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Merge tag 'for-4.15-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave...
[mirror_ubuntu-bionic-kernel.git] / arch / x86 / kernel / signal.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
5 *
6 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
7 * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
8 * 2000-2002 x86-64 support by Andi Kleen
9 */
10
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13 #include <linux/sched.h>
14 #include <linux/sched/task_stack.h>
15 #include <linux/mm.h>
16 #include <linux/smp.h>
17 #include <linux/kernel.h>
18 #include <linux/errno.h>
19 #include <linux/wait.h>
20 #include <linux/tracehook.h>
21 #include <linux/unistd.h>
22 #include <linux/stddef.h>
23 #include <linux/personality.h>
24 #include <linux/uaccess.h>
25 #include <linux/user-return-notifier.h>
26 #include <linux/uprobes.h>
27 #include <linux/context_tracking.h>
28
29 #include <asm/processor.h>
30 #include <asm/ucontext.h>
31 #include <asm/fpu/internal.h>
32 #include <asm/fpu/signal.h>
33 #include <asm/vdso.h>
34 #include <asm/mce.h>
35 #include <asm/sighandling.h>
36 #include <asm/vm86.h>
37
38 #ifdef CONFIG_X86_64
39 #include <asm/proto.h>
40 #include <asm/ia32_unistd.h>
41 #endif /* CONFIG_X86_64 */
42
43 #include <asm/syscall.h>
44 #include <asm/syscalls.h>
45
46 #include <asm/sigframe.h>
47 #include <asm/signal.h>
48
49 #define COPY(x) do { \
50 get_user_ex(regs->x, &sc->x); \
51 } while (0)
52
53 #define GET_SEG(seg) ({ \
54 unsigned short tmp; \
55 get_user_ex(tmp, &sc->seg); \
56 tmp; \
57 })
58
59 #define COPY_SEG(seg) do { \
60 regs->seg = GET_SEG(seg); \
61 } while (0)
62
63 #define COPY_SEG_CPL3(seg) do { \
64 regs->seg = GET_SEG(seg) | 3; \
65 } while (0)
66
67 #ifdef CONFIG_X86_64
68 /*
69 * If regs->ss will cause an IRET fault, change it. Otherwise leave it
70 * alone. Using this generally makes no sense unless
71 * user_64bit_mode(regs) would return true.
72 */
73 static void force_valid_ss(struct pt_regs *regs)
74 {
75 u32 ar;
76 asm volatile ("lar %[old_ss], %[ar]\n\t"
77 "jz 1f\n\t" /* If invalid: */
78 "xorl %[ar], %[ar]\n\t" /* set ar = 0 */
79 "1:"
80 : [ar] "=r" (ar)
81 : [old_ss] "rm" ((u16)regs->ss));
82
83 /*
84 * For a valid 64-bit user context, we need DPL 3, type
85 * read-write data or read-write exp-down data, and S and P
86 * set. We can't use VERW because VERW doesn't check the
87 * P bit.
88 */
89 ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK;
90 if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) &&
91 ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
92 regs->ss = __USER_DS;
93 }
94 #endif
95
96 static int restore_sigcontext(struct pt_regs *regs,
97 struct sigcontext __user *sc,
98 unsigned long uc_flags)
99 {
100 unsigned long buf_val;
101 void __user *buf;
102 unsigned int tmpflags;
103 unsigned int err = 0;
104
105 /* Always make any pending restarted system calls return -EINTR */
106 current->restart_block.fn = do_no_restart_syscall;
107
108 get_user_try {
109
110 #ifdef CONFIG_X86_32
111 set_user_gs(regs, GET_SEG(gs));
112 COPY_SEG(fs);
113 COPY_SEG(es);
114 COPY_SEG(ds);
115 #endif /* CONFIG_X86_32 */
116
117 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
118 COPY(dx); COPY(cx); COPY(ip); COPY(ax);
119
120 #ifdef CONFIG_X86_64
121 COPY(r8);
122 COPY(r9);
123 COPY(r10);
124 COPY(r11);
125 COPY(r12);
126 COPY(r13);
127 COPY(r14);
128 COPY(r15);
129 #endif /* CONFIG_X86_64 */
130
131 COPY_SEG_CPL3(cs);
132 COPY_SEG_CPL3(ss);
133
134 #ifdef CONFIG_X86_64
135 /*
136 * Fix up SS if needed for the benefit of old DOSEMU and
137 * CRIU.
