1/*
2 * Copyright (C) 2004-2006 Atmel Corporation
3 *
4 * Based on linux/arch/sh/kernel/signal.c
5 *  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
6 *  Copyright (C) 1991, 1992  Linus Torvalds
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/sched.h>
14#include <linux/mm.h>
15#include <linux/errno.h>
16#include <linux/ptrace.h>
17#include <linux/unistd.h>
18#include <linux/freezer.h>
19
20#include <asm/uaccess.h>
21#include <asm/ucontext.h>
22
23#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
24
25asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
26			       struct pt_regs *regs)
27{
28	return do_sigaltstack(uss, uoss, regs->sp);
29}
30
31struct rt_sigframe
32{
33	struct siginfo info;
34	struct ucontext uc;
35	unsigned long retcode;
36};
37
38static int
39restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
40{
41	int err = 0;
42
43#define COPY(x)		err |= __get_user(regs->x, &sc->x)
44	COPY(sr);
45	COPY(pc);
46	COPY(lr);
47	COPY(sp);
48	COPY(r12);
49	COPY(r11);
50	COPY(r10);
51	COPY(r9);
52	COPY(r8);
53	COPY(r7);
54	COPY(r6);
55	COPY(r5);
56	COPY(r4);
57	COPY(r3);
58	COPY(r2);
59	COPY(r1);
60	COPY(r0);
61#undef	COPY
62
63	/*
64	 * Don't allow anyone to pretend they're running in supervisor
65	 * mode or something...
66	 */
67	err |= !valid_user_regs(regs);
68
69	return err;
70}
71
72
73asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
74{
75	struct rt_sigframe __user *frame;
76	sigset_t set;
77
78	frame = (struct rt_sigframe __user *)regs->sp;
79	pr_debug("SIG return: frame = %p\n", frame);
80
81	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
82		goto badframe;
83
84	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
85		goto badframe;
86
87	sigdelsetmask(&set, ~_BLOCKABLE);
88	spin_lock_irq(&current->sighand->siglock);
89	current->blocked = set;
90	recalc_sigpending();
91	spin_unlock_irq(&current->sighand->siglock);
92
93	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
94		goto badframe;
95
96	pr_debug("Context restored: pc = %08lx, lr = %08lx, sp = %08lx\n",
97		 regs->pc, regs->lr, regs->sp);
98
99	return regs->r12;
100
101badframe:
102	force_sig(SIGSEGV, current);
103	return 0;
104}
105
106static int
107setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
108{
109	int err = 0;
110
111#define COPY(x)		err |= __put_user(regs->x, &sc->x)
112	COPY(sr);
113	COPY(pc);
114	COPY(lr);
115	COPY(sp);
116	COPY(r12);
117	COPY(r11);
118	COPY(r10);
119	COPY(r9);
120	COPY(r8);
121	COPY(r7);
122	COPY(r6);
123	COPY(r5);
124	COPY(r4);
125	COPY(r3);
126	COPY(r2);
127	COPY(r1);
128	COPY(r0);
129#undef	COPY
130
131	return err;
132}
133
134static inline void __user *
135get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
136{
137	unsigned long sp = regs->sp;
138
139	if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
140		sp = current->sas_ss_sp + current->sas_ss_size;
141
142	return (void __user *)((sp - framesize) & ~3);
143}
144
145static int
146setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
147	       sigset_t *set, struct pt_regs *regs)
148{
149	struct rt_sigframe __user *frame;
150	int err = 0;
151
152	frame = get_sigframe(ka, regs, sizeof(*frame));
153	err = -EFAULT;
154	if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
155		goto out;
156
157	/*
158	 * Set up the return code:
159	 *
160	 *	mov	r8, __NR_rt_sigreturn
161	 *	scall
162	 *
163	 * Note: This will blow up since we're using a non-executable
164	 * stack. Better use SA_RESTORER.
