1 /*
2  * linux/arch/unicore32/kernel/signal.c
3  *
4  * Code specific to PKUnity SoC and UniCore ISA
5  *
6  * Copyright (C) 2001-2010 GUAN Xue-tao
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 #include <linux/errno.h>
13 #include <linux/signal.h>
14 #include <linux/personality.h>
15 #include <linux/freezer.h>
16 #include <linux/uaccess.h>
17 #include <linux/tracehook.h>
18 #include <linux/elf.h>
19 #include <linux/unistd.h>
20 
21 #include <asm/cacheflush.h>
22 #include <asm/ucontext.h>
23 
24 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
25 
26 /*
27  * For UniCore syscalls, we encode the syscall number into the instruction.
28  */
29 #define SWI_SYS_SIGRETURN	(0xff000000) /* error number for new abi */
30 #define SWI_SYS_RT_SIGRETURN	(0xff000000 | (__NR_rt_sigreturn))
31 #define SWI_SYS_RESTART		(0xff000000 | (__NR_restart_syscall))
32 
33 #define KERN_SIGRETURN_CODE	(KUSER_VECPAGE_BASE + 0x00000500)
34 #define KERN_RESTART_CODE	(KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))
35 
36 const unsigned long sigreturn_codes[3] = {
37 	SWI_SYS_SIGRETURN, SWI_SYS_RT_SIGRETURN,
38 };
39 
40 const unsigned long syscall_restart_code[2] = {
41 	SWI_SYS_RESTART,	/* swi	__NR_restart_syscall */
42 	0x69efc004,		/* ldr	pc, [sp], #4 */
43 };
44 
45 /*
46  * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
47  */
48 struct sigframe {
49 	struct ucontext uc;
50 	unsigned long retcode[2];
51 };
52 
53 struct rt_sigframe {
54 	struct siginfo info;
55 	struct sigframe sig;
56 };
57 
restore_sigframe(struct pt_regs * regs,struct sigframe __user * sf)58 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
59 {
60 	sigset_t set;
61 	int err;
62 
63 	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
64 	if (err == 0) {
65 		sigdelsetmask(&set, ~_BLOCKABLE);
66 		set_current_blocked(&set);
67 	}
68 
69 	err |= __get_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
70 	err |= __get_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
71 	err |= __get_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
72 	err |= __get_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
73 	err |= __get_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
74 	err |= __get_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
75 	err |= __get_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
76 	err |= __get_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
77 	err |= __get_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
78 	err |= __get_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
79 	err |= __get_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
80 	err |= __get_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
81 	err |= __get_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
82 	err |= __get_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
83 	err |= __get_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
84 	err |= __get_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
85 	err |= __get_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
86 	err |= __get_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
87 	err |= __get_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
88 	err |= __get_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
89 	err |= __get_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
90 	err |= __get_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
91 	err |= __get_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
92 	err |= __get_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
93 	err |= __get_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
94 	err |= __get_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
95 	err |= __get_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
96 	err |= __get_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
97 	err |= __get_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
98 	err |= __get_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
99 	err |= __get_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
100 	err |= __get_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
101 	err |= __get_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
102 
103 	err |= !valid_user_regs(regs);
104 
105 	return err;
106 }
107 
__sys_rt_sigreturn(struct pt_regs * regs)108 asmlinkage int __sys_rt_sigreturn(struct pt_regs *regs)
109 {
110 	struct rt_sigframe __user *frame;
111 
112 	/* Always make any pending restarted system calls return -EINTR */
113 	current_thread_info()->restart_block.fn = do_no_restart_syscall;
114 
115 	/*
116 	 * Since we stacked the signal on a 64-bit boundary,
117 	 * then 'sp' should be word aligned here.  If it's
118 	 * not, then the user is trying to mess with us.
