signal.c 13.9 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3
/*
 *  arch/s390/kernel/signal.c
 *
4
 *    Copyright (C) IBM Corp. 1999,2006
Linus Torvalds's avatar
Linus Torvalds committed
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55
 *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
 *
 *    Based on Intel version
 * 
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 */

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/tty.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/lowcore.h>

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))


typedef struct 
{
	__u8 callee_used_stack[__SIGNAL_FRAMESIZE];
	struct sigcontext sc;
	_sigregs sregs;
	int signo;
	__u8 retcode[S390_SYSCALL_SIZE];
} sigframe;

typedef struct 
{
	__u8 callee_used_stack[__SIGNAL_FRAMESIZE];
	__u8 retcode[S390_SYSCALL_SIZE];
	struct siginfo info;
	struct ucontext uc;
} rt_sigframe;

/*
 * Atomically swap in the new signal mask, and wait for a signal.
 */
asmlinkage int
56
sys_sigsuspend(int history0, int history1, old_sigset_t mask)
Linus Torvalds's avatar
Linus Torvalds committed
57 58 59
{
	mask &= _BLOCKABLE;
	spin_lock_irq(&current->sighand->siglock);
60
	current->saved_sigmask = current->blocked;
Linus Torvalds's avatar
Linus Torvalds committed
61 62 63 64
	siginitset(&current->blocked, mask);
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

65 66 67
	current->state = TASK_INTERRUPTIBLE;
	schedule();
	set_thread_flag(TIF_RESTORE_SIGMASK);
Linus Torvalds's avatar
Linus Torvalds committed
68

69
	return -ERESTARTNOHAND;
Linus Torvalds's avatar
Linus Torvalds committed
70 71 72 73 74 75 76 77 78 79 80 81 82
}

asmlinkage long
sys_sigaction(int sig, const struct old_sigaction __user *act,
	      struct old_sigaction __user *oact)
{
	struct k_sigaction new_ka, old_ka;
	int ret;

	if (act) {
		old_sigset_t mask;
		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
		    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
83 84 85
		    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
		    __get_user(mask, &act->sa_mask))
Linus Torvalds's avatar
Linus Torvalds committed
86 87 88 89 90 91 92 93 94
			return -EFAULT;
		siginitset(&new_ka.sa.sa_mask, mask);
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);

	if (!ret && oact) {
		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
		    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
95 96 97
		    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
Linus Torvalds's avatar
Linus Torvalds committed
98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115
			return -EFAULT;
	}

	return ret;
}

asmlinkage long
sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
					struct pt_regs *regs)
{
	return do_sigaltstack(uss, uoss, regs->gprs[15]);
}



/* Returns non-zero on fault. */
static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
{
116 117
	_sigregs user_sregs;

Linus Torvalds's avatar
Linus Torvalds committed
118 119 120 121
	save_access_regs(current->thread.acrs);

	/* Copy a 'clean' PSW mask to the user to avoid leaking
	   information about whether PER is currently on.  */
122 123 124
	user_sregs.regs.psw.mask = PSW_MASK_MERGE(PSW_USER_BITS, regs->psw.mask);
	user_sregs.regs.psw.addr = regs->psw.addr;
	memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
125 126
	memcpy(&user_sregs.regs.acrs, current->thread.acrs,
	       sizeof(sregs->regs.acrs));
Linus Torvalds's avatar
Linus Torvalds committed
127 128 129 130 131
	/* 
	 * We have to store the fp registers to current->thread.fp_regs
	 * to merge them with the emulated registers.
	 */
	save_fp_regs(&current->thread.fp_regs);
132 133 134
	memcpy(&user_sregs.fpregs, &current->thread.fp_regs,
	       sizeof(s390_fp_regs));
	return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs));
Linus Torvalds's avatar
Linus Torvalds committed
135 136 137 138 139 140
}

/* Returns positive number on error */
static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
{
	int err;
141
	_sigregs user_sregs;
Linus Torvalds's avatar
Linus Torvalds committed
142 143 144 145

	/* Alwys make any pending restarted system call return -EINTR */
	current_thread_info()->restart_block.fn = do_no_restart_syscall;

