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Restartable sequences: x86 32/64 architecture support
[deliverable/linux.git] / arch / x86 / kernel / signal.c
1 /*
2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
4 *
5 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
6 * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
7 * 2000-2002 x86-64 support by Andi Kleen
8 */
9
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12 #include <linux/sched.h>
13 #include <linux/mm.h>
14 #include <linux/smp.h>
15 #include <linux/kernel.h>
16 #include <linux/errno.h>
17 #include <linux/wait.h>
18 #include <linux/tracehook.h>
19 #include <linux/unistd.h>
20 #include <linux/stddef.h>
21 #include <linux/personality.h>
22 #include <linux/uaccess.h>
23 #include <linux/user-return-notifier.h>
24 #include <linux/uprobes.h>
25 #include <linux/context_tracking.h>
26
27 #include <asm/processor.h>
28 #include <asm/ucontext.h>
29 #include <asm/fpu/internal.h>
30 #include <asm/fpu/signal.h>
31 #include <asm/vdso.h>
32 #include <asm/mce.h>
33 #include <asm/sighandling.h>
34 #include <asm/vm86.h>
35
36 #ifdef CONFIG_X86_64
37 #include <asm/proto.h>
38 #include <asm/ia32_unistd.h>
39 #endif /* CONFIG_X86_64 */
40
41 #include <asm/syscall.h>
42 #include <asm/syscalls.h>
43
44 #include <asm/sigframe.h>
45
46 #define COPY(x) do { \
47 get_user_ex(regs->x, &sc->x); \
48 } while (0)
49
50 #define GET_SEG(seg) ({ \
51 unsigned short tmp; \
52 get_user_ex(tmp, &sc->seg); \
53 tmp; \
54 })
55
56 #define COPY_SEG(seg) do { \
57 regs->seg = GET_SEG(seg); \
58 } while (0)
59
60 #define COPY_SEG_CPL3(seg) do { \
61 regs->seg = GET_SEG(seg) | 3; \
62 } while (0)
63
64 #ifdef CONFIG_X86_64
65 /*
66 * If regs->ss will cause an IRET fault, change it. Otherwise leave it
67 * alone. Using this generally makes no sense unless
68 * user_64bit_mode(regs) would return true.
69 */
70 static void force_valid_ss(struct pt_regs *regs)
71 {
72 u32 ar;
73 asm volatile ("lar %[old_ss], %[ar]\n\t"
74 "jz 1f\n\t" /* If invalid: */
75 "xorl %[ar], %[ar]\n\t" /* set ar = 0 */
76 "1:"
77 : [ar] "=r" (ar)
78 : [old_ss] "rm" ((u16)regs->ss));
79
80 /*
81 * For a valid 64-bit user context, we need DPL 3, type
82 * read-write data or read-write exp-down data, and S and P
83 * set. We can't use VERW because VERW doesn't check the
84 * P bit.
85 */
86 ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK;
87 if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) &&
88 ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
89 regs->ss = __USER_DS;
90 }
91 #endif
92
93 static int restore_sigcontext(struct pt_regs *regs,
94 struct sigcontext __user *sc,
95 unsigned long uc_flags)
96 {
97 unsigned long buf_val;
98 void __user *buf;
99 unsigned int tmpflags;
100 unsigned int err = 0;
101
102 /* Always make any pending restarted system calls return -EINTR */
103 current->restart_block.fn = do_no_restart_syscall;
104
105 get_user_try {
106
107 #ifdef CONFIG_X86_32
108 set_user_gs(regs, GET_SEG(gs));
109 COPY_SEG(fs);
110 COPY_SEG(es);
111 COPY_SEG(ds);
112 #endif /* CONFIG_X86_32 */
113
114 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
115 COPY(dx); COPY(cx); COPY(ip); COPY(ax);
116
117 #ifdef CONFIG_X86_64
118 COPY(r8);
119 COPY(r9);
120 COPY(r10);
121 COPY(r11);
122 COPY(r12);
123 COPY(r13);
124 COPY(r14);
125 COPY(r15);
126 #endif /* CONFIG_X86_64 */
127
128 COPY_SEG_CPL3(cs);
129 COPY_SEG_CPL3(ss);
130
131 #ifdef CONFIG_X86_64
132 /*
133 * Fix up SS if needed for the benefit of old DOSEMU and
134 * CRIU.
