1 /*
2  *  Port on Texas Instruments TMS320C6x architecture
3  *
4  *  Copyright (C) 2004, 2006, 2009, 2010, 2011 Texas Instruments Incorporated
5  *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
6  *
7  *  Updated for 2.6.34: Mark Salter <msalter@redhat.com>
8  *
9  *  This program is free software; you can redistribute it and/or modify
10  *  it under the terms of the GNU General Public License version 2 as
11  *  published by the Free Software Foundation.
12  */
13 
14 #include <linux/kernel.h>
15 #include <linux/uaccess.h>
16 #include <linux/syscalls.h>
17 #include <linux/tracehook.h>
18 
19 #include <asm/ucontext.h>
20 #include <asm/cacheflush.h>
21 
22 
23 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
24 
25 /*
26  * Do a signal return, undo the signal stack.
27  */
28 
29 #define RETCODE_SIZE (9 << 2)	/* 9 instructions = 36 bytes */
30 
31 struct rt_sigframe {
32 	struct siginfo __user *pinfo;
33 	void __user *puc;
34 	struct siginfo info;
35 	struct ucontext uc;
36 	unsigned long retcode[RETCODE_SIZE >> 2];
37 };
38 
restore_sigcontext(struct pt_regs * regs,struct sigcontext __user * sc)39 static int restore_sigcontext(struct pt_regs *regs,
40 			      struct sigcontext __user *sc)
41 {
42 	int err = 0;
43 
44 	/* The access_ok check was done by caller, so use __get_user here */
45 #define COPY(x)  (err |= __get_user(regs->x, &sc->sc_##x))
46 
47 	COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
48 	COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
49 	COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
50 
51 	COPY(a16); COPY(a17); COPY(a18); COPY(a19);
52 	COPY(a20); COPY(a21); COPY(a22); COPY(a23);
53 	COPY(a24); COPY(a25); COPY(a26); COPY(a27);
54 	COPY(a28); COPY(a29); COPY(a30); COPY(a31);
55 	COPY(b16); COPY(b17); COPY(b18); COPY(b19);
56 	COPY(b20); COPY(b21); COPY(b22); COPY(b23);
57 	COPY(b24); COPY(b25); COPY(b26); COPY(b27);
58 	COPY(b28); COPY(b29); COPY(b30); COPY(b31);
59 
60 	COPY(csr); COPY(pc);
61 
62 #undef COPY
63 
64 	return err;
65 }
66 
do_rt_sigreturn(struct pt_regs * regs)67 asmlinkage int do_rt_sigreturn(struct pt_regs *regs)
68 {
69 	struct rt_sigframe __user *frame;
70 	sigset_t set;
71 
72 	/*
73 	 * Since we stacked the signal on a dword boundary,
74 	 * 'sp' should be dword aligned here.  If it's
75 	 * not, then the user is trying to mess with us.
76 	 */
77 	if (regs->sp & 7)
78 		goto badframe;
79 
80 	frame = (struct rt_sigframe __user *) ((unsigned long) regs->sp + 8);
81 
82 	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
83 		goto badframe;
84 	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
85 		goto badframe;
86 
87 	sigdelsetmask(&set, ~_BLOCKABLE);
88 	spin_lock_irq(&current->sighand->siglock);
89 	current->blocked = set;
90 	recalc_sigpending();
91 	spin_unlock_irq(&current->sighand->siglock);
92 
93 	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
94 		goto badframe;
95 
96 	return regs->a4;
97 
98 badframe:
99 	force_sig(SIGSEGV, current);
100 	return 0;
101 }
102 
setup_sigcontext(struct sigcontext __user * sc,struct pt_regs * regs,unsigned long mask)103 static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
104 			    unsigned long mask)
105 {
106 	int err = 0;
107 
108 	err |= __put_user(mask, &sc->sc_mask);
109 
110 	/* The access_ok check was done by caller, so use __put_user here */
111 #define COPY(x) (err |= __put_user(regs->x, &sc->sc_##x))
112 
113 	COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
114 	COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
115 	COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
116 
117 	COPY(a16); COPY(a17); COPY(a18); COPY(a19);
118 	COPY(a20); COPY(a21); COPY(a22); COPY(a23);
119 	COPY(a24); COPY(a25); COPY(a26); COPY(a27);
120 	COPY(a28); COPY(a29); COPY(a30); COPY(a31);
121 	COPY(b16); COPY(b17); COPY(b18); COPY(b19);
122 	COPY(b20); COPY(b21); COPY(b22); COPY(b23);
123 	COPY(b24); COPY(b25); COPY(b26); COPY(b27);
124 	COPY(b28); COPY(b29); COPY(b30); COPY(b31);
125 
126 	COPY(csr); COPY(pc);
127 
128 #undef COPY
129 
130 	return err;
131 }
132 
get_sigframe(struct k_sigaction * ka,struct pt_regs * regs,unsigned long framesize)133 static inline void __user *get_sigframe(struct k_sigaction *ka,
134 					struct pt_regs *regs,
135 					unsigned long framesize)
136 {
137 	unsigned long sp = regs->sp;
138 
139 	/*
140 	 * This is the X/Open sanctioned signal stack switching.
