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#include <linux/tracehook.h>
20
21#include <asm/uaccess.h>
22#include <asm/ucontext.h>
23#include <asm/syscalls.h>
24
25#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
26
27asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
28			       struct pt_regs *regs)
29{
30	return do_sigaltstack(uss, uoss, regs->sp);
31}
32
33struct rt_sigframe
34{
35	struct siginfo info;
36	struct ucontext uc;
37	unsigned long retcode;
38};
39
40static int
41restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
42{
43	int err = 0;
44
45#define COPY(x)		err |= __get_user(regs->x, &sc->x)
46	COPY(sr);
47	COPY(pc);
48	COPY(lr);
49	COPY(sp);
50	COPY(r12);
51	COPY(r11);
52	COPY(r10);
53	COPY(r9);
54	COPY(r8);
55	COPY(r7);
56	COPY(r6);
57	COPY(r5);
58	COPY(r4);
59	COPY(r3);
60	COPY(r2);
61	COPY(r1);
62	COPY(r0);
63#undef	COPY
64
65	/*
66	 * Don't allow anyone to pretend they're running in supervisor
67	 * mode or something...
68	 */
69	err |= !valid_user_regs(regs);
70
71	return err;
72}
73
74
75asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
76{
77	struct rt_sigframe __user *frame;
78	sigset_t set;
79
80	frame = (struct rt_sigframe __user *)regs->sp;
81	pr_debug("SIG return: frame = %p\n", frame);
82
83	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
84		goto badframe;
85
86	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
87		goto badframe;
88
89	sigdelsetmask(&set, ~_BLOCKABLE);
90	spin_lock_irq(&current->sighand->siglock);
91	current->blocked = set;
92	recalc_sigpending();
93	spin_unlock_irq(&current->sighand->siglock);
94
95	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
96		goto badframe;
97
98	if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
99		goto badframe;
100
101	pr_debug("Context restored: pc = %08lx, lr = %08lx, sp = %08lx\n",
102		 regs->pc, regs->lr, regs->sp);
103
104	return regs->r12;
105
106badframe:
107	force_sig(SIGSEGV, current);
108	return 0;
109}
110
111static int
112setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
113{
114	int err = 0;
115
116#define COPY(x)		err |= __put_user(regs->x, &sc->x)
117	COPY(sr);
118	COPY(pc);
119	COPY(lr);
120	COPY(sp);
121	COPY(r12);
122	COPY(r11);
123	COPY(r10);
124	COPY(r9);
125	COPY(r8);
126	COPY(r7);
127	COPY(r6);
128	COPY(r5);
129	COPY(r4);
130	COPY(r3);
131	COPY(r2);
132	COPY(r1);
133	COPY(r0);
134#undef	COPY
135
136	return err;
137}
138
139static inline void __user *
140get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
141{
142	unsigned long sp = regs->sp;
143
144	if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
145		sp = current->sas_ss_sp + current->sas_ss_size;
146
147	return (void __user *)((sp - framesize) & ~3);
148}
149
150static int
151setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
152	       sigset_t *set, struct pt_regs *regs)
153{
154	struct rt_sigframe __user *frame;
155	int err = 0;
156
157	frame = get_sigframe(ka, regs, sizeof(*frame));
158	err = -EFAULT;
159	if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
160		goto out;
161
162	/*
163	 * Set up the return code:
164	 *
165	 *	mov	r8, __NR_rt_sigreturn
166	 *	scall
167	 *
168	 * Note: This will blow up since we're using a non-executable
169	 * stack. Better use SA_RESTORER.
