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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#include <linux/sched.h>
10#include <linux/mm.h>
11#include <linux/smp.h>
12#include <linux/kernel.h>
13#include <linux/errno.h>
14#include <linux/wait.h>
15#include <linux/tracehook.h>
16#include <linux/unistd.h>
17#include <linux/stddef.h>
18#include <linux/personality.h>
19#include <linux/uaccess.h>
20#include <linux/user-return-notifier.h>
21#include <linux/uprobes.h>
22
23#include <asm/processor.h>
24#include <asm/ucontext.h>
25#include <asm/i387.h>
26#include <asm/fpu-internal.h>
27#include <asm/vdso.h>
28#include <asm/mce.h>
29#include <asm/sighandling.h>
30
31#ifdef CONFIG_X86_64
32#include <asm/proto.h>
33#include <asm/ia32_unistd.h>
34#include <asm/sys_ia32.h>
35#endif /* CONFIG_X86_64 */
36
37#include <asm/syscall.h>
38#include <asm/syscalls.h>
39
40#include <asm/sigframe.h>
41
42#ifdef CONFIG_X86_32
43# define FIX_EFLAGS (__FIX_EFLAGS | X86_EFLAGS_RF)
44#else
45# define FIX_EFLAGS __FIX_EFLAGS
46#endif
47
48#define COPY(x) do { \
49 get_user_ex(regs->x, &sc->x); \
50} while (0)
51
52#define GET_SEG(seg) ({ \
53 unsigned short tmp; \
54 get_user_ex(tmp, &sc->seg); \
55 tmp; \
56})
57
58#define COPY_SEG(seg) do { \
59 regs->seg = GET_SEG(seg); \
60} while (0)
61
62#define COPY_SEG_CPL3(seg) do { \
63 regs->seg = GET_SEG(seg) | 3; \
64} while (0)
65
66int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
67 unsigned long *pax)
68{
69 void __user *buf;
70 unsigned int tmpflags;
71 unsigned int err = 0;
72
73 /* Always make any pending restarted system calls return -EINTR */
74 current_thread_info()->restart_block.fn = do_no_restart_syscall;
75
76 get_user_try {
77
78#ifdef CONFIG_X86_32
79 set_user_gs(regs, GET_SEG(gs));
80 COPY_SEG(fs);
81 COPY_SEG(es);
82 COPY_SEG(ds);
83#endif /* CONFIG_X86_32 */
84
85 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
86 COPY(dx); COPY(cx); COPY(ip);
87
88#ifdef CONFIG_X86_64
89 COPY(r8);
90 COPY(r9);
91 COPY(r10);
92 COPY(r11);
93 COPY(r12);
94 COPY(r13);
95 COPY(r14);
96 COPY(r15);
97#endif /* CONFIG_X86_64 */
98
99#ifdef CONFIG_X86_32
100 COPY_SEG_CPL3(cs);
101 COPY_SEG_CPL3(ss);
102#else /* !CONFIG_X86_32 */
103 /* Kernel saves and restores only the CS segment register on signals,
104 * which is the bare minimum needed to allow mixed 32/64-bit code.
105 * App's signal handler can save/restore other segments if needed. */
106 COPY_SEG_CPL3(cs);
107#endif /* CONFIG_X86_32 */
108
109 get_user_ex(tmpflags, &sc->flags);
110 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
111 regs->orig_ax = -1; /* disable syscall checks */
112
113 get_user_ex(buf, &sc->fpstate);
114 err |= restore_i387_xstate(buf);
115
116 get_user_ex(*pax, &sc->ax);
117 } get_user_catch(err);
118
119 return err;
120}
121
122int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
123 struct pt_regs *regs, unsigned long mask)
124{
125 int err = 0;
126
127 put_user_try {
128
129#ifdef CONFIG_X86_32
130 put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
131 put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
132 put_user_ex(regs->es, (unsigned int __user *)&sc->es);
133 put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
134#endif /* CONFIG_X86_32 */
135
136 put_user_ex(regs->di, &sc->di);
137 put_user_ex(regs->si, &sc->si);
138 put_user_ex(regs->bp, &sc->bp);
139 put_user_ex(regs->sp, &sc->sp);
140 put_user_ex(regs->bx, &sc->bx);
141 put_user_ex(regs->dx, &sc->dx);
142 put_user_ex(regs->cx, &sc->cx);
143 put_user_ex(regs->ax, &sc->ax);
144#ifdef CONFIG_X86_64
145 put_user_ex(regs->r8, &sc->r8);
146 put_user_ex(regs->r9, &sc->r9);
147 put_user_ex(regs->r10, &sc->r10);
148 put_user_ex(regs->r11, &sc->r11);
149 put_user_ex(regs->r12, &sc->r12);
150 put_user_ex(regs->r13, &sc->r13);
151 put_user_ex(regs->r14, &sc->r14);
152 put_user_ex(regs->r15, &sc->r15);
153#endif /* CONFIG_X86_64 */
154
155 put_user_ex(current->thread.trap_nr, &sc->trapno);
156 put_user_ex(current->thread.error_code, &sc->err);
157 put_user_ex(regs->ip, &sc->ip);
158#ifdef CONFIG_X86_32
159 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
160 put_user_ex(regs->flags, &sc->flags);
161 put_user_ex(regs->sp, &sc->sp_at_signal);
162 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
163#else /* !CONFIG_X86_32 */
164 put_user_ex(regs->flags, &sc->flags);
165 put_user_ex(regs->cs, &sc->cs);
166 put_user_ex(0, &sc->gs);
167 put_user_ex(0, &sc->fs);
168#endif /* CONFIG_X86_32 */
169
170 put_user_ex(fpstate, &sc->fpstate);
171
172 /* non-iBCS2 extensions.. */
173 put_user_ex(mask, &sc->oldmask);
174 put_user_ex(current->thread.cr2, &sc->cr2);
175 } put_user_catch(err);
176
177 return err;
178}
179
180/*
181 * Set up a signal frame.
182 */
183
184/*
185 * Determine which stack to use..
186 */
187static unsigned long align_sigframe(unsigned long sp)
188{
189#ifdef CONFIG_X86_32
190 /*
191 * Align the stack pointer according to the i386 ABI,
192 * i.e. so that on function entry ((sp + 4) & 15) == 0.