135 */
136 if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) &&
137 user_64bit_mode(regs)))
138 force_valid_ss(regs);
139 #endif
140
141 get_user_ex(tmpflags, &sc->flags);
142 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
143 regs->orig_ax = -1; /* disable syscall checks */
144
145 get_user_ex(buf_val, &sc->fpstate);
146 buf = (void __user *)buf_val;
147 } get_user_catch(err);
148
149 err |= fpu__restore_sig(buf, IS_ENABLED(CONFIG_X86_32));
150
151 force_iret();
152
153 return err;
154 }
155
156 int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
157 struct pt_regs *regs, unsigned long mask)
158 {
159 int err = 0;
160
161 put_user_try {
162
163 #ifdef CONFIG_X86_32
164 put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
165 put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
166 put_user_ex(regs->es, (unsigned int __user *)&sc->es);
167 put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
168 #endif /* CONFIG_X86_32 */
169
170 put_user_ex(regs->di, &sc->di);
171 put_user_ex(regs->si, &sc->si);
172 put_user_ex(regs->bp, &sc->bp);
173 put_user_ex(regs->sp, &sc->sp);
174 put_user_ex(regs->bx, &sc->bx);
175 put_user_ex(regs->dx, &sc->dx);
176 put_user_ex(regs->cx, &sc->cx);
177 put_user_ex(regs->ax, &sc->ax);
178 #ifdef CONFIG_X86_64
179 put_user_ex(regs->r8, &sc->r8);
180 put_user_ex(regs->r9, &sc->r9);
181 put_user_ex(regs->r10, &sc->r10);
182 put_user_ex(regs->r11, &sc->r11);
183 put_user_ex(regs->r12, &sc->r12);
184 put_user_ex(regs->r13, &sc->r13);
185 put_user_ex(regs->r14, &sc->r14);
186 put_user_ex(regs->r15, &sc->r15);
187 #endif /* CONFIG_X86_64 */
188
189 put_user_ex(current->thread.trap_nr, &sc->trapno);
190 put_user_ex(current->thread.error_code, &sc->err);
191 put_user_ex(regs->ip, &sc->ip);
192 #ifdef CONFIG_X86_32
193 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
194 put_user_ex(regs->flags, &sc->flags);
195 put_user_ex(regs->sp, &sc->sp_at_signal);
196 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
197 #else /* !CONFIG_X86_32 */
198 put_user_ex(regs->flags, &sc->flags);
199 put_user_ex(regs->cs, &sc->cs);
200 put_user_ex(0, &sc->gs);
201 put_user_ex(0, &sc->fs);
202 put_user_ex(regs->ss, &sc->ss);
203 #endif /* CONFIG_X86_32 */
204
205 put_user_ex(fpstate, &sc->fpstate);
206
207 /* non-iBCS2 extensions.. */
208 put_user_ex(mask, &sc->oldmask);
209 put_user_ex(current->thread.cr2, &sc->cr2);
210 } put_user_catch(err);
211
212 return err;
213 }
214
215 /*
216 * Set up a signal frame.
217 */
218
219 /*
220 * Determine which stack to use..
221 */
222 static unsigned long align_sigframe(unsigned long sp)
223 {
224 #ifdef CONFIG_X86_32
225 /*
226 * Align the stack pointer according to the i386 ABI,
227 * i.e. so that on function entry ((sp + 4) & 15) == 0.
