xref: /openbmc/linux/arch/sh/kernel/signal_32.c (revision 293d5b43)
1 /*
2  *  linux/arch/sh/kernel/signal.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  *
6  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
7  *
8  *  SuperH version:  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
9  *
10  */
11 #include <linux/sched.h>
12 #include <linux/mm.h>
13 #include <linux/smp.h>
14 #include <linux/kernel.h>
15 #include <linux/signal.h>
16 #include <linux/errno.h>
17 #include <linux/wait.h>
18 #include <linux/ptrace.h>
19 #include <linux/unistd.h>
20 #include <linux/stddef.h>
21 #include <linux/tty.h>
22 #include <linux/elf.h>
23 #include <linux/personality.h>
24 #include <linux/binfmts.h>
25 #include <linux/io.h>
26 #include <linux/tracehook.h>
27 #include <asm/ucontext.h>
28 #include <asm/uaccess.h>
29 #include <asm/pgtable.h>
30 #include <asm/cacheflush.h>
31 #include <asm/syscalls.h>
32 #include <asm/fpu.h>
33 
34 struct fdpic_func_descriptor {
35 	unsigned long	text;
36 	unsigned long	GOT;
37 };
38 
39 /*
40  * The following define adds a 64 byte gap between the signal
41  * stack frame and previous contents of the stack.  This allows
42  * frame unwinding in a function epilogue but only if a frame
43  * pointer is used in the function.  This is necessary because
44  * current gcc compilers (<4.3) do not generate unwind info on
45  * SH for function epilogues.
46  */
47 #define UNWINDGUARD 64
48 
49 /*
50  * Do a signal return; undo the signal stack.
51  */
52 
53 #define MOVW(n)	 (0x9300|((n)-2))	/* Move mem word at PC+n to R3 */
54 #if defined(CONFIG_CPU_SH2)
55 #define TRAP_NOARG 0xc320		/* Syscall w/no args (NR in R3) */
56 #else
57 #define TRAP_NOARG 0xc310		/* Syscall w/no args (NR in R3) */
58 #endif
59 #define OR_R0_R0 0x200b			/* or r0,r0 (insert to avoid hardware bug) */
60 
61 struct sigframe
62 {
63 	struct sigcontext sc;
64 	unsigned long extramask[_NSIG_WORDS-1];
65 	u16 retcode[8];
66 };
67 
68 struct rt_sigframe
69 {
70 	struct siginfo info;
71 	struct ucontext uc;
72 	u16 retcode[8];
73 };
74 
75 #ifdef CONFIG_SH_FPU
76 static inline int restore_sigcontext_fpu(struct sigcontext __user *sc)
77 {
78 	struct task_struct *tsk = current;
79 
80 	if (!(boot_cpu_data.flags & CPU_HAS_FPU))
81 		return 0;
82 
83 	set_used_math();
84 	return __copy_from_user(&tsk->thread.xstate->hardfpu, &sc->sc_fpregs[0],
85 				sizeof(long)*(16*2+2));
86 }
87 
88 static inline int save_sigcontext_fpu(struct sigcontext __user *sc,
89 				      struct pt_regs *regs)
90 {
91 	struct task_struct *tsk = current;
92 
93 	if (!(boot_cpu_data.flags & CPU_HAS_FPU))
94 		return 0;
95 
96 	if (!used_math())
97 		return __put_user(0, &sc->sc_ownedfp);
98 
99 	if (__put_user(1, &sc->sc_ownedfp))
100 		return -EFAULT;
101 
102 	/* This will cause a "finit" to be triggered by the next
103 	   attempted FPU operation by the 'current' process.