193 */
194 sp = ((sp + 4) & -16ul) - 4;
195#else /* !CONFIG_X86_32 */
196 sp = round_down(sp, 16) - 8;
197#endif
198 return sp;
199}
200
201static inline void __user *
202get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
203 void __user **fpstate)
204{
205 /* Default to using normal stack */
206 unsigned long sp = regs->sp;
207 int onsigstack = on_sig_stack(sp);
208
209#ifdef CONFIG_X86_64
210 /* redzone */
211 sp -= 128;
212#endif /* CONFIG_X86_64 */
213
214 if (!onsigstack) {
215 /* This is the X/Open sanctioned signal stack switching. */
216 if (ka->sa.sa_flags & SA_ONSTACK) {
217 if (current->sas_ss_size)
218 sp = current->sas_ss_sp + current->sas_ss_size;
219 } else {
220#ifdef CONFIG_X86_32
221 /* This is the legacy signal stack switching. */
222 if ((regs->ss & 0xffff) != __USER_DS &&
223 !(ka->sa.sa_flags & SA_RESTORER) &&
224 ka->sa.sa_restorer)
225 sp = (unsigned long) ka->sa.sa_restorer;
226#endif /* CONFIG_X86_32 */
227 }
228 }
229
230 if (used_math()) {
231 sp -= sig_xstate_size;
232#ifdef CONFIG_X86_64
233 sp = round_down(sp, 64);
234#endif /* CONFIG_X86_64 */
235 *fpstate = (void __user *)sp;
236 }
237
238 sp = align_sigframe(sp - frame_size);
239
240 /*
241 * If we are on the alternate signal stack and would overflow it, don't.
242 * Return an always-bogus address instead so we will die with SIGSEGV.
243 */
244 if (onsigstack && !likely(on_sig_stack(sp)))
245 return (void __user *)-1L;
246
247 /* save i387 state */
248 if (used_math() && save_i387_xstate(*fpstate) < 0)
249 return (void __user *)-1L;
250
251 return (void __user *)sp;
252}
253
254#ifdef CONFIG_X86_32
255static const struct {
256 u16 poplmovl;
257 u32 val;
258 u16 int80;
259} __attribute__((packed)) retcode = {
260 0xb858, /* popl %eax; movl $..., %eax */
261 __NR_sigreturn,
262 0x80cd, /* int $0x80 */
263};
264
265static const struct {
266 u8 movl;
267 u32 val;
268 u16 int80;
269 u8 pad;
270} __attribute__((packed)) rt_retcode = {
271 0xb8, /* movl $..., %eax */
272 __NR_rt_sigreturn,
273 0x80cd, /* int $0x80 */
274 0
275};
276
277static int
278__setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
279 struct pt_regs *regs)
280{
281 struct sigframe __user *frame;
282 void __user *restorer;
283 int err = 0;
284 void __user *fpstate = NULL;
285
286 frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
287
288 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
289 return -EFAULT;
290
291 if (__put_user(sig, &frame->sig))
292 return -EFAULT;
293
294 if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
295 return -EFAULT;
296
297 if (_NSIG_WORDS > 1) {
298 if (__copy_to_user(&frame->extramask, &set->sig[1],
299 sizeof(frame->extramask)))
300 return -EFAULT;
301 }
302
303 if (current->mm->context.vdso)
304 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
305 else
306 restorer = &frame->retcode;
307 if (ka->sa.sa_flags & SA_RESTORER)
308 restorer = ka->sa.sa_restorer;
309
310 /* Set up to return from userspace. */
311 err |= __put_user(restorer, &frame->pretcode);
312
313 /*
314 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
315 *
316 * WE DO NOT USE IT ANY MORE! It's only left here for historical
317 * reasons and because gdb uses it as a signature to notice
318 * signal handler stack frames.
319 */
320 err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
321
322 if (err)
323 return -EFAULT;
324
325 /* Set up registers for signal handler */
326 regs->sp = (unsigned long)frame;
327 regs->ip = (unsigned long)ka->sa.sa_handler;
328 regs->ax = (unsigned long)sig;
329 regs->dx = 0;
330 regs->cx = 0;
331
332 regs->ds = __USER_DS;
333 regs->es = __USER_DS;
334 regs->ss = __USER_DS;
335 regs->cs = __USER_CS;
336
337 return 0;
338}
339
340static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
341 sigset_t *set, struct pt_regs *regs)
342{
343 struct rt_sigframe __user *frame;
344 void __user *restorer;
345 int err = 0;
346 void __user *fpstate = NULL;
347
348 frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
349
350 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
351 return -EFAULT;
352
353 put_user_try {
354 put_user_ex(sig, &frame->sig);
355 put_user_ex(&frame->info, &frame->pinfo);
356 put_user_ex(&frame->uc, &frame->puc);
357 err |= copy_siginfo_to_user(&frame->info, info);
358
359 /* Create the ucontext. */
360 if (cpu_has_xsave)
361 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
362 else
363 put_user_ex(0, &frame->uc.uc_flags);
364 put_user_ex(0, &frame->uc.uc_link);
365 put_user_ex(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
366 put_user_ex(sas_ss_flags(regs->sp),
367 &frame->uc.uc_stack.ss_flags);
368 put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
369 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
370 regs, set->sig[0]);
371 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
372
373 /* Set up to return from userspace. */
374 restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
375 if (ka->sa.sa_flags & SA_RESTORER)
376 restorer = ka->sa.sa_restorer;
377 put_user_ex(restorer, &frame->pretcode);
378
379 /*
380 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
381 *
382 * WE DO NOT USE IT ANY MORE! It's only left here for historical
383 * reasons and because gdb uses it as a signature to notice
384 * signal handler stack frames.