138 */
139 if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) &&
140 user_64bit_mode(regs)))
141 force_valid_ss(regs);
142 #endif
143
144 get_user_ex(tmpflags, &sc->flags);
145 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
146 regs->orig_ax = -1; /* disable syscall checks */
147
148 get_user_ex(buf_val, &sc->fpstate);
149 buf = (void __user *)buf_val;
150 } get_user_catch(err);
151
152 err |= fpu__restore_sig(buf, IS_ENABLED(CONFIG_X86_32));
153
154 force_iret();
155
156 return err;
157 }
158
159 int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
160 struct pt_regs *regs, unsigned long mask)
161 {
162 int err = 0;
163
164 put_user_try {
165
166 #ifdef CONFIG_X86_32
167 put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
168 put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
169 put_user_ex(regs->es, (unsigned int __user *)&sc->es);
170 put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
171 #endif /* CONFIG_X86_32 */
172
173 put_user_ex(regs->di, &sc->di);
174 put_user_ex(regs->si, &sc->si);
175 put_user_ex(regs->bp, &sc->bp);
176 put_user_ex(regs->sp, &sc->sp);
177 put_user_ex(regs->bx, &sc->bx);
178 put_user_ex(regs->dx, &sc->dx);
179 put_user_ex(regs->cx, &sc->cx);
180 put_user_ex(regs->ax, &sc->ax);
181 #ifdef CONFIG_X86_64
182 put_user_ex(regs->r8, &sc->r8);
183 put_user_ex(regs->r9, &sc->r9);
184 put_user_ex(regs->r10, &sc->r10);
185 put_user_ex(regs->r11, &sc->r11);
186 put_user_ex(regs->r12, &sc->r12);
187 put_user_ex(regs->r13, &sc->r13);
188 put_user_ex(regs->r14, &sc->r14);
189 put_user_ex(regs->r15, &sc->r15);
190 #endif /* CONFIG_X86_64 */
191
192 put_user_ex(current->thread.trap_nr, &sc->trapno);
193 put_user_ex(current->thread.error_code, &sc->err);
194 put_user_ex(regs->ip, &sc->ip);
195 #ifdef CONFIG_X86_32
196 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
197 put_user_ex(regs->flags, &sc->flags);
198 put_user_ex(regs->sp, &sc->sp_at_signal);
199 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
200 #else /* !CONFIG_X86_32 */
201 put_user_ex(regs->flags, &sc->flags);
202 put_user_ex(regs->cs, &sc->cs);
203 put_user_ex(0, &sc->gs);
204 put_user_ex(0, &sc->fs);
205 put_user_ex(regs->ss, &sc->ss);
206 #endif /* CONFIG_X86_32 */
207
208 put_user_ex(fpstate, &sc->fpstate);
209
210 /* non-iBCS2 extensions.. */
211 put_user_ex(mask, &sc->oldmask);
212 put_user_ex(current->thread.cr2, &sc->cr2);
213 } put_user_catch(err);
214
215 return err;
216 }
217
218 /*
219 * Set up a signal frame.
220 */
221
222 /*
223 * Determine which stack to use..
224 */
225 static unsigned long align_sigframe(unsigned long sp)
226 {
227 #ifdef CONFIG_X86_32
228 /*
229 * Align the stack pointer according to the i386 ABI,
230 * i.e. so that on function entry ((sp + 4) & 15) == 0.