146
	err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));
Linus Torvalds's avatar
Linus Torvalds committed
147 148
	if (err)
		return err;
149 150 151 152
	regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask,
					user_sregs.regs.psw.mask);
	regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr;
	memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
153 154
	memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
	       sizeof(sregs->regs.acrs));
Linus Torvalds's avatar
Linus Torvalds committed
155 156
	restore_access_regs(current->thread.acrs);

157 158
	memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
	       sizeof(s390_fp_regs));
Linus Torvalds's avatar
Linus Torvalds committed
159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210
	current->thread.fp_regs.fpc &= FPC_VALID_MASK;

	restore_fp_regs(&current->thread.fp_regs);
	regs->trap = -1;	/* disable syscall checks */
	return 0;
}

asmlinkage long sys_sigreturn(struct pt_regs *regs)
{
	sigframe __user *frame = (sigframe __user *)regs->gprs[15];
	sigset_t set;

	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;
	if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
		goto badframe;

	sigdelsetmask(&set, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);
	current->blocked = set;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	if (restore_sigregs(regs, &frame->sregs))
		goto badframe;

	return regs->gprs[2];

badframe:
	force_sig(SIGSEGV, current);
	return 0;
}

asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
{
	rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
	sigset_t set;

	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;
	if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
		goto badframe;

	sigdelsetmask(&set, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);
	current->blocked = set;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	if (restore_sigregs(regs, &frame->uc.uc_mcontext))
		goto badframe;

211 212 213
	if (do_sigaltstack(&frame->uc.uc_stack, NULL,
			   regs->gprs[15]) == -EFAULT)
		goto badframe;
Linus Torvalds's avatar
Linus Torvalds committed
214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262
	return regs->gprs[2];

badframe:
	force_sig(SIGSEGV, current);
	return 0;
}

/*
 * Set up a signal frame.
 */


/*
 * Determine which stack to use..
 */
static inline void __user *
get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
{
	unsigned long sp;

	/* Default to using normal stack */
	sp = regs->gprs[15];

	/* This is the X/Open sanctioned signal stack switching.  */
	if (ka->sa.sa_flags & SA_ONSTACK) {
		if (! sas_ss_flags(sp))
			sp = current->sas_ss_sp + current->sas_ss_size;
	}

	/* This is the legacy signal stack switching. */
	else if (!user_mode(regs) &&
		 !(ka->sa.sa_flags & SA_RESTORER) &&
		 ka->sa.sa_restorer) {
		sp = (unsigned long) ka->sa.sa_restorer;
	}

	return (void __user *)((sp - frame_size) & -8ul);
}

static inline int map_signal(int sig)
{
	if (current_thread_info()->exec_domain
	    && current_thread_info()->exec_domain->signal_invmap
	    && sig < 32)
		return current_thread_info()->exec_domain->signal_invmap[sig];
	else
		return sig;
}

263 264
static int setup_frame(int sig, struct k_sigaction *ka,
		       sigset_t *set, struct pt_regs * regs)
Linus Torvalds's avatar
Linus Torvalds committed
265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311
{
	sigframe __user *frame;

	frame = get_sigframe(ka, regs, sizeof(sigframe));
	if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
		goto give_sigsegv;

	if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
		goto give_sigsegv;

	if (save_sigregs(regs, &frame->sregs))
		goto give_sigsegv;
	if (__put_user(&frame->sregs, &frame->sc.sregs))
		goto give_sigsegv;

	/* Set up to return from userspace.  If provided, use a stub
	   already in userspace.  */
	if (ka->sa.sa_flags & SA_RESTORER) {
                regs->gprs[14] = (unsigned long)
			ka->sa.sa_restorer | PSW_ADDR_AMODE;
	} else {
                regs->gprs[14] = (unsigned long)
			frame->retcode | PSW_ADDR_AMODE;
		if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
	                       (u16 __user *)(frame->retcode)))
			goto give_sigsegv;
	}

	/* Set up backchain. */
	if (__put_user(regs->gprs[15], (addr_t __user *) frame))
		goto give_sigsegv;

	/* Set up registers for signal handler */
	regs->gprs[15] = (unsigned long) frame;
	regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;

	regs->gprs[2] = map_signal(sig);
	regs->gprs[3] = (unsigned long) &frame->sc;

	/* We forgot to include these in the sigcontext.
	   To avoid breaking binary compatibility, they are passed as args. */
	regs->gprs[4] = current->thread.trap_no;
	regs->gprs[5] = current->thread.prot_addr;