385 */
386 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
387 } put_user_catch(err);
388
389 if (err)
390 return -EFAULT;
391
392 /* Set up registers for signal handler */
393 regs->sp = (unsigned long)frame;
394 regs->ip = (unsigned long)ka->sa.sa_handler;
395 regs->ax = (unsigned long)sig;
396 regs->dx = (unsigned long)&frame->info;
397 regs->cx = (unsigned long)&frame->uc;
398
399 regs->ds = __USER_DS;
400 regs->es = __USER_DS;
401 regs->ss = __USER_DS;
402 regs->cs = __USER_CS;
403
404 return 0;
405}
406#else /* !CONFIG_X86_32 */
407static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
408 sigset_t *set, struct pt_regs *regs)
409{
410 struct rt_sigframe __user *frame;
411 void __user *fp = NULL;
412 int err = 0;
413 struct task_struct *me = current;
414
415 frame = get_sigframe(ka, regs, sizeof(struct rt_sigframe), &fp);
416
417 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
418 return -EFAULT;
419
420 if (ka->sa.sa_flags & SA_SIGINFO) {
421 if (copy_siginfo_to_user(&frame->info, info))
422 return -EFAULT;
423 }
424
425 put_user_try {
426 /* Create the ucontext. */
427 if (cpu_has_xsave)
428 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
429 else
430 put_user_ex(0, &frame->uc.uc_flags);
431 put_user_ex(0, &frame->uc.uc_link);
432 put_user_ex(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
433 put_user_ex(sas_ss_flags(regs->sp),
434 &frame->uc.uc_stack.ss_flags);
435 put_user_ex(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
436 err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
437 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
438
439 /* Set up to return from userspace. If provided, use a stub
440 already in userspace. */
441 /* x86-64 should always use SA_RESTORER. */
442 if (ka->sa.sa_flags & SA_RESTORER) {
443 put_user_ex(ka->sa.sa_restorer, &frame->pretcode);
444 } else {
445 /* could use a vstub here */
446 err |= -EFAULT;
447 }
448 } put_user_catch(err);
449
450 if (err)
451 return -EFAULT;
452
453 /* Set up registers for signal handler */
454 regs->di = sig;
455 /* In case the signal handler was declared without prototypes */
456 regs->ax = 0;
457
458 /* This also works for non SA_SIGINFO handlers because they expect the
459 next argument after the signal number on the stack. */
460 regs->si = (unsigned long)&frame->info;
461 regs->dx = (unsigned long)&frame->uc;
462 regs->ip = (unsigned long) ka->sa.sa_handler;
463
464 regs->sp = (unsigned long)frame;
465
466 /* Set up the CS register to run signal handlers in 64-bit mode,
467 even if the handler happens to be interrupting 32-bit code. */
468 regs->cs = __USER_CS;
469
470 return 0;
471}
472#endif /* CONFIG_X86_32 */
473
474#ifdef CONFIG_X86_32
475/*
476 * Atomically swap in the new signal mask, and wait for a signal.
477 */
478asmlinkage int
479sys_sigsuspend(int history0, int history1, old_sigset_t mask)
480{
481 sigset_t blocked;
482 siginitset(&blocked, mask);
483 return sigsuspend(&blocked);
484}
485
486asmlinkage int
487sys_sigaction(int sig, const struct old_sigaction __user *act,
488 struct old_sigaction __user *oact)
489{
490 struct k_sigaction new_ka, old_ka;
491 int ret = 0;
492
493 if (act) {
494 old_sigset_t mask;
495
496 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
497 return -EFAULT;
498
499 get_user_try {
500 get_user_ex(new_ka.sa.sa_handler, &act->sa_handler);
501 get_user_ex(new_ka.sa.sa_flags, &act->sa_flags);
502 get_user_ex(mask, &act->sa_mask);
503 get_user_ex(new_ka.sa.sa_restorer, &act->sa_restorer);
504 } get_user_catch(ret);
505
506 if (ret)
507 return -EFAULT;
508 siginitset(&new_ka.sa.sa_mask, mask);
509 }
510
511 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
512
513 if (!ret && oact) {
514 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
515 return -EFAULT;
516
517 put_user_try {
518 put_user_ex(old_ka.sa.sa_handler, &oact->sa_handler);
519 put_user_ex(old_ka.sa.sa_flags, &oact->sa_flags);
520 put_user_ex(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
521 put_user_ex(old_ka.sa.sa_restorer, &oact->sa_restorer);
522 } put_user_catch(ret);
523
524 if (ret)
525 return -EFAULT;
526 }
527
528 return ret;
529}
530#endif /* CONFIG_X86_32 */
531
532long
533sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
534 struct pt_regs *regs)
535{
536 return do_sigaltstack(uss, uoss, regs->sp);
537}
538
539/*
540 * Do a signal return; undo the signal stack.
541 */
542#ifdef CONFIG_X86_32
543unsigned long sys_sigreturn(struct pt_regs *regs)
544{
545 struct sigframe __user *frame;
546 unsigned long ax;
547 sigset_t set;
548
549 frame = (struct sigframe __user *)(regs->sp - 8);
550
551 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
552 goto badframe;
553 if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
554 && __copy_from_user(&set.sig[1], &frame->extramask,
555 sizeof(frame->extramask))))
556 goto badframe;
557
558 set_current_blocked(&set);
559
560 if (restore_sigcontext(regs, &frame->sc, &ax))
561 goto badframe;
562 return ax;
563
564badframe:
565 signal_fault(regs, frame, "sigreturn");
566
567 return 0;
568}
569#endif /* CONFIG_X86_32 */
570
571long sys_rt_sigreturn(struct pt_regs *regs)
572{
573 struct rt_sigframe __user *frame;
574 unsigned long ax;
575 sigset_t set;
576
577 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
578 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
579 goto badframe;
580 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
581 goto badframe;
582
583 set_current_blocked(&set);
584
585 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
586 goto badframe;
587
588 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
589 goto badframe;
590
591 return ax;
592
593badframe:
594 signal_fault(regs, frame, "rt_sigreturn");
595 return 0;
596}
597
598/*
