xref: /openbmc/linux/arch/microblaze/kernel/signal.c (revision b6dcefde)
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 <asm/entry.h>
35 #include <asm/ucontext.h>
36 #include <linux/uaccess.h>
37 #include <asm/pgtable.h>
38 #include <asm/pgalloc.h>
39 #include <linux/syscalls.h>
40 #include <asm/cacheflush.h>
41 #include <asm/syscalls.h>
42 
43 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
44 
45 asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_sycall);
46 
47 asmlinkage long
48 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
49 		struct pt_regs *regs)
50 {
51 	return do_sigaltstack(uss, uoss, regs->r1);
52 }
53 
54 /*
55  * Do a signal return; undo the signal stack.
56  */
57 struct sigframe {
58 	struct sigcontext sc;
59 	unsigned long extramask[_NSIG_WORDS-1];
60 	unsigned long tramp[2];	/* signal trampoline */
61 };
62 
63 struct rt_sigframe {
64 	struct siginfo info;
65 	struct ucontext uc;
66 	unsigned long tramp[2];	/* signal trampoline */
67 };
68 
69 static int restore_sigcontext(struct pt_regs *regs,
70 				struct sigcontext __user *sc, int *rval_p)
71 {
72 	unsigned int err = 0;
73 
74 #define COPY(x)		{err |= __get_user(regs->x, &sc->regs.x); }
75 	COPY(r0);
76 	COPY(r1);
77 	COPY(r2);	COPY(r3);	COPY(r4);	COPY(r5);
78 	COPY(r6);	COPY(r7);	COPY(r8);	COPY(r9);
79 	COPY(r10);	COPY(r11);	COPY(r12);	COPY(r13);
80 	COPY(r14);	COPY(r15);	COPY(r16);	COPY(r17);
81 	COPY(r18);	COPY(r19);	COPY(r20);	COPY(r21);
82 	COPY(r22);	COPY(r23);	COPY(r24);	COPY(r25);
83 	COPY(r26);	COPY(r27);	COPY(r28);	COPY(r29);
84 	COPY(r30);	COPY(r31);
85 	COPY(pc);	COPY(ear);	COPY(esr);	COPY(fsr);
86 #undef COPY
87 
88 	*rval_p = regs->r3;
89 
90 	return err;
91 }
92 
93 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
94 {
95 	struct rt_sigframe __user *frame =
96 		(struct rt_sigframe __user *)(regs->r1 + STATE_SAVE_ARG_SPACE);
97 
98 	sigset_t set;
99 	int rval;
100 
101 	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
102 		goto badframe;
103 
104 	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
105 		goto badframe;
106 
107 	sigdelsetmask(&set, ~_BLOCKABLE);
108 	spin_lock_irq(&current->sighand->siglock);
109 	current->blocked = set;
110 	recalc_sigpending();
111 	spin_unlock_irq(&current->sighand->siglock);
112 
113 	if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval))
114 		goto badframe;
115 
116 	/* It is more difficult to avoid calling this function than to
117 	 call it and ignore errors. */
118 	if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->r1))
119 		goto badframe;
120 
121 	return rval;
122 
123 badframe:
124 	force_sig(SIGSEGV, current);
125 	return 0;
126 }
127 
128 /*
129  * Set up a signal frame.
130  */
131 
132 static int
133 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
134 		unsigned long mask)
135 {
136 	int err = 0;
137 
138 #define COPY(x)		{err |= __put_user(regs->x, &sc->regs.x); }
139 	COPY(r0);
140 	COPY(r1);
141 	COPY(r2);	COPY(r3);	COPY(r4);	COPY(r5);
142 	COPY(r6);	COPY(r7);	COPY(r8);	COPY(r9);
143 	COPY(r10);	COPY(r11);	COPY(r12);	COPY(r13);
144 	COPY(r14);	COPY(r15);	COPY(r16);	COPY(r17);
145 	COPY(r18);	COPY(r19);	COPY(r20);	COPY(r21);
146 	COPY(r22);	COPY(r23);	COPY(r24);	COPY(r25);
147 	COPY(r26);	COPY(r27);	COPY(r28);	COPY(r29);
148 	COPY(r30);	COPY(r31);
149 	COPY(pc);	COPY(ear);	COPY(esr);	COPY(fsr);
150 #undef COPY
151 
152 	err |= __put_user(mask, &sc->oldmask);
153 
154 	return err;
155 }
156 
157 /*
158  * Determine which stack to use..
