/arch/ppc64/kernel/signal.c

  1/*
  2 *  linux/arch/ppc64/kernel/signal.c
  3 *
  4 *  PowerPC version 
  5 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
  6 *
  7 *  Derived from "arch/i386/kernel/signal.c"
  8 *    Copyright (C) 1991, 1992 Linus Torvalds
  9 *    1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 10 *
 11 *  This program is free software; you can redistribute it and/or
 12 *  modify it under the terms of the GNU General Public License
 13 *  as published by the Free Software Foundation; either version
 14 *  2 of the License, or (at your option) any later version.
 15 */
 16
 17#include <linux/config.h>
 18#include <linux/sched.h>
 19#include <linux/mm.h>
 20#include <linux/smp.h>
 21#include <linux/smp_lock.h>
 22#include <linux/kernel.h>
 23#include <linux/signal.h>
 24#include <linux/errno.h>
 25#include <linux/wait.h>
 26#include <linux/unistd.h>
 27#include <linux/stddef.h>
 28#include <linux/elf.h>
 29#include <linux/ptrace.h>
 30#include <linux/module.h>
 31
 32#include <asm/sigcontext.h>
 33#include <asm/ucontext.h>
 34#include <asm/uaccess.h>
 35#include <asm/pgtable.h>
 36#include <asm/ppcdebug.h>
 37#include <asm/unistd.h>
 38#include <asm/cacheflush.h>
 39#include <asm/vdso.h>
 40
 41#define DEBUG_SIG 0
 42
 43#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 44
 45#ifndef MIN
 46#define MIN(a,b) (((a) < (b)) ? (a) : (b))
 47#endif
 48
 49#define GP_REGS_SIZE	MIN(sizeof(elf_gregset_t), sizeof(struct pt_regs))
 50#define FP_REGS_SIZE	sizeof(elf_fpregset_t)
 51
 52#define TRAMP_TRACEBACK	3
 53#define TRAMP_SIZE	6
 54
 55/*
 56 * When we have signals to deliver, we set up on the user stack,
 57 * going down from the original stack pointer:
 58 *	1) a rt_sigframe struct which contains the ucontext	
 59 *	2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller
 60 *	   frame for the signal handler.
 61 */
 62
 63struct rt_sigframe {
 64	/* sys_rt_sigreturn requires the ucontext be the first field */
 65	struct ucontext uc;
 66	unsigned long _unused[2];
 67	unsigned int tramp[TRAMP_SIZE];
 68	struct siginfo *pinfo;
 69	void *puc;
 70	struct siginfo info;
 71	/* 64 bit ABI allows for 288 bytes below sp before decrementing it. */
 72	char abigap[288];
 73} __attribute__ ((aligned (16)));
 74
 75
 76/*
 77 * Atomically swap in the new signal mask, and wait for a signal.
 78 */
 79long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, int p3, int p4,
 80		       int p6, int p7, struct pt_regs *regs)
 81{
 82	sigset_t saveset, newset;
 83
 84	/* XXX: Don't preclude handling different sized sigset_t's.  */
 85	if (sigsetsize != sizeof(sigset_t))
 86		return -EINVAL;
 87
 88	if (copy_from_user(&newset, unewset, sizeof(newset)))
 89		return -EFAULT;
 90	sigdelsetmask(&newset, ~_BLOCKABLE);
 91
 92	spin_lock_irq(&current->sighand->siglock);
 93	saveset = current->blocked;
 94	current->blocked = newset;
 95	recalc_sigpending();
 96	spin_unlock_irq(&current->sighand->siglock);
 97
 98	regs->result = -EINTR;
 99	regs->gpr[3] = EINTR;
100	regs->ccr |= 0x10000000;
101	while (1) {
102		current->state = TASK_INTERRUPTIBLE;
103		schedule();
104		if (do_signal(&saveset, regs))
105			return 0;
106	}
107}
108
109long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, unsigned long r5,
110		     unsigned long r6, unsigned long r7, unsigned long r8,
111		     struct pt_regs *regs)
112{
113	return do_sigaltstack(uss, uoss, regs->gpr[1]);
114}
115
116
117/*
118 * Set up the sigcontext for the signal frame.