599 * OK, we're invoking a handler:
600 */
601static int signr_convert(int sig)
602{
603#ifdef CONFIG_X86_32
604 struct thread_info *info = current_thread_info();
605
606 if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
607 return info->exec_domain->signal_invmap[sig];
608#endif /* CONFIG_X86_32 */
609 return sig;
610}
611
612#ifdef CONFIG_X86_32
613
614#define is_ia32 1
615#define ia32_setup_frame __setup_frame
616#define ia32_setup_rt_frame __setup_rt_frame
617
618#else /* !CONFIG_X86_32 */
619
620#ifdef CONFIG_IA32_EMULATION
621#define is_ia32 test_thread_flag(TIF_IA32)
622#else /* !CONFIG_IA32_EMULATION */
623#define is_ia32 0
624#endif /* CONFIG_IA32_EMULATION */
625
626#ifdef CONFIG_X86_X32_ABI
627#define is_x32 test_thread_flag(TIF_X32)
628
629static int x32_setup_rt_frame(int sig, struct k_sigaction *ka,
630 siginfo_t *info, compat_sigset_t *set,
631 struct pt_regs *regs);
632#else /* !CONFIG_X86_X32_ABI */
633#define is_x32 0
634#endif /* CONFIG_X86_X32_ABI */
635
636int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
637 sigset_t *set, struct pt_regs *regs);
638int ia32_setup_frame(int sig, struct k_sigaction *ka,
639 sigset_t *set, struct pt_regs *regs);
640
641#endif /* CONFIG_X86_32 */
642
643static int
644setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
645 struct pt_regs *regs)
646{
647 int usig = signr_convert(sig);
648 sigset_t *set = sigmask_to_save();
649
650 /* Set up the stack frame */
651 if (is_ia32) {
652 if (ka->sa.sa_flags & SA_SIGINFO)
653 return ia32_setup_rt_frame(usig, ka, info, set, regs);
654 else
655 return ia32_setup_frame(usig, ka, set, regs);
656#ifdef CONFIG_X86_X32_ABI
657 } else if (is_x32) {
658 return x32_setup_rt_frame(usig, ka, info,
659 (compat_sigset_t *)set, regs);
660#endif
661 } else {
662 return __setup_rt_frame(sig, ka, info, set, regs);
663 }
664}
665
666static void
667handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
668 struct pt_regs *regs)
669{
670 /* Are we from a system call? */
671 if (syscall_get_nr(current, regs) >= 0) {
672 /* If so, check system call restarting.. */
673 switch (syscall_get_error(current, regs)) {
674 case -ERESTART_RESTARTBLOCK:
675 case -ERESTARTNOHAND:
676 regs->ax = -EINTR;
677 break;
678
679 case -ERESTARTSYS:
680 if (!(ka->sa.sa_flags & SA_RESTART)) {
681 regs->ax = -EINTR;
682 break;
683 }
684 /* fallthrough */
685 case -ERESTARTNOINTR:
686 regs->ax = regs->orig_ax;
687 regs->ip -= 2;
688 break;
689 }
690 }
691
692 /*
693 * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
694 * flag so that register information in the sigcontext is correct.
695 */
696 if (unlikely(regs->flags & X86_EFLAGS_TF) &&
697 likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
698 regs->flags &= ~X86_EFLAGS_TF;
699
700 if (setup_rt_frame(sig, ka, info, regs) < 0) {
701 force_sigsegv(sig, current);
702 return;
703 }
704
705 /*
706 * Clear the direction flag as per the ABI for function entry.
707 */
708 regs->flags &= ~X86_EFLAGS_DF;
709
710 /*
711 * Clear TF when entering the signal handler, but
712 * notify any tracer that was single-stepping it.
713 * The tracer may want to single-step inside the
714 * handler too.
715 */
716 regs->flags &= ~X86_EFLAGS_TF;
717
718 signal_delivered(sig, info, ka, regs,
719 test_thread_flag(TIF_SINGLESTEP));
720}
721
722#ifdef CONFIG_X86_32
723#define NR_restart_syscall __NR_restart_syscall
724#else /* !CONFIG_X86_32 */
725#define NR_restart_syscall \
726 test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
727#endif /* CONFIG_X86_32 */
728
729/*
730 * Note that 'init' is a special process: it doesn't get signals it doesn't
731 * want to handle. Thus you cannot kill init even with a SIGKILL even by
732 * mistake.
733 */
734static void do_signal(struct pt_regs *regs)
735{
736 struct k_sigaction ka;
737 siginfo_t info;
738 int signr;
739
740 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
741 if (signr > 0) {
742 /* Whee! Actually deliver the signal. */
743 handle_signal(signr, &info, &ka, regs);
744 return;
745 }
746
747 /* Did we come from a system call? */
748 if (syscall_get_nr(current, regs) >= 0) {
749 /* Restart the system call - no handlers present */
750 switch (syscall_get_error(current, regs)) {
751 case -ERESTARTNOHAND:
752 case -ERESTARTSYS:
753 case -ERESTARTNOINTR:
754 regs->ax = regs->orig_ax;
755 regs->ip -= 2;
756 break;
757
758 case -ERESTART_RESTARTBLOCK:
759 regs->ax = NR_restart_syscall;
760 regs->ip -= 2;
761 break;
762 }
763 }
764
765 /*
766 * If there's no signal to deliver, we just put the saved sigmask
767 * back.
768 */
769 restore_saved_sigmask();
770}
771
772/*
773 * notification of userspace execution resumption
774 * - triggered by the TIF_WORK_MASK flags
775 */
776void
777do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
778{
779#ifdef CONFIG_X86_MCE
780 /* notify userspace of pending MCEs */
781 if (thread_info_flags & _TIF_MCE_NOTIFY)
782 mce_notify_process();
783#endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
784
785 if (thread_info_flags & _TIF_UPROBE) {
786 clear_thread_flag(TIF_UPROBE);
787 uprobe_notify_resume(regs);
788 }
789
790 /* deal with pending signal delivery */
791 if (thread_info_flags & _TIF_SIGPENDING)
792 do_signal(regs);
793
794 if (thread_info_flags & _TIF_NOTIFY_RESUME) {
795 clear_thread_flag(TIF_NOTIFY_RESUME);
796 tracehook_notify_resume(regs);
797 }
798 if (thread_info_flags & _TIF_USER_RETURN_NOTIFY)
799 fire_user_return_notifiers();
800
801#ifdef CONFIG_X86_32
802 clear_thread_flag(TIF_IRET);
803#endif /* CONFIG_X86_32 */
804}
805
806void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
807{
808 struct task_struct *me = current;
809
810 if (show_unhandled_signals && printk_ratelimit()) {
811 printk("%s"
812 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
