1 /*
2  * Copyright (C) 2003 PathScale, Inc.
3  * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4  * Licensed under the GPL
5  */
6 
7 
8 #include <linux/personality.h>
9 #include <linux/ptrace.h>
10 #include <linux/kernel.h>
11 #include <asm/unistd.h>
12 #include <linux/uaccess.h>
13 #include <asm/ucontext.h>
14 #include <frame_kern.h>
15 #include <skas.h>
16 
17 #ifdef CONFIG_X86_32
18 
19 /*
20  * FPU tag word conversions.
21  */
22 
twd_i387_to_fxsr(unsigned short twd)23 static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
24 {
25 	unsigned int tmp; /* to avoid 16 bit prefixes in the code */
26 
27 	/* Transform each pair of bits into 01 (valid) or 00 (empty) */
28 	tmp = ~twd;
29 	tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
30 	/* and move the valid bits to the lower byte. */
31 	tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
32 	tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
33 	tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
34 	return tmp;
35 }
36 
twd_fxsr_to_i387(struct user_fxsr_struct * fxsave)37 static inline unsigned long twd_fxsr_to_i387(struct user_fxsr_struct *fxsave)
38 {
39 	struct _fpxreg *st = NULL;
40 	unsigned long twd = (unsigned long) fxsave->twd;
41 	unsigned long tag;
42 	unsigned long ret = 0xffff0000;
43 	int i;
44 
45 #define FPREG_ADDR(f, n)	((char *)&(f)->st_space + (n) * 16)
46 
47 	for (i = 0; i < 8; i++) {
48 		if (twd & 0x1) {
49 			st = (struct _fpxreg *) FPREG_ADDR(fxsave, i);
50 
51 			switch (st->exponent & 0x7fff) {
52 			case 0x7fff:
53 				tag = 2;		/* Special */
54 				break;
55 			case 0x0000:
56 				if ( !st->significand[0] &&
57 				     !st->significand[1] &&
58 				     !st->significand[2] &&
59 				     !st->significand[3] ) {
60 					tag = 1;	/* Zero */
61 				} else {
62 					tag = 2;	/* Special */
63 				}
64 				break;
65 			default:
66 				if (st->significand[3] & 0x8000) {
67 					tag = 0;	/* Valid */
68 				} else {
69 					tag = 2;	/* Special */
70 				}
71 				break;
72 			}
73 		} else {
74 			tag = 3;			/* Empty */
75 		}
76 		ret |= (tag << (2 * i));
77 		twd = twd >> 1;
78 	}
79 	return ret;
80 }
81 
convert_fxsr_to_user(struct _fpstate __user * buf,struct user_fxsr_struct * fxsave)82 static int convert_fxsr_to_user(struct _fpstate __user *buf,
83 				struct user_fxsr_struct *fxsave)
84 {
85 	unsigned long env[7];
86 	struct _fpreg __user *to;
87 	struct _fpxreg *from;
88 	int i;
89 
90 	env[0] = (unsigned long)fxsave->cwd | 0xffff0000ul;
91 	env[1] = (unsigned long)fxsave->swd | 0xffff0000ul;
92 	env[2] = twd_fxsr_to_i387(fxsave);
93 	env[3] = fxsave->fip;
94 	env[4] = fxsave->fcs | ((unsigned long)fxsave->fop << 16);
95 	env[5] = fxsave->foo;
96 	env[6] = fxsave->fos;
97 
98 	if (__copy_to_user(buf, env, 7 * sizeof(unsigned long)))
99 		return 1;
100 
101 	to = &buf->_st[0];
102 	from = (struct _fpxreg *) &fxsave->st_space[0];
103 	for (i = 0; i < 8; i++, to++, from++) {
104 		unsigned long __user *t = (unsigned long __user *)to;
105 		unsigned long *f = (unsigned long *)from;
106 
107 		if (__put_user(*f, t) ||
108 				__put_user(*(f + 1), t + 1) ||
109 				__put_user(from->exponent, &to->exponent))
110 			return 1;