	/* Place signal number on stack to allow backtrace from handler.  */
	if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
		goto give_sigsegv;
312
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
313 314 315

give_sigsegv:
	force_sigsegv(sig, current);
316
	return -EFAULT;
Linus Torvalds's avatar
Linus Torvalds committed
317 318
}

319
static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
Linus Torvalds's avatar
Linus Torvalds committed
320 321 322 323 324 325 326 327 328 329 330 331 332 333
			   sigset_t *set, struct pt_regs * regs)
{
	int err = 0;
	rt_sigframe __user *frame;

	frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
	if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
		goto give_sigsegv;

	if (copy_siginfo_to_user(&frame->info, info))
		goto give_sigsegv;

	/* Create the ucontext.  */
	err |= __put_user(0, &frame->uc.uc_flags);
Al Viro's avatar
Al Viro committed
334 335
	err |= __put_user(NULL, &frame->uc.uc_link);
	err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
Linus Torvalds's avatar
Linus Torvalds committed
336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351
	err |= __put_user(sas_ss_flags(regs->gprs[15]),
			  &frame->uc.uc_stack.ss_flags);
	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
	err |= save_sigregs(regs, &frame->uc.uc_mcontext);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
	if (err)
		goto give_sigsegv;

	/* Set up to return from userspace.  If provided, use a stub
	   already in userspace.  */
	if (ka->sa.sa_flags & SA_RESTORER) {
                regs->gprs[14] = (unsigned long)
			ka->sa.sa_restorer | PSW_ADDR_AMODE;
	} else {
                regs->gprs[14] = (unsigned long)
			frame->retcode | PSW_ADDR_AMODE;
352 353 354
		if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
			       (u16 __user *)(frame->retcode)))
			goto give_sigsegv;
Linus Torvalds's avatar
Linus Torvalds committed
355 356 357 358 359 360 361 362 363 364 365 366 367
	}

	/* Set up backchain. */
	if (__put_user(regs->gprs[15], (addr_t __user *) frame))
		goto give_sigsegv;

	/* Set up registers for signal handler */
	regs->gprs[15] = (unsigned long) frame;
	regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;

	regs->gprs[2] = map_signal(sig);
	regs->gprs[3] = (unsigned long) &frame->info;
	regs->gprs[4] = (unsigned long) &frame->uc;
368
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
369 370 371

give_sigsegv:
	force_sigsegv(sig, current);
372
	return -EFAULT;
Linus Torvalds's avatar
Linus Torvalds committed
373 374 375 376 377 378
}

/*
 * OK, we're invoking a handler
 */	

379
static int
Linus Torvalds's avatar
Linus Torvalds committed
380 381 382
handle_signal(unsigned long sig, struct k_sigaction *ka,
	      siginfo_t *info, sigset_t *oldset, struct pt_regs * regs)
{
383 384
	int ret;

Linus Torvalds's avatar
Linus Torvalds committed
385 386
	/* Set up the stack frame */
	if (ka->sa.sa_flags & SA_SIGINFO)
387
		ret = setup_rt_frame(sig, ka, info, oldset, regs);
Linus Torvalds's avatar
Linus Torvalds committed
388
	else
389 390 391 392 393 394 395 396 397 398
		ret = setup_frame(sig, ka, oldset, regs);

	if (ret == 0) {
		spin_lock_irq(&current->sighand->siglock);
		sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
		if (!(ka->sa.sa_flags & SA_NODEFER))
			sigaddset(&current->blocked,sig);
		recalc_sigpending();
		spin_unlock_irq(&current->sighand->siglock);
	}
Linus Torvalds's avatar
Linus Torvalds committed
399

400
	return ret;
Linus Torvalds's avatar
Linus Torvalds committed
401 402 403 404 405 406 407 408 409 410 411
}

/*
 * Note that 'init' is a special process: it doesn't get signals it doesn't
 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 * mistake.
 *
 * Note that we go through the signals twice: once to check the signals that
 * the kernel can handle, and then we build all the user-level signal handling
 * stack-frames in one go after that.
 */
412
void do_signal(struct pt_regs *regs)
Linus Torvalds's avatar
Linus Torvalds committed
413 414 415 416 417
{
	unsigned long retval = 0, continue_addr = 0, restart_addr = 0;
	siginfo_t info;
	int signr;
	struct k_sigaction ka;
418
	sigset_t *oldset;
Linus Torvalds's avatar
Linus Torvalds committed
419 420 421 422 423 424 425 426