119 	 */
120 	if (regs->UCreg_sp & 7)
121 		goto badframe;
122 
123 	frame = (struct rt_sigframe __user *)regs->UCreg_sp;
124 
125 	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
126 		goto badframe;
127 
128 	if (restore_sigframe(regs, &frame->sig))
129 		goto badframe;
130 
131 	if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->UCreg_sp)
132 			== -EFAULT)
133 		goto badframe;
134 
135 	return regs->UCreg_00;
136 
137 badframe:
138 	force_sig(SIGSEGV, current);
139 	return 0;
140 }
141 
setup_sigframe(struct sigframe __user * sf,struct pt_regs * regs,sigset_t * set)142 static int setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs,
143 		sigset_t *set)
144 {
145 	int err = 0;
146 
147 	err |= __put_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
148 	err |= __put_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
149 	err |= __put_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
150 	err |= __put_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
151 	err |= __put_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
152 	err |= __put_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
153 	err |= __put_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
154 	err |= __put_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
155 	err |= __put_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
156 	err |= __put_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
157 	err |= __put_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
158 	err |= __put_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
159 	err |= __put_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
160 	err |= __put_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
161 	err |= __put_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
162 	err |= __put_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
163 	err |= __put_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
164 	err |= __put_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
165 	err |= __put_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
166 	err |= __put_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
167 	err |= __put_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
168 	err |= __put_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
169 	err |= __put_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
170 	err |= __put_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
171 	err |= __put_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
172 	err |= __put_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
173 	err |= __put_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
174 	err |= __put_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
175 	err |= __put_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
176 	err |= __put_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
177 	err |= __put_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
178 	err |= __put_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
179 	err |= __put_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
180 
181 	err |= __put_user(current->thread.trap_no,
182 			&sf->uc.uc_mcontext.trap_no);
183 	err |= __put_user(current->thread.error_code,
184 			&sf->uc.uc_mcontext.error_code);
185 	err |= __put_user(current->thread.address,
186 			&sf->uc.uc_mcontext.fault_address);
187 	err |= __put_user(set->sig[0], &sf->uc.uc_mcontext.oldmask);
188 
189 	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
190 
191 	return err;
192 }
193 
get_sigframe(struct k_sigaction * ka,struct pt_regs * regs,int framesize)194 static inline void __user *get_sigframe(struct k_sigaction *ka,
195 		struct pt_regs *regs, int framesize)
196 {
197 	unsigned long sp = regs->UCreg_sp;
198 	void __user *frame;
199 
200 	/*
201 	 * This is the X/Open sanctioned signal stack switching.
202 	 */
203 	if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
204 		sp = current->sas_ss_sp + current->sas_ss_size;
205 
206 	/*
207 	 * ATPCS B01 mandates 8-byte alignment
208 	 */
209 	frame = (void __user *)((sp - framesize) & ~7);
210 
211 	/*
212 	 * Check that we can actually write to the signal frame.
213 	 */
214 	if (!access_ok(VERIFY_WRITE, frame, framesize))
215 		frame = NULL;
216 
217 	return frame;
218 }
219 
setup_return(struct pt_regs * regs,struct k_sigaction * ka,unsigned long __user * rc,void __user * frame,int usig)220 static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,
221 	     unsigned long __user *rc, void __user *frame, int usig)
222 {
223 	unsigned long handler = (unsigned long)ka->sa.sa_handler;
224 	unsigned long retcode;
225 	unsigned long asr = regs->UCreg_asr & ~PSR_f;
226 
227 	unsigned int idx = 0;
228 
229 	if (ka->sa.sa_flags & SA_SIGINFO)
230 		idx += 1;
231 
232 	if (__put_user(sigreturn_codes[idx],   rc) ||
233 	    __put_user(sigreturn_codes[idx+1], rc+1))
234 		return 1;
235 
236 	retcode = KERN_SIGRETURN_CODE + (idx << 2);
237 
238 	regs->UCreg_00 = usig;
239 	regs->UCreg_sp = (unsigned long)frame;
240 	regs->UCreg_lr = retcode;
241 	regs->UCreg_pc = handler;
242 	regs->UCreg_asr = asr;
243 
244 	return 0;
245 }
246 
setup_frame(int usig,struct k_sigaction * ka,sigset_t * set,struct pt_regs * regs)247 static int setup_frame(int usig, struct k_sigaction *ka,
248 		sigset_t *set, struct pt_regs *regs)
249 {
250 	struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
251 	int err = 0;
252 
253 	if (!frame)
254 		return 1;
255 
256 	/*
257 	 * Set uc.uc_flags to a value which sc.trap_no would never have.