813 task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
814 me->comm, me->pid, where, frame,
815 regs->ip, regs->sp, regs->orig_ax);
816 print_vma_addr(" in ", regs->ip);
817 printk(KERN_CONT "\n");
818 }
819
820 force_sig(SIGSEGV, me);
821}
822
823#ifdef CONFIG_X86_X32_ABI
824static int x32_setup_rt_frame(int sig, struct k_sigaction *ka,
825 siginfo_t *info, compat_sigset_t *set,
826 struct pt_regs *regs)
827{
828 struct rt_sigframe_x32 __user *frame;
829 void __user *restorer;
830 int err = 0;
831 void __user *fpstate = NULL;
832
833 frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
834
835 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
836 return -EFAULT;
837
838 if (ka->sa.sa_flags & SA_SIGINFO) {
839 if (copy_siginfo_to_user32(&frame->info, info))
840 return -EFAULT;
841 }
842
843 put_user_try {
844 /* Create the ucontext. */
845 if (cpu_has_xsave)
846 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
847 else
848 put_user_ex(0, &frame->uc.uc_flags);
849 put_user_ex(0, &frame->uc.uc_link);
850 put_user_ex(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
851 put_user_ex(sas_ss_flags(regs->sp),
852 &frame->uc.uc_stack.ss_flags);
853 put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
854 put_user_ex(0, &frame->uc.uc__pad0);
855 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
856 regs, set->sig[0]);
857 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
858
859 if (ka->sa.sa_flags & SA_RESTORER) {
860 restorer = ka->sa.sa_restorer;
861 } else {
862 /* could use a vstub here */
863 restorer = NULL;
864 err |= -EFAULT;
865 }
866 put_user_ex(restorer, &frame->pretcode);
867 } put_user_catch(err);
868
869 if (err)
870 return -EFAULT;
871
872 /* Set up registers for signal handler */
873 regs->sp = (unsigned long) frame;
874 regs->ip = (unsigned long) ka->sa.sa_handler;
875
876 /* We use the x32 calling convention here... */
877 regs->di = sig;
878 regs->si = (unsigned long) &frame->info;
879 regs->dx = (unsigned long) &frame->uc;
880
881 loadsegment(ds, __USER_DS);
882 loadsegment(es, __USER_DS);
883
884 regs->cs = __USER_CS;
885 regs->ss = __USER_DS;
886
887 return 0;
888}
889
890asmlinkage long sys32_x32_rt_sigreturn(struct pt_regs *regs)
891{
892 struct rt_sigframe_x32 __user *frame;
893 sigset_t set;
894 unsigned long ax;
895 struct pt_regs tregs;
896
897 frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
898
899 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
900 goto badframe;
901 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
902 goto badframe;
903
904 set_current_blocked(&set);
905
906 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
907 goto badframe;
908
909 tregs = *regs;
910 if (sys32_sigaltstack(&frame->uc.uc_stack, NULL, &tregs) == -EFAULT)
911 goto badframe;
912
913 return ax;
914
915badframe:
916 signal_fault(regs, frame, "x32 rt_sigreturn");
917 return 0;
918}
919#endif
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#include <linux/entry-common.h>
29#include <linux/syscalls.h>
30
31#include <asm/processor.h>
32#include <asm/ucontext.h>
33#include <asm/fpu/internal.h>
34#include <asm/fpu/signal.h>
35#include <asm/vdso.h>
36#include <asm/mce.h>
37#include <asm/sighandling.h>
38#include <asm/vm86.h>
39
40#ifdef CONFIG_X86_64
41#include <linux/compat.h>
42#include <asm/proto.h>
43#include <asm/ia32_unistd.h>
44#endif /* CONFIG_X86_64 */
45
46#include <asm/syscall.h>
47#include <asm/sigframe.h>
48#include <asm/signal.h>
49
50#ifdef CONFIG_X86_64
51/*
52 * If regs->ss will cause an IRET fault, change it. Otherwise leave it
53 * alone. Using this generally makes no sense unless
54 * user_64bit_mode(regs) would return true.
55 */
56static void force_valid_ss(struct pt_regs *regs)
57{
58 u32 ar;
59 asm volatile ("lar %[old_ss], %[ar]\n\t"
60 "jz 1f\n\t" /* If invalid: */
61 "xorl %[ar], %[ar]\n\t" /* set ar = 0 */
62 "1:"
63 : [ar] "=r" (ar)
64 : [old_ss] "rm" ((u16)regs->ss));
65
66 /*
67 * For a valid 64-bit user context, we need DPL 3, type
68 * read-write data or read-write exp-down data, and S and P
69 * set. We can't use VERW because VERW doesn't check the
70 * P bit.
71 */
72 ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK;
73 if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) &&
74 ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
75 regs->ss = __USER_DS;
76}
77# define CONTEXT_COPY_SIZE offsetof(struct sigcontext, reserved1)
78#else
79# define CONTEXT_COPY_SIZE sizeof(struct sigcontext)
80#endif
81
82static int restore_sigcontext(struct pt_regs *regs,
83 struct sigcontext __user *usc,
84 unsigned long uc_flags)
85{
86 struct sigcontext sc;
87
88 /* Always make any pending restarted system calls return -EINTR */
89 current->restart_block.fn = do_no_restart_syscall;
90
91 if (copy_from_user(&sc, usc, CONTEXT_COPY_SIZE))
92 return -EFAULT;
93
94#ifdef CONFIG_X86_32
95 set_user_gs(regs, sc.gs);
96 regs->fs = sc.fs;
97 regs->es = sc.es;
98 regs->ds = sc.ds;
99#endif /* CONFIG_X86_32 */
100
101 regs->bx = sc.bx;
102 regs->cx = sc.cx;
103 regs->dx = sc.dx;
104 regs->si = sc.si;
105 regs->di = sc.di;
106 regs->bp = sc.bp;
107 regs->ax = sc.ax;
108 regs->sp = sc.sp;
109 regs->ip = sc.ip;
110
111#ifdef CONFIG_X86_64
112 regs->r8 = sc.r8;
113 regs->r9 = sc.r9;
114 regs->r10 = sc.r10;
115 regs->r11 = sc.r11;
116 regs->r12 = sc.r12;
117 regs->r13 = sc.r13;
118 regs->r14 = sc.r14;
119 regs->r15 = sc.r15;
120#endif /* CONFIG_X86_64 */
121
122 /* Get CS/SS and force CPL3 */
123 regs->cs = sc.cs | 0x03;
124 regs->ss = sc.ss | 0x03;
125
126 regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
127 /* disable syscall checks */
128 regs->orig_ax = -1;
129
130#ifdef CONFIG_X86_64
131 /*
132 * Fix up SS if needed for the benefit of old DOSEMU and
133 * CRIU.
