1/*
2 * Signal handling
3 *
4 * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
5 * Copyright (C) 2008-2009 PetaLogix
6 * Copyright (C) 2003,2004 John Williams <jwilliams@itee.uq.edu.au>
7 * Copyright (C) 2001 NEC Corporation
8 * Copyright (C) 2001 Miles Bader <miles@gnu.org>
9 * Copyright (C) 1999,2000 Niibe Yutaka & Kaz Kojima
10 * Copyright (C) 1991,1992 Linus Torvalds
11 *
12 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
13 *
14 * This file was was derived from the sh version, arch/sh/kernel/signal.c
15 *
16 * This file is subject to the terms and conditions of the GNU General
17 * Public License. See the file COPYING in the main directory of this
18 * archive for more details.
19 */
20
21#include <linux/sched.h>
22#include <linux/mm.h>
23#include <linux/smp.h>
24#include <linux/kernel.h>
25#include <linux/signal.h>
26#include <linux/errno.h>
27#include <linux/wait.h>
28#include <linux/ptrace.h>
29#include <linux/unistd.h>
30#include <linux/stddef.h>
31#include <linux/personality.h>
32#include <linux/percpu.h>
33#include <linux/linkage.h>
34#include <linux/tracehook.h>
35#include <asm/entry.h>
36#include <asm/ucontext.h>
37#include <linux/uaccess.h>
38#include <asm/pgtable.h>
39#include <asm/pgalloc.h>
40#include <linux/syscalls.h>
41#include <asm/cacheflush.h>
42#include <asm/syscalls.h>
43
44/*
45 * Do a signal return; undo the signal stack.
46 */
47struct sigframe {
48	struct sigcontext sc;
49	unsigned long extramask[_NSIG_WORDS-1];
50	unsigned long tramp[2];	/* signal trampoline */
51};
52
53struct rt_sigframe {
54	struct siginfo info;
55	struct ucontext uc;
56	unsigned long tramp[2];	/* signal trampoline */
57};
58
59static int restore_sigcontext(struct pt_regs *regs,
60				struct sigcontext __user *sc, int *rval_p)
61{
62	unsigned int err = 0;
63
64#define COPY(x)		{err |= __get_user(regs->x, &sc->regs.x); }
65	COPY(r0);
66	COPY(r1);
67	COPY(r2);	COPY(r3);	COPY(r4);	COPY(r5);
68	COPY(r6);	COPY(r7);	COPY(r8);	COPY(r9);
69	COPY(r10);	COPY(r11);	COPY(r12);	COPY(r13);
70	COPY(r14);	COPY(r15);	COPY(r16);	COPY(r17);
71	COPY(r18);	COPY(r19);	COPY(r20);	COPY(r21);
72	COPY(r22);	COPY(r23);	COPY(r24);	COPY(r25);
73	COPY(r26);	COPY(r27);	COPY(r28);	COPY(r29);
74	COPY(r30);	COPY(r31);
75	COPY(pc);	COPY(ear);	COPY(esr);	COPY(fsr);
76#undef COPY
77
78	*rval_p = regs->r3;
79
80	return err;
81}
82
83asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
84{
85	struct rt_sigframe __user *frame =
86		(struct rt_sigframe __user *)(regs->r1);
87
88	sigset_t set;
89	int rval;
90
91	/* Always make any pending restarted system calls return -EINTR */
92	current->restart_block.fn = do_no_restart_syscall;
93
94	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
95		goto badframe;
96
97	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
98		goto badframe;
99
100	set_current_blocked(&set);
101
102	if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval))
103		goto badframe;
104
105	if (restore_altstack(&frame->uc.uc_stack))
106		goto badframe;
107
108	return rval;
109
110badframe:
111	force_sig(SIGSEGV, current);
112	return 0;
113}
114
115/*
116 * Set up a signal frame.
117 */
118
119static int
120setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
121		unsigned long mask)
122{
123	int err = 0;
124
125#define COPY(x)		{err |= __put_user(regs->x, &sc->regs.x); }
126	COPY(r0);
127	COPY(r1);
128	COPY(r2);	COPY(r3);	COPY(r4);	COPY(r5);
129	COPY(r6);	COPY(r7);	COPY(r8);	COPY(r9);
130	COPY(r10);	COPY(r11);	COPY(r12);	COPY(r13);
131	COPY(r14);	COPY(r15);	COPY(r16);	COPY(r17);
132	COPY(r18);	COPY(r19);	COPY(r20);	COPY(r21);
133	COPY(r22);	COPY(r23);	COPY(r24);	COPY(r25);
134	COPY(r26);	COPY(r27);	COPY(r28);	COPY(r29);
135	COPY(r30);	COPY(r31);
136	COPY(pc);	COPY(ear);	COPY(esr);	COPY(fsr);
137#undef COPY
138
139	err |= __put_user(mask, &sc->oldmask);
140
141	return err;
142}
143
144/*
145 * Determine which stack to use..