258 	 */
259 	err |= __put_user(0x5ac3c35a, &frame->uc.uc_flags);
260 
261 	err |= setup_sigframe(frame, regs, set);
262 	if (err == 0)
263 		err |= setup_return(regs, ka, frame->retcode, frame, usig);
264 
265 	return err;
266 }
267 
setup_rt_frame(int usig,struct k_sigaction * ka,siginfo_t * info,sigset_t * set,struct pt_regs * regs)268 static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
269 	       sigset_t *set, struct pt_regs *regs)
270 {
271 	struct rt_sigframe __user *frame =
272 			get_sigframe(ka, regs, sizeof(*frame));
273 	stack_t stack;
274 	int err = 0;
275 
276 	if (!frame)
277 		return 1;
278 
279 	err |= copy_siginfo_to_user(&frame->info, info);
280 
281 	err |= __put_user(0, &frame->sig.uc.uc_flags);
282 	err |= __put_user(NULL, &frame->sig.uc.uc_link);
283 
284 	memset(&stack, 0, sizeof(stack));
285 	stack.ss_sp = (void __user *)current->sas_ss_sp;
286 	stack.ss_flags = sas_ss_flags(regs->UCreg_sp);
287 	stack.ss_size = current->sas_ss_size;
288 	err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));
289 
290 	err |= setup_sigframe(&frame->sig, regs, set);
291 	if (err == 0)
292 		err |= setup_return(regs, ka, frame->sig.retcode, frame, usig);
293 
294 	if (err == 0) {
295 		/*
296 		 * For realtime signals we must also set the second and third
297 		 * arguments for the signal handler.
298 		 */
299 		regs->UCreg_01 = (unsigned long)&frame->info;
300 		regs->UCreg_02 = (unsigned long)&frame->sig.uc;
301 	}
302 
303 	return err;
304 }
305 
setup_syscall_restart(struct pt_regs * regs)306 static inline void setup_syscall_restart(struct pt_regs *regs)
307 {
308 	regs->UCreg_00 = regs->UCreg_ORIG_00;
309 	regs->UCreg_pc -= 4;
310 }
311 
312 /*
313  * OK, we're invoking a handler
314  */
handle_signal(unsigned long sig,struct k_sigaction * ka,siginfo_t * info,sigset_t * oldset,struct pt_regs * regs,int syscall)315 static int handle_signal(unsigned long sig, struct k_sigaction *ka,
316 	      siginfo_t *info, sigset_t *oldset,
317 	      struct pt_regs *regs, int syscall)
318 {
319 	struct thread_info *thread = current_thread_info();
320 	struct task_struct *tsk = current;
321 	sigset_t blocked;
322 	int usig = sig;
323 	int ret;
324 
325 	/*
326 	 * If we were from a system call, check for system call restarting...
327 	 */
328 	if (syscall) {
329 		switch (regs->UCreg_00) {
330 		case -ERESTART_RESTARTBLOCK:
331 		case -ERESTARTNOHAND:
332 			regs->UCreg_00 = -EINTR;
333 			break;
334 		case -ERESTARTSYS:
335 			if (!(ka->sa.sa_flags & SA_RESTART)) {
336 				regs->UCreg_00 = -EINTR;
337 				break;
338 			}
339 			/* fallthrough */
340 		case -ERESTARTNOINTR:
341 			setup_syscall_restart(regs);
342 		}
343 	}
344 
345 	/*
346 	 * translate the signal
347 	 */
348 	if (usig < 32 && thread->exec_domain
349 			&& thread->exec_domain->signal_invmap)
350 		usig = thread->exec_domain->signal_invmap[usig];
351 
352 	/*
353 	 * Set up the stack frame
354 	 */
355 	if (ka->sa.sa_flags & SA_SIGINFO)
356 		ret = setup_rt_frame(usig, ka, info, oldset, regs);
357 	else
358 		ret = setup_frame(usig, ka, oldset, regs);
359 
360 	/*
361 	 * Check that the resulting registers are actually sane.
362 	 */
363 	ret |= !valid_user_regs(regs);
364 
365 	if (ret != 0) {
366 		force_sigsegv(sig, tsk);
367 		return ret;
368 	}
369 
370 	/*
371 	 * Block the signal if we were successful.
