aboutsummaryrefslogtreecommitdiffstats
path: root/arch/sh/kernel/signal_32.c
blob: 97292890b51bc4d36121cfa35fde08c79e3260f5 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
/*
 *  linux/arch/sh/kernel/signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 *
 *  SuperH version:  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
 *
 */
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/tty.h>
#include <linux/elf.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <linux/io.h>
#include <linux/tracehook.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
#include <asm/syscalls.h>
#include <asm/fpu.h>

struct fdpic_func_descriptor {
	unsigned long	text;
	unsigned long	GOT;
};

/*
 * The following define adds a 64 byte gap between the signal
 * stack frame and previous contents of the stack.  This allows
 * frame unwinding in a function epilogue but only if a frame
 * pointer is used in the function.  This is necessary because
 * current gcc compilers (<4.3) do not generate unwind info on
 * SH for function epilogues.
 */
#define UNWINDGUARD 64

/*
 * Do a signal return; undo the signal stack.
 */

#define MOVW(n)	 (0x9300|((n)-2))	/* Move mem word at PC+n to R3 */
#if defined(CONFIG_CPU_SH2)
#define TRAP_NOARG 0xc320		/* Syscall w/no args (NR in R3) */
#else
#define TRAP_NOARG 0xc310		/* Syscall w/no args (NR in R3) */
#endif
#define OR_R0_R0 0x200b			/* or r0,r0 (insert to avoid hardware bug) */

struct sigframe
{
	struct sigcontext sc;
	unsigned long extramask[_NSIG_WORDS-1];
	u16 retcode[8];
};

struct rt_sigframe
{
	struct siginfo info;
	struct ucontext uc;
	u16 retcode[8];
};

#ifdef CONFIG_SH_FPU
static inline int restore_sigcontext_fpu(struct sigcontext __user *sc)
{
	struct task_struct *tsk = current;

	if (!(boot_cpu_data.flags & CPU_HAS_FPU))
		return 0;

	set_used_math();
	return __copy_from_user(&tsk->thread.xstate->hardfpu, &sc->sc_fpregs[0],
				sizeof(long)*(16*2+2));
}

static inline int save_sigcontext_fpu(struct sigcontext __user *sc,
				      struct pt_regs *regs)
{
	struct task_struct *tsk = current;

	if (!(boot_cpu_data.flags & CPU_HAS_FPU))
		return 0;

	if (!used_math())
		return __put_user(0, &sc->sc_ownedfp);

	if (__put_user(1, &sc->sc_ownedfp))
		return -EFAULT;

	/* This will cause a "finit" to be triggered by the next
	   attempted FPU operation by the 'current' process.
	   */
	clear_used_math();

	unlazy_fpu(tsk, regs);
	return __copy_to_user(&sc->sc_fpregs[0], &tsk->thread.xstate->hardfpu,
			      sizeof(long)*(16*2+2));
}
#endif /* CONFIG_SH_FPU */

static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *r0_p)
{
	unsigned int err = 0;

#define COPY(x)		err |= __get_user(regs->x, &sc->sc_##x)
			COPY(regs[1]);
	COPY(regs[2]);	COPY(regs[3]);
	COPY(regs[4]);	COPY(regs[5]);
	COPY(regs[6]);	COPY(regs[7]);
	COPY(regs[8]);	COPY(regs[9]);
	COPY(regs[10]);	COPY(regs[11]);
	COPY(regs[12]);	COPY(regs[13]);
	COPY(regs[14]);	COPY(regs[15]);
	COPY(gbr);	COPY(mach);
	COPY(macl);	COPY(pr);
	COPY(sr);	COPY(pc);
#undef COPY