170	 */
171#if __NR_rt_sigreturn > 127
172# error __NR_rt_sigreturn must be < 127 to fit in a short mov
173#endif
174	err = __put_user(0x3008d733 | (__NR_rt_sigreturn << 20),
175			 &frame->retcode);
176
177	err |= copy_siginfo_to_user(&frame->info, info);
178
179	/* Set up the ucontext */
180	err |= __put_user(0, &frame->uc.uc_flags);
181	err |= __put_user(NULL, &frame->uc.uc_link);
182	err |= __put_user((void __user *)current->sas_ss_sp,
183			  &frame->uc.uc_stack.ss_sp);
184	err |= __put_user(sas_ss_flags(regs->sp),
185			  &frame->uc.uc_stack.ss_flags);
186	err |= __put_user(current->sas_ss_size,
187			  &frame->uc.uc_stack.ss_size);
188	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
189	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
190
191	if (err)
192		goto out;
193
194	regs->r12 = sig;
195	regs->r11 = (unsigned long) &frame->info;
196	regs->r10 = (unsigned long) &frame->uc;
197	regs->sp = (unsigned long) frame;
198	if (ka->sa.sa_flags & SA_RESTORER)
199		regs->lr = (unsigned long)ka->sa.sa_restorer;
200	else {
201		printk(KERN_NOTICE "[%s:%d] did not set SA_RESTORER\n",
202		       current->comm, current->pid);
203		regs->lr = (unsigned long) &frame->retcode;
204	}
205
206	pr_debug("SIG deliver [%s:%d]: sig=%d sp=0x%lx pc=0x%lx->0x%p lr=0x%lx\n",
207		 current->comm, current->pid, sig, regs->sp,
208		 regs->pc, ka->sa.sa_handler, regs->lr);
209
210	regs->pc = (unsigned long) ka->sa.sa_handler;
211
212out:
213	return err;
214}
215
216static inline void setup_syscall_restart(struct pt_regs *regs)
217{
218	if (regs->r12 == -ERESTART_RESTARTBLOCK)
219		regs->r8 = __NR_restart_syscall;
220	else
221		regs->r12 = regs->r12_orig;
222	regs->pc -= 2;
223}
224
225static inline void
226handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
227	      sigset_t *oldset, struct pt_regs *regs, int syscall)
228{
229	int ret;
230
231	/*
232	 * Set up the stack frame
233	 */
234	ret = setup_rt_frame(sig, ka, info, oldset, regs);
235
236	/*
237	 * Check that the resulting registers are sane
238	 */
239	ret |= !valid_user_regs(regs);
240
241	/*
242	 * Block the signal if we were unsuccessful.
243	 */
244	if (ret != 0 || !(ka->sa.sa_flags & SA_NODEFER)) {
245		spin_lock_irq(&current->sighand->siglock);
246		sigorsets(&current->blocked, &current->blocked,
247			  &ka->sa.sa_mask);
248		sigaddset(&current->blocked, sig);
249		recalc_sigpending();
250		spin_unlock_irq(&current->sighand->siglock);
251	}
252
253	if (ret == 0)
254		return;
255
256	force_sigsegv(sig, current);
257}
258
259/*
260 * Note that 'init' is a special process: it doesn't get signals it
261 * doesn't want to handle. Thus you cannot kill init even with a
262 * SIGKILL even by mistake.
263 */
264int do_signal(struct pt_regs *regs, sigset_t *oldset, int syscall)
265{
266	siginfo_t info;
267	int signr;
268	struct k_sigaction ka;
269
270	/*
271	 * We want the common case to go fast, which is why we may in
272	 * certain cases get here from kernel mode. Just return
273	 * without doing anything if so.
274	 */
275	if (!user_mode(regs))
276		return 0;
277
278	if (test_thread_flag(TIF_RESTORE_SIGMASK))
279		oldset = &current->saved_sigmask;
280	else if (!oldset)
281		oldset = &current->blocked;
282
283	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
284	if (syscall) {
285		switch (regs->r12) {
286		case -ERESTART_RESTARTBLOCK:
287		case -ERESTARTNOHAND:
288			if (signr > 0) {
289				regs->r12 = -EINTR;
290				break;
291			}
292			/* fall through */
293		case -ERESTARTSYS:
294			if (signr > 0 && !(ka.sa.sa_flags & SA_RESTART)) {
295				regs->r12 = -EINTR;
296				break;
297			}
298			/* fall through */
299		case -ERESTARTNOINTR:
300			setup_syscall_restart(regs);
301		}
302	}
303
304	if (signr == 0) {
305		/* No signal to deliver -- put the saved sigmask back */
306		if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
307			clear_thread_flag(TIF_RESTORE_SIGMASK);
308			sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
309		}
310		return 0;
311	}
312
313	handle_signal(signr, &ka, &info, oldset, regs, syscall);
314	return 1;
315}
316
317asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
318{
319	int syscall = 0;
320
321	if ((sysreg_read(SR) & MODE_MASK) == MODE_SUPERVISOR)
322		syscall = 1;
323
324	if (ti->flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
325		do_signal(regs, &current->blocked, syscall);
326
327	if (ti->flags & _TIF_NOTIFY_RESUME) {
328		clear_thread_flag(TIF_NOTIFY_RESUME);
329		tracehook_notify_resume(regs);
330		if (current->replacement_session_keyring)
331			key_replace_session_keyring();
332	}
333}
334