111 	}
112 	return 0;
113 }
114 
convert_fxsr_from_user(struct user_fxsr_struct * fxsave,struct _fpstate __user * buf)115 static int convert_fxsr_from_user(struct user_fxsr_struct *fxsave,
116 				  struct _fpstate __user *buf)
117 {
118 	unsigned long env[7];
119 	struct _fpxreg *to;
120 	struct _fpreg __user *from;
121 	int i;
122 
123 	if (copy_from_user( env, buf, 7 * sizeof(long)))
124 		return 1;
125 
126 	fxsave->cwd = (unsigned short)(env[0] & 0xffff);
127 	fxsave->swd = (unsigned short)(env[1] & 0xffff);
128 	fxsave->twd = twd_i387_to_fxsr((unsigned short)(env[2] & 0xffff));
129 	fxsave->fip = env[3];
130 	fxsave->fop = (unsigned short)((env[4] & 0xffff0000ul) >> 16);
131 	fxsave->fcs = (env[4] & 0xffff);
132 	fxsave->foo = env[5];
133 	fxsave->fos = env[6];
134 
135 	to = (struct _fpxreg *) &fxsave->st_space[0];
136 	from = &buf->_st[0];
137 	for (i = 0; i < 8; i++, to++, from++) {
138 		unsigned long *t = (unsigned long *)to;
139 		unsigned long __user *f = (unsigned long __user *)from;
140 
141 		if (__get_user(*t, f) ||
142 		    __get_user(*(t + 1), f + 1) ||
143 		    __get_user(to->exponent, &from->exponent))
144 			return 1;
145 	}
146 	return 0;
147 }
148 
149 extern int have_fpx_regs;
150 
151 #endif
152 
copy_sc_from_user(struct pt_regs * regs,struct sigcontext __user * from)153 static int copy_sc_from_user(struct pt_regs *regs,
154 			     struct sigcontext __user *from)
155 {
156 	struct sigcontext sc;
157 	int err, pid;
158 
159 	/* Always make any pending restarted system calls return -EINTR */
160 	current->restart_block.fn = do_no_restart_syscall;
161 
162 	err = copy_from_user(&sc, from, sizeof(sc));
163 	if (err)
164 		return err;
165 
166 #define GETREG(regno, regname) regs->regs.gp[HOST_##regno] = sc.regname
167 
168 #ifdef CONFIG_X86_32
169 	GETREG(GS, gs);
170 	GETREG(FS, fs);
171 	GETREG(ES, es);
172 	GETREG(DS, ds);
173 #endif
174 	GETREG(DI, di);
175 	GETREG(SI, si);
176 	GETREG(BP, bp);
177 	GETREG(SP, sp);
178 	GETREG(BX, bx);
179 	GETREG(DX, dx);
180 	GETREG(CX, cx);
181 	GETREG(AX, ax);
182 	GETREG(IP, ip);
183 
184 #ifdef CONFIG_X86_64
185 	GETREG(R8, r8);
186 	GETREG(R9, r9);
187 	GETREG(R10, r10);
188 	GETREG(R11, r11);
189 	GETREG(R12, r12);
190 	GETREG(R13, r13);
191 	GETREG(R14, r14);
192 	GETREG(R15, r15);
193 #endif
194 
195 	GETREG(CS, cs);
196 	GETREG(EFLAGS, flags);
197 #ifdef CONFIG_X86_32
198 	GETREG(SS, ss);
199 #endif
200 
201 #undef GETREG
202 
203 	pid = userspace_pid[current_thread_info()->cpu];
204 #ifdef CONFIG_X86_32
205 	if (have_fpx_regs) {
206 		struct user_fxsr_struct fpx;
207 
208 		err = copy_from_user(&fpx,
209 			&((struct _fpstate __user *)sc.fpstate)->_fxsr_env[0],
210 				     sizeof(struct user_fxsr_struct));
211 		if (err)
212 			return 1;
213 
214 		err = convert_fxsr_from_user(&fpx, (void *)sc.fpstate);
215 		if (err)
216 			return 1;
217 
218 		err = restore_fpx_registers(pid, (unsigned long *) &fpx);
219 		if (err < 0) {
220 			printk(KERN_ERR "copy_sc_from_user - "
221 			       "restore_fpx_registers failed, errno = %d\n",
222 			       -err);
223 			return 1;
224 		}
225 	} else
226 #endif
227 	{
228 		err = copy_from_user(regs->regs.fp, (void *)sc.fpstate,
