1 /*
2 * Signal support for Hexagon processor
3 *
4 * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 and
8 * only version 2 as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
18 * 02110-1301, USA.
19 */
20
21 #include <linux/linkage.h>
22 #include <linux/syscalls.h>
23 #include <linux/freezer.h>
24 #include <linux/tracehook.h>
25 #include <asm/registers.h>
26 #include <asm/thread_info.h>
27 #include <asm/unistd.h>
28 #include <asm/uaccess.h>
29 #include <asm/ucontext.h>
30 #include <asm/cacheflush.h>
31 #include <asm/signal.h>
32 #include <asm/vdso.h>
33
34 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
35
36 struct rt_sigframe {
37 unsigned long tramp[2];
38 struct siginfo info;
39 struct ucontext uc;
40 };
41
get_sigframe(struct k_sigaction * ka,struct pt_regs * regs,size_t frame_size)42 static void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
43 size_t frame_size)
44 {
45 unsigned long sp = regs->r29;
46
47 /* Switch to signal stack if appropriate */
48 if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
49 sp = current->sas_ss_sp + current->sas_ss_size;
50
51 return (void __user *)((sp - frame_size) & ~(sizeof(long long) - 1));
52 }
53
setup_sigcontext(struct pt_regs * regs,struct sigcontext __user * sc)54 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
55 {
56 unsigned long tmp;
57 int err = 0;
58
59 err |= copy_to_user(&sc->sc_regs.r0, ®s->r00,
60 32*sizeof(unsigned long));
61
62 err |= __put_user(regs->sa0, &sc->sc_regs.sa0);
63 err |= __put_user(regs->lc0, &sc->sc_regs.lc0);
64 err |= __put_user(regs->sa1, &sc->sc_regs.sa1);
65 err |= __put_user(regs->lc1, &sc->sc_regs.lc1);
66 err |= __put_user(regs->m0, &sc->sc_regs.m0);
67 err |= __put_user(regs->m1, &sc->sc_regs.m1);
68 err |= __put_user(regs->usr, &sc->sc_regs.usr);
69 err |= __put_user(regs->preds, &sc->sc_regs.p3_0);
70 err |= __put_user(regs->gp, &sc->sc_regs.gp);
71 err |= __put_user(regs->ugp, &sc->sc_regs.ugp);
72
73 tmp = pt_elr(regs); err |= __put_user(tmp, &sc->sc_regs.pc);
74 tmp = pt_cause(regs); err |= __put_user(tmp, &sc->sc_regs.cause);
75 tmp = pt_badva(regs); err |= __put_user(tmp, &sc->sc_regs.badva);
76
77 return err;
78 }
79
restore_sigcontext(struct pt_regs * regs,struct sigcontext __user * sc)80 static int restore_sigcontext(struct pt_regs *regs,
81 struct sigcontext __user *sc)
82 {
83 unsigned long tmp;
84 int err = 0;
85
86 err |= copy_from_user(®s->r00, &sc->sc_regs.r0,
87 32 * sizeof(unsigned long));
88
89 err |= __get_user(regs->sa0, &sc->sc_regs.sa0);
90 err |= __get_user(regs->lc0, &sc->sc_regs.lc0);
91 err |= __get_user(regs->sa1, &sc->sc_regs.sa1);
92 err |= __get_user(regs->lc1, &sc->sc_regs.lc1);
93 err |= __get_user(regs->m0, &sc->sc_regs.m0);
94 err |= __get_user(regs->m1, &sc->sc_regs.m1);
95 err |= __get_user(regs->usr, &sc->sc_regs.usr);
96 err |= __get_user(regs->preds, &sc->sc_regs.p3_0);
97 err |= __get_user(regs->gp, &sc->sc_regs.gp);
98 err |= __get_user(regs->ugp, &sc->sc_regs.ugp);
99
100 err |= __get_user(tmp, &sc->sc_regs.pc); pt_set_elr(regs, tmp);
101
102 return err;
103 }
104
105 /*
106 * Setup signal stack frame with siginfo structure
107 */
setup_rt_frame(int signr,struct k_sigaction * ka,siginfo_t * info,sigset_t * set,struct pt_regs * regs)108 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
109 sigset_t *set, struct pt_regs *regs)
110 {
111 int err = 0;
112 struct rt_sigframe __user *frame;
113 struct hexagon_vdso *vdso = current->mm->context.vdso;
114
115 frame = get_sigframe(ka, regs, sizeof(struct rt_sigframe));
116
117 if (!access_ok(VERIFY_WRITE, frame, sizeof(struct rt_sigframe)))
118 goto sigsegv;
119
120 if (copy_siginfo_to_user(&frame->info, info))
121 goto sigsegv;
122
123 /* The on-stack signal trampoline is no longer executed;
124 * however, the libgcc signal frame unwinding code checks for
125 * the presence of these two numeric magic values.