119 */
120
121static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
122		 int signr, sigset_t *set, unsigned long handler)
123{
124	/* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the
125	 * process never used altivec yet (MSR_VEC is zero in pt_regs of
126	 * the context). This is very important because we must ensure we
127	 * don't lose the VRSAVE content that may have been set prior to
128	 * the process doing its first vector operation
129	 * Userland shall check AT_HWCAP to know wether it can rely on the
130	 * v_regs pointer or not
131	 */
132#ifdef CONFIG_ALTIVEC
133	elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful);
134#endif
135	long err = 0;
136
137	flush_fp_to_thread(current);
138
139	/* Make sure signal doesn't get spurrious FP exceptions */
140	current->thread.fpscr = 0;
141
142#ifdef CONFIG_ALTIVEC
143	err |= __put_user(v_regs, &sc->v_regs);
144
145	/* save altivec registers */
146	if (current->thread.used_vr) {
147		flush_altivec_to_thread(current);
148		/* Copy 33 vec registers (vr0..31 and vscr) to the stack */
149		err |= __copy_to_user(v_regs, current->thread.vr, 33 * sizeof(vector128));
150		/* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg)
151		 * contains valid data.
152		 */
153		regs->msr |= MSR_VEC;
154	}
155	/* We always copy to/from vrsave, it's 0 if we don't have or don't
156	 * use altivec.
157	 */
158	err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
159#else /* CONFIG_ALTIVEC */
160	err |= __put_user(0, &sc->v_regs);
161#endif /* CONFIG_ALTIVEC */
162	err |= __put_user(&sc->gp_regs, &sc->regs);
163	err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE);
164	err |= __copy_to_user(&sc->fp_regs, &current->thread.fpr, FP_REGS_SIZE);
165	err |= __put_user(signr, &sc->signal);
166	err |= __put_user(handler, &sc->handler);
167	if (set != NULL)
168		err |=  __put_user(set->sig[0], &sc->oldmask);
169
170	return err;
171}
172
173/*
174 * Restore the sigcontext from the signal frame.
175 */
176
177static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
178			      struct sigcontext __user *sc)
179{
180#ifdef CONFIG_ALTIVEC
181	elf_vrreg_t __user *v_regs;
182#endif
183	unsigned long err = 0;
184	unsigned long save_r13 = 0;
185	elf_greg_t *gregs = (elf_greg_t *)regs;
186#ifdef CONFIG_ALTIVEC
187	unsigned long msr;
188#endif
189	int i;
190
191	/* If this is not a signal return, we preserve the TLS in r13 */
192	if (!sig)
193		save_r13 = regs->gpr[13];
194
195	/* copy everything before MSR */
196	err |= __copy_from_user(regs, &sc->gp_regs,
197				PT_MSR*sizeof(unsigned long));
198
199	/* skip MSR and SOFTE */
200	for (i = PT_MSR+1; i <= PT_RESULT; i++) {
201		if (i == PT_SOFTE)
202			continue;
203		err |= __get_user(gregs[i], &sc->gp_regs[i]);
204	}
205
206	if (!sig)
207		regs->gpr[13] = save_r13;
208	err |= __copy_from_user(&current->thread.fpr, &sc->fp_regs, FP_REGS_SIZE);
209	if (set != NULL)
210		err |=  __get_user(set->sig[0], &sc->oldmask);
211
212#ifdef CONFIG_ALTIVEC
213	err |= __get_user(v_regs, &sc->v_regs);
214	err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
215	if (err)
216		return err;
217	/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
218	if (v_regs != 0 && (msr & MSR_VEC) != 0)
219		err |= __copy_from_user(current->thread.vr, v_regs,
220					33 * sizeof(vector128));
221	else if (current->thread.used_vr)
222		memset(current->thread.vr, 0, 33 * sizeof(vector128));
223	/* Always get VRSAVE back */
224	if (v_regs != 0)
225		err |= __get_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