134 */
135 if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs)))
136 force_valid_ss(regs);
137#endif
138
139 return fpu__restore_sig((void __user *)sc.fpstate,
140 IS_ENABLED(CONFIG_X86_32));
141}
142
143static __always_inline int
144__unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
145 struct pt_regs *regs, unsigned long mask)
146{
147#ifdef CONFIG_X86_32
148 unsafe_put_user(get_user_gs(regs),
149 (unsigned int __user *)&sc->gs, Efault);
150 unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault);
151 unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault);
152 unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault);
153#endif /* CONFIG_X86_32 */
154
155 unsafe_put_user(regs->di, &sc->di, Efault);
156 unsafe_put_user(regs->si, &sc->si, Efault);
157 unsafe_put_user(regs->bp, &sc->bp, Efault);
158 unsafe_put_user(regs->sp, &sc->sp, Efault);
159 unsafe_put_user(regs->bx, &sc->bx, Efault);
160 unsafe_put_user(regs->dx, &sc->dx, Efault);
161 unsafe_put_user(regs->cx, &sc->cx, Efault);
162 unsafe_put_user(regs->ax, &sc->ax, Efault);
163#ifdef CONFIG_X86_64
164 unsafe_put_user(regs->r8, &sc->r8, Efault);
165 unsafe_put_user(regs->r9, &sc->r9, Efault);
166 unsafe_put_user(regs->r10, &sc->r10, Efault);
167 unsafe_put_user(regs->r11, &sc->r11, Efault);
168 unsafe_put_user(regs->r12, &sc->r12, Efault);
169 unsafe_put_user(regs->r13, &sc->r13, Efault);
170 unsafe_put_user(regs->r14, &sc->r14, Efault);
171 unsafe_put_user(regs->r15, &sc->r15, Efault);
172#endif /* CONFIG_X86_64 */
173
174 unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
175 unsafe_put_user(current->thread.error_code, &sc->err, Efault);
176 unsafe_put_user(regs->ip, &sc->ip, Efault);
177#ifdef CONFIG_X86_32
178 unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault);
179 unsafe_put_user(regs->flags, &sc->flags, Efault);
180 unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault);
181 unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault);
182#else /* !CONFIG_X86_32 */
183 unsafe_put_user(regs->flags, &sc->flags, Efault);
184 unsafe_put_user(regs->cs, &sc->cs, Efault);
185 unsafe_put_user(0, &sc->gs, Efault);
186 unsafe_put_user(0, &sc->fs, Efault);
187 unsafe_put_user(regs->ss, &sc->ss, Efault);
188#endif /* CONFIG_X86_32 */
189
190 unsafe_put_user(fpstate, (unsigned long __user *)&sc->fpstate, Efault);
191
192 /* non-iBCS2 extensions.. */
193 unsafe_put_user(mask, &sc->oldmask, Efault);
194 unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
195 return 0;
196Efault:
197 return -EFAULT;
198}
199
200#define unsafe_put_sigcontext(sc, fp, regs, set, label) \
201do { \
202 if (__unsafe_setup_sigcontext(sc, fp, regs, set->sig[0])) \
203 goto label; \
204} while(0);
205
206#define unsafe_put_sigmask(set, frame, label) \
207 unsafe_put_user(*(__u64 *)(set), \
208 (__u64 __user *)&(frame)->uc.uc_sigmask, \
209 label)
210
211/*
212 * Set up a signal frame.
213 */
214
215/*
216 * Determine which stack to use..
217 */
218static unsigned long align_sigframe(unsigned long sp)
219{
220#ifdef CONFIG_X86_32
221 /*
222 * Align the stack pointer according to the i386 ABI,
223 * i.e. so that on function entry ((sp + 4) & 15) == 0.
224 */
225 sp = ((sp + 4) & -16ul) - 4;
226#else /* !CONFIG_X86_32 */
227 sp = round_down(sp, 16) - 8;
228#endif
229 return sp;
230}
231
232static void __user *
233get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
234 void __user **fpstate)
235{
236 /* Default to using normal stack */
237 unsigned long math_size = 0;
238 unsigned long sp = regs->sp;
239 unsigned long buf_fx = 0;
240 int onsigstack = on_sig_stack(sp);
241 int ret;
242
243 /* redzone */
244 if (IS_ENABLED(CONFIG_X86_64))
245 sp -= 128;
246
247 /* This is the X/Open sanctioned signal stack switching. */
248 if (ka->sa.sa_flags & SA_ONSTACK) {
249 if (sas_ss_flags(sp) == 0)
250 sp = current->sas_ss_sp + current->sas_ss_size;
251 } else if (IS_ENABLED(CONFIG_X86_32) &&
252 !onsigstack &&
253 regs->ss != __USER_DS &&
254 !(ka->sa.sa_flags & SA_RESTORER) &&
255 ka->sa.sa_restorer) {
256 /* This is the legacy signal stack switching. */
257 sp = (unsigned long) ka->sa.sa_restorer;
258 }
259
260 sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
261 &buf_fx, &math_size);
262 *fpstate = (void __user *)sp;
263
264 sp = align_sigframe(sp - frame_size);
265
266 /*
267 * If we are on the alternate signal stack and would overflow it, don't.
268 * Return an always-bogus address instead so we will die with SIGSEGV.
269 */
270 if (onsigstack && !likely(on_sig_stack(sp)))
271 return (void __user *)-1L;
272
273 /* save i387 and extended state */
274 ret = copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size);
275 if (ret < 0)
276 return (void __user *)-1L;
277
278 return (void __user *)sp;
279}
280
281#ifdef CONFIG_X86_32
282static const struct {
283 u16 poplmovl;
284 u32 val;
285 u16 int80;
286} __attribute__((packed)) retcode = {
287 0xb858, /* popl %eax; movl $..., %eax */
288 __NR_sigreturn,
289 0x80cd, /* int $0x80 */
290};
291
292static const struct {
293 u8 movl;
294 u32 val;
295 u16 int80;
296 u8 pad;
297} __attribute__((packed)) rt_retcode = {
298 0xb8, /* movl $..., %eax */
299 __NR_rt_sigreturn,
300 0x80cd, /* int $0x80 */
301 0
302};
303
304static int
305__setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
306 struct pt_regs *regs)
307{
308 struct sigframe __user *frame;
309 void __user *restorer;
310 void __user *fp = NULL;
311
312 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
313
314 if (!user_access_begin(frame, sizeof(*frame)))
315 return -EFAULT;
316
317 unsafe_put_user(sig, &frame->sig, Efault);
318 unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault);
319 unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
320 if (current->mm->context.vdso)
321 restorer = current->mm->context.vdso +
322 vdso_image_32.sym___kernel_sigreturn;
323 else
324 restorer = &frame->retcode;
325 if (ksig->ka.sa.sa_flags & SA_RESTORER)
326 restorer = ksig->ka.sa.sa_restorer;
327
328 /* Set up to return from userspace. */
329 unsafe_put_user(restorer, &frame->pretcode, Efault);
330
331 /*
332 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
333 *
334 * WE DO NOT USE IT ANY MORE! It's only left here for historical
335 * reasons and because gdb uses it as a signature to notice
336 * signal handler stack frames.