#ifdef CONFIG_SH_FPU
	if (boot_cpu_data.flags & CPU_HAS_FPU) {
		int owned_fp;
		struct task_struct *tsk = current;

		regs->sr |= SR_FD; /* Release FPU */
		clear_fpu(tsk, regs);
		clear_used_math();
		err |= __get_user (owned_fp, &sc->sc_ownedfp);
		if (owned_fp)
			err |= restore_sigcontext_fpu(sc);
	}
#endif

	regs->tra = -1;		/* disable syscall checks */
	err |= __get_user(*r0_p, &sc->sc_regs[0]);
	return err;
}

asmlinkage int sys_sigreturn(void)
{
	struct pt_regs *regs = current_pt_regs();
	struct sigframe __user *frame = (struct sigframe __user *)regs->regs[15];
	sigset_t set;
	int r0;

        /* Always make any pending restarted system calls return -EINTR */
	current->restart_block.fn = do_no_restart_syscall;

	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;

	if (__get_user(set.sig[0], &frame->sc.oldmask)
	    || (_NSIG_WORDS > 1
		&& __copy_from_user(&set.sig[1], &frame->extramask,
				    sizeof(frame->extramask))))
		goto badframe;

	set_current_blocked(&set);

	if (restore_sigcontext(regs, &frame->sc, &r0))
		goto badframe;
	return r0;

badframe:
	force_sig(SIGSEGV, current);
	return 0;
}

asmlinkage int sys_rt_sigreturn(void)
{
	struct pt_regs *regs = current_pt_regs();
	struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->regs[15];
	sigset_t set;
	int r0;

	/* Always make any pending restarted system calls return -EINTR */
	current->restart_block.fn = do_no_restart_syscall;

	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;

	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
		goto badframe;

	set_current_blocked(&set);

	if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
		goto badframe;

	if (restore_altstack(&frame->uc.uc_stack))
		goto badframe;

	return r0;

badframe:
	force_sig(SIGSEGV, current);
	return 0;
}

/*
 * Set up a signal frame.
 */

static int
setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
		 unsigned long mask)
{
	int err = 0;

#define COPY(x)		err |= __put_user(regs->x, &sc->sc_##x)
	COPY(regs[0]);	COPY(regs[1]);
	COPY(regs[2]);	COPY(regs[3]);
	COPY(regs[4]);	COPY(regs[5]);
	COPY(regs[6]);	COPY(regs[7]);
	COPY(regs[8]);	COPY(regs[9]);
	COPY(regs[10]);	COPY(regs[11]);
	COPY(regs[12]);	COPY(regs[13]);
	COPY(regs[14]);	COPY(regs[15]);
	COPY(gbr);	COPY(mach);
	COPY(macl);	COPY(pr);
	COPY(sr);	COPY(pc);
#undef COPY

#ifdef CONFIG_SH_FPU
	err |= save_sigcontext_fpu(sc, regs);
#endif

	/* non-iBCS2 extensions.. */
	err |= __put_user(mask, &sc->oldmask);

	return err;
}

/*
 * Determine which stack to use..
 */
static inline void __user *
get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
{
	if (ka->sa.sa_flags & SA_ONSTACK) {
		if (sas_ss_flags(sp) == 0)
			sp = current->sas_ss_sp + current->sas_ss_size;
	}

	return (void __user *)((sp - (frame_size+UNWINDGUARD)) & -8ul);
}

/* These symbols are defined with the addresses in the vsyscall page.
   See vsyscall-trapa.S.  */
extern void __kernel_sigreturn(void);
extern void __kernel_rt_sigreturn(void);

static int setup_frame(struct ksignal *ksig, sigset_t *set,
		       struct pt_regs *regs)
{
	struct sigframe __user *frame;
	int err = 0, sig = ksig->sig;
	int signal;

	frame = get_sigframe(&ksig->ka, regs->regs[15], sizeof(*frame));

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		return -EFAULT;

	signal = current_thread_info()->exec_domain
		&& current_thread_info()->exec_domain->signal_invmap
		&& sig < 32
		? current_thread_info()->exec_domain->signal_invmap[sig]
		: sig;

	err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);

	if (_NSIG_WORDS > 1)
		err |= __copy_to_user(frame->extramask, &set->sig[1],
				      sizeof(frame->extramask));

