1/* signal.c: FRV specific bits of signal handling
2 *
3 * Copyright (C) 2003-5 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 * - Derived from arch/m68k/kernel/signal.c
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 */
12
13#include <linux/sched.h>
14#include <linux/mm.h>
15#include <linux/smp.h>
16#include <linux/kernel.h>
17#include <linux/signal.h>
18#include <linux/errno.h>
19#include <linux/wait.h>
20#include <linux/ptrace.h>
21#include <linux/unistd.h>
22#include <linux/personality.h>
23#include <linux/tracehook.h>
24#include <asm/ucontext.h>
25#include <asm/uaccess.h>
26#include <asm/cacheflush.h>
27
28#define DEBUG_SIG 0
29
30struct fdpic_func_descriptor {
31	unsigned long	text;
32	unsigned long	GOT;
33};
34
35/*
36 * Do a signal return; undo the signal stack.
37 */
38
39struct sigframe
40{
41	__sigrestore_t pretcode;
42	int sig;
43	struct sigcontext sc;
44	unsigned long extramask[_NSIG_WORDS-1];
45	uint32_t retcode[2];
46};
47
48struct rt_sigframe
49{
50	__sigrestore_t pretcode;
51	int sig;
52	struct siginfo __user *pinfo;
53	void __user *puc;
54	struct siginfo info;
55	struct ucontext uc;
56	uint32_t retcode[2];
57};
58
59static int restore_sigcontext(struct sigcontext __user *sc, int *_gr8)
60{
61	struct user_context *user = current->thread.user;
62	unsigned long tbr, psr;
63
64	/* Always make any pending restarted system calls return -EINTR */
65	current->restart_block.fn = do_no_restart_syscall;
66
67	tbr = user->i.tbr;
68	psr = user->i.psr;
69	if (copy_from_user(user, &sc->sc_context, sizeof(sc->sc_context)))
70		goto badframe;
71	user->i.tbr = tbr;
72	user->i.psr = psr;
73
74	restore_user_regs(user);
75
76	user->i.syscallno = -1;		/* disable syscall checks */
77
78	*_gr8 = user->i.gr[8];
79	return 0;
80
81 badframe:
82	return 1;
83}
84
85asmlinkage int sys_sigreturn(void)
86{
87	struct sigframe __user *frame = (struct sigframe __user *) __frame->sp;
88	sigset_t set;
89	int gr8;
90
91	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
92		goto badframe;
93	if (__get_user(set.sig[0], &frame->sc.sc_oldmask))
94		goto badframe;
95
96	if (_NSIG_WORDS > 1 &&
97	    __copy_from_user(&set.sig[1], &frame->extramask, sizeof(frame->extramask)))
98		goto badframe;
99
100	set_current_blocked(&set);
101
102	if (restore_sigcontext(&frame->sc, &gr8))
103		goto badframe;
104	return gr8;
105
106 badframe:
107	force_sig(SIGSEGV, current);
108	return 0;
109}
110
111asmlinkage int sys_rt_sigreturn(void)
112{
113	struct rt_sigframe __user *frame = (struct rt_sigframe __user *) __frame->sp;
114	sigset_t set;
115	int gr8;
116
117	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
118		goto badframe;
119	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
120		goto badframe;
121
122	set_current_blocked(&set);
123
124	if (restore_sigcontext(&frame->uc.uc_mcontext, &gr8))
125		goto badframe;
126
127	if (restore_altstack(&frame->uc.uc_stack))
128		goto badframe;
129
130	return gr8;
131
132badframe:
133	force_sig(SIGSEGV, current);
134	return 0;
135}
136
137/*
138 * Set up a signal frame
139 */
140static int setup_sigcontext(struct sigcontext __user *sc, unsigned long mask)
141{
142	save_user_regs(current->thread.user);
143
144	if (copy_to_user(&sc->sc_context, current->thread.user, sizeof(sc->sc_context)) != 0)
145		goto badframe;
146
147	/* non-iBCS2 extensions.. */
148	if (__put_user(mask, &sc->sc_oldmask) < 0)
149		goto badframe;
150
151	return 0;
152
153 badframe:
154	return 1;
155}
156
157/*****************************************************************************/
158/*
159 * Determine which stack to use..