228 */
229 sp = ((sp + 4) & -16ul) - 4;
230 #else /* !CONFIG_X86_32 */
231 sp = round_down(sp, 16) - 8;
232 #endif
233 return sp;
234 }
235
236 static void __user *
237 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
238 void __user **fpstate)
239 {
240 /* Default to using normal stack */
241 unsigned long math_size = 0;
242 unsigned long sp = regs->sp;
243 unsigned long buf_fx = 0;
244 int onsigstack = on_sig_stack(sp);
245 struct fpu *fpu = &current->thread.fpu;
246
247 /* redzone */
248 if (IS_ENABLED(CONFIG_X86_64))
249 sp -= 128;
250
251 /* This is the X/Open sanctioned signal stack switching. */
252 if (ka->sa.sa_flags & SA_ONSTACK) {
253 if (sas_ss_flags(sp) == 0)
254 sp = current->sas_ss_sp + current->sas_ss_size;
255 } else if (IS_ENABLED(CONFIG_X86_32) &&
256 !onsigstack &&
257 (regs->ss & 0xffff) != __USER_DS &&
258 !(ka->sa.sa_flags & SA_RESTORER) &&
259 ka->sa.sa_restorer) {
260 /* This is the legacy signal stack switching. */
261 sp = (unsigned long) ka->sa.sa_restorer;
262 }
263
264 if (fpu->fpstate_active) {
265 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
266 &buf_fx, &math_size);
267 *fpstate = (void __user *)sp;
268 }
269
270 sp = align_sigframe(sp - frame_size);
271
272 /*
273 * If we are on the alternate signal stack and would overflow it, don't.
274 * Return an always-bogus address instead so we will die with SIGSEGV.
275 */
276 if (onsigstack && !likely(on_sig_stack(sp)))
277 return (void __user *)-1L;
278
279 /* save i387 and extended state */
280 if (fpu->fpstate_active &&
281 copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size) < 0)
282 return (void __user *)-1L;
283
284 return (void __user *)sp;
285 }
286
287 #ifdef CONFIG_X86_32
288 static const struct {
289 u16 poplmovl;
290 u32 val;
291 u16 int80;
292 } __attribute__((packed)) retcode = {
293 0xb858, /* popl %eax; movl $..., %eax */
294 __NR_sigreturn,
295 0x80cd, /* int $0x80 */
296 };
297
298 static const struct {
299 u8 movl;
300 u32 val;
301 u16 int80;
302 u8 pad;
303 } __attribute__((packed)) rt_retcode = {
304 0xb8, /* movl $..., %eax */
305 __NR_rt_sigreturn,
306 0x80cd, /* int $0x80 */
307 0
308 };
309
310 static int
311 __setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
312 struct pt_regs *regs)
313 {
314 struct sigframe __user *frame;
315 void __user *restorer;
316 int err = 0;
317 void __user *fpstate = NULL;
318
319 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
320
321 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
322 return -EFAULT;
323
324 if (__put_user(sig, &frame->sig))
325 return -EFAULT;
326
327 if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
328 return -EFAULT;
329
330 if (_NSIG_WORDS > 1) {
331 if (__copy_to_user(&frame->extramask, &set->sig[1],
332 sizeof(frame->extramask)))
333 return -EFAULT;
334 }
335
336 if (current->mm->context.vdso)
337 restorer = current->mm->context.vdso +
338 vdso_image_32.sym___kernel_sigreturn;
339 else
340 restorer = &frame->retcode;
341 if (ksig->ka.sa.sa_flags & SA_RESTORER)
342 restorer = ksig->ka.sa.sa_restorer;
343
344 /* Set up to return from userspace. */
345 err |= __put_user(restorer, &frame->pretcode);
346
347 /*
348 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
349 *
350 * WE DO NOT USE IT ANY MORE! It's only left here for historical
351 * reasons and because gdb uses it as a signature to notice
352 * signal handler stack frames.
