/arch/um/sys-i386/signal.c

  1/*
  2 * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  3 * Licensed under the GPL
  4 */
  5
  6#include <linux/ptrace.h>
  7#include <asm/unistd.h>
  8#include <asm/uaccess.h>
  9#include <asm/ucontext.h>
 10#include "frame_kern.h"
 11#include "skas.h"
 12
 13void copy_sc(struct uml_pt_regs *regs, void *from)
 14{
 15	struct sigcontext *sc = from;
 16
 17	REGS_GS(regs->gp) = sc->gs;
 18	REGS_FS(regs->gp) = sc->fs;
 19	REGS_ES(regs->gp) = sc->es;
 20	REGS_DS(regs->gp) = sc->ds;
 21	REGS_EDI(regs->gp) = sc->di;
 22	REGS_ESI(regs->gp) = sc->si;
 23	REGS_EBP(regs->gp) = sc->bp;
 24	REGS_SP(regs->gp) = sc->sp;
 25	REGS_EBX(regs->gp) = sc->bx;
 26	REGS_EDX(regs->gp) = sc->dx;
 27	REGS_ECX(regs->gp) = sc->cx;
 28	REGS_EAX(regs->gp) = sc->ax;
 29	REGS_IP(regs->gp) = sc->ip;
 30	REGS_CS(regs->gp) = sc->cs;
 31	REGS_EFLAGS(regs->gp) = sc->flags;
 32	REGS_SS(regs->gp) = sc->ss;
 33}
 34
 35/*
 36 * FPU tag word conversions.
 37 */
 38
 39static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
 40{
 41	unsigned int tmp; /* to avoid 16 bit prefixes in the code */
 42
 43	/* Transform each pair of bits into 01 (valid) or 00 (empty) */
 44	tmp = ~twd;
 45	tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
 46	/* and move the valid bits to the lower byte. */
 47	tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
 48	tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
 49	tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
 50	return tmp;
 51}
 52
 53static inline unsigned long twd_fxsr_to_i387(struct user_fxsr_struct *fxsave)
 54{
 55	struct _fpxreg *st = NULL;
 56	unsigned long twd = (unsigned long) fxsave->twd;
 57	unsigned long tag;
 58	unsigned long ret = 0xffff0000;
 59	int i;
 60
 61#define FPREG_ADDR(f, n)	((char *)&(f)->st_space + (n) * 16);
 62
 63	for (i = 0; i < 8; i++) {
 64		if (twd & 0x1) {
 65			st = (struct _fpxreg *) FPREG_ADDR(fxsave, i);
 66
 67			switch (st->exponent & 0x7fff) {
 68			case 0x7fff:
 69				tag = 2;		/* Special */
 70				break;
 71			case 0x0000:
 72				if ( !st->significand[0] &&
 73				     !st->significand[1] &&
 74				     !st->significand[2] &&
 75				     !st->significand[3] ) {
 76					tag = 1;	/* Zero */
 77				} else {
 78					tag = 2;	/* Special */
 79				}
 80				break;
 81			default:
 82				if (st->significand[3] & 0x8000) {
 83					tag = 0;	/* Valid */
 84				} else {
 85					tag = 2;	/* Special */
 86				}
 87				break;
 88			}
 89		} else {
 90			tag = 3;			/* Empty */
 91		}
 92		ret |= (tag << (2 * i));
 93		twd = twd >> 1;
 94	}
 95	return ret;
 96}
 97
 98static int convert_fxsr_to_user(struct _fpstate __user *buf,
 99				struct user_fxsr_struct *fxsave)
100{
101	unsigned long env[7];
102	struct _fpreg __user *to;
103	struct _fpxreg *from;
104	int i;
105
106	env[0] = (unsigned long)fxsave->cwd | 0xffff0000ul;
107	env[1] = (unsigned long)fxsave->swd | 0xffff0000ul;
108	env[2] = twd_fxsr_to_i387(fxsave);
109	env[3] = fxsave->fip;
110	env[4] = fxsave->fcs | ((unsigned long)fxsave->fop << 16);
111	env[5] = fxsave->foo;
112	env[6] = fxsave->fos;
113
114	if (__copy_to_user(buf, env, 7 * sizeof(unsigned long)))
115		return 1;
116
117	to = &buf->_st[0];
118	from = (struct _fpxreg *) &fxsave->st_space[0];
119	for (i = 0; i < 8; i++, to++, from++) {
120		unsigned long __user *t = (unsigned long __user *)to;
121		unsigned long *f = (unsigned long *)from;
122
123		if (__put_user(*f, t) ||
124				__put_user(*(f + 1), t + 1) ||
125				__put_user(from->exponent, &to->exponent))