231 */
232 sp = ((sp + 4) & -16ul) - 4;
233 #else /* !CONFIG_X86_32 */
234 sp = round_down(sp, 16) - 8;
235 #endif
236 return sp;
237 }
238
239 static void __user *
240 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
241 void __user **fpstate)
242 {
243 /* Default to using normal stack */
244 unsigned long math_size = 0;
245 unsigned long sp = regs->sp;
246 unsigned long buf_fx = 0;
247 int onsigstack = on_sig_stack(sp);
248 struct fpu *fpu = &current->thread.fpu;
249
250 /* redzone */
251 if (IS_ENABLED(CONFIG_X86_64))
252 sp -= 128;
253
254 /* This is the X/Open sanctioned signal stack switching. */
255 if (ka->sa.sa_flags & SA_ONSTACK) {
256 if (sas_ss_flags(sp) == 0)
257 sp = current->sas_ss_sp + current->sas_ss_size;
258 } else if (IS_ENABLED(CONFIG_X86_32) &&
259 !onsigstack &&
260 regs->ss != __USER_DS &&
261 !(ka->sa.sa_flags & SA_RESTORER) &&
262 ka->sa.sa_restorer) {
263 /* This is the legacy signal stack switching. */
264 sp = (unsigned long) ka->sa.sa_restorer;
265 }
266
267 if (fpu->initialized) {
268 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
269 &buf_fx, &math_size);
270 *fpstate = (void __user *)sp;
271 }
272
273 sp = align_sigframe(sp - frame_size);
274
275 /*
276 * If we are on the alternate signal stack and would overflow it, don't.
277 * Return an always-bogus address instead so we will die with SIGSEGV.
278 */
279 if (onsigstack && !likely(on_sig_stack(sp)))
280 return (void __user *)-1L;
281
282 /* save i387 and extended state */
283 if (fpu->initialized &&
284 copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size) < 0)
285 return (void __user *)-1L;
286
287 return (void __user *)sp;
288 }
289
290 #ifdef CONFIG_X86_32
291 static const struct {
292 u16 poplmovl;
293 u32 val;
294 u16 int80;
295 } __attribute__((packed)) retcode = {
296 0xb858, /* popl %eax; movl $..., %eax */
297 __NR_sigreturn,
298 0x80cd, /* int $0x80 */
299 };
300
301 static const struct {
302 u8 movl;
303 u32 val;
304 u16 int80;
305 u8 pad;
306 } __attribute__((packed)) rt_retcode = {
307 0xb8, /* movl $..., %eax */
308 __NR_rt_sigreturn,
309 0x80cd, /* int $0x80 */
310 0
311 };
312
313 static int
314 __setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
315 struct pt_regs *regs)
316 {
317 struct sigframe __user *frame;
318 void __user *restorer;
319 int err = 0;
320 void __user *fpstate = NULL;
321
322 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
323
324 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
325 return -EFAULT;
326
327 if (__put_user(sig, &frame->sig))
328 return -EFAULT;
329
330 if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
331 return -EFAULT;
332
333 if (_NSIG_WORDS > 1) {
334 if (__copy_to_user(&frame->extramask, &set->sig[1],
335 sizeof(frame->extramask)))
336 return -EFAULT;
337 }
338
339 if (current->mm->context.vdso)
340 restorer = current->mm->context.vdso +
341 vdso_image_32.sym___kernel_sigreturn;
342 else
343 restorer = &frame->retcode;
344 if (ksig->ka.sa.sa_flags & SA_RESTORER)
345 restorer = ksig->ka.sa.sa_restorer;
346
347 /* Set up to return from userspace. */
348 err |= __put_user(restorer, &frame->pretcode);
349
350 /*
351 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
352 *
353 * WE DO NOT USE IT ANY MORE! It's only left here for historical
354 * reasons and because gdb uses it as a signature to notice
355 * signal handler stack frames.