160 */
161static inline void __user *get_sigframe(struct ksignal *ksig,
162					size_t frame_size)
163{
164	unsigned long sp = sigsp(__frame->sp, ksig);
165
166	return (void __user *) ((sp - frame_size) & ~7UL);
167
168} /* end get_sigframe() */
169
170/*****************************************************************************/
171/*
172 *
173 */
174static int setup_frame(struct ksignal *ksig, sigset_t *set)
175{
176	struct sigframe __user *frame;
177	int sig = ksig->sig;
178
179	frame = get_sigframe(ksig, sizeof(*frame));
180
181	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
182		return -EFAULT;
183
184	if (__put_user(sig, &frame->sig) < 0)
185		return -EFAULT;
186
187	if (setup_sigcontext(&frame->sc, set->sig[0]))
188		return -EFAULT;
189
190	if (_NSIG_WORDS > 1) {
191		if (__copy_to_user(frame->extramask, &set->sig[1],
192				   sizeof(frame->extramask)))
193			return -EFAULT;
194	}
195
196	/* Set up to return from userspace.  If provided, use a stub
197	 * already in userspace.  */
198	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
199		if (__put_user(ksig->ka.sa.sa_restorer, &frame->pretcode) < 0)
200			return -EFAULT;
201	}
202	else {
203		/* Set up the following code on the stack:
204		 *	setlos	#__NR_sigreturn,gr7
205		 *	tira	gr0,0
206		 */
207		if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
208		    __put_user(0x8efc0000|__NR_sigreturn, &frame->retcode[0]) ||
209		    __put_user(0xc0700000, &frame->retcode[1]))
210			return -EFAULT;
211
212		flush_icache_range((unsigned long) frame->retcode,
213				   (unsigned long) (frame->retcode + 2));
214	}
215
216	/* Set up registers for the signal handler */
217	if (current->personality & FDPIC_FUNCPTRS) {
218		struct fdpic_func_descriptor __user *funcptr =
219			(struct fdpic_func_descriptor __user *) ksig->ka.sa.sa_handler;
220		struct fdpic_func_descriptor desc;
221		if (copy_from_user(&desc, funcptr, sizeof(desc)))
222			return -EFAULT;
223		__frame->pc = desc.text;
224		__frame->gr15 = desc.GOT;
225	} else {
226		__frame->pc   = (unsigned long) ksig->ka.sa.sa_handler;
227		__frame->gr15 = 0;
228	}
229
230	__frame->sp   = (unsigned long) frame;
231	__frame->lr   = (unsigned long) &frame->retcode;
232	__frame->gr8  = sig;
233
234#if DEBUG_SIG
235	printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
236	       sig, current->comm, current->pid, frame, __frame->pc,
237	       frame->pretcode);
238#endif
239
240	return 0;
241} /* end setup_frame() */
242
243/*****************************************************************************/
244/*
245 *
246 */
247static int setup_rt_frame(struct ksignal *ksig, sigset_t *set)
248{
249	struct rt_sigframe __user *frame;
250	int sig = ksig->sig;
251
252	frame = get_sigframe(ksig, sizeof(*frame));
253
254	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
255		return -EFAULT;
256
257	if (__put_user(sig,		&frame->sig) ||
258	    __put_user(&frame->info,	&frame->pinfo) ||
259	    __put_user(&frame->uc,	&frame->puc))
260		return -EFAULT;
261
262	if (copy_siginfo_to_user(&frame->info, &ksig->info))
263		return -EFAULT;
264
265	/* Create the ucontext.  */
266	if (__put_user(0, &frame->uc.uc_flags) ||
267	    __put_user(NULL, &frame->uc.uc_link) ||
268	    __save_altstack(&frame->uc.uc_stack, __frame->sp))
269		return -EFAULT;
270
271	if (setup_sigcontext(&frame->uc.uc_mcontext, set->sig[0]))
272		return -EFAULT;
273
274	if (__copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)))
275		return -EFAULT;
276
277	/* Set up to return from userspace.  If provided, use a stub
278	 * already in userspace.  */
279	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
280		if (__put_user(ksig->ka.sa.sa_restorer, &frame->pretcode))
281			return -EFAULT;
282	}
283	else {
284		/* Set up the following code on the stack:
285		 *	setlos	#__NR_sigreturn,gr7
286		 *	tira	gr0,0
287		 */
288		if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
289		    __put_user(0x8efc0000|__NR_rt_sigreturn, &frame->retcode[0]) ||