337 */
338 unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault);
339 user_access_end();
340
341 /* Set up registers for signal handler */
342 regs->sp = (unsigned long)frame;
343 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
344 regs->ax = (unsigned long)sig;
345 regs->dx = 0;
346 regs->cx = 0;
347
348 regs->ds = __USER_DS;
349 regs->es = __USER_DS;
350 regs->ss = __USER_DS;
351 regs->cs = __USER_CS;
352
353 return 0;
354
355Efault:
356 user_access_end();
357 return -EFAULT;
358}
359
360static int __setup_rt_frame(int sig, struct ksignal *ksig,
361 sigset_t *set, struct pt_regs *regs)
362{
363 struct rt_sigframe __user *frame;
364 void __user *restorer;
365 void __user *fp = NULL;
366
367 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
368
369 if (!user_access_begin(frame, sizeof(*frame)))
370 return -EFAULT;
371
372 unsafe_put_user(sig, &frame->sig, Efault);
373 unsafe_put_user(&frame->info, &frame->pinfo, Efault);
374 unsafe_put_user(&frame->uc, &frame->puc, Efault);
375
376 /* Create the ucontext. */
377 if (static_cpu_has(X86_FEATURE_XSAVE))
378 unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
379 else
380 unsafe_put_user(0, &frame->uc.uc_flags, Efault);
381 unsafe_put_user(0, &frame->uc.uc_link, Efault);
382 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
383
384 /* Set up to return from userspace. */
385 restorer = current->mm->context.vdso +
386 vdso_image_32.sym___kernel_rt_sigreturn;
387 if (ksig->ka.sa.sa_flags & SA_RESTORER)
388 restorer = ksig->ka.sa.sa_restorer;
389 unsafe_put_user(restorer, &frame->pretcode, Efault);
390
391 /*
392 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
393 *
394 * WE DO NOT USE IT ANY MORE! It's only left here for historical
395 * reasons and because gdb uses it as a signature to notice
396 * signal handler stack frames.
397 */
398 unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault);
399 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
400 unsafe_put_sigmask(set, frame, Efault);
401 user_access_end();
402
403 if (copy_siginfo_to_user(&frame->info, &ksig->info))
404 return -EFAULT;
405
406 /* Set up registers for signal handler */
407 regs->sp = (unsigned long)frame;
408 regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
409 regs->ax = (unsigned long)sig;
410 regs->dx = (unsigned long)&frame->info;
411 regs->cx = (unsigned long)&frame->uc;
412
413 regs->ds = __USER_DS;
414 regs->es = __USER_DS;
415 regs->ss = __USER_DS;
416 regs->cs = __USER_CS;
417
418 return 0;
419Efault:
420 user_access_end();
421 return -EFAULT;
422}
423#else /* !CONFIG_X86_32 */
424static unsigned long frame_uc_flags(struct pt_regs *regs)
425{
426 unsigned long flags;
427
428 if (boot_cpu_has(X86_FEATURE_XSAVE))
429 flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
430 else
431 flags = UC_SIGCONTEXT_SS;
432
433 if (likely(user_64bit_mode(regs)))
434 flags |= UC_STRICT_RESTORE_SS;
435
436 return flags;
437}
438
439static int __setup_rt_frame(int sig, struct ksignal *ksig,
440 sigset_t *set, struct pt_regs *regs)
441{
442 struct rt_sigframe __user *frame;
443 void __user *fp = NULL;
444 unsigned long uc_flags;
445
446 /* x86-64 should always use SA_RESTORER. */
447 if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
448 return -EFAULT;
449
450 frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
451 uc_flags = frame_uc_flags(regs);
452
453 if (!user_access_begin(frame, sizeof(*frame)))
454 return -EFAULT;
455
456 /* Create the ucontext. */
457 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
458 unsafe_put_user(0, &frame->uc.uc_link, Efault);
459 unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
460
461 /* Set up to return from userspace. If provided, use a stub
462 already in userspace. */
463 unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault);
464 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
465 unsafe_put_sigmask(set, frame, Efault);
466 user_access_end();
467
468 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
469 if (copy_siginfo_to_user(&frame->info, &ksig->info))
470 return -EFAULT;
471 }
472
473 /* Set up registers for signal handler */
474 regs->di = sig;
475 /* In case the signal handler was declared without prototypes */
476 regs->ax = 0;
477
478 /* This also works for non SA_SIGINFO handlers because they expect the
479 next argument after the signal number on the stack. */
480 regs->si = (unsigned long)&frame->info;
481 regs->dx = (unsigned long)&frame->uc;
482 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
483
484 regs->sp = (unsigned long)frame;
485
486 /*
487 * Set up the CS and SS registers to run signal handlers in
488 * 64-bit mode, even if the handler happens to be interrupting
489 * 32-bit or 16-bit code.
490 *
491 * SS is subtle. In 64-bit mode, we don't need any particular
492 * SS descriptor, but we do need SS to be valid. It's possible
493 * that the old SS is entirely bogus -- this can happen if the
494 * signal we're trying to deliver is #GP or #SS caused by a bad
495 * SS value. We also have a compatbility issue here: DOSEMU
496 * relies on the contents of the SS register indicating the
497 * SS value at the time of the signal, even though that code in
498 * DOSEMU predates sigreturn's ability to restore SS. (DOSEMU
499 * avoids relying on sigreturn to restore SS; instead it uses
500 * a trampoline.) So we do our best: if the old SS was valid,
501 * we keep it. Otherwise we replace it.