126			return 1;
127	}
128	return 0;
129}
130
131static int convert_fxsr_from_user(struct user_fxsr_struct *fxsave,
132				  struct _fpstate __user *buf)
133{
134	unsigned long env[7];
135	struct _fpxreg *to;
136	struct _fpreg __user *from;
137	int i;
138
139	if (copy_from_user( env, buf, 7 * sizeof(long)))
140		return 1;
141
142	fxsave->cwd = (unsigned short)(env[0] & 0xffff);
143	fxsave->swd = (unsigned short)(env[1] & 0xffff);
144	fxsave->twd = twd_i387_to_fxsr((unsigned short)(env[2] & 0xffff));
145	fxsave->fip = env[3];
146	fxsave->fop = (unsigned short)((env[4] & 0xffff0000ul) >> 16);
147	fxsave->fcs = (env[4] & 0xffff);
148	fxsave->foo = env[5];
149	fxsave->fos = env[6];
150
151	to = (struct _fpxreg *) &fxsave->st_space[0];
152	from = &buf->_st[0];
153	for (i = 0; i < 8; i++, to++, from++) {
154		unsigned long *t = (unsigned long *)to;
155		unsigned long __user *f = (unsigned long __user *)from;
156
157		if (__get_user(*t, f) ||
158		    __get_user(*(t + 1), f + 1) ||
159		    __get_user(to->exponent, &from->exponent))
160			return 1;
161	}
162	return 0;
163}
164
165extern int have_fpx_regs;
166
167static int copy_sc_from_user(struct pt_regs *regs,
168			     struct sigcontext __user *from)
169{
170	struct sigcontext sc;
171	int err, pid;
172
173	err = copy_from_user(&sc, from, sizeof(sc));
174	if (err)
175		return err;
176
177	pid = userspace_pid[current_thread_info()->cpu];
178	copy_sc(&regs->regs, &sc);
179	if (have_fpx_regs) {
180		struct user_fxsr_struct fpx;
181
182		err = copy_from_user(&fpx,
183			&((struct _fpstate __user *)sc.fpstate)->_fxsr_env[0],
184				     sizeof(struct user_fxsr_struct));
185		if (err)
186			return 1;
187
188		err = convert_fxsr_from_user(&fpx, sc.fpstate);
189		if (err)
190			return 1;
191
192		err = restore_fpx_registers(pid, (unsigned long *) &fpx);
193		if (err < 0) {
194			printk(KERN_ERR "copy_sc_from_user - "
195			       "restore_fpx_registers failed, errno = %d\n",
196			       -err);
197			return 1;
198		}
199	}
200	else {
201		struct user_i387_struct fp;
202
203		err = copy_from_user(&fp, sc.fpstate,
204				     sizeof(struct user_i387_struct));
205		if (err)
206			return 1;
207
208		err = restore_fp_registers(pid, (unsigned long *) &fp);
209		if (err < 0) {
210			printk(KERN_ERR "copy_sc_from_user - "
211			       "restore_fp_registers failed, errno = %d\n",
212			       -err);
213			return 1;
214		}
215	}
216
217	return 0;
218}
219
220static int copy_sc_to_user(struct sigcontext __user *to,
221			   struct _fpstate __user *to_fp, struct pt_regs *regs,
222			   unsigned long sp)
223{
224	struct sigcontext sc;
225	struct faultinfo * fi = &current->thread.arch.faultinfo;
226	int err, pid;
227
228	sc.gs = REGS_GS(regs->regs.gp);
229	sc.fs = REGS_FS(regs->regs.gp);
230	sc.es = REGS_ES(regs->regs.gp);
231	sc.ds = REGS_DS(regs->regs.gp);
232	sc.di = REGS_EDI(regs->regs.gp);
233	sc.si = REGS_ESI(regs->regs.gp);
234	sc.bp = REGS_EBP(regs->regs.gp);
235	sc.sp = sp;
236	sc.bx = REGS_EBX(regs->regs.gp);
237	sc.dx = REGS_EDX(regs->regs.gp);
238	sc.cx = REGS_ECX(regs->regs.gp);
239	sc.ax = REGS_EAX(regs->regs.gp);
240	sc.ip = REGS_IP(regs->regs.gp);
241	sc.cs = REGS_CS(regs->regs.gp);
242	sc.flags = REGS_EFLAGS(regs->regs.gp);
243	sc.sp_at_signal = regs->regs.gp[UESP];
244	sc.ss = regs->regs.gp[SS];
245	sc.cr2 = fi->cr2;
246	sc.err = fi->error_code;
247	sc.trapno = fi->trap_no;
248
249	to_fp = (to_fp ? to_fp : (struct _fpstate __user *) (to + 1));
250	sc.fpstate = to_fp;
251
252	pid = userspace_pid[current_thread_info()->cpu];