159  */
160 static inline void __user *
161 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
162 {
163 	/* Default to using normal stack */
164 	unsigned long sp = regs->r1;
165 
166 	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && !on_sig_stack(sp))
167 		sp = current->sas_ss_sp + current->sas_ss_size;
168 
169 	return (void __user *)((sp - frame_size) & -8UL);
170 }
171 
172 static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
173 			sigset_t *set, struct pt_regs *regs)
174 {
175 	struct rt_sigframe __user *frame;
176 	int err = 0;
177 	int signal;
178 	unsigned long address = 0;
179 #ifdef CONFIG_MMU
180 	pmd_t *pmdp;
181 	pte_t *ptep;
182 #endif
183 
184 	frame = get_sigframe(ka, regs, sizeof(*frame));
185 
186 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
187 		goto give_sigsegv;
188 
189 	signal = current_thread_info()->exec_domain
190 		&& current_thread_info()->exec_domain->signal_invmap
191 		&& sig < 32
192 		? current_thread_info()->exec_domain->signal_invmap[sig]
193 		: sig;
194 
195 	if (info)
196 		err |= copy_siginfo_to_user(&frame->info, info);
197 
198 	/* Create the ucontext. */
199 	err |= __put_user(0, &frame->uc.uc_flags);
200 	err |= __put_user(0, &frame->uc.uc_link);
201 	err |= __put_user((void *)current->sas_ss_sp,
202 			&frame->uc.uc_stack.ss_sp);
203 	err |= __put_user(sas_ss_flags(regs->r1),
204 			&frame->uc.uc_stack.ss_flags);
205 	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
206 	err |= setup_sigcontext(&frame->uc.uc_mcontext,
207 			regs, set->sig[0]);
208 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
209 
210 	/* Set up to return from userspace. If provided, use a stub
211 	 already in userspace. */
212 	/* minus 8 is offset to cater for "rtsd r15,8" */
213 	/* addi r12, r0, __NR_sigreturn */
214 	err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
215 			frame->tramp + 0);
216 	/* brki r14, 0x8 */
217 	err |= __put_user(0xb9cc0008, frame->tramp + 1);
218 
219 	/* Return from sighandler will jump to the tramp.
220 	 Negative 8 offset because return is rtsd r15, 8 */
221 	regs->r15 = ((unsigned long)frame->tramp)-8;
222 
223 	address = ((unsigned long)frame->tramp);
224 #ifdef CONFIG_MMU
225 	pmdp = pmd_offset(pud_offset(
226 			pgd_offset(current->mm, address),
227 					address), address);
228 
229 	preempt_disable();
230 	ptep = pte_offset_map(pmdp, address);
231 	if (pte_present(*ptep)) {
232 		address = (unsigned long) page_address(pte_page(*ptep));
233 		/* MS: I need add offset in page */
234 		address += ((unsigned long)frame->tramp) & ~PAGE_MASK;
235 		/* MS address is virtual */
236 		address = virt_to_phys(address);
237 		invalidate_icache_range(address, address + 8);
238 		flush_dcache_range(address, address + 8);
239 	}
240 	pte_unmap(ptep);
241 	preempt_enable();
242 #else
243 	flush_icache_range(address, address + 8);
244 	flush_dcache_range(address, address + 8);
245 #endif
246 	if (err)
247 		goto give_sigsegv;
248 
249 	/* Set up registers for signal handler */
250 	regs->r1 = (unsigned long) frame - STATE_SAVE_ARG_SPACE;
251 
252 	/* Signal handler args: */
253 	regs->r5 = signal; /* arg 0: signum */
254 	regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */
255 	regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */
256 	/* Offset to handle microblaze rtid r14, 0 */
257 	regs->pc = (unsigned long)ka->sa.sa_handler;
258 
259 	set_fs(USER_DS);
260 
261 	/* the tracer may want to single-step inside the handler */
262 	if (test_thread_flag(TIF_SINGLESTEP))
263 		ptrace_notify(SIGTRAP);
264 
265 #ifdef DEBUG_SIG
266 	printk(KERN_INFO "SIG deliver (%s:%d): sp=%p pc=%08lx\n",
267 		current->comm, current->pid, frame, regs->pc);
268 #endif
269 
270 	return;
271 
272 give_sigsegv:
273 	if (sig == SIGSEGV)
274 		ka->sa.sa_handler = SIG_DFL;
275 	force_sig(SIGSEGV, current);