229 				     sizeof(struct _xstate));
230 		if (err)
231 			return 1;
232 	}
233 	return 0;
234 }
235 
copy_sc_to_user(struct sigcontext __user * to,struct _xstate __user * to_fp,struct pt_regs * regs,unsigned long mask)236 static int copy_sc_to_user(struct sigcontext __user *to,
237 			   struct _xstate __user *to_fp, struct pt_regs *regs,
238 			   unsigned long mask)
239 {
240 	struct sigcontext sc;
241 	struct faultinfo * fi = &current->thread.arch.faultinfo;
242 	int err, pid;
243 	memset(&sc, 0, sizeof(struct sigcontext));
244 
245 #define PUTREG(regno, regname) sc.regname = regs->regs.gp[HOST_##regno]
246 
247 #ifdef CONFIG_X86_32
248 	PUTREG(GS, gs);
249 	PUTREG(FS, fs);
250 	PUTREG(ES, es);
251 	PUTREG(DS, ds);
252 #endif
253 	PUTREG(DI, di);
254 	PUTREG(SI, si);
255 	PUTREG(BP, bp);
256 	PUTREG(SP, sp);
257 	PUTREG(BX, bx);
258 	PUTREG(DX, dx);
259 	PUTREG(CX, cx);
260 	PUTREG(AX, ax);
261 #ifdef CONFIG_X86_64
262 	PUTREG(R8, r8);
263 	PUTREG(R9, r9);
264 	PUTREG(R10, r10);
265 	PUTREG(R11, r11);
266 	PUTREG(R12, r12);
267 	PUTREG(R13, r13);
268 	PUTREG(R14, r14);
269 	PUTREG(R15, r15);
270 #endif
271 
272 	sc.cr2 = fi->cr2;
273 	sc.err = fi->error_code;
274 	sc.trapno = fi->trap_no;
275 	PUTREG(IP, ip);
276 	PUTREG(CS, cs);
277 	PUTREG(EFLAGS, flags);
278 #ifdef CONFIG_X86_32
279 	PUTREG(SP, sp_at_signal);
280 	PUTREG(SS, ss);
281 #endif
282 #undef PUTREG
283 	sc.oldmask = mask;
284 	sc.fpstate = (unsigned long)to_fp;
285 
286 	err = copy_to_user(to, &sc, sizeof(struct sigcontext));
287 	if (err)
288 		return 1;
289 
290 	pid = userspace_pid[current_thread_info()->cpu];
291 
292 #ifdef CONFIG_X86_32
293 	if (have_fpx_regs) {
294 		struct user_fxsr_struct fpx;
295 
296 		err = save_fpx_registers(pid, (unsigned long *) &fpx);
297 		if (err < 0){
298 			printk(KERN_ERR "copy_sc_to_user - save_fpx_registers "
299 			       "failed, errno = %d\n", err);
300 			return 1;
301 		}
302 
303 		err = convert_fxsr_to_user(&to_fp->fpstate, &fpx);
304 		if (err)
305 			return 1;
306 
307 		err |= __put_user(fpx.swd, &to_fp->fpstate.status);
308 		err |= __put_user(X86_FXSR_MAGIC, &to_fp->fpstate.magic);
309 		if (err)
310 			return 1;
311 
312 		if (copy_to_user(&to_fp->fpstate._fxsr_env[0], &fpx,
313 				 sizeof(struct user_fxsr_struct)))
314 			return 1;
315 	} else
316 #endif
317 	{
318 		if (copy_to_user(to_fp, regs->regs.fp, sizeof(struct _xstate)))
319 			return 1;
320 	}
321 
322 	return 0;
323 }
324 
325 #ifdef CONFIG_X86_32
copy_ucontext_to_user(struct ucontext __user * uc,struct _xstate __user * fp,sigset_t * set,unsigned long sp)326 static int copy_ucontext_to_user(struct ucontext __user *uc,
327 				 struct _xstate __user *fp, sigset_t *set,
328 				 unsigned long sp)
329 {
330 	int err = 0;
331 
332 	err |= __save_altstack(&uc->uc_stack, sp);
333 	err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs, 0);
334 	err |= copy_to_user(&uc->uc_sigmask, set, sizeof(*set));
335 	return err;
336 }
337 
338 struct sigframe
339 {
340 	char __user *pretcode;
341 	int sig;
342 	struct sigcontext sc;
343 	struct _xstate fpstate;
344 	unsigned long extramask[_NSIG_WORDS-1];
345 	char retcode[8];
346 };
347 