356 */
357 err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
358
359 if (err)
360 return -EFAULT;
361
362 /* Set up registers for signal handler */
363 regs->sp = (unsigned long)frame;
364 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
365 regs->ax = (unsigned long)sig;
366 regs->dx = 0;
367 regs->cx = 0;
368
369 regs->ds = __USER_DS;
370 regs->es = __USER_DS;
371 regs->ss = __USER_DS;
372 regs->cs = __USER_CS;
373
374 return 0;
375 }
376
377 static int __setup_rt_frame(int sig, struct ksignal *ksig,
378 sigset_t *set, struct pt_regs *regs)
379 {
380 struct rt_sigframe __user *frame;
381 void __user *restorer;
382 int err = 0;
383 void __user *fpstate = NULL;
384
385 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
386
387 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
388 return -EFAULT;
389
390 put_user_try {
391 put_user_ex(sig, &frame->sig);
392 put_user_ex(&frame->info, &frame->pinfo);
393 put_user_ex(&frame->uc, &frame->puc);
394
395 /* Create the ucontext. */
396 if (boot_cpu_has(X86_FEATURE_XSAVE))
397 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
398 else
399 put_user_ex(0, &frame->uc.uc_flags);
400 put_user_ex(0, &frame->uc.uc_link);
401 save_altstack_ex(&frame->uc.uc_stack, regs->sp);
402
403 /* Set up to return from userspace. */
404 restorer = current->mm->context.vdso +
405 vdso_image_32.sym___kernel_rt_sigreturn;
406 if (ksig->ka.sa.sa_flags & SA_RESTORER)
407 restorer = ksig->ka.sa.sa_restorer;
408 put_user_ex(restorer, &frame->pretcode);
409
410 /*
411 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
412 *
413 * WE DO NOT USE IT ANY MORE! It's only left here for historical
414 * reasons and because gdb uses it as a signature to notice
415 * signal handler stack frames.
416 */
417 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
418 } put_user_catch(err);
419
420 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
421 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
422 regs, set->sig[0]);
423 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
424
425 if (err)
426 return -EFAULT;
427
428 /* Set up registers for signal handler */
429 regs->sp = (unsigned long)frame;
430 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
431 regs->ax = (unsigned long)sig;
432 regs->dx = (unsigned long)&frame->info;
433 regs->cx = (unsigned long)&frame->uc;
434
435 regs->ds = __USER_DS;
436 regs->es = __USER_DS;
437 regs->ss = __USER_DS;
438 regs->cs = __USER_CS;
439
440 return 0;
441 }
442 #else /* !CONFIG_X86_32 */
443 static unsigned long frame_uc_flags(struct pt_regs *regs)
444 {
445 unsigned long flags;
446
447 if (boot_cpu_has(X86_FEATURE_XSAVE))
448 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
449 else
450 flags = UC_SIGCONTEXT_SS;
451
452 if (likely(user_64bit_mode(regs)))
453 flags |= UC_STRICT_RESTORE_SS;
454
455 return flags;
456 }
457
458 static int __setup_rt_frame(int sig, struct ksignal *ksig,
459 sigset_t *set, struct pt_regs *regs)
460 {
461 struct rt_sigframe __user *frame;
462 void __user *fp = NULL;
463 int err = 0;
464
465 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
466
467 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
468 return -EFAULT;
469
470 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
471 if (copy_siginfo_to_user(&frame->info, &ksig->info))
472 return -EFAULT;
473 }
474
475 put_user_try {
476 /* Create the ucontext. */
477 put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags);
478 put_user_ex(0, &frame->uc.uc_link);
479 save_altstack_ex(&frame->uc.uc_stack, regs->sp);
480
481 /* Set up to return from userspace. If provided, use a stub
482 already in userspace. */
483 /* x86-64 should always use SA_RESTORER. */
484 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
485 put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);
486 } else {
487 /* could use a vstub here */
488 err |= -EFAULT;
489 }
490 } put_user_catch(err);
491
492 err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
493 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
494
495 if (err)
496 return -EFAULT;
497
498 /* Set up registers for signal handler */
499 regs->di = sig;
500 /* In case the signal handler was declared without prototypes */
501 regs->ax = 0;
502
503 /* This also works for non SA_SIGINFO handlers because they expect the
504 next argument after the signal number on the stack. */
505 regs->si = (unsigned long)&frame->info;
506 regs->dx = (unsigned long)&frame->uc;
507 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
508
509 regs->sp = (unsigned long)frame;
510
511 /*
512 * Set up the CS and SS registers to run signal handlers in
513 * 64-bit mode, even if the handler happens to be interrupting
514 * 32-bit or 16-bit code.