276 }
277 
278 /* Handle restarting system calls */
279 static inline void
280 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
281 {
282 	switch (regs->r3) {
283 	case -ERESTART_RESTARTBLOCK:
284 	case -ERESTARTNOHAND:
285 		if (!has_handler)
286 			goto do_restart;
287 		regs->r3 = -EINTR;
288 		break;
289 	case -ERESTARTSYS:
290 		if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
291 			regs->r3 = -EINTR;
292 			break;
293 	}
294 	/* fallthrough */
295 	case -ERESTARTNOINTR:
296 do_restart:
297 		/* offset of 4 bytes to re-execute trap (brki) instruction */
298 #ifndef CONFIG_MMU
299 		regs->pc -= 4;
300 #else
301 		/* offset of 8 bytes required = 4 for rtbd
302 		   offset, plus 4 for size of
303 			"brki r14,8"
304 		   instruction. */
305 		regs->pc -= 8;
306 #endif
307 		break;
308 	}
309 }
310 
311 /*
312  * OK, we're invoking a handler
313  */
314 
315 static int
316 handle_signal(unsigned long sig, struct k_sigaction *ka,
317 		siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
318 {
319 	/* Set up the stack frame */
320 	if (ka->sa.sa_flags & SA_SIGINFO)
321 		setup_rt_frame(sig, ka, info, oldset, regs);
322 	else
323 		setup_rt_frame(sig, ka, NULL, oldset, regs);
324 
325 	if (ka->sa.sa_flags & SA_ONESHOT)
326 		ka->sa.sa_handler = SIG_DFL;
327 
328 	if (!(ka->sa.sa_flags & SA_NODEFER)) {
329 		spin_lock_irq(&current->sighand->siglock);
330 		sigorsets(&current->blocked,
331 				&current->blocked, &ka->sa.sa_mask);
332 		sigaddset(&current->blocked, sig);
333 		recalc_sigpending();
334 		spin_unlock_irq(&current->sighand->siglock);
335 	}
336 	return 1;
337 }
338 
339 /*
340  * Note that 'init' is a special process: it doesn't get signals it doesn't
341  * want to handle. Thus you cannot kill init even with a SIGKILL even by
342  * mistake.
343  *
344  * Note that we go through the signals twice: once to check the signals that
345  * the kernel can handle, and then we build all the user-level signal handling
346  * stack-frames in one go after that.
347  */
348 int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_syscall)
349 {
350 	siginfo_t info;
351 	int signr;
352 	struct k_sigaction ka;
353 #ifdef DEBUG_SIG
354 	printk(KERN_INFO "do signal: %p %p %d\n", regs, oldset, in_syscall);
355 	printk(KERN_INFO "do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1,
356 			regs->r12, current_thread_info()->flags);
357 #endif
358 	/*
359 	 * We want the common case to go fast, which
360 	 * is why we may in certain cases get here from
361 	 * kernel mode. Just return without doing anything
362 	 * if so.
363 	 */
364 	if (kernel_mode(regs))
365 		return 1;
366 
367 	if (current_thread_info()->status & TS_RESTORE_SIGMASK)
368 		oldset = &current->saved_sigmask;
369 	else
370 		oldset = &current->blocked;
371 
372 	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
373 	if (signr > 0) {
374 		/* Whee! Actually deliver the signal. */
375 		if (in_syscall)
376 			handle_restart(regs, &ka, 1);
377 		if (handle_signal(signr, &ka, &info, oldset, regs)) {
378 			/*
379 			 * A signal was successfully delivered; the saved
380 			 * sigmask will have been stored in the signal frame,
381 			 * and will be restored by sigreturn, so we can simply
382 			 * clear the TS_RESTORE_SIGMASK flag.
383 			 */
384 			current_thread_info()->status &=
385 			    ~TS_RESTORE_SIGMASK;
386 		}
387 		return 1;
388 	}
389 
390 	if (in_syscall)
391 		handle_restart(regs, NULL, 0);
392 
393 	/*
394 	 * If there's no signal to deliver, we just put the saved sigmask
395 	 * back.
396 	 */
397 	if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
398 		current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
399 		sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
400 	}
401 
402 	/* Did we come from a system call? */
403 	return 0;
404 }
405