146 */
147static inline void __user *
148get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t frame_size)
149{
150	/* Default to using normal stack */
151	unsigned long sp = sigsp(regs->r1, ksig);
152
153	return (void __user *)((sp - frame_size) & -8UL);
154}
155
156static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
157			  struct pt_regs *regs)
158{
159	struct rt_sigframe __user *frame;
160	int err = 0, sig = ksig->sig;
161	unsigned long address = 0;
162#ifdef CONFIG_MMU
163	pmd_t *pmdp;
164	pte_t *ptep;
165#endif
166
167	frame = get_sigframe(ksig, regs, sizeof(*frame));
168
169	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
170		return -EFAULT;
171
172	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
173		err |= copy_siginfo_to_user(&frame->info, &ksig->info);
174
175	/* Create the ucontext. */
176	err |= __put_user(0, &frame->uc.uc_flags);
177	err |= __put_user(NULL, &frame->uc.uc_link);
178	err |= __save_altstack(&frame->uc.uc_stack, regs->r1);
179	err |= setup_sigcontext(&frame->uc.uc_mcontext,
180			regs, set->sig[0]);
181	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
182
183	/* Set up to return from userspace. If provided, use a stub
184	 already in userspace. */
185	/* minus 8 is offset to cater for "rtsd r15,8" */
186	/* addi r12, r0, __NR_sigreturn */
187	err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
188			frame->tramp + 0);
189	/* brki r14, 0x8 */
190	err |= __put_user(0xb9cc0008, frame->tramp + 1);
191
192	/* Return from sighandler will jump to the tramp.
193	 Negative 8 offset because return is rtsd r15, 8 */
194	regs->r15 = ((unsigned long)frame->tramp)-8;
195
196	address = ((unsigned long)frame->tramp);
197#ifdef CONFIG_MMU
198	pmdp = pmd_offset(pud_offset(
199			pgd_offset(current->mm, address),
200					address), address);
201
202	preempt_disable();
203	ptep = pte_offset_map(pmdp, address);
204	if (pte_present(*ptep)) {
205		address = (unsigned long) page_address(pte_page(*ptep));
206		/* MS: I need add offset in page */
207		address += ((unsigned long)frame->tramp) & ~PAGE_MASK;
208		/* MS address is virtual */
209		address = __virt_to_phys(address);
210		invalidate_icache_range(address, address + 8);
211		flush_dcache_range(address, address + 8);
212	}
213	pte_unmap(ptep);
214	preempt_enable();
215#else
216	flush_icache_range(address, address + 8);
217	flush_dcache_range(address, address + 8);
218#endif
219	if (err)
220		return -EFAULT;
221
222	/* Set up registers for signal handler */
223	regs->r1 = (unsigned long) frame;
224
225	/* Signal handler args: */
226	regs->r5 = sig; /* arg 0: signum */
227	regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */
228	regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */
229	/* Offset to handle microblaze rtid r14, 0 */
230	regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
231
232#ifdef DEBUG_SIG
233	pr_info("SIG deliver (%s:%d): sp=%p pc=%08lx\n",
234		current->comm, current->pid, frame, regs->pc);
235#endif
236
237	return 0;
238}
239
240/* Handle restarting system calls */
241static inline void
242handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
243{
244	switch (regs->r3) {
245	case -ERESTART_RESTARTBLOCK:
246	case -ERESTARTNOHAND:
247		if (!has_handler)
248			goto do_restart;
249		regs->r3 = -EINTR;
250		break;
251	case -ERESTARTSYS:
252		if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
253			regs->r3 = -EINTR;
254			break;
255	}
256	/* fallthrough */
257	case -ERESTARTNOINTR:
258do_restart:
259		/* offset of 4 bytes to re-execute trap (brki) instruction */
260		regs->pc -= 4;
261		break;
262	}
263}
264
265/*
266 * OK, we're invoking a handler
267 */
268
269static void
270handle_signal(struct ksignal *ksig, struct pt_regs *regs)
271{
272	sigset_t *oldset = sigmask_to_save();
273	int ret;
274
275	/* Set up the stack frame */
276	ret = setup_rt_frame(ksig, oldset, regs);
277
278	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
279}
280
281/*
282 * Note that 'init' is a special process: it doesn't get signals it doesn't
283 * want to handle. Thus you cannot kill init even with a SIGKILL even by
284 * mistake.
285 *
286 * Note that we go through the signals twice: once to check the signals that
287 * the kernel can handle, and then we build all the user-level signal handling
288 * stack-frames in one go after that.
289 */
290static void do_signal(struct pt_regs *regs, int in_syscall)
291{
292	struct ksignal ksig;
293
294#ifdef DEBUG_SIG
295	pr_info("do signal: %p %d\n", regs, in_syscall);
296	pr_info("do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1,
297			regs->r12, current_thread_info()->flags);
298#endif
299
300	if (get_signal(&ksig)) {
301		/* Whee! Actually deliver the signal. */
302		if (in_syscall)
303			handle_restart(regs, &ksig.ka, 1);
304		handle_signal(&ksig, regs);
305		return;
306	}
307
308	if (in_syscall)
309		handle_restart(regs, NULL, 0);
310
311	/*
312	 * If there's no signal to deliver, we just put the saved sigmask
313	 * back.
314	 */
315	restore_saved_sigmask();
316}
317
318asmlinkage void do_notify_resume(struct pt_regs *regs, int in_syscall)
319{
320	if (test_thread_flag(TIF_SIGPENDING))
321		do_signal(regs, in_syscall);
322
323	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
324		tracehook_notify_resume(regs);
325}
326