165	 */
166#if __NR_rt_sigreturn > 127
167# error __NR_rt_sigreturn must be < 127 to fit in a short mov
168#endif
169	err = __put_user(0x3008d733 | (__NR_rt_sigreturn << 20),
170			 &frame->retcode);
171
172	err |= copy_siginfo_to_user(&frame->info, info);
173
174	/* Set up the ucontext */
175	err |= __put_user(0, &frame->uc.uc_flags);
176	err |= __put_user(NULL, &frame->uc.uc_link);
177	err |= __put_user((void __user *)current->sas_ss_sp,
178			  &frame->uc.uc_stack.ss_sp);
179	err |= __put_user(sas_ss_flags(regs->sp),
180			  &frame->uc.uc_stack.ss_flags);
181	err |= __put_user(current->sas_ss_size,
182			  &frame->uc.uc_stack.ss_size);
183	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
184	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
185
186	if (err)
187		goto out;
188
189	regs->r12 = sig;
190	regs->r11 = (unsigned long) &frame->info;
191	regs->r10 = (unsigned long) &frame->uc;
192	regs->sp = (unsigned long) frame;
193	if (ka->sa.sa_flags & SA_RESTORER)
194		regs->lr = (unsigned long)ka->sa.sa_restorer;
195	else {
196		printk(KERN_NOTICE "[%s:%d] did not set SA_RESTORER\n",
197		       current->comm, current->pid);
198		regs->lr = (unsigned long) &frame->retcode;
199	}
200
201	pr_debug("SIG deliver [%s:%d]: sig=%d sp=0x%lx pc=0x%lx->0x%p lr=0x%lx\n",
202		 current->comm, current->pid, sig, regs->sp,
203		 regs->pc, ka->sa.sa_handler, regs->lr);
204
205	regs->pc = (unsigned long) ka->sa.sa_handler;
206
207out:
208	return err;
209}
210
211static inline void restart_syscall(struct pt_regs *regs)
212{
213	if (regs->r12 == -ERESTART_RESTARTBLOCK)
214		regs->r8 = __NR_restart_syscall;
215	else
216		regs->r12 = regs->r12_orig;
217	regs->pc -= 2;
218}
219
220static inline void
221handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
222	      sigset_t *oldset, struct pt_regs *regs, int syscall)
223{
224	int ret;
225
226	/*
227	 * Set up the stack frame
228	 */
229	ret = setup_rt_frame(sig, ka, info, oldset, regs);
230
231	/*
232	 * Check that the resulting registers are sane
233	 */
234	ret |= !valid_user_regs(regs);
235
236	/*
237	 * Block the signal if we were unsuccessful.
238	 */
239	if (ret != 0 || !(ka->sa.sa_flags & SA_NODEFER)) {
240		spin_lock_irq(&current->sighand->siglock);
241		sigorsets(&current->blocked, &current->blocked,
242			  &ka->sa.sa_mask);
243		sigaddset(&current->blocked, sig);
244		recalc_sigpending();
245		spin_unlock_irq(&current->sighand->siglock);
246	}
247
248	if (ret == 0)
249		return;
250
251	force_sigsegv(sig, current);
252}
253
254/*
255 * Note that 'init' is a special process: it doesn't get signals it
256 * doesn't want to handle. Thus you cannot kill init even with a
257 * SIGKILL even by mistake.
258 */
259int do_signal(struct pt_regs *regs, sigset_t *oldset, int syscall)
260{
261	siginfo_t info;
262	int signr;
263	struct k_sigaction ka;
264
265	/*
266	 * We want the common case to go fast, which is why we may in
267	 * certain cases get here from kernel mode. Just return
268	 * without doing anything if so.
269	 */
270	if (!user_mode(regs))
271		return 0;
272
273	if (try_to_freeze()) {
274		signr = 0;
275		if (!signal_pending(current))
276			goto no_signal;
277	}
278
279	if (test_thread_flag(TIF_RESTORE_SIGMASK))
280		oldset = &current->saved_sigmask;
281	else if (!oldset)
282		oldset = &current->blocked;
283
284	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
285no_signal:
286	if (syscall) {
287		switch (regs->r12) {
288		case -ERESTART_RESTARTBLOCK:
289		case -ERESTARTNOHAND:
290			if (signr > 0) {
291				regs->r12 = -EINTR;
292				break;
293			}
294			/* fall through */
295		case -ERESTARTSYS:
296			if (signr > 0 && !(ka.sa.sa_flags & SA_RESTART)) {
297				regs->r12 = -EINTR;
298				break;
299			}
300			/* fall through */
301		case -ERESTARTNOINTR:
302			restart_syscall(regs);
303		}
304	}
305
306	if (signr == 0) {
307		/* No signal to deliver -- put the saved sigmask back */
308		if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
309			clear_thread_flag(TIF_RESTORE_SIGMASK);
310			sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
311		}
312		return 0;
313	}
314
315	handle_signal(signr, &ka, &info, oldset, regs, syscall);
316	return 1;
317}
318
319asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
320{
321	int syscall = 0;
322
323	if ((sysreg_read(SR) & MODE_MASK) == MODE_SUPERVISOR)
324		syscall = 1;
325
326	if (ti->flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
327		do_signal(regs, &current->blocked, syscall);
328}
329