104 	   */
105 	clear_used_math();
106 
107 	unlazy_fpu(tsk, regs);
108 	return __copy_to_user(&sc->sc_fpregs[0], &tsk->thread.xstate->hardfpu,
109 			      sizeof(long)*(16*2+2));
110 }
111 #endif /* CONFIG_SH_FPU */
112 
113 static int
114 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *r0_p)
115 {
116 	unsigned int err = 0;
117 
118 #define COPY(x)		err |= __get_user(regs->x, &sc->sc_##x)
119 			COPY(regs[1]);
120 	COPY(regs[2]);	COPY(regs[3]);
121 	COPY(regs[4]);	COPY(regs[5]);
122 	COPY(regs[6]);	COPY(regs[7]);
123 	COPY(regs[8]);	COPY(regs[9]);
124 	COPY(regs[10]);	COPY(regs[11]);
125 	COPY(regs[12]);	COPY(regs[13]);
126 	COPY(regs[14]);	COPY(regs[15]);
127 	COPY(gbr);	COPY(mach);
128 	COPY(macl);	COPY(pr);
129 	COPY(sr);	COPY(pc);
130 #undef COPY
131 
132 #ifdef CONFIG_SH_FPU
133 	if (boot_cpu_data.flags & CPU_HAS_FPU) {
134 		int owned_fp;
135 		struct task_struct *tsk = current;
136 
137 		regs->sr |= SR_FD; /* Release FPU */
138 		clear_fpu(tsk, regs);
139 		clear_used_math();
140 		err |= __get_user (owned_fp, &sc->sc_ownedfp);
141 		if (owned_fp)
142 			err |= restore_sigcontext_fpu(sc);
143 	}
144 #endif
145 
146 	regs->tra = -1;		/* disable syscall checks */
147 	err |= __get_user(*r0_p, &sc->sc_regs[0]);
148 	return err;
149 }
150 
151 asmlinkage int sys_sigreturn(void)
152 {
153 	struct pt_regs *regs = current_pt_regs();
154 	struct sigframe __user *frame = (struct sigframe __user *)regs->regs[15];
155 	sigset_t set;
156 	int r0;
157 
158         /* Always make any pending restarted system calls return -EINTR */
159 	current->restart_block.fn = do_no_restart_syscall;
160 
161 	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
162 		goto badframe;
163 
164 	if (__get_user(set.sig[0], &frame->sc.oldmask)
165 	    || (_NSIG_WORDS > 1
166 		&& __copy_from_user(&set.sig[1], &frame->extramask,
167 				    sizeof(frame->extramask))))
168 		goto badframe;
169 
170 	set_current_blocked(&set);
171 
172 	if (restore_sigcontext(regs, &frame->sc, &r0))
173 		goto badframe;
174 	return r0;
175 
176 badframe:
177 	force_sig(SIGSEGV, current);
178 	return 0;
179 }
180 
181 asmlinkage int sys_rt_sigreturn(void)
182 {
183 	struct pt_regs *regs = current_pt_regs();
184 	struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->regs[15];
185 	sigset_t set;
186 	int r0;
187 
188 	/* Always make any pending restarted system calls return -EINTR */
189 	current->restart_block.fn = do_no_restart_syscall;
190 
191 	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
192 		goto badframe;
193 
194 	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
195 		goto badframe;
196 
197 	set_current_blocked(&set);
198 
199 	if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
200 		goto badframe;
201 
202 	if (restore_altstack(&frame->uc.uc_stack))
203 		goto badframe;
204 
205 	return r0;
206 
207 badframe:
208 	force_sig(SIGSEGV, current);
209 	return 0;
210 }
211 
212 /*
213  * Set up a signal frame.
214  */
215 
216 static int
217 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
218 		 unsigned long mask)
219 {
220 	int err = 0;
221 
222 #define COPY(x)		err |= __put_user(regs->x, &sc->sc_##x)
223 	COPY(regs[0]);	COPY(regs[1]);
224 	COPY(regs[2]);	COPY(regs[3]);
225 	COPY(regs[4]);	COPY(regs[5]);
226 	COPY(regs[6]);	COPY(regs[7]);
227 	COPY(regs[8]);	COPY(regs[9]);
228 	COPY(regs[10]);	COPY(regs[11]);
229 	COPY(regs[12]);	COPY(regs[13]);
230 	COPY(regs[14]);	COPY(regs[15]);
231 	COPY(gbr);	COPY(mach);
232 	COPY(macl);	COPY(pr);
233 	COPY(sr);	COPY(pc);
234 #undef COPY
235 
236 #ifdef CONFIG_SH_FPU
237 	err |= save_sigcontext_fpu(sc, regs);
238 #endif
239 
240 	/* non-iBCS2 extensions.. */
241 	err |= __put_user(mask, &sc->oldmask);
242 
243 	return err;
244 }
245 
246 /*
247  * Determine which stack to use..
248  */
249 static inline void __user *
250 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
251 {
252 	if (ka->sa.sa_flags & SA_ONSTACK) {
253 		if (sas_ss_flags(sp) == 0)
254 			sp = current->sas_ss_sp + current->sas_ss_size;
255 	}
256 
257 	return (void __user *)((sp - (frame_size+UNWINDGUARD)) & -8ul);
258 }
259 
260 /* These symbols are defined with the addresses in the vsyscall page.