348 struct rt_sigframe
349 {
350 	char __user *pretcode;
351 	int sig;
352 	struct siginfo __user *pinfo;
353 	void __user *puc;
354 	struct siginfo info;
355 	struct ucontext uc;
356 	struct _xstate fpstate;
357 	char retcode[8];
358 };
359 
setup_signal_stack_sc(unsigned long stack_top,struct ksignal * ksig,struct pt_regs * regs,sigset_t * mask)360 int setup_signal_stack_sc(unsigned long stack_top, struct ksignal *ksig,
361 			  struct pt_regs *regs, sigset_t *mask)
362 {
363 	struct sigframe __user *frame;
364 	void __user *restorer;
365 	int err = 0, sig = ksig->sig;
366 
367 	/* This is the same calculation as i386 - ((sp + 4) & 15) == 0 */
368 	stack_top = ((stack_top + 4) & -16UL) - 4;
369 	frame = (struct sigframe __user *) stack_top - 1;
370 	if (!access_ok(frame, sizeof(*frame)))
371 		return 1;
372 
373 	restorer = frame->retcode;
374 	if (ksig->ka.sa.sa_flags & SA_RESTORER)
375 		restorer = ksig->ka.sa.sa_restorer;
376 
377 	err |= __put_user(restorer, &frame->pretcode);
378 	err |= __put_user(sig, &frame->sig);
379 	err |= copy_sc_to_user(&frame->sc, &frame->fpstate, regs, mask->sig[0]);
380 	if (_NSIG_WORDS > 1)
381 		err |= __copy_to_user(&frame->extramask, &mask->sig[1],
382 				      sizeof(frame->extramask));
383 
384 	/*
385 	 * This is popl %eax ; movl $,%eax ; int $0x80
386 	 *
387 	 * WE DO NOT USE IT ANY MORE! It's only left here for historical
388 	 * reasons and because gdb uses it as a signature to notice
389 	 * signal handler stack frames.
390 	 */
391 	err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
392 	err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
393 	err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
394 
395 	if (err)
396 		return err;
397 
398 	PT_REGS_SP(regs) = (unsigned long) frame;
399 	PT_REGS_IP(regs) = (unsigned long) ksig->ka.sa.sa_handler;
400 	PT_REGS_AX(regs) = (unsigned long) sig;
401 	PT_REGS_DX(regs) = (unsigned long) 0;
402 	PT_REGS_CX(regs) = (unsigned long) 0;
403 	return 0;
404 }
405 
setup_signal_stack_si(unsigned long stack_top,struct ksignal * ksig,struct pt_regs * regs,sigset_t * mask)406 int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig,
407 			  struct pt_regs *regs, sigset_t *mask)
408 {
409 	struct rt_sigframe __user *frame;
410 	void __user *restorer;
411 	int err = 0, sig = ksig->sig;
412 
413 	stack_top &= -8UL;
414 	frame = (struct rt_sigframe __user *) stack_top - 1;
415 	if (!access_ok(frame, sizeof(*frame)))
416 		return 1;
417 
418 	restorer = frame->retcode;
419 	if (ksig->ka.sa.sa_flags & SA_RESTORER)
420 		restorer = ksig->ka.sa.sa_restorer;
421 
422 	err |= __put_user(restorer, &frame->pretcode);
423 	err |= __put_user(sig, &frame->sig);
424 	err |= __put_user(&frame->info, &frame->pinfo);
425 	err |= __put_user(&frame->uc, &frame->puc);
426 	err |= copy_siginfo_to_user(&frame->info, &ksig->info);
427 	err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask,
428 					PT_REGS_SP(regs));
429 
430 	/*
431 	 * This is movl $,%eax ; int $0x80
432 	 *
433 	 * WE DO NOT USE IT ANY MORE! It's only left here for historical
434 	 * reasons and because gdb uses it as a signature to notice
435 	 * signal handler stack frames.