253	if (have_fpx_regs) {
254		struct user_fxsr_struct fpx;
255
256		err = save_fpx_registers(pid, (unsigned long *) &fpx);
257		if (err < 0){
258			printk(KERN_ERR "copy_sc_to_user - save_fpx_registers "
259			       "failed, errno = %d\n", err);
260			return 1;
261		}
262
263		err = convert_fxsr_to_user(to_fp, &fpx);
264		if (err)
265			return 1;
266
267		err |= __put_user(fpx.swd, &to_fp->status);
268		err |= __put_user(X86_FXSR_MAGIC, &to_fp->magic);
269		if (err)
270			return 1;
271
272		if (copy_to_user(&to_fp->_fxsr_env[0], &fpx,
273				 sizeof(struct user_fxsr_struct)))
274			return 1;
275	}
276	else {
277		struct user_i387_struct fp;
278
279		err = save_fp_registers(pid, (unsigned long *) &fp);
280		if (copy_to_user(to_fp, &fp, sizeof(struct user_i387_struct)))
281			return 1;
282	}
283
284	return copy_to_user(to, &sc, sizeof(sc));
285}
286
287static int copy_ucontext_to_user(struct ucontext __user *uc,
288				 struct _fpstate __user *fp, sigset_t *set,
289				 unsigned long sp)
290{
291	int err = 0;
292
293	err |= put_user(current->sas_ss_sp, &uc->uc_stack.ss_sp);
294	err |= put_user(sas_ss_flags(sp), &uc->uc_stack.ss_flags);
295	err |= put_user(current->sas_ss_size, &uc->uc_stack.ss_size);
296	err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs, sp);
297	err |= copy_to_user(&uc->uc_sigmask, set, sizeof(*set));
298	return err;
299}
300
301struct sigframe
302{
303	char __user *pretcode;
304	int sig;
305	struct sigcontext sc;
306	struct _fpstate fpstate;
307	unsigned long extramask[_NSIG_WORDS-1];
308	char retcode[8];
309};
310
311struct rt_sigframe
312{
313	char __user *pretcode;
314	int sig;
315	struct siginfo __user *pinfo;
316	void __user *puc;
317	struct siginfo info;
318	struct ucontext uc;
319	struct _fpstate fpstate;
320	char retcode[8];
321};
322
323int setup_signal_stack_sc(unsigned long stack_top, int sig,
324			  struct k_sigaction *ka, struct pt_regs *regs,
325			  sigset_t *mask)
326{
327	struct sigframe __user *frame;
328	void __user *restorer;
329	unsigned long save_sp = PT_REGS_SP(regs);
330	int err = 0;
331
332	/* This is the same calculation as i386 - ((sp + 4) & 15) == 0 */
333	stack_top = ((stack_top + 4) & -16UL) - 4;
334	frame = (struct sigframe __user *) stack_top - 1;
335	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
336		return 1;
337
338	restorer = frame->retcode;
339	if (ka->sa.sa_flags & SA_RESTORER)
340		restorer = ka->sa.sa_restorer;
341
342	/* Update SP now because the page fault handler refuses to extend
343	 * the stack if the faulting address is too far below the current
344	 * SP, which frame now certainly is.  If there's an error, the original
345	 * value is restored on the way out.
346	 * When writing the sigcontext to the stack, we have to write the
347	 * original value, so that's passed to copy_sc_to_user, which does
348	 * the right thing with it.
349	 */
350	PT_REGS_SP(regs) = (unsigned long) frame;
351
352	err |= __put_user(restorer, &frame->pretcode);
353	err |= __put_user(sig, &frame->sig);
354	err |= copy_sc_to_user(&frame->sc, NULL, regs, save_sp);
355	err |= __put_user(mask->sig[0], &frame->sc.oldmask);
356	if (_NSIG_WORDS > 1)
357		err |= __copy_to_user(&frame->extramask, &mask->sig[1],
358				      sizeof(frame->extramask));
359
360	/*
361	 * This is popl %eax ; movl $,%eax ; int $0x80
362	 *
363	 * WE DO NOT USE IT ANY MORE! It's only left here for historical
364	 * reasons and because gdb uses it as a signature to notice
365	 * signal handler stack frames.