502 */
503 regs->cs = __USER_CS;
504
505 if (unlikely(regs->ss != __USER_DS))
506 force_valid_ss(regs);
507
508 return 0;
509
510Efault:
511 user_access_end();
512 return -EFAULT;
513}
514#endif /* CONFIG_X86_32 */
515
516#ifdef CONFIG_X86_X32_ABI
517static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to,
518 const struct kernel_siginfo *from)
519{
520 struct compat_siginfo new;
521
522 copy_siginfo_to_external32(&new, from);
523 if (from->si_signo == SIGCHLD) {
524 new._sifields._sigchld_x32._utime = from->si_utime;
525 new._sifields._sigchld_x32._stime = from->si_stime;
526 }
527 if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
528 return -EFAULT;
529 return 0;
530}
531
532int copy_siginfo_to_user32(struct compat_siginfo __user *to,
533 const struct kernel_siginfo *from)
534{
535 if (in_x32_syscall())
536 return x32_copy_siginfo_to_user(to, from);
537 return __copy_siginfo_to_user32(to, from);
538}
539#endif /* CONFIG_X86_X32_ABI */
540
541static int x32_setup_rt_frame(struct ksignal *ksig,
542 compat_sigset_t *set,
543 struct pt_regs *regs)
544{
545#ifdef CONFIG_X86_X32_ABI
546 struct rt_sigframe_x32 __user *frame;
547 unsigned long uc_flags;
548 void __user *restorer;
549 void __user *fp = NULL;
550
551 if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
552 return -EFAULT;
553
554 frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
555
556 uc_flags = frame_uc_flags(regs);
557
558 if (!user_access_begin(frame, sizeof(*frame)))
559 return -EFAULT;
560
561 /* Create the ucontext. */
562 unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
563 unsafe_put_user(0, &frame->uc.uc_link, Efault);
564 unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
565 unsafe_put_user(0, &frame->uc.uc__pad0, Efault);
566 restorer = ksig->ka.sa.sa_restorer;
567 unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault);
568 unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
569 unsafe_put_sigmask(set, frame, Efault);
570 user_access_end();
571
572 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
573 if (x32_copy_siginfo_to_user(&frame->info, &ksig->info))
574 return -EFAULT;
575 }
576
577 /* Set up registers for signal handler */
578 regs->sp = (unsigned long) frame;
579 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
580
581 /* We use the x32 calling convention here... */
582 regs->di = ksig->sig;
583 regs->si = (unsigned long) &frame->info;
584 regs->dx = (unsigned long) &frame->uc;
585
586 loadsegment(ds, __USER_DS);
587 loadsegment(es, __USER_DS);
588
589 regs->cs = __USER_CS;
590 regs->ss = __USER_DS;
591#endif /* CONFIG_X86_X32_ABI */
592
593 return 0;
594#ifdef CONFIG_X86_X32_ABI
595Efault:
596 user_access_end();
597 return -EFAULT;
598#endif
599}
600
601/*
602 * Do a signal return; undo the signal stack.
603 */
604#ifdef CONFIG_X86_32
605SYSCALL_DEFINE0(sigreturn)
606{
607 struct pt_regs *regs = current_pt_regs();
608 struct sigframe __user *frame;
609 sigset_t set;
610
611 frame = (struct sigframe __user *)(regs->sp - 8);
612
613 if (!access_ok(frame, sizeof(*frame)))
614 goto badframe;
615 if (__get_user(set.sig[0], &frame->sc.oldmask) ||
616 __get_user(set.sig[1], &frame->extramask[0]))
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
629badframe:
630 signal_fault(regs, frame, "sigreturn");
631
632 return 0;
633}
634#endif /* CONFIG_X86_32 */
635
636SYSCALL_DEFINE0(rt_sigreturn)
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(frame, sizeof(*frame)))
645 goto badframe;
646 if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
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
661badframe:
662 signal_fault(regs, frame, "rt_sigreturn");
663 return 0;
664}
665
666static 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
672static inline int is_ia32_frame(struct ksignal *ksig)
673{
674 return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
675}
676
677static 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
683static int
684setup_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 /* Perform fixup for the pre-signal frame. */
691 rseq_signal_deliver(ksig, regs);
692
693 /* Set up the stack frame */
694 if (is_ia32_frame(ksig)) {
695 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
696 return ia32_setup_rt_frame(usig, ksig, cset, regs);
697 else
698 return ia32_setup_frame(usig, ksig, cset, regs);
699 } else if (is_x32_frame(ksig)) {
700 return x32_setup_rt_frame(ksig, cset, regs);
701 } else {
702 return __setup_rt_frame(ksig->sig, ksig, set, regs);
703 }
704}
705
706static void
707handle_signal(struct ksignal *ksig, struct pt_regs *regs)
708{
709 bool stepping, failed;
710 struct fpu *fpu = ¤t->thread.fpu;
711
712 if (v8086_mode(regs))
713 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
714
715 /* Are we from a system call? */
716 if (syscall_get_nr(current, regs) >= 0) {
717 /* If so, check system call restarting.. */
718 switch (syscall_get_error(current, regs)) {
719 case -ERESTART_RESTARTBLOCK:
720 case -ERESTARTNOHAND:
721 regs->ax = -EINTR;
722 break;
723
724 case -ERESTARTSYS:
725 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
726 regs->ax = -EINTR;
727 break;
728 }
729 fallthrough;
730 case -ERESTARTNOINTR:
731 regs->ax = regs->orig_ax;
732 regs->ip -= 2;
733 break;
734 }
735 }
736
737 /*
738 * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
739 * so that register information in the sigcontext is correct and
740 * then notify the tracer before entering the signal handler.
741 */
742 stepping = test_thread_flag(TIF_SINGLESTEP);
743 if (stepping)
744 user_disable_single_step(current);
745
746 failed = (setup_rt_frame(ksig, regs) < 0);
747 if (!failed) {
748 /*
749 * Clear the direction flag as per the ABI for function entry.
750 *
751 * Clear RF when entering the signal handler, because
752 * it might disable possible debug exception from the
753 * signal handler.
754 *
755 * Clear TF for the case when it wasn't set by debugger to
756 * avoid the recursive send_sigtrap() in SIGTRAP handler.
757 */
758 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
759 /*
760 * Ensure the signal handler starts with the new fpu state.
761 */
762 fpu__clear_user_states(fpu);
763 }
764 signal_setup_done(failed, ksig, stepping);
765}
766
767static 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 */
807void arch_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
842void 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(KERN_CONT " in ", regs->ip);
853 pr_cont("\n");
854 }
855
856 force_sig(SIGSEGV);
857}
858
859#ifdef CONFIG_X86_X32_ABI
860COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
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(frame, sizeof(*frame)))
870 goto badframe;
871 if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
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
886badframe:
887 signal_fault(regs, frame, "x32 rt_sigreturn");
888 return 0;
889}
890#endif