 ptrace(PTRACE_GETSIGINFO, pid, 0, (struct siginfo *)&si);
372
373 switch (sig) {
374 case SIGSEGV:
375 if (PTRACE_FULL_FAULTINFO) {
376 get_skas_faultinfo(pid,
377 ®s->faultinfo);
378 (*sig_info[SIGSEGV])(SIGSEGV, (struct siginfo *)&si,
379 regs);
380 }
381 else handle_segv(pid, regs);
382 break;
383 case SIGTRAP + 0x80:
384 handle_trap(pid, regs, local_using_sysemu);
385 break;
386 case SIGTRAP:
387 relay_signal(SIGTRAP, (struct siginfo *)&si, regs);
388 break;
389 case SIGALRM:
390 break;
391 case SIGIO:
392 case SIGILL:
393 case SIGBUS:
394 case SIGFPE:
395 case SIGWINCH:
396 block_signals();
397 (*sig_info[sig])(sig, (struct siginfo *)&si, regs);
398 unblock_signals();
399 break;
400 default:
401 printk(UM_KERN_ERR "userspace - child stopped "
402 "with signal %d\n", sig);
403 fatal_sigsegv();
404 }
405 pid = userspace_pid[0];
406 interrupt_end();
407
408 /* Avoid -ERESTARTSYS handling in host */
409 if (PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
410 PT_SYSCALL_NR(regs->gp) = -1;
411 }
412 }
413}
414
415static unsigned long thread_regs[MAX_REG_NR];
416static unsigned long thread_fp_regs[FP_SIZE];
417
418static int __init init_thread_regs(void)
419{
420 get_safe_registers(thread_regs, thread_fp_regs);
421 /* Set parent's instruction pointer to start of clone-stub */
422 thread_regs[REGS_IP_INDEX] = STUB_CODE +
423 (unsigned long) stub_clone_handler -
424 (unsigned long) __syscall_stub_start;
425 thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
426 sizeof(void *);
427#ifdef __SIGNAL_FRAMESIZE
428 thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
429#endif
430 return 0;
431}
432
433__initcall(init_thread_regs);
434
435int copy_context_skas0(unsigned long new_stack, int pid)
436{
437 int err;
438 unsigned long current_stack = current_stub_stack();
439 struct stub_data *data = (struct stub_data *) current_stack;
440 struct stub_data *child_data = (struct stub_data *) new_stack;
441 unsigned long long new_offset;
442 int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
443
444 /*
445 * prepare offset and fd of child's stack as argument for parent's
446 * and child's mmap2 calls
447 */
448 *data = ((struct stub_data) {
449 .offset = MMAP_OFFSET(new_offset),
450 .fd = new_fd
451 });
452
453 err = ptrace_setregs(pid, thread_regs);
454 if (err < 0) {
455 err = -errno;
456 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_SETREGS "
457 "failed, pid = %d, errno = %d\n", pid, -err);
458 return err;
459 }
460
461 err = put_fp_registers(pid, thread_fp_regs);
462 if (err < 0) {
463 printk(UM_KERN_ERR "copy_context_skas0 : put_fp_registers "
464 "failed, pid = %d, err = %d\n", pid, err);
465 return err;
466 }
467
468 /* set a well known return code for detection of child write failure */
469 child_data->err = 12345678;
470
471 /*
472 * Wait, until parent has finished its work: read child's pid from
473 * parent's stack, and check, if bad result.
474 */
475 err = ptrace(PTRACE_CONT, pid, 0, 0);
476 if (err) {
477 err = -errno;
478 printk(UM_KERN_ERR "Failed to continue new process, pid = %d, "
479 "errno = %d\n", pid, errno);
480 return err;
481 }
482
483 wait_stub_done(pid);
484
485 pid = data->err;
486 if (pid < 0) {
487 printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports "
488 "error %d\n", -pid);
489 return pid;
490 }
491
492 /*
493 * Wait, until child has finished too: read child's result from
494 * child's stack and check it.
495 */
496 wait_stub_done(pid);
497 if (child_data->err != STUB_DATA) {
498 printk(UM_KERN_ERR "copy_context_skas0 - stub-child reports "
499 "error %ld\n", child_data->err);
500 err = child_data->err;
501 goto out_kill;
502 }
503
504 if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
505 (void *)PTRACE_O_TRACESYSGOOD) < 0) {
506 err = -errno;
507 printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_OLDSETOPTIONS "
508 "failed, errno = %d\n", errno);
509 goto out_kill;
510 }
511
512 return pid;
513
514 out_kill:
515 os_kill_ptraced_process(pid, 1);
516 return err;
517}
518
519void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
520{
521 (*buf)[0].JB_IP = (unsigned long) handler;
522 (*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE -
523 sizeof(void *);
524}
525
526#define INIT_JMP_NEW_THREAD 0
527#define INIT_JMP_CALLBACK 1
528#define INIT_JMP_HALT 2
529#define INIT_JMP_REBOOT 3
530
531void switch_threads(jmp_buf *me, jmp_buf *you)
532{
533 if (UML_SETJMP(me) == 0)
534 UML_LONGJMP(you, 1);
535}
536
537static jmp_buf initial_jmpbuf;
538
539/* XXX Make these percpu */
540static void (*cb_proc)(void *arg);
541static void *cb_arg;
542static jmp_buf *cb_back;
543
544int start_idle_thread(void *stack, jmp_buf *switch_buf)
545{
546 int n;
547
548 set_handler(SIGWINCH);
549
550 /*
551 * Can't use UML_SETJMP or UML_LONGJMP here because they save
552 * and restore signals, with the possible side-effect of
553 * trying to handle any signals which came when they were
554 * blocked, which can't be done on this stack.
555 * Signals must be blocked when jumping back here and restored
556 * after returning to the jumper.
557 */
558 n = setjmp(initial_jmpbuf);
559 switch (n) {
560 case INIT_JMP_NEW_THREAD:
561 (*switch_buf)[0].JB_IP = (unsigned long) uml_finishsetup;
562 (*switch_buf)[0].JB_SP = (unsigned long) stack +
563 UM_THREAD_SIZE - sizeof(void *);
564 break;
565 case INIT_JMP_CALLBACK:
566 (*cb_proc)(cb_arg);
567 longjmp(*cb_back, 1);
568 break;
569 case INIT_JMP_HALT:
570 kmalloc_ok = 0;
571 return 0;
572 case INIT_JMP_REBOOT:
573 kmalloc_ok = 0;
574 return 1;
575 default:
576 printk(UM_KERN_ERR "Bad sigsetjmp return in "
577 "start_idle_thread - %d\n", n);
578 fatal_sigsegv();
579 }
580 longjmp(*switch_buf, 1);
581}
582
583void initial_thread_cb_skas(void (*proc)(void *), void *arg)
584{
585 jmp_buf here;
586
587 cb_proc = proc;
588 cb_arg = arg;
589 cb_back = &here;
590
591 block_signals();
592 if (UML_SETJMP(&here) == 0)
593 UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
594 unblock_signals();
595
596 cb_proc = NULL;
597 cb_arg = NULL;
598 cb_back = NULL;
599}
600
601void halt_skas(void)
602{
603 block_signals();
604 UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
605}
606
607void reboot_skas(void)
608{
609 block_signals();
610 UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
611}
612
613void __switch_mm(struct mm_id *mm_idp)
614{
615 userspace_pid[0] = mm_idp->u.pid;
616}