366	 */
367	err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
368	err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
369	err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
370
371	if (err)
372		goto err;
373
374	PT_REGS_SP(regs) = (unsigned long) frame;
375	PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
376	PT_REGS_EAX(regs) = (unsigned long) sig;
377	PT_REGS_EDX(regs) = (unsigned long) 0;
378	PT_REGS_ECX(regs) = (unsigned long) 0;
379
380	if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
381		ptrace_notify(SIGTRAP);
382	return 0;
383
384err:
385	PT_REGS_SP(regs) = save_sp;
386	return err;
387}
388
389int setup_signal_stack_si(unsigned long stack_top, int sig,
390			  struct k_sigaction *ka, struct pt_regs *regs,
391			  siginfo_t *info, sigset_t *mask)
392{
393	struct rt_sigframe __user *frame;
394	void __user *restorer;
395	unsigned long save_sp = PT_REGS_SP(regs);
396	int err = 0;
397
398	stack_top &= -8UL;
399	frame = (struct rt_sigframe __user *) stack_top - 1;
400	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
401		return 1;
402
403	restorer = frame->retcode;
404	if (ka->sa.sa_flags & SA_RESTORER)
405		restorer = ka->sa.sa_restorer;
406
407	/* See comment above about why this is here */
408	PT_REGS_SP(regs) = (unsigned long) frame;
409
410	err |= __put_user(restorer, &frame->pretcode);
411	err |= __put_user(sig, &frame->sig);
412	err |= __put_user(&frame->info, &frame->pinfo);
413	err |= __put_user(&frame->uc, &frame->puc);
414	err |= copy_siginfo_to_user(&frame->info, info);
415	err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask,
416				     save_sp);
417
418	/*
419	 * This is movl $,%eax ; int $0x80
420	 *
421	 * WE DO NOT USE IT ANY MORE! It's only left here for historical
422	 * reasons and because gdb uses it as a signature to notice
423	 * signal handler stack frames.
424	 */
425	err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
426	err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
427	err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
428
429	if (err)
430		goto err;
431
432	PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
433	PT_REGS_EAX(regs) = (unsigned long) sig;
434	PT_REGS_EDX(regs) = (unsigned long) &frame->info;
435	PT_REGS_ECX(regs) = (unsigned long) &frame->uc;
436
437	if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
438		ptrace_notify(SIGTRAP);
439	return 0;
440
441err:
442	PT_REGS_SP(regs) = save_sp;
443	return err;
444}
445
446long sys_sigreturn(struct pt_regs regs)
447{
448	unsigned long sp = PT_REGS_SP(&current->thread.regs);
449	struct sigframe __user *frame = (struct sigframe __user *)(sp - 8);
450	sigset_t set;
451	struct sigcontext __user *sc = &frame->sc;
452	unsigned long __user *oldmask = &sc->oldmask;
453	unsigned long __user *extramask = frame->extramask;
454	int sig_size = (_NSIG_WORDS - 1) * sizeof(unsigned long);
455
456	if (copy_from_user(&set.sig[0], oldmask, sizeof(set.sig[0])) ||
457	    copy_from_user(&set.sig[1], extramask, sig_size))
458		goto segfault;
459
460	sigdelsetmask(&set, ~_BLOCKABLE);
461
462	spin_lock_irq(&current->sighand->siglock);
463	current->blocked = set;
464	recalc_sigpending();
465	spin_unlock_irq(&current->sighand->siglock);
466
467	if (copy_sc_from_user(&current->thread.regs, sc))
468		goto segfault;
469
470	/* Avoid ERESTART handling */
471	PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
472	return PT_REGS_SYSCALL_RET(&current->thread.regs);
473
474 segfault:
475	force_sig(SIGSEGV, current);
476	return 0;
477}
478
479long sys_rt_sigreturn(struct pt_regs regs)
480{
481	unsigned long sp = PT_REGS_SP(&current->thread.regs);
482	struct rt_sigframe __user *frame =
483		(struct rt_sigframe __user *) (sp - 4);
484	sigset_t set;
485	struct ucontext __user *uc = &frame->uc;
486	int sig_size = _NSIG_WORDS * sizeof(unsigned long);
487
488	if (copy_from_user(&set, &uc->uc_sigmask, sig_size))
489		goto segfault;
490
491	sigdelsetmask(&set, ~_BLOCKABLE);
492
493	spin_lock_irq(&current->sighand->siglock);
494	current->blocked = set;
495	recalc_sigpending();
496	spin_unlock_irq(&current->sighand->siglock);
497
498	if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
499		goto segfault;
500
501	/* Avoid ERESTART handling */
502	PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
503	return PT_REGS_SYSCALL_RET(&current->thread.regs);
504
505 segfault:
506	force_sig(SIGSEGV, current);
507	return 0;
508}