126 */
127 err |= __put_user(0x7800d166, &frame->tramp[0]);
128 err |= __put_user(0x5400c004, &frame->tramp[1]);
129 err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
130 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
131 if (err)
132 goto sigsegv;
133
134 /* Load r0/r1 pair with signumber/siginfo pointer... */
135 regs->r0100 = ((unsigned long long)((unsigned long)&frame->info) << 32)
136 | (unsigned long long)signr;
137 regs->r02 = (unsigned long) &frame->uc;
138 regs->r31 = (unsigned long) vdso->rt_signal_trampoline;
139 pt_psp(regs) = (unsigned long) frame;
140 pt_set_elr(regs, (unsigned long)ka->sa.sa_handler);
141
142 return 0;
143
144 sigsegv:
145 force_sigsegv(signr, current);
146 return -EFAULT;
147 }
148
149 /*
150 * Setup invocation of signal handler
151 */
handle_signal(int sig,siginfo_t * info,struct k_sigaction * ka,sigset_t * oldset,struct pt_regs * regs)152 static int handle_signal(int sig, siginfo_t *info, struct k_sigaction *ka,
153 sigset_t *oldset, struct pt_regs *regs)
154 {
155 int rc;
156
157 /*
158 * If we're handling a signal that aborted a system call,
159 * set up the error return value before adding the signal
160 * frame to the stack.
161 */
162
163 if (regs->syscall_nr >= 0) {
164 switch (regs->r00) {
165 case -ERESTART_RESTARTBLOCK:
166 case -ERESTARTNOHAND:
167 regs->r00 = -EINTR;
168 break;
169 case -ERESTARTSYS:
170 if (!(ka->sa.sa_flags & SA_RESTART)) {
171 regs->r00 = -EINTR;
172 break;
173 }
174 /* Fall through */
175 case -ERESTARTNOINTR:
176 regs->r06 = regs->syscall_nr;
177 pt_set_elr(regs, pt_elr(regs) - 4);
178 regs->r00 = regs->restart_r0;
179 break;
180 default:
181 break;
182 }
183 }
184
185 /*
186 * Set up the stack frame; not doing the SA_SIGINFO thing. We
187 * only set up the rt_frame flavor.
188 */
189 rc = setup_rt_frame(sig, ka, info, oldset, regs);
190
191 /* If there was an error on setup, no signal was delivered. */
192 if (rc)
193 return rc;
194
195 block_sigmask(ka, sig);
196
197 return 0;
198 }
199
200 /*
201 * Called from return-from-event code.
202 */
do_signal(struct pt_regs * regs)203 static void do_signal(struct pt_regs *regs)
204 {
205 struct k_sigaction sigact;
206 siginfo_t info;
207 int signo;
208
209 if (!user_mode(regs))
210 return;
211
212 if (try_to_freeze())
213 goto no_signal;
214
215 signo = get_signal_to_deliver(&info, &sigact, regs, NULL);
216
217 if (signo > 0) {
218 sigset_t *oldset;
219
220 if (test_thread_flag(TIF_RESTORE_SIGMASK))
221 oldset = ¤t->saved_sigmask;
222 else
223 oldset = ¤t->blocked;
224
225 if (handle_signal(signo, &info, &sigact, oldset, regs) == 0) {
226 /*
227 * Successful delivery case. The saved sigmask is
228 * stored in the signal frame, and will be restored
229 * by sigreturn. We can clear the TIF flag.