515 *
516 * SS is subtle. In 64-bit mode, we don't need any particular
517 * SS descriptor, but we do need SS to be valid. It's possible
518 * that the old SS is entirely bogus -- this can happen if the
519 * signal we're trying to deliver is #GP or #SS caused by a bad
520 * SS value. We also have a compatbility issue here: DOSEMU
521 * relies on the contents of the SS register indicating the
522 * SS value at the time of the signal, even though that code in
523 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU
524 * avoids relying on sigreturn to restore SS; instead it uses
525 * a trampoline.) So we do our best: if the old SS was valid,
526 * we keep it. Otherwise we replace it.
527 */
528 regs->cs = __USER_CS;
529
530 if (unlikely(regs->ss != __USER_DS))
531 force_valid_ss(regs);
532
533 return 0;
534 }
535 #endif /* CONFIG_X86_32 */
536
537 static int x32_setup_rt_frame(struct ksignal *ksig,
538 compat_sigset_t *set,
539 struct pt_regs *regs)
540 {
541 #ifdef CONFIG_X86_X32_ABI
542 struct rt_sigframe_x32 __user *frame;
543 void __user *restorer;
544 int err = 0;
545 void __user *fpstate = NULL;
546
547 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
548
549 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
550 return -EFAULT;
551
552 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
553 if (__copy_siginfo_to_user32(&frame->info, &ksig->info, true))
554 return -EFAULT;
555 }
556
557 put_user_try {
558 /* Create the ucontext. */
559 put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags);
560 put_user_ex(0, &frame->uc.uc_link);
561 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
562 put_user_ex(0, &frame->uc.uc__pad0);
563
564 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
565 restorer = ksig->ka.sa.sa_restorer;
566 } else {
567 /* could use a vstub here */
568 restorer = NULL;
569 err |= -EFAULT;
570 }
571 put_user_ex(restorer, &frame->pretcode);
572 } put_user_catch(err);
573
574 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
575 regs, set->sig[0]);
576 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
577
578 if (err)
579 return -EFAULT;
580
581 /* Set up registers for signal handler */
582 regs->sp = (unsigned long) frame;
583 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
584
585 /* We use the x32 calling convention here... */
586 regs->di = ksig->sig;
587 regs->si = (unsigned long) &frame->info;
588 regs->dx = (unsigned long) &frame->uc;
589
590 loadsegment(ds, __USER_DS);
591 loadsegment(es, __USER_DS);
592
593 regs->cs = __USER_CS;
594 regs->ss = __USER_DS;
595 #endif /* CONFIG_X86_X32_ABI */
596
597 return 0;
598 }
599
600 /*
601 * Do a signal return; undo the signal stack.
602 */
603 #ifdef CONFIG_X86_32
604 asmlinkage unsigned long sys_sigreturn(void)
605 {
606 struct pt_regs *regs = current_pt_regs();
607 struct sigframe __user *frame;
608 sigset_t set;
609
610 frame = (struct sigframe __user *)(regs->sp - 8);
611
612 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
613 goto badframe;
614 if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
615 && __copy_from_user(&set.sig[1], &frame->extramask,
616 sizeof(frame->extramask))))
617 goto badframe;
618
619 set_current_blocked(&set);
620
621 /*
622 * x86_32 has no uc_flags bits relevant to restore_sigcontext.