	/*
	 * We want the common case to go fast, which
	 * is why we may in certain cases get here from
	 * kernel mode. Just return without doing anything
	 * if so.
	 */
	if (!user_mode(regs))
427
		return;
Linus Torvalds's avatar
Linus Torvalds committed
428

429 430 431
	if (test_thread_flag(TIF_RESTORE_SIGMASK))
		oldset = &current->saved_sigmask;
	else
Linus Torvalds's avatar
Linus Torvalds committed
432 433 434 435 436 437 438 439 440 441
		oldset = &current->blocked;

	/* Are we from a system call? */
	if (regs->trap == __LC_SVC_OLD_PSW) {
		continue_addr = regs->psw.addr;
		restart_addr = continue_addr - regs->ilc;
		retval = regs->gprs[2];

		/* Prepare for system call restart.  We do this here so that a
		   debugger will see the already changed PSW. */
442 443 444 445
		switch (retval) {
		case -ERESTARTNOHAND:
		case -ERESTARTSYS:
		case -ERESTARTNOINTR:
Linus Torvalds's avatar
Linus Torvalds committed
446 447
			regs->gprs[2] = regs->orig_gpr2;
			regs->psw.addr = restart_addr;
448 449
			break;
		case -ERESTART_RESTARTBLOCK:
Linus Torvalds's avatar
Linus Torvalds committed
450 451
			regs->gprs[2] = -EINTR;
		}
452
		regs->trap = -1;	/* Don't deal with this again. */
Linus Torvalds's avatar
Linus Torvalds committed
453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472
	}

	/* Get signal to deliver.  When running under ptrace, at this point
	   the debugger may change all our registers ... */
	signr = get_signal_to_deliver(&info, &ka, regs, NULL);

	/* Depending on the signal settings we may need to revert the
	   decision to restart the system call. */
	if (signr > 0 && regs->psw.addr == restart_addr) {
		if (retval == -ERESTARTNOHAND
		    || (retval == -ERESTARTSYS
			 && !(current->sighand->action[signr-1].sa.sa_flags
			      & SA_RESTART))) {
			regs->gprs[2] = -EINTR;
			regs->psw.addr = continue_addr;
		}
	}

	if (signr > 0) {
		/* Whee!  Actually deliver the signal.  */
473
#ifdef CONFIG_COMPAT
Linus Torvalds's avatar
Linus Torvalds committed
474
		if (test_thread_flag(TIF_31BIT)) {
475 476 477 478 479 480 481 482 483 484 485
			extern int handle_signal32(unsigned long sig,
						   struct k_sigaction *ka,
						   siginfo_t *info,
						   sigset_t *oldset,
						   struct pt_regs *regs);
			if (handle_signal32(
				    signr, &ka, &info, oldset, regs) == 0) {
				if (test_thread_flag(TIF_RESTORE_SIGMASK))
					clear_thread_flag(TIF_RESTORE_SIGMASK);
			}
			return;
Linus Torvalds's avatar
Linus Torvalds committed
486 487
	        }
#endif
488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506
		if (handle_signal(signr, &ka, &info, oldset, regs) == 0) {
			/*
			 * A signal was successfully delivered; the saved
			 * sigmask will have been stored in the signal frame,
			 * and will be restored by sigreturn, so we can simply
			 * clear the TIF_RESTORE_SIGMASK flag.
			 */
			if (test_thread_flag(TIF_RESTORE_SIGMASK))
				clear_thread_flag(TIF_RESTORE_SIGMASK);
		}
		return;
	}

	/*
	 * If there's no signal to deliver, we just put the saved sigmask back.
	 */
	if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
		clear_thread_flag(TIF_RESTORE_SIGMASK);
		sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
507 508 509 510 511 512 513 514 515
	}

	/* Restart a different system call. */
	if (retval == -ERESTART_RESTARTBLOCK
	    && regs->psw.addr == continue_addr) {
		regs->gprs[2] = __NR_restart_syscall;
		set_thread_flag(TIF_RESTART_SVC);
	}
}