	/* Set up to return from userspace.  If provided, use a stub
	   already in userspace.  */
	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
		regs->pr = (unsigned long) ksig->ka.sa.sa_restorer;
#ifdef CONFIG_VSYSCALL
	} else if (likely(current->mm->context.vdso)) {
		regs->pr = VDSO_SYM(&__kernel_sigreturn);
#endif
	} else {
		/* Generate return code (system call to sigreturn) */
		err |= __put_user(MOVW(7), &frame->retcode[0]);
		err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
		err |= __put_user(OR_R0_R0, &frame->retcode[2]);
		err |= __put_user(OR_R0_R0, &frame->retcode[3]);
		err |= __put_user(OR_R0_R0, &frame->retcode[4]);
		err |= __put_user(OR_R0_R0, &frame->retcode[5]);
		err |= __put_user(OR_R0_R0, &frame->retcode[6]);
		err |= __put_user((__NR_sigreturn), &frame->retcode[7]);
		regs->pr = (unsigned long) frame->retcode;
		flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
	}

	if (err)
		return -EFAULT;

	/* Set up registers for signal handler */
	regs->regs[15] = (unsigned long) frame;
	regs->regs[4] = signal; /* Arg for signal handler */
	regs->regs[5] = 0;
	regs->regs[6] = (unsigned long) &frame->sc;

	if (current->personality & FDPIC_FUNCPTRS) {
		struct fdpic_func_descriptor __user *funcptr =
			(struct fdpic_func_descriptor __user *)ksig->ka.sa.sa_handler;

		err |= __get_user(regs->pc, &funcptr->text);
		err |= __get_user(regs->regs[12], &funcptr->GOT);
	} else
		regs->pc = (unsigned long)ksig->ka.sa.sa_handler;

	if (err)
		return -EFAULT;

	pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
		 current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);

	return 0;
}

static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
			  struct pt_regs *regs)
{
	struct rt_sigframe __user *frame;
	int err = 0, sig = ksig->sig;
	int signal;

	frame = get_sigframe(&ksig->ka, regs->regs[15], sizeof(*frame));

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		return -EFAULT;

	signal = current_thread_info()->exec_domain
		&& current_thread_info()->exec_domain->signal_invmap
		&& sig < 32
		? current_thread_info()->exec_domain->signal_invmap[sig]
		: sig;

	err |= copy_siginfo_to_user(&frame->info, &ksig->info);

	/* Create the ucontext.  */
	err |= __put_user(0, &frame->uc.uc_flags);
	err |= __put_user(NULL, &frame->uc.uc_link);
	err |= __save_altstack(&frame->uc.uc_stack, regs->regs[15]);
	err |= setup_sigcontext(&frame->uc.uc_mcontext,
			        regs, set->sig[0]);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

	/* Set up to return from userspace.  If provided, use a stub
	   already in userspace.  */
	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
		regs->pr = (unsigned long) ksig->ka.sa.sa_restorer;
#ifdef CONFIG_VSYSCALL
	} else if (likely(current->mm->context.vdso)) {
		regs->pr = VDSO_SYM(&__kernel_rt_sigreturn);
#endif
	} else {
		/* Generate return code (system call to rt_sigreturn) */
		err |= __put_user(MOVW(7), &frame->retcode[0]);
		err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
		err |= __put_user(OR_R0_R0, &frame->retcode[2]);
		err |= __put_user(OR_R0_R0, &frame->retcode[3]);
		err |= __put_user(OR_R0_R0, &frame->retcode[4]);
		err |= __put_user(OR_R0_R0, &frame->retcode[5]);
		err |= __put_user(OR_R0_R0, &frame->retcode[6]);
		err |= __put_user((__NR_rt_sigreturn), &frame->retcode[7]);
		regs->pr = (unsigned long) frame->retcode;
		flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
	}

	if (err)
		return -EFAULT;