436 	 */
437 	err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
438 	err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
439 	err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
440 
441 	if (err)
442 		return err;
443 
444 	PT_REGS_SP(regs) = (unsigned long) frame;
445 	PT_REGS_IP(regs) = (unsigned long) ksig->ka.sa.sa_handler;
446 	PT_REGS_AX(regs) = (unsigned long) sig;
447 	PT_REGS_DX(regs) = (unsigned long) &frame->info;
448 	PT_REGS_CX(regs) = (unsigned long) &frame->uc;
449 	return 0;
450 }
451 
sys_sigreturn(void)452 long sys_sigreturn(void)
453 {
454 	unsigned long sp = PT_REGS_SP(&current->thread.regs);
455 	struct sigframe __user *frame = (struct sigframe __user *)(sp - 8);
456 	sigset_t set;
457 	struct sigcontext __user *sc = &frame->sc;
458 	int sig_size = (_NSIG_WORDS - 1) * sizeof(unsigned long);
459 
460 	if (copy_from_user(&set.sig[0], &sc->oldmask, sizeof(set.sig[0])) ||
461 	    copy_from_user(&set.sig[1], frame->extramask, sig_size))
462 		goto segfault;
463 
464 	set_current_blocked(&set);
465 
466 	if (copy_sc_from_user(&current->thread.regs, sc))
467 		goto segfault;
468 
469 	/* Avoid ERESTART handling */
470 	PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
471 	return PT_REGS_SYSCALL_RET(&current->thread.regs);
472 
473  segfault:
474 	force_sig(SIGSEGV);
475 	return 0;
476 }
477 
478 #else
479 
480 struct rt_sigframe
481 {
482 	char __user *pretcode;
483 	struct ucontext uc;
484 	struct siginfo info;
485 	struct _xstate fpstate;
486 };
487 
setup_signal_stack_si(unsigned long stack_top,struct ksignal * ksig,struct pt_regs * regs,sigset_t * set)488 int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig,
489 			  struct pt_regs *regs, sigset_t *set)
490 {
491 	struct rt_sigframe __user *frame;
492 	int err = 0, sig = ksig->sig;
493 	unsigned long fp_to;
494 
495 	frame = (struct rt_sigframe __user *)
496 		round_down(stack_top - sizeof(struct rt_sigframe), 16);
497 	/* Subtract 128 for a red zone and 8 for proper alignment */
498 	frame = (struct rt_sigframe __user *) ((unsigned long) frame - 128 - 8);
499 
500 	if (!access_ok(frame, sizeof(*frame)))
501 		goto out;
502 
503 	if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
504 		err |= copy_siginfo_to_user(&frame->info, &ksig->info);
505 		if (err)
506 			goto out;
507 	}
508 
509 	/* Create the ucontext.  */
510 	err |= __put_user(0, &frame->uc.uc_flags);
511 	err |= __put_user(0, &frame->uc.uc_link);
512 	err |= __save_altstack(&frame->uc.uc_stack, PT_REGS_SP(regs));
513 	err |= copy_sc_to_user(&frame->uc.uc_mcontext, &frame->fpstate, regs,
514 			       set->sig[0]);
515 
516 	fp_to = (unsigned long)&frame->fpstate;
517 
518 	err |= __put_user(fp_to, &frame->uc.uc_mcontext.fpstate);
519 	if (sizeof(*set) == 16) {
520 		err |= __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
521 		err |= __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
522 	}
523 	else
524 		err |= __copy_to_user(&frame->uc.uc_sigmask, set,
525 				      sizeof(*set));
526 
527 	/*
528 	 * Set up to return from userspace.  If provided, use a stub
529 	 * already in userspace.
530 	 */
531 	/* x86-64 should always use SA_RESTORER. */
532 	if (ksig->ka.sa.sa_flags & SA_RESTORER)
533 		err |= __put_user((void *)ksig->ka.sa.sa_restorer,
534 				  &frame->pretcode);
535 	else
536 		/* could use a vstub here */
537 		return err;
538 
539 	if (err)
540 		return err;
541 
542 	PT_REGS_SP(regs) = (unsigned long) frame;
543 	PT_REGS_DI(regs) = sig;
544 	/* In case the signal handler was declared without prototypes */
545 	PT_REGS_AX(regs) = 0;
546 
547 	/*
548 	 * This also works for non SA_SIGINFO handlers because they expect the
549 	 * next argument after the signal number on the stack.
550 	 */
551 	PT_REGS_SI(regs) = (unsigned long) &frame->info;
552 	PT_REGS_DX(regs) = (unsigned long) &frame->uc;
553 	PT_REGS_IP(regs) = (unsigned long) ksig->ka.sa.sa_handler;
554  out:
555 	return err;
556 }
557 #endif
558 
sys_rt_sigreturn(void)559 long sys_rt_sigreturn(void)
560 {
561 	unsigned long sp = PT_REGS_SP(&current->thread.regs);
562 	struct rt_sigframe __user *frame =
563 		(struct rt_sigframe __user *)(sp - sizeof(long));
564 	struct ucontext __user *uc = &frame->uc;
565 	sigset_t set;
566 
567 	if (copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
568 		goto segfault;
569 
570 	set_current_blocked(&set);
571 
572 	if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
573 		goto segfault;
574 
575 	/* Avoid ERESTART handling */
576 	PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
577 	return PT_REGS_SYSCALL_RET(&current->thread.regs);
578 
579  segfault:
580 	force_sig(SIGSEGV);
581 	return 0;
582 }
583