372 	 */
373 	sigorsets(&blocked, &tsk->blocked, &ka->sa.sa_mask);
374 	if (!(ka->sa.sa_flags & SA_NODEFER))
375 		sigaddset(&blocked, sig);
376 	set_current_blocked(&blocked);
377 
378 	return 0;
379 }
380 
381 /*
382  * Note that 'init' is a special process: it doesn't get signals it doesn't
383  * want to handle. Thus you cannot kill init even with a SIGKILL even by
384  * mistake.
385  *
386  * Note that we go through the signals twice: once to check the signals that
387  * the kernel can handle, and then we build all the user-level signal handling
388  * stack-frames in one go after that.
389  */
do_signal(struct pt_regs * regs,int syscall)390 static void do_signal(struct pt_regs *regs, int syscall)
391 {
392 	struct k_sigaction ka;
393 	siginfo_t info;
394 	int signr;
395 
396 	/*
397 	 * We want the common case to go fast, which
398 	 * is why we may in certain cases get here from
399 	 * kernel mode. Just return without doing anything
400 	 * if so.
401 	 */
402 	if (!user_mode(regs))
403 		return;
404 
405 	if (try_to_freeze())
406 		goto no_signal;
407 
408 	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
409 	if (signr > 0) {
410 		sigset_t *oldset;
411 
412 		if (test_thread_flag(TIF_RESTORE_SIGMASK))
413 			oldset = &current->saved_sigmask;
414 		else
415 			oldset = &current->blocked;
416 		if (handle_signal(signr, &ka, &info, oldset, regs, syscall)
417 				== 0) {
418 			/*
419 			 * A signal was successfully delivered; the saved
420 			 * sigmask will have been stored in the signal frame,
421 			 * and will be restored by sigreturn, so we can simply
422 			 * clear the TIF_RESTORE_SIGMASK flag.
423 			 */
424 			if (test_thread_flag(TIF_RESTORE_SIGMASK))
425 				clear_thread_flag(TIF_RESTORE_SIGMASK);
426 		}
427 		return;
428 	}
429 
430  no_signal:
431 	/*
432 	 * No signal to deliver to the process - restart the syscall.
433 	 */
434 	if (syscall) {
435 		if (regs->UCreg_00 == -ERESTART_RESTARTBLOCK) {
436 				u32 __user *usp;
437 
438 				regs->UCreg_sp -= 4;
439 				usp = (u32 __user *)regs->UCreg_sp;
440 
441 				if (put_user(regs->UCreg_pc, usp) == 0) {
442 					regs->UCreg_pc = KERN_RESTART_CODE;
443 				} else {
444 					regs->UCreg_sp += 4;
445 					force_sigsegv(0, current);
446 				}
447 		}
448 		if (regs->UCreg_00 == -ERESTARTNOHAND ||
449 		    regs->UCreg_00 == -ERESTARTSYS ||
450 		    regs->UCreg_00 == -ERESTARTNOINTR) {
451 			setup_syscall_restart(regs);
452 		}
453 
454 		/* If there's no signal to deliver, we just put the saved
455 		 * sigmask back.
456 		 */
457 		if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
458 			clear_thread_flag(TIF_RESTORE_SIGMASK);
459 			sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
460 		}
461 	}
462 }
463 
do_notify_resume(struct pt_regs * regs,unsigned int thread_flags,int syscall)464 asmlinkage void do_notify_resume(struct pt_regs *regs,
465 		unsigned int thread_flags, int syscall)
466 {
467 	if (thread_flags & _TIF_SIGPENDING)
468 		do_signal(regs, syscall);
469 
470 	if (thread_flags & _TIF_NOTIFY_RESUME) {
471 		clear_thread_flag(TIF_NOTIFY_RESUME);
472 		tracehook_notify_resume(regs);
473 		if (current->replacement_session_keyring)
474 			key_replace_session_keyring();
475 	}
476 }
477 
478 /*
479  * Copy signal return handlers into the vector page, and
480  * set sigreturn to be a pointer to these.
481  */
early_signal_init(void)482 void __init early_signal_init(void)
483 {
484 	memcpy((void *)kuser_vecpage_to_vectors(KERN_SIGRETURN_CODE),
485 			sigreturn_codes, sizeof(sigreturn_codes));
486 	memcpy((void *)kuser_vecpage_to_vectors(KERN_RESTART_CODE),
487 			syscall_restart_code, sizeof(syscall_restart_code));
488 	/* Need not to flush icache, since early_trap_init will do it last. */
489 }
490