261    See vsyscall-trapa.S.  */
262 extern void __kernel_sigreturn(void);
263 extern void __kernel_rt_sigreturn(void);
264 
265 static int setup_frame(struct ksignal *ksig, sigset_t *set,
266 		       struct pt_regs *regs)
267 {
268 	struct sigframe __user *frame;
269 	int err = 0, sig = ksig->sig;
270 
271 	frame = get_sigframe(&ksig->ka, regs->regs[15], sizeof(*frame));
272 
273 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
274 		return -EFAULT;
275 
276 	err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
277 
278 	if (_NSIG_WORDS > 1)
279 		err |= __copy_to_user(frame->extramask, &set->sig[1],
280 				      sizeof(frame->extramask));
281 
282 	/* Set up to return from userspace.  If provided, use a stub
283 	   already in userspace.  */
284 	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
285 		regs->pr = (unsigned long) ksig->ka.sa.sa_restorer;
286 #ifdef CONFIG_VSYSCALL
287 	} else if (likely(current->mm->context.vdso)) {
288 		regs->pr = VDSO_SYM(&__kernel_sigreturn);
289 #endif
290 	} else {
291 		/* Generate return code (system call to sigreturn) */
292 		err |= __put_user(MOVW(7), &frame->retcode[0]);
293 		err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
294 		err |= __put_user(OR_R0_R0, &frame->retcode[2]);
295 		err |= __put_user(OR_R0_R0, &frame->retcode[3]);
296 		err |= __put_user(OR_R0_R0, &frame->retcode[4]);
297 		err |= __put_user(OR_R0_R0, &frame->retcode[5]);
298 		err |= __put_user(OR_R0_R0, &frame->retcode[6]);
299 		err |= __put_user((__NR_sigreturn), &frame->retcode[7]);
300 		regs->pr = (unsigned long) frame->retcode;
301 		flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
302 	}
303 
304 	if (err)
305 		return -EFAULT;
306 
307 	/* Set up registers for signal handler */
308 	regs->regs[15] = (unsigned long) frame;
309 	regs->regs[4] = sig; /* Arg for signal handler */
310 	regs->regs[5] = 0;
311 	regs->regs[6] = (unsigned long) &frame->sc;
312 
313 	if (current->personality & FDPIC_FUNCPTRS) {
314 		struct fdpic_func_descriptor __user *funcptr =
315 			(struct fdpic_func_descriptor __user *)ksig->ka.sa.sa_handler;
316 
317 		err |= __get_user(regs->pc, &funcptr->text);
318 		err |= __get_user(regs->regs[12], &funcptr->GOT);
319 	} else
320 		regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
321 
322 	if (err)
323 		return -EFAULT;
324 
325 	pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
326 		 current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
327 
328 	return 0;
329 }
330 
331 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
332 			  struct pt_regs *regs)
333 {
334 	struct rt_sigframe __user *frame;
335 	int err = 0, sig = ksig->sig;
336 
337 	frame = get_sigframe(&ksig->ka, regs->regs[15], sizeof(*frame));
338 
339 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
340 		return -EFAULT;
341 
342 	err |= copy_siginfo_to_user(&frame->info, &ksig->info);
343 
344 	/* Create the ucontext.  */
345 	err |= __put_user(0, &frame->uc.uc_flags);
346 	err |= __put_user(NULL, &frame->uc.uc_link);
347 	err |= __save_altstack(&frame->uc.uc_stack, regs->regs[15]);
348 	err |= setup_sigcontext(&frame->uc.uc_mcontext,
349 			        regs, set->sig[0]);
350 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
351 
352 	/* Set up to return from userspace.  If provided, use a stub
353 	   already in userspace.  */
354 	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
355 		regs->pr = (unsigned long) ksig->ka.sa.sa_restorer;
356 #ifdef CONFIG_VSYSCALL
357 	} else if (likely(current->mm->context.vdso)) {
358 		regs->pr = VDSO_SYM(&__kernel_rt_sigreturn);
359 #endif
360 	} else {
361 		/* Generate return code (system call to rt_sigreturn) */
362 		err |= __put_user(MOVW(7), &frame->retcode[0]);
363 		err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
364 		err |= __put_user(OR_R0_R0, &frame->retcode[2]);
365 		err |= __put_user(OR_R0_R0, &frame->retcode[3]);
366 		err |= __put_user(OR_R0_R0, &frame->retcode[4]);
367 		err |= __put_user(OR_R0_R0, &frame->retcode[5]);
368 		err |= __put_user(OR_R0_R0, &frame->retcode[6]);
369 		err |= __put_user((__NR_rt_sigreturn), &frame->retcode[7]);
370 		regs->pr = (unsigned long) frame->retcode;