230 */
231 clear_thread_flag(TIF_RESTORE_SIGMASK);
232
233 tracehook_signal_handler(signo, &info, &sigact, regs,
234 test_thread_flag(TIF_SINGLESTEP));
235 }
236 return;
237 }
238
239 no_signal:
240 /*
241 * If we came from a system call, handle the restart.
242 */
243 if (regs->syscall_nr >= 0) {
244 switch (regs->r00) {
245 case -ERESTARTNOHAND:
246 case -ERESTARTSYS:
247 case -ERESTARTNOINTR:
248 regs->r06 = regs->syscall_nr;
249 break;
250 case -ERESTART_RESTARTBLOCK:
251 regs->r06 = __NR_restart_syscall;
252 break;
253 default:
254 goto no_restart;
255 }
256 pt_set_elr(regs, pt_elr(regs) - 4);
257 regs->r00 = regs->restart_r0;
258 }
259
260 no_restart:
261 /* If there's no signal to deliver, put the saved sigmask back */
262 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
263 clear_thread_flag(TIF_RESTORE_SIGMASK);
264 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL);
265 }
266 }
267
do_notify_resume(struct pt_regs * regs,unsigned long thread_info_flags)268 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
269 {
270 if (thread_info_flags & _TIF_SIGPENDING)
271 do_signal(regs);
272
273 if (thread_info_flags & _TIF_NOTIFY_RESUME) {
274 clear_thread_flag(TIF_NOTIFY_RESUME);
275 if (current->replacement_session_keyring)
276 key_replace_session_keyring();
277 }
278 }
279
280 /*
281 * Architecture-specific wrappers for signal-related system calls
282 */
sys_sigaltstack(const stack_t __user * uss,stack_t __user * uoss)283 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
284 {
285 struct pt_regs *regs = current_thread_info()->regs;
286
287 return do_sigaltstack(uss, uoss, regs->r29);
288 }
289
sys_rt_sigreturn(void)290 asmlinkage int sys_rt_sigreturn(void)
291 {
292 struct pt_regs *regs = current_thread_info()->regs;
293 struct rt_sigframe __user *frame;
294 sigset_t blocked;
295
296 frame = (struct rt_sigframe __user *)pt_psp(regs);
297 if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
298 goto badframe;
299 if (__copy_from_user(&blocked, &frame->uc.uc_sigmask, sizeof(blocked)))
300 goto badframe;
301
302 sigdelsetmask(&blocked, ~_BLOCKABLE);
303 set_current_blocked(&blocked);
304
305 if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
306 goto badframe;
307
308 /* Restore the user's stack as well */
309 pt_psp(regs) = regs->r29;
310
311 /*
312 * Leave a trace in the stack frame that this was a sigreturn.
313 * If the system call is to replay, we've already restored the
314 * number in the GPR slot and it will be regenerated on the
315 * new system call trap entry. Note that if restore_sigcontext()
316 * did something other than a bulk copy of the pt_regs struct,
317 * we could avoid this assignment by simply not overwriting
318 * regs->syscall_nr.
319 */
320 regs->syscall_nr = __NR_rt_sigreturn;
321
322 /*
323 * If we were meticulous, we'd only call this if we knew that
324 * we were actually going to use an alternate stack, and we'd
325 * consider any error to be fatal. What we do here, in common
326 * with many other architectures, is call it blindly and only
327 * consider the -EFAULT return case to be proof of a problem.
328 */
329 if (do_sigaltstack(&frame->uc.uc_stack, NULL, pt_psp(regs)) == -EFAULT)
330 goto badframe;
331
332 return 0;
333
334 badframe:
335 force_sig(SIGSEGV, current);
336 return 0;
337 }
338