623 * Save a few cycles by skipping the __get_user.
624 */
625 if (restore_sigcontext(regs, &frame->sc, 0))
626 goto badframe;
627 return regs->ax;
628
629 badframe:
630 signal_fault(regs, frame, "sigreturn");
631
632 return 0;
633 }
634 #endif /* CONFIG_X86_32 */
635
636 asmlinkage long sys_rt_sigreturn(void)
637 {
638 struct pt_regs *regs = current_pt_regs();
639 struct rt_sigframe __user *frame;
640 sigset_t set;
641 unsigned long uc_flags;
642
643 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
644 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
645 goto badframe;
646 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
647 goto badframe;
648 if (__get_user(uc_flags, &frame->uc.uc_flags))
649 goto badframe;
650
651 set_current_blocked(&set);
652
653 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
654 goto badframe;
655
656 if (restore_altstack(&frame->uc.uc_stack))
657 goto badframe;
658
659 return regs->ax;
660
661 badframe:
662 signal_fault(regs, frame, "rt_sigreturn");
663 return 0;
664 }
665
666 static inline int is_ia32_compat_frame(struct ksignal *ksig)
667 {
668 return IS_ENABLED(CONFIG_IA32_EMULATION) &&
669 ksig->ka.sa.sa_flags & SA_IA32_ABI;
670 }
671
672 static inline int is_ia32_frame(struct ksignal *ksig)
673 {
674 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
675 }
676
677 static inline int is_x32_frame(struct ksignal *ksig)
678 {
679 return IS_ENABLED(CONFIG_X86_X32_ABI) &&
680 ksig->ka.sa.sa_flags & SA_X32_ABI;
681 }
682
683 static int
684 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
685 {
686 int usig = ksig->sig;
687 sigset_t *set = sigmask_to_save();
688 compat_sigset_t *cset = (compat_sigset_t *) set;
689
690 /* Set up the stack frame */
691 if (is_ia32_frame(ksig)) {
692 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
693 return ia32_setup_rt_frame(usig, ksig, cset, regs);
694 else
695 return ia32_setup_frame(usig, ksig, cset, regs);
696 } else if (is_x32_frame(ksig)) {
697 return x32_setup_rt_frame(ksig, cset, regs);
698 } else {
699 return __setup_rt_frame(ksig->sig, ksig, set, regs);
700 }
701 }
702
703 static void
704 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
705 {
706 bool stepping, failed;
707 struct fpu *fpu = &current->thread.fpu;
708
709 if (v8086_mode(regs))
710 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
711
712 /* Are we from a system call? */
713 if (syscall_get_nr(current, regs) >= 0) {
714 /* If so, check system call restarting.. */
715 switch (syscall_get_error(current, regs)) {
716 case -ERESTART_RESTARTBLOCK:
717 case -ERESTARTNOHAND:
718 regs->ax = -EINTR;
719 break;
720
721 case -ERESTARTSYS:
722 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
723 regs->ax = -EINTR;
724 break;
725 }
726 /* fallthrough */
727 case -ERESTARTNOINTR:
728 regs->ax = regs->orig_ax;
729 regs->ip -= 2;
730 break;
731 }
732 }
733
734 /*
735 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
736 * so that register information in the sigcontext is correct and
737 * then notify the tracer before entering the signal handler.
738 */
739 stepping = test_thread_flag(TIF_SINGLESTEP);
740 if (stepping)
741 user_disable_single_step(current);
742
743 failed = (setup_rt_frame(ksig, regs) < 0);
744 if (!failed) {
745 /*
746 * Clear the direction flag as per the ABI for function entry.
747 *
748 * Clear RF when entering the signal handler, because
749 * it might disable possible debug exception from the
750 * signal handler.
751 *
752 * Clear TF for the case when it wasn't set by debugger to
753 * avoid the recursive send_sigtrap() in SIGTRAP handler.
754 */
755 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
756 /*
757 * Ensure the signal handler starts with the new fpu state.