226	else
227		current->thread.vrsave = 0;
228#endif /* CONFIG_ALTIVEC */
229
230#ifndef CONFIG_SMP
231	preempt_disable();
232	if (last_task_used_math == current)
233		last_task_used_math = NULL;
234	if (last_task_used_altivec == current)
235		last_task_used_altivec = NULL;
236	preempt_enable();
237#endif
238	/* Force reload of FP/VEC */
239	regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC);
240
241	return err;
242}
243
244/*
245 * Allocate space for the signal frame
246 */
247static inline void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
248				  size_t frame_size)
249{
250        unsigned long newsp;
251
252        /* Default to using normal stack */
253        newsp = regs->gpr[1];
254
255	if (ka->sa.sa_flags & SA_ONSTACK) {
256		if (! on_sig_stack(regs->gpr[1]))
257			newsp = (current->sas_ss_sp + current->sas_ss_size);
258	}
259
260        return (void __user *)((newsp - frame_size) & -16ul);
261}
262
263/*
264 * Setup the trampoline code on the stack
265 */
266static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp)
267{
268	int i;
269	long err = 0;
270
271	/* addi r1, r1, __SIGNAL_FRAMESIZE  # Pop the dummy stackframe */
272	err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]);
273	/* li r0, __NR_[rt_]sigreturn| */
274	err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]);
275	/* sc */
276	err |= __put_user(0x44000002UL, &tramp[2]);
277
278	/* Minimal traceback info */
279	for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++)
280		err |= __put_user(0, &tramp[i]);
281
282	if (!err)
283		flush_icache_range((unsigned long) &tramp[0],
284			   (unsigned long) &tramp[TRAMP_SIZE]);
285
286	return err;
287}
288
289/*
290 * Restore the user process's signal mask (also used by signal32.c)
291 */
292void restore_sigmask(sigset_t *set)
293{
294	sigdelsetmask(set, ~_BLOCKABLE);
295	spin_lock_irq(&current->sighand->siglock);
296	current->blocked = *set;
297	recalc_sigpending();
298	spin_unlock_irq(&current->sighand->siglock);
299}
300
301
302/*
303 * Handle {get,set,swap}_context operations
304 */
305int sys_swapcontext(struct ucontext __user *old_ctx,
306		    struct ucontext __user *new_ctx,
307		    long ctx_size, long r6, long r7, long r8, struct pt_regs *regs)
308{
309	unsigned char tmp;
310	sigset_t set;
311
312	/* Context size is for future use. Right now, we only make sure
313	 * we are passed something we understand
314	 */
315	if (ctx_size < sizeof(struct ucontext))
316		return -EINVAL;
317
318	if (old_ctx != NULL) {
319		if (!access_ok(VERIFY_WRITE, old_ctx, sizeof(*old_ctx))
320		    || setup_sigcontext(&old_ctx->uc_mcontext, regs, 0, NULL, 0)
321		    || __copy_to_user(&old_ctx->uc_sigmask,
322				      &current->blocked, sizeof(sigset_t)))
323			return -EFAULT;
324	}
325	if (new_ctx == NULL)
326		return 0;
327	if (!access_ok(VERIFY_READ, new_ctx, sizeof(*new_ctx))
328	    || __get_user(tmp, (u8 __user *) new_ctx)
329	    || __get_user(tmp, (u8 __user *) (new_ctx + 1) - 1))
330		return -EFAULT;
331
332	/*
333	 * If we get a fault copying the context into the kernel's
334	 * image of the user's registers, we can't just return -EFAULT
335	 * because the user's registers will be corrupted.  For instance
336	 * the NIP value may have been updated but not some of the
337	 * other registers.  Given that we have done the access_ok
338	 * and successfully read the first and last bytes of the region
339	 * above, this should only happen in an out-of-memory situation
340	 * or if another thread unmaps the region containing the context.