353 */
354 err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
355
356 if (err)
357 return -EFAULT;
358
359 /* Set up registers for signal handler */
360 regs->sp = (unsigned long)frame;
361 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
362 regs->ax = (unsigned long)sig;
363 regs->dx = 0;
364 regs->cx = 0;
365
366 regs->ds = __USER_DS;
367 regs->es = __USER_DS;
368 regs->ss = __USER_DS;
369 regs->cs = __USER_CS;
370
371 return 0;
372 }
373
374 static int __setup_rt_frame(int sig, struct ksignal *ksig,
375 sigset_t *set, struct pt_regs *regs)
376 {
377 struct rt_sigframe __user *frame;
378 void __user *restorer;
379 int err = 0;
380 void __user *fpstate = NULL;
381
382 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
383
384 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
385 return -EFAULT;
386
387 put_user_try {
388 put_user_ex(sig, &frame->sig);
389 put_user_ex(&frame->info, &frame->pinfo);
390 put_user_ex(&frame->uc, &frame->puc);
391
392 /* Create the ucontext. */
393 if (boot_cpu_has(X86_FEATURE_XSAVE))
394 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
395 else
396 put_user_ex(0, &frame->uc.uc_flags);
397 put_user_ex(0, &frame->uc.uc_link);
398 save_altstack_ex(&frame->uc.uc_stack, regs->sp);
399
400 /* Set up to return from userspace. */
401 restorer = current->mm->context.vdso +
402 vdso_image_32.sym___kernel_rt_sigreturn;
403 if (ksig->ka.sa.sa_flags & SA_RESTORER)
404 restorer = ksig->ka.sa.sa_restorer;
405 put_user_ex(restorer, &frame->pretcode);
406
407 /*
408 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
409 *
410 * WE DO NOT USE IT ANY MORE! It's only left here for historical
411 * reasons and because gdb uses it as a signature to notice
412 * signal handler stack frames.
413 */
414 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
415 } put_user_catch(err);
416
417 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
418 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
419 regs, set->sig[0]);
420 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
421
422 if (err)
423 return -EFAULT;
424
425 /* Set up registers for signal handler */
426 regs->sp = (unsigned long)frame;
427 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
428 regs->ax = (unsigned long)sig;
429 regs->dx = (unsigned long)&frame->info;
430 regs->cx = (unsigned long)&frame->uc;
431
432 regs->ds = __USER_DS;
433 regs->es = __USER_DS;
434 regs->ss = __USER_DS;
435 regs->cs = __USER_CS;
436
437 return 0;
438 }
439 #else /* !CONFIG_X86_32 */
440 static unsigned long frame_uc_flags(struct pt_regs *regs)
441 {
442 unsigned long flags;
443
444 if (boot_cpu_has(X86_FEATURE_XSAVE))
445 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
446 else
447 flags = UC_SIGCONTEXT_SS;
448
449 if (likely(user_64bit_mode(regs)))
450 flags |= UC_STRICT_RESTORE_SS;
451
452 return flags;
453 }
454
455 static int __setup_rt_frame(int sig, struct ksignal *ksig,
456 sigset_t *set, struct pt_regs *regs)
457 {
458 struct rt_sigframe __user *frame;
459 void __user *fp = NULL;
460 int err = 0;
461
462 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
463
464 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
465 return -EFAULT;
466
467 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
468 if (copy_siginfo_to_user(&frame->info, &ksig->info))
469 return -EFAULT;
470 }
471
472 put_user_try {
473 /* Create the ucontext. */
474 put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags);
475 put_user_ex(0, &frame->uc.uc_link);
476 save_altstack_ex(&frame->uc.uc_stack, regs->sp);
477
478 /* Set up to return from userspace. If provided, use a stub
479 already in userspace. */
480 /* x86-64 should always use SA_RESTORER. */
481 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
482 put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);
483 } else {
484 /* could use a vstub here */
485 err |= -EFAULT;
486 }
487 } put_user_catch(err);
488
489 err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
490 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
491
492 if (err)
493 return -EFAULT;
494
495 /* Set up registers for signal handler */
496 regs->di = sig;
497 /* In case the signal handler was declared without prototypes */
498 regs->ax = 0;
499
500 /* This also works for non SA_SIGINFO handlers because they expect the
501 next argument after the signal number on the stack. */
502 regs->si = (unsigned long)&frame->info;
503 regs->dx = (unsigned long)&frame->uc;
504 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
505
506 regs->sp = (unsigned long)frame;
507
508 /*
509 * Set up the CS and SS registers to run signal handlers in
510 * 64-bit mode, even if the handler happens to be interrupting
511 * 32-bit or 16-bit code.
