aboutsummaryrefslogtreecommitdiff
path: root/arch/hexagon/kernel/signal.c
blob: c9caf7401191d2ce4c92f99d5d29e233fd660320 (plain)
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
/*
 * Signal support for Hexagon processor
 *
 * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

#include <linux/linkage.h>
#include <linux/syscalls.h>
#include <linux/freezer.h>
#include <linux/tracehook.h>
#include <asm/registers.h>
#include <asm/thread_info.h>
#include <asm/unistd.h>
#include <asm/uaccess.h>
#include <asm/ucontext.h>
#include <asm/cacheflush.h>
#include <asm/signal.h>
#include <asm/vdso.h>

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

struct rt_sigframe {
	unsigned long tramp[2];
	struct siginfo info;
	struct ucontext uc;
};

static void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
			  size_t frame_size)
{
	unsigned long sp = regs->r29;

	/* Switch to signal stack if appropriate */
	if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
		sp = current->sas_ss_sp + current->sas_ss_size;

	return (void __user *)((sp - frame_size) & ~(sizeof(long long) - 1));
}

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

	err |= copy_to_user(&sc->sc_regs.r0, &regs->r00,
			    32*sizeof(unsigned long));

	err |= __put_user(regs->sa0, &sc->sc_regs.sa0);
	err |= __put_user(regs->lc0, &sc->sc_regs.lc0);
	err |= __put_user(regs->sa1, &sc->sc_regs.sa1);
	err |= __put_user(regs->lc1, &sc->sc_regs.lc1);
	err |= __put_user(regs->m0, &sc->sc_regs.m0);
	err |= __put_user(regs->m1, &sc->sc_regs.m1);
	err |= __put_user(regs->usr, &sc->sc_regs.usr);
	err |= __put_user(regs->preds, &sc->sc_regs.p3_0);
	err |= __put_user(regs->gp, &sc->sc_regs.gp);
	err |= __put_user(regs->ugp, &sc->sc_regs.ugp);

	tmp = pt_elr(regs); err |= __put_user(tmp, &sc->sc_regs.pc);
	tmp = pt_cause(regs); err |= __put_user(tmp, &sc->sc_regs.cause);
	tmp = pt_badva(regs); err |= __put_user(tmp, &sc->sc_regs.badva);

	return err;
}

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

	err |= copy_from_user(&regs->r00, &sc->sc_regs.r0,
			      32 * sizeof(unsigned long));

	err |= __get_user(regs->sa0, &sc->sc_regs.sa0);
	err |= __get_user(regs->lc0, &sc->sc_regs.lc0);
	err |= __get_user(regs->sa1, &sc->sc_regs.sa1);
	err |= __get_user(regs->lc1, &sc->sc_regs.lc1);
	err |= __get_user(regs->m0, &sc->sc_regs.m0);
	err |= __get_user(regs->m1, &sc->sc_regs.m1);
	err |= __get_user(regs->usr, &sc->sc_regs.usr);
	err |= __get_user(regs->preds, &sc->sc_regs.p3_0);
	err |= __get_user(regs->gp, &sc->sc_regs.gp);
	err |= __get_user(regs->ugp, &sc->sc_regs.ugp);

	err |= __get_user(tmp, &sc->sc_regs.pc); pt_set_elr(regs, tmp);

	return err;
}

/*
 * Setup signal stack frame with siginfo structure
 */
static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
			  sigset_t *set,  struct pt_regs *regs)
{
	int err = 0;
	struct rt_sigframe __user *frame;
	struct hexagon_vdso *vdso = current->mm->context.vdso;

	frame = get_sigframe(ka, regs, sizeof(struct rt_sigframe));

	if (!access_ok(VERIFY_WRITE, frame, sizeof(struct rt_sigframe)))
		goto	sigsegv;

	if (copy_siginfo_to_user(&frame->info, info))
		goto	sigsegv;

	/* The on-stack signal trampoline is no longer executed;
	 * however, the libgcc signal frame unwinding code checks for
	 * the presence of these two numeric magic values.
	 */
	err |= __put_user(0x7800d166, &frame->tramp[0]);
	err |= __put_user(0x5400c004, &frame->tramp[1]);
	err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
	if (err)
		goto sigsegv;