758 */
759 if (fpu->initialized)
760 fpu__clear(fpu);
761 }
762 signal_setup_done(failed, ksig, stepping);
763 }
764
765 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
766 {
767 /*
768 * This function is fundamentally broken as currently
769 * implemented.
770 *
771 * The idea is that we want to trigger a call to the
772 * restart_block() syscall and that we want in_ia32_syscall(),
773 * in_x32_syscall(), etc. to match whatever they were in the
774 * syscall being restarted. We assume that the syscall
775 * instruction at (regs->ip - 2) matches whatever syscall
776 * instruction we used to enter in the first place.
777 *
778 * The problem is that we can get here when ptrace pokes
779 * syscall-like values into regs even if we're not in a syscall
780 * at all.
781 *
782 * For now, we maintain historical behavior and guess based on
783 * stored state. We could do better by saving the actual
784 * syscall arch in restart_block or (with caveats on x32) by
785 * checking if regs->ip points to 'int $0x80'. The current
786 * behavior is incorrect if a tracer has a different bitness
787 * than the tracee.
788 */
789 #ifdef CONFIG_IA32_EMULATION
790 if (current->thread.status & (TS_COMPAT|TS_I386_REGS_POKED))
791 return __NR_ia32_restart_syscall;
792 #endif
793 #ifdef CONFIG_X86_X32_ABI
794 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
795 #else
796 return __NR_restart_syscall;
797 #endif
798 }
799
800 /*
801 * Note that 'init' is a special process: it doesn't get signals it doesn't
802 * want to handle. Thus you cannot kill init even with a SIGKILL even by
803 * mistake.
804 */
805 void do_signal(struct pt_regs *regs)
806 {
807 struct ksignal ksig;
808
809 if (get_signal(&ksig)) {
810 /* Whee! Actually deliver the signal. */
811 handle_signal(&ksig, regs);
812 return;
813 }
814
815 /* Did we come from a system call? */
816 if (syscall_get_nr(current, regs) >= 0) {
817 /* Restart the system call - no handlers present */
818 switch (syscall_get_error(current, regs)) {
819 case -ERESTARTNOHAND:
820 case -ERESTARTSYS:
821 case -ERESTARTNOINTR:
822 regs->ax = regs->orig_ax;
823 regs->ip -= 2;
824 break;
825
826 case -ERESTART_RESTARTBLOCK:
827 regs->ax = get_nr_restart_syscall(regs);
828 regs->ip -= 2;
829 break;
830 }
831 }
832
833 /*
834 * If there's no signal to deliver, we just put the saved sigmask
835 * back.
836 */
837 restore_saved_sigmask();
838 }
839
840 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
841 {
842 struct task_struct *me = current;
843
844 if (show_unhandled_signals && printk_ratelimit()) {
845 printk("%s"
846 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
847 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
848 me->comm, me->pid, where, frame,
849 regs->ip, regs->sp, regs->orig_ax);
850 print_vma_addr(KERN_CONT " in ", regs->ip);
851 pr_cont("\n");
852 }
853
854 force_sig(SIGSEGV, me);
855 }
856
857 #ifdef CONFIG_X86_X32_ABI
858 asmlinkage long sys32_x32_rt_sigreturn(void)
859 {
860 struct pt_regs *regs = current_pt_regs();
861 struct rt_sigframe_x32 __user *frame;
862 sigset_t set;
863 unsigned long uc_flags;
864
865 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
866
867 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
868 goto badframe;
869 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
870 goto badframe;
871 if (__get_user(uc_flags, &frame->uc.uc_flags))
872 goto badframe;
873
874 set_current_blocked(&set);
875
876 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
877 goto badframe;
878
879 if (compat_restore_altstack(&frame->uc.uc_stack))
880 goto badframe;
881
882 return regs->ax;
883
884 badframe:
885 signal_fault(regs, frame, "x32 rt_sigreturn");
886 return 0;
887 }
888 #endif
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