371 		flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
372 	}
373 
374 	if (err)
375 		return -EFAULT;
376 
377 	/* Set up registers for signal handler */
378 	regs->regs[15] = (unsigned long) frame;
379 	regs->regs[4] = sig; /* Arg for signal handler */
380 	regs->regs[5] = (unsigned long) &frame->info;
381 	regs->regs[6] = (unsigned long) &frame->uc;
382 
383 	if (current->personality & FDPIC_FUNCPTRS) {
384 		struct fdpic_func_descriptor __user *funcptr =
385 			(struct fdpic_func_descriptor __user *)ksig->ka.sa.sa_handler;
386 
387 		err |= __get_user(regs->pc, &funcptr->text);
388 		err |= __get_user(regs->regs[12], &funcptr->GOT);
389 	} else
390 		regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
391 
392 	if (err)
393 		return -EFAULT;
394 
395 	pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
396 		 current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
397 
398 	return 0;
399 }
400 
401 static inline void
402 handle_syscall_restart(unsigned long save_r0, struct pt_regs *regs,
403 		       struct sigaction *sa)
404 {
405 	/* If we're not from a syscall, bail out */
406 	if (regs->tra < 0)
407 		return;
408 
409 	/* check for system call restart.. */
410 	switch (regs->regs[0]) {
411 		case -ERESTART_RESTARTBLOCK:
412 		case -ERESTARTNOHAND:
413 		no_system_call_restart:
414 			regs->regs[0] = -EINTR;
415 			break;
416 
417 		case -ERESTARTSYS:
418 			if (!(sa->sa_flags & SA_RESTART))
419 				goto no_system_call_restart;
420 		/* fallthrough */
421 		case -ERESTARTNOINTR:
422 			regs->regs[0] = save_r0;
423 			regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
424 			break;
425 	}
426 }
427 
428 /*
429  * OK, we're invoking a handler
430  */
431 static void
432 handle_signal(struct ksignal *ksig, struct pt_regs *regs, unsigned int save_r0)
433 {
434 	sigset_t *oldset = sigmask_to_save();
435 	int ret;
436 
437 	/* Set up the stack frame */
438 	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
439 		ret = setup_rt_frame(ksig, oldset, regs);
440 	else
441 		ret = setup_frame(ksig, oldset, regs);
442 
443 	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
444 }
445 
446 /*
447  * Note that 'init' is a special process: it doesn't get signals it doesn't
448  * want to handle. Thus you cannot kill init even with a SIGKILL even by
449  * mistake.
450  *
451  * Note that we go through the signals twice: once to check the signals that
452  * the kernel can handle, and then we build all the user-level signal handling
453  * stack-frames in one go after that.
454  */
455 static void do_signal(struct pt_regs *regs, unsigned int save_r0)
456 {
457 	struct ksignal ksig;
458 
459 	/*
460 	 * We want the common case to go fast, which
461 	 * is why we may in certain cases get here from
462 	 * kernel mode. Just return without doing anything
463 	 * if so.
464 	 */
465 	if (!user_mode(regs))
466 		return;
467 
468 	if (get_signal(&ksig)) {
469 		handle_syscall_restart(save_r0, regs, &ksig.ka.sa);
470 
471 		/* Whee!  Actually deliver the signal.  */
472 		handle_signal(&ksig, regs, save_r0);
473 		return;
474 	}
475 
476 	/* Did we come from a system call? */
477 	if (regs->tra >= 0) {
478 		/* Restart the system call - no handlers present */
479 		if (regs->regs[0] == -ERESTARTNOHAND ||
480 		    regs->regs[0] == -ERESTARTSYS ||
481 		    regs->regs[0] == -ERESTARTNOINTR) {
482 			regs->regs[0] = save_r0;
483 			regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
484 		} else if (regs->regs[0] == -ERESTART_RESTARTBLOCK) {
485 			regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
486 			regs->regs[3] = __NR_restart_syscall;
487 		}
488 	}
489 
490 	/*
491 	 * If there's no signal to deliver, we just put the saved sigmask
492 	 * back.
493 	 */
494 	restore_saved_sigmask();
495 }
496 
497 asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
498 				 unsigned long thread_info_flags)
499 {
500 	/* deal with pending signal delivery */
501 	if (thread_info_flags & _TIF_SIGPENDING)
502 		do_signal(regs, save_r0);
503 
504 	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
505 		clear_thread_flag(TIF_NOTIFY_RESUME);
506 		tracehook_notify_resume(regs);
507 	}
508 }
509