512 *
513 * SS is subtle. In 64-bit mode, we don't need any particular
514 * SS descriptor, but we do need SS to be valid. It's possible
515 * that the old SS is entirely bogus -- this can happen if the
516 * signal we're trying to deliver is #GP or #SS caused by a bad
517 * SS value. We also have a compatbility issue here: DOSEMU
518 * relies on the contents of the SS register indicating the
519 * SS value at the time of the signal, even though that code in
520 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU
521 * avoids relying on sigreturn to restore SS; instead it uses
522 * a trampoline.) So we do our best: if the old SS was valid,
523 * we keep it. Otherwise we replace it.
524 */
525 regs->cs = __USER_CS;
526
527 if (unlikely(regs->ss != __USER_DS))
528 force_valid_ss(regs);
529
530 return 0;
531 }
532 #endif /* CONFIG_X86_32 */
533
534 static int x32_setup_rt_frame(struct ksignal *ksig,
535 compat_sigset_t *set,
536 struct pt_regs *regs)
537 {
538 #ifdef CONFIG_X86_X32_ABI
539 struct rt_sigframe_x32 __user *frame;
540 void __user *restorer;
541 int err = 0;
542 void __user *fpstate = NULL;
543
544 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
545
546 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
547 return -EFAULT;
548
549 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
550 if (copy_siginfo_to_user32(&frame->info, &ksig->info))
551 return -EFAULT;
552 }
553
554 put_user_try {
555 /* Create the ucontext. */
556 put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags);
557 put_user_ex(0, &frame->uc.uc_link);
558 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
559 put_user_ex(0, &frame->uc.uc__pad0);
560
561 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
562 restorer = ksig->ka.sa.sa_restorer;
563 } else {
564 /* could use a vstub here */
565 restorer = NULL;
566 err |= -EFAULT;
567 }
568 put_user_ex(restorer, &frame->pretcode);
569 } put_user_catch(err);
570
571 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
572 regs, set->sig[0]);
573 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
574
575 if (err)
576 return -EFAULT;
577
578 /* Set up registers for signal handler */
579 regs->sp = (unsigned long) frame;
580 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
581
582 /* We use the x32 calling convention here... */
583 regs->di = ksig->sig;
584 regs->si = (unsigned long) &frame->info;
585 regs->dx = (unsigned long) &frame->uc;
586
587 loadsegment(ds, __USER_DS);
588 loadsegment(es, __USER_DS);
589
590 regs->cs = __USER_CS;
591 regs->ss = __USER_DS;
592 #endif /* CONFIG_X86_X32_ABI */
593
594 return 0;
595 }
596
597 /*
598 * Do a signal return; undo the signal stack.
599 */
600 #ifdef CONFIG_X86_32
601 asmlinkage unsigned long sys_sigreturn(void)
602 {
603 struct pt_regs *regs = current_pt_regs();
604 struct sigframe __user *frame;
605 sigset_t set;
606
607 frame = (struct sigframe __user *)(regs->sp - 8);
608
609 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
610 goto badframe;
611 if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
612 && __copy_from_user(&set.sig[1], &frame->extramask,
613 sizeof(frame->extramask))))
614 goto badframe;
615
616 set_current_blocked(&set);
617
618 /*
619 * x86_32 has no uc_flags bits relevant to restore_sigcontext.