	/* Set up registers for signal handler */
	regs->regs[15] = (unsigned long) frame;
	regs->regs[4] = signal; /* Arg for signal handler */
	regs->regs[5] = (unsigned long) &frame->info;
	regs->regs[6] = (unsigned long) &frame->uc;

	if (current->personality & FDPIC_FUNCPTRS) {
		struct fdpic_func_descriptor __user *funcptr =
			(struct fdpic_func_descriptor __user *)ksig->ka.sa.sa_handler;

		err |= __get_user(regs->pc, &funcptr->text);
		err |= __get_user(regs->regs[12], &funcptr->GOT);
	} else
		regs->pc = (unsigned long)ksig->ka.sa.sa_handler;

	if (err)
		return -EFAULT;

	pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
		 current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);

	return 0;
}

static inline void
handle_syscall_restart(unsigned long save_r0, struct pt_regs *regs,
		       struct sigaction *sa)
{
	/* If we're not from a syscall, bail out */
	if (regs->tra < 0)
		return;

	/* check for system call restart.. */
	switch (regs->regs[0]) {
		case -ERESTART_RESTARTBLOCK:
		case -ERESTARTNOHAND:
		no_system_call_restart:
			regs->regs[0] = -EINTR;
			break;

		case -ERESTARTSYS:
			if (!(sa->sa_flags & SA_RESTART))
				goto no_system_call_restart;
		/* fallthrough */
		case -ERESTARTNOINTR:
			regs->regs[0] = save_r0;
			regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
			break;
	}
}

/*
 * OK, we're invoking a handler
 */
static void
handle_signal(struct ksignal *ksig, struct pt_regs *regs, unsigned int save_r0)
{
	sigset_t *oldset = sigmask_to_save();
	int ret;

	/* Set up the stack frame */
	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
		ret = setup_rt_frame(ksig, oldset, regs);
	else
		ret = setup_frame(ksig, oldset, regs);

	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
}

/*
 * Note that 'init' is a special process: it doesn't get signals it doesn't
 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 * mistake.
 *
 * Note that we go through the signals twice: once to check the signals that
 * the kernel can handle, and then we build all the user-level signal handling
 * stack-frames in one go after that.
 */
static void do_signal(struct pt_regs *regs, unsigned int save_r0)
{
	struct ksignal ksig;

	/*
	 * We want the common case to go fast, which
	 * is why we may in certain cases get here from
	 * kernel mode. Just return without doing anything
	 * if so.
	 */
	if (!user_mode(regs))
		return;

	if (get_signal(&ksig)) {
		handle_syscall_restart(save_r0, regs, &ksig.ka.sa);

		/* Whee!  Actually deliver the signal.  */
		handle_signal(&ksig, regs, save_r0);
		return;
	}

	/* Did we come from a system call? */
	if (regs->tra >= 0) {
		/* Restart the system call - no handlers present */
		if (regs->regs[0] == -ERESTARTNOHAND ||
		    regs->regs[0] == -ERESTARTSYS ||
		    regs->regs[0] == -ERESTARTNOINTR) {
			regs->regs[0] = save_r0;
			regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
		} else if (regs->regs[0] == -ERESTART_RESTARTBLOCK) {
			regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
			regs->regs[3] = __NR_restart_syscall;
		}
	}

	/*
	 * If there's no signal to deliver, we just put the saved sigmask
	 * back.
	 */
	restore_saved_sigmask();
}

asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
				 unsigned long thread_info_flags)
{
	/* deal with pending signal delivery */
	if (thread_info_flags & _TIF_SIGPENDING)
		do_signal(regs, save_r0);

	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
		clear_thread_flag(TIF_NOTIFY_RESUME);
		tracehook_notify_resume(regs);
	}
}