341	 * We kill the task with a SIGSEGV in this situation.
342	 */
343
344	if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set)))
345		do_exit(SIGSEGV);
346	restore_sigmask(&set);
347	if (restore_sigcontext(regs, NULL, 0, &new_ctx->uc_mcontext))
348		do_exit(SIGSEGV);
349
350	/* This returns like rt_sigreturn */
351	return 0;
352}
353
354
355/*
356 * Do a signal return; undo the signal stack.
357 */
358
359int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
360		     unsigned long r6, unsigned long r7, unsigned long r8,
361		     struct pt_regs *regs)
362{
363	struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1];
364	sigset_t set;
365
366	/* Always make any pending restarted system calls return -EINTR */
367	current_thread_info()->restart_block.fn = do_no_restart_syscall;
368
369	if (!access_ok(VERIFY_READ, uc, sizeof(*uc)))
370		goto badframe;
371
372	if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
373		goto badframe;
374	restore_sigmask(&set);
375	if (restore_sigcontext(regs, NULL, 1, &uc->uc_mcontext))
376		goto badframe;
377
378	/* do_sigaltstack expects a __user pointer and won't modify
379	 * what's in there anyway
380	 */
381	do_sigaltstack(&uc->uc_stack, NULL, regs->gpr[1]);
382
383	return regs->result;
384
385badframe:
386#if DEBUG_SIG
387	printk("badframe in sys_rt_sigreturn, regs=%p uc=%p &uc->uc_mcontext=%p\n",
388	       regs, uc, &uc->uc_mcontext);
389#endif
390	force_sig(SIGSEGV, current);
391	return 0;
392}
393
394static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
395		sigset_t *set, struct pt_regs *regs)
396{
397	/* Handler is *really* a pointer to the function descriptor for
398	 * the signal routine.  The first entry in the function
399	 * descriptor is the entry address of signal and the second
400	 * entry is the TOC value we need to use.
401	 */
402	func_descr_t __user *funct_desc_ptr;
403	struct rt_sigframe __user *frame;
404	unsigned long newsp = 0;
405	long err = 0;
406
407	frame = get_sigframe(ka, regs, sizeof(*frame));
408
409	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
410		goto badframe;
411
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	if (err)
416		goto badframe;
417
418	/* Create the ucontext.  */
419	err |= __put_user(0, &frame->uc.uc_flags);
420	err |= __put_user(0, &frame->uc.uc_link);
421	err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
422	err |= __put_user(sas_ss_flags(regs->gpr[1]),
423			  &frame->uc.uc_stack.ss_flags);
424	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
425	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL,
426				(unsigned long)ka->sa.sa_handler);
427	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
428	if (err)
429		goto badframe;
430
431	/* Set up to return from userspace. */
432	if (vdso64_rt_sigtramp && current->thread.vdso_base) {
433		regs->link = current->thread.vdso_base + vdso64_rt_sigtramp;
434	} else {
435		err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]);
436		if (err)
437			goto badframe;
438		regs->link = (unsigned long) &frame->tramp[0];
439	}
440	funct_desc_ptr = (func_descr_t __user *) ka->sa.sa_handler;
441
442	/* Allocate a dummy caller frame for the signal handler. */
443	newsp = (unsigned long)frame - __SIGNAL_FRAMESIZE;
444	err |= put_user(regs->gpr[1], (unsigned long __user *)newsp);
445
446	/* Set up "regs" so we "return" to the signal handler. */
447	err |= get_user(regs->nip, &funct_desc_ptr->entry);
448	regs->gpr[1] = newsp;
449	err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
450	regs->gpr[3] = signr;