620 * Save a few cycles by skipping the __get_user.
621 */
622 if (restore_sigcontext(regs, &frame->sc, 0))
623 goto badframe;
624 return regs->ax;
625
626 badframe:
627 signal_fault(regs, frame, "sigreturn");
628
629 return 0;
630 }
631 #endif /* CONFIG_X86_32 */
632
633 asmlinkage long sys_rt_sigreturn(void)
634 {
635 struct pt_regs *regs = current_pt_regs();
636 struct rt_sigframe __user *frame;
637 sigset_t set;
638 unsigned long uc_flags;
639
640 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
641 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
642 goto badframe;
643 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
644 goto badframe;
645 if (__get_user(uc_flags, &frame->uc.uc_flags))
646 goto badframe;
647
648 set_current_blocked(&set);
649
650 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
651 goto badframe;
652
653 if (restore_altstack(&frame->uc.uc_stack))
654 goto badframe;
655
656 return regs->ax;
657
658 badframe:
659 signal_fault(regs, frame, "rt_sigreturn");
660 return 0;
661 }
662
663 static inline int is_ia32_compat_frame(void)
664 {
665 return IS_ENABLED(CONFIG_IA32_EMULATION) &&
666 test_thread_flag(TIF_IA32);
667 }
668
669 static inline int is_ia32_frame(void)
670 {
671 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame();
672 }
673
674 static inline int is_x32_frame(void)
675 {
676 return IS_ENABLED(CONFIG_X86_X32_ABI) && test_thread_flag(TIF_X32);
677 }
678
679 static int
680 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
681 {
682 int usig = ksig->sig;
683 sigset_t *set = sigmask_to_save();
684 compat_sigset_t *cset = (compat_sigset_t *) set;
685
686 /*
687 * Increment event counter and perform fixup for the pre-signal
688 * frame.
689 */
690 rseq_signal_deliver(regs);
691
692 /* Set up the stack frame */
693 if (is_ia32_frame()) {
694 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
695 return ia32_setup_rt_frame(usig, ksig, cset, regs);
696 else
697 return ia32_setup_frame(usig, ksig, cset, regs);
698 } else if (is_x32_frame()) {
699 return x32_setup_rt_frame(ksig, cset, regs);
700 } else {
701 return __setup_rt_frame(ksig->sig, ksig, set, regs);
702 }
703 }
704
705 static void
706 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
707 {
708 bool stepping, failed;
709 struct fpu *fpu = &current->thread.fpu;
710
711 if (v8086_mode(regs))
712 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
713
714 /* Are we from a system call? */
715 if (syscall_get_nr(current, regs) >= 0) {
716 /* If so, check system call restarting.. */
717 switch (syscall_get_error(current, regs)) {
718 case -ERESTART_RESTARTBLOCK:
719 case -ERESTARTNOHAND:
720 regs->ax = -EINTR;
721 break;
722
723 case -ERESTARTSYS:
724 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
725 regs->ax = -EINTR;
726 break;
727 }
728 /* fallthrough */
729 case -ERESTARTNOINTR:
730 regs->ax = regs->orig_ax;
731 regs->ip -= 2;
732 break;
733 }
734 }
735
736 /*
737 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
738 * so that register information in the sigcontext is correct and
739 * then notify the tracer before entering the signal handler.
740 */
741 stepping = test_thread_flag(TIF_SINGLESTEP);
742 if (stepping)
743 user_disable_single_step(current);
744
745 failed = (setup_rt_frame(ksig, regs) < 0);
746 if (!failed) {
747 /*
748 * Clear the direction flag as per the ABI for function entry.
749 *
750 * Clear RF when entering the signal handler, because
751 * it might disable possible debug exception from the
752 * signal handler.
753 *
754 * Clear TF for the case when it wasn't set by debugger to
755 * avoid the recursive send_sigtrap() in SIGTRAP handler.
756 */
757 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
758 /*
759 * Ensure the signal handler starts with the new fpu state.