	/* Load r0/r1 pair with signumber/siginfo pointer... */
	regs->r0100 = ((unsigned long long)((unsigned long)&frame->info) << 32)
		| (unsigned long long)signr;
	regs->r02 = (unsigned long) &frame->uc;
	regs->r31 = (unsigned long) vdso->rt_signal_trampoline;
	pt_psp(regs) = (unsigned long) frame;
	pt_set_elr(regs, (unsigned long)ka->sa.sa_handler);

	return 0;

sigsegv:
	force_sigsegv(signr, current);
	return -EFAULT;
}

/*
 * Setup invocation of signal handler
 */
static void handle_signal(int sig, siginfo_t *info, struct k_sigaction *ka,
			 struct pt_regs *regs)
{
	/*
	 * If we're handling a signal that aborted a system call,
	 * set up the error return value before adding the signal
	 * frame to the stack.
	 */

	if (regs->syscall_nr >= 0) {
		switch (regs->r00) {
		case -ERESTART_RESTARTBLOCK:
		case -ERESTARTNOHAND:
			regs->r00 = -EINTR;
			break;
		case -ERESTARTSYS:
			if (!(ka->sa.sa_flags & SA_RESTART)) {
				regs->r00 = -EINTR;
				break;
			}
			/* Fall through */
		case -ERESTARTNOINTR:
			regs->r06 = regs->syscall_nr;
			pt_set_elr(regs, pt_elr(regs) - 4);
			regs->r00 = regs->restart_r0;
			break;
		default:
			break;
		}
	}

	/*
	 * Set up the stack frame; not doing the SA_SIGINFO thing.  We
	 * only set up the rt_frame flavor.
	 */
	/* If there was an error on setup, no signal was delivered. */
	if (setup_rt_frame(sig, ka, info, sigmask_to_save(), regs) < 0)
		return;

	block_sigmask(ka, sig);
	tracehook_signal_handler(sig, info, ka, regs,
			test_thread_flag(TIF_SINGLESTEP));
}

/*
 * Called from return-from-event code.
 */
static void do_signal(struct pt_regs *regs)
{
	struct k_sigaction sigact;
	siginfo_t info;
	int signo;

	if (!user_mode(regs))
		return;

	signo = get_signal_to_deliver(&info, &sigact, regs, NULL);

	if (signo > 0) {
		handle_signal(signo, &info, &sigact, regs);
		return;
	}

	/*
	 * If we came from a system call, handle the restart.
	 */
	if (regs->syscall_nr >= 0) {
		switch (regs->r00) {
		case -ERESTARTNOHAND:
		case -ERESTARTSYS:
		case -ERESTARTNOINTR:
			regs->r06 = regs->syscall_nr;
			break;
		case -ERESTART_RESTARTBLOCK:
			regs->r06 = __NR_restart_syscall;
			break;
		default:
			goto no_restart;
		}
		pt_set_elr(regs, pt_elr(regs) - 4);
		regs->r00 = regs->restart_r0;
	}

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

void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
{
	if (thread_info_flags & _TIF_SIGPENDING)
		do_signal(regs);

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

/*
 * Architecture-specific wrappers for signal-related system calls
 */
asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
{
	struct pt_regs *regs = current_thread_info()->regs;

	return do_sigaltstack(uss, uoss, regs->r29);
}

asmlinkage int sys_rt_sigreturn(void)
{
	struct pt_regs *regs = current_thread_info()->regs;
	struct rt_sigframe __user *frame;
	sigset_t blocked;

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

	frame = (struct rt_sigframe __user *)pt_psp(regs);
	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;
	if (__copy_from_user(&blocked, &frame->uc.uc_sigmask, sizeof(blocked)))
		goto badframe;

	sigdelsetmask(&blocked, ~_BLOCKABLE);
	set_current_blocked(&blocked);

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

	/* Restore the user's stack as well */
	pt_psp(regs) = regs->r29;

	/*
	 * Leave a trace in the stack frame that this was a sigreturn.
	 * If the system call is to replay, we've already restored the
	 * number in the GPR slot and it will be regenerated on the
	 * new system call trap entry. Note that if restore_sigcontext()
	 * did something other than a bulk copy of the pt_regs struct,
	 * we could avoid this assignment by simply not overwriting
	 * regs->syscall_nr.
	 */
	regs->syscall_nr = __NR_rt_sigreturn;

	/*
	 * If we were meticulous, we'd only call this if we knew that
	 * we were actually going to use an alternate stack, and we'd
	 * consider any error to be fatal.  What we do here, in common
	 * with many other architectures, is call it blindly and only
	 * consider the -EFAULT return case to be proof of a problem.
	 */
	if (do_sigaltstack(&frame->uc.uc_stack, NULL, pt_psp(regs)) == -EFAULT)
		goto badframe;

	return 0;

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