290		    __put_user(0xc0700000, &frame->retcode[1]))
291			return -EFAULT;
292
293		flush_icache_range((unsigned long) frame->retcode,
294				   (unsigned long) (frame->retcode + 2));
295	}
296
297	/* Set up registers for signal handler */
298	if (current->personality & FDPIC_FUNCPTRS) {
299		struct fdpic_func_descriptor __user *funcptr =
300			(struct fdpic_func_descriptor __user *) ksig->ka.sa.sa_handler;
301		struct fdpic_func_descriptor desc;
302		if (copy_from_user(&desc, funcptr, sizeof(desc)))
303			return -EFAULT;
304		__frame->pc = desc.text;
305		__frame->gr15 = desc.GOT;
306	} else {
307		__frame->pc   = (unsigned long) ksig->ka.sa.sa_handler;
308		__frame->gr15 = 0;
309	}
310
311	__frame->sp  = (unsigned long) frame;
312	__frame->lr  = (unsigned long) &frame->retcode;
313	__frame->gr8 = sig;
314	__frame->gr9 = (unsigned long) &frame->info;
315
316#if DEBUG_SIG
317	printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
318	       sig, current->comm, current->pid, frame, __frame->pc,
319	       frame->pretcode);
320#endif
321	return 0;
322
323} /* end setup_rt_frame() */
324
325/*****************************************************************************/
326/*
327 * OK, we're invoking a handler
328 */
329static void handle_signal(struct ksignal *ksig)
330{
331	sigset_t *oldset = sigmask_to_save();
332	int ret;
333
334	/* Are we from a system call? */
335	if (__frame->syscallno != -1) {
336		/* If so, check system call restarting.. */
337		switch (__frame->gr8) {
338		case -ERESTART_RESTARTBLOCK:
339		case -ERESTARTNOHAND:
340			__frame->gr8 = -EINTR;
341			break;
342
343		case -ERESTARTSYS:
344			if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
345				__frame->gr8 = -EINTR;
346				break;
347			}
348
349			/* fallthrough */
350		case -ERESTARTNOINTR:
351			__frame->gr8 = __frame->orig_gr8;
352			__frame->pc -= 4;
353		}
354		__frame->syscallno = -1;
355	}
356
357	/* Set up the stack frame */
358	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
359		ret = setup_rt_frame(ksig, oldset);
360	else
361		ret = setup_frame(ksig, oldset);
362
363	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
364} /* end handle_signal() */
365
366/*****************************************************************************/
367/*
368 * Note that 'init' is a special process: it doesn't get signals it doesn't
369 * want to handle. Thus you cannot kill init even with a SIGKILL even by
370 * mistake.
371 */
372static void do_signal(void)
373{
374	struct ksignal ksig;
375
376	if (get_signal(&ksig)) {
377		handle_signal(&ksig);
378		return;
379	}
380
381	/* Did we come from a system call? */
382	if (__frame->syscallno != -1) {
383		/* Restart the system call - no handlers present */
384		switch (__frame->gr8) {
385		case -ERESTARTNOHAND:
386		case -ERESTARTSYS:
387		case -ERESTARTNOINTR:
388			__frame->gr8 = __frame->orig_gr8;
389			__frame->pc -= 4;
390			break;
391
392		case -ERESTART_RESTARTBLOCK:
393			__frame->gr7 = __NR_restart_syscall;
394			__frame->pc -= 4;
395			break;
396		}
397		__frame->syscallno = -1;
398	}
399
400	/* if there's no signal to deliver, we just put the saved sigmask
401	 * back */
402	restore_saved_sigmask();
403} /* end do_signal() */
404
405/*****************************************************************************/
406/*
407 * notification of userspace execution resumption
408 * - triggered by the TIF_WORK_MASK flags
409 */
410asmlinkage void do_notify_resume(__u32 thread_info_flags)
411{
412	/* pending single-step? */
413	if (thread_info_flags & _TIF_SINGLESTEP)
414		clear_thread_flag(TIF_SINGLESTEP);
415
416	/* deal with pending signal delivery */
417	if (thread_info_flags & _TIF_SIGPENDING)
418		do_signal();
419
420	/* deal with notification on about to resume userspace execution */
421	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
422		clear_thread_flag(TIF_NOTIFY_RESUME);
423		tracehook_notify_resume(__frame);
424	}
425
426} /* end do_notify_resume() */
427