760 */
761 if (fpu->fpstate_active)
762 fpu__clear(fpu);
763 }
764 signal_setup_done(failed, ksig, stepping);
765 }
766
767 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
768 {
769 /*
770 * This function is fundamentally broken as currently
771 * implemented.
772 *
773 * The idea is that we want to trigger a call to the
774 * restart_block() syscall and that we want in_ia32_syscall(),
775 * in_x32_syscall(), etc. to match whatever they were in the
776 * syscall being restarted. We assume that the syscall
777 * instruction at (regs->ip - 2) matches whatever syscall
778 * instruction we used to enter in the first place.
779 *
780 * The problem is that we can get here when ptrace pokes
781 * syscall-like values into regs even if we're not in a syscall
782 * at all.
783 *
784 * For now, we maintain historical behavior and guess based on
785 * stored state. We could do better by saving the actual
786 * syscall arch in restart_block or (with caveats on x32) by
787 * checking if regs->ip points to 'int $0x80'. The current
788 * behavior is incorrect if a tracer has a different bitness
789 * than the tracee.
790 */
791 #ifdef CONFIG_IA32_EMULATION
792 if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED))
793 return __NR_ia32_restart_syscall;
794 #endif
795 #ifdef CONFIG_X86_X32_ABI
796 return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
797 #else
798 return __NR_restart_syscall;
799 #endif
800 }
801
802 /*
803 * Note that 'init' is a special process: it doesn't get signals it doesn't
804 * want to handle. Thus you cannot kill init even with a SIGKILL even by
805 * mistake.
806 */
807 void do_signal(struct pt_regs *regs)
808 {
809 struct ksignal ksig;
810
811 if (get_signal(&ksig)) {
812 /* Whee! Actually deliver the signal. */
813 handle_signal(&ksig, regs);
814 return;
815 }
816
817 /* Did we come from a system call? */
818 if (syscall_get_nr(current, regs) >= 0) {
819 /* Restart the system call - no handlers present */
820 switch (syscall_get_error(current, regs)) {
821 case -ERESTARTNOHAND:
822 case -ERESTARTSYS:
823 case -ERESTARTNOINTR:
824 regs->ax = regs->orig_ax;
825 regs->ip -= 2;
826 break;
827
828 case -ERESTART_RESTARTBLOCK:
829 regs->ax = get_nr_restart_syscall(regs);
830 regs->ip -= 2;
831 break;
832 }
833 }
834
835 /*
836 * If there's no signal to deliver, we just put the saved sigmask
837 * back.
838 */
839 restore_saved_sigmask();
840 }
841
842 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
843 {
844 struct task_struct *me = current;
845
846 if (show_unhandled_signals && printk_ratelimit()) {
847 printk("%s"
848 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
849 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
850 me->comm, me->pid, where, frame,
851 regs->ip, regs->sp, regs->orig_ax);
852 print_vma_addr(" in ", regs->ip);
853 pr_cont("\n");
854 }
855
856 force_sig(SIGSEGV, me);
857 }
858
859 #ifdef CONFIG_X86_X32_ABI
860 asmlinkage long sys32_x32_rt_sigreturn(void)
861 {
862 struct pt_regs *regs = current_pt_regs();
863 struct rt_sigframe_x32 __user *frame;
864 sigset_t set;
865 unsigned long uc_flags;
866
867 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
868
869 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
870 goto badframe;
871 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
872 goto badframe;
873 if (__get_user(uc_flags, &frame->uc.uc_flags))
874 goto badframe;
875
876 set_current_blocked(&set);
877
878 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
879 goto badframe;
880
881 if (compat_restore_altstack(&frame->uc.uc_stack))
882 goto badframe;
883
884 return regs->ax;
885
886 badframe:
887 signal_fault(regs, frame, "x32 rt_sigreturn");
888 return 0;
889 }
890 #endif
Linux kernel - Deliverables
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