451	regs->result = 0;
452	if (ka->sa.sa_flags & SA_SIGINFO) {
453		err |= get_user(regs->gpr[4], (unsigned long __user *)&frame->pinfo);
454		err |= get_user(regs->gpr[5], (unsigned long __user *)&frame->puc);
455		regs->gpr[6] = (unsigned long) frame;
456	} else {
457		regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext;
458	}
459	if (err)
460		goto badframe;
461
462	if (test_thread_flag(TIF_SINGLESTEP))
463		ptrace_notify(SIGTRAP);
464
465	return 1;
466
467badframe:
468#if DEBUG_SIG
469	printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n",
470	       regs, frame, newsp);
471#endif
472	force_sigsegv(signr, current);
473	return 0;
474}
475
476
477/*
478 * OK, we're invoking a handler
479 */
480static int handle_signal(unsigned long sig, struct k_sigaction *ka,
481			 siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
482{
483	int ret;
484
485	/* Set up Signal Frame */
486	ret = setup_rt_frame(sig, ka, info, oldset, regs);
487
488	if (ret && !(ka->sa.sa_flags & SA_NODEFER)) {
489		spin_lock_irq(&current->sighand->siglock);
490		sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
491		sigaddset(&current->blocked,sig);
492		recalc_sigpending();
493		spin_unlock_irq(&current->sighand->siglock);
494	}
495
496	return ret;
497}
498
499static inline void syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
500{
501	switch ((int)regs->result) {
502	case -ERESTART_RESTARTBLOCK:
503	case -ERESTARTNOHAND:
504		/* ERESTARTNOHAND means that the syscall should only be
505		 * restarted if there was no handler for the signal, and since
506		 * we only get here if there is a handler, we dont restart.
507		 */
508		regs->result = -EINTR;
509		break;
510	case -ERESTARTSYS:
511		/* ERESTARTSYS means to restart the syscall if there is no
512		 * handler or the handler was registered with SA_RESTART
513		 */
514		if (!(ka->sa.sa_flags & SA_RESTART)) {
515			regs->result = -EINTR;
516			break;
517		}
518		/* fallthrough */
519	case -ERESTARTNOINTR:
520		/* ERESTARTNOINTR means that the syscall should be
521		 * called again after the signal handler returns.
522		 */
523		regs->gpr[3] = regs->orig_gpr3;
524		regs->nip -= 4;
525		regs->result = 0;
526		break;
527	}
528}
529
530/*
531 * Note that 'init' is a special process: it doesn't get signals it doesn't
532 * want to handle. Thus you cannot kill init even with a SIGKILL even by
533 * mistake.
534 */
535int do_signal(sigset_t *oldset, struct pt_regs *regs)
536{
537	siginfo_t info;
538	int signr;
539	struct k_sigaction ka;
540
541	/*
542	 * If the current thread is 32 bit - invoke the
543	 * 32 bit signal handling code
544	 */
545	if (test_thread_flag(TIF_32BIT))
546		return do_signal32(oldset, regs);
547
548	if (!oldset)
549		oldset = &current->blocked;
550
551	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
552	if (signr > 0) {
553		/* Whee!  Actually deliver the signal.  */
554		if (TRAP(regs) == 0x0C00)
555			syscall_restart(regs, &ka);
556		return handle_signal(signr, &ka, &info, oldset, regs);
557	}
558
559	if (TRAP(regs) == 0x0C00) {	/* System Call! */
560		if ((int)regs->result == -ERESTARTNOHAND ||
561		    (int)regs->result == -ERESTARTSYS ||
562		    (int)regs->result == -ERESTARTNOINTR) {
563			regs->gpr[3] = regs->orig_gpr3;
564			regs->nip -= 4; /* Back up & retry system call */
565			regs->result = 0;
566		} else if ((int)regs->result == -ERESTART_RESTARTBLOCK) {
567			regs->gpr[0] = __NR_restart_syscall;
568			regs->nip -= 4;
569			regs->result = 0;
570		}
571	}
572
573	return 0;
574}
575EXPORT_SYMBOL(do_signal);