141 	 */
142 	if ((ka->sa.sa_flags & SA_ONSTACK) && sas_ss_flags(sp) == 0)
143 		sp = current->sas_ss_sp + current->sas_ss_size;
144 
145 	/*
146 	 * No matter what happens, 'sp' must be dword
147 	 * aligned. Otherwise, nasty things will happen
148 	 */
149 	return (void __user *)((sp - framesize) & ~7);
150 }
151 
setup_rt_frame(int signr,struct k_sigaction * ka,siginfo_t * info,sigset_t * set,struct pt_regs * regs)152 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
153 			   sigset_t *set, struct pt_regs *regs)
154 {
155 	struct rt_sigframe __user *frame;
156 	unsigned long __user *retcode;
157 	int err = 0;
158 
159 	frame = get_sigframe(ka, regs, sizeof(*frame));
160 
161 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
162 		goto segv_and_exit;
163 
164 	err |= __put_user(&frame->info, &frame->pinfo);
165 	err |= __put_user(&frame->uc, &frame->puc);
166 	err |= copy_siginfo_to_user(&frame->info, info);
167 
168 	/* Clear all the bits of the ucontext we don't use.  */
169 	err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
170 
171 	err |= setup_sigcontext(&frame->uc.uc_mcontext,	regs, set->sig[0]);
172 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
173 
174 	/* Set up to return from userspace */
175 	retcode = (unsigned long __user *) &frame->retcode;
176 
177 	/* The access_ok check was done above, so use __put_user here */
178 #define COPY(x) (err |= __put_user(x, retcode++))
179 
180 	COPY(0x0000002AUL | (__NR_rt_sigreturn << 7));
181 				/* MVK __NR_rt_sigreturn,B0 */
182 	COPY(0x10000000UL);	/* SWE */
183 	COPY(0x00006000UL);	/* NOP 4 */
184 	COPY(0x00006000UL);	/* NOP 4 */
185 	COPY(0x00006000UL);	/* NOP 4 */
186 	COPY(0x00006000UL);	/* NOP 4 */
187 	COPY(0x00006000UL);	/* NOP 4 */
188 	COPY(0x00006000UL);	/* NOP 4 */
189 	COPY(0x00006000UL);	/* NOP 4 */
190 
191 #undef COPY
192 
193 	if (err)
194 		goto segv_and_exit;
195 
196 	flush_icache_range((unsigned long) &frame->retcode,
197 			   (unsigned long) &frame->retcode + RETCODE_SIZE);
198 
199 	retcode = (unsigned long __user *) &frame->retcode;
200 
201 	/* Change user context to branch to signal handler */
202 	regs->sp = (unsigned long) frame - 8;
203 	regs->b3 = (unsigned long) retcode;
204 	regs->pc = (unsigned long) ka->sa.sa_handler;
205 
206 	/* Give the signal number to the handler */
207 	regs->a4 = signr;
208 
209 	/*
210 	 * For realtime signals we must also set the second and third
211 	 * arguments for the signal handler.
212 	 *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
213 	 */
214 	regs->b4 = (unsigned long)&frame->info;
215 	regs->a6 = (unsigned long)&frame->uc;
216 
217 	return 0;
218 
219 segv_and_exit:
220 	force_sigsegv(signr, current);
221 	return -EFAULT;
222 }
223 
224 static inline void
handle_restart(struct pt_regs * regs,struct k_sigaction * ka,int has_handler)225 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
226 {
227 	switch (regs->a4) {
228 	case -ERESTARTNOHAND:
229 		if (!has_handler)
230 			goto do_restart;
231 		regs->a4 = -EINTR;
232 		break;
233 
234 	case -ERESTARTSYS:
235 		if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
236 			regs->a4 = -EINTR;
237 			break;
238 		}
239 	/* fallthrough */
240 	case -ERESTARTNOINTR:
241 do_restart:
242 		regs->a4 = regs->orig_a4;
243 		regs->pc -= 4;
244 		break;
245 	}
246 }
247 
248 /*
249  * handle the actual delivery of a signal to userspace
250  */
handle_signal(int sig,siginfo_t * info,struct k_sigaction * ka,sigset_t * oldset,struct pt_regs * regs,int syscall)251 static int handle_signal(int sig,
252 			 siginfo_t *info, struct k_sigaction *ka,
253 			 sigset_t *oldset, struct pt_regs *regs,
254 			 int syscall)
255 {
256 	int ret;
257 
258 	/* Are we from a system call? */
259 	if (syscall) {
260 		/* If so, check system call restarting.. */
261 		switch (regs->a4) {
262 		case -ERESTART_RESTARTBLOCK:
263 		case -ERESTARTNOHAND:
264 			regs->a4 = -EINTR;
265 			break;
266 
267 		case -ERESTARTSYS:
268 			if (!(ka->sa.sa_flags & SA_RESTART)) {
269 				regs->a4 = -EINTR;
270 				break;
271 			}
272 
273 			/* fallthrough */
274 		case -ERESTARTNOINTR:
275 			regs->a4 = regs->orig_a4;
276 			regs->pc -= 4;
277 		}
278 	}
279 
280 	/* Set up the stack frame */
281 	ret = setup_rt_frame(sig, ka, info, oldset, regs);
282 	if (ret == 0) {
283 		spin_lock_irq(&current->sighand->siglock);
284 		sigorsets(&current->blocked, &current->blocked,
285 			  &ka->sa.sa_mask);
286 		if (!(ka->sa.sa_flags & SA_NODEFER))
287 			sigaddset(&current->blocked, sig);
288 		recalc_sigpending();
289 		spin_unlock_irq(&current->sighand->siglock);
290 	}
291 
292 	return ret;
293 }
294 
295 /*
296  * handle a potential signal
297  */
do_signal(struct pt_regs * regs,int syscall)298 static void do_signal(struct pt_regs *regs, int syscall)
299 {
300 	struct k_sigaction ka;
301 	siginfo_t info;
302 	sigset_t *oldset;
303 	int signr;
304 
305 	/* we want the common case to go fast, which is why we may in certain
306 	 * cases get here from kernel mode */
307 	if (!user_mode(regs))
308 		return;
309 
310 	if (test_thread_flag(TIF_RESTORE_SIGMASK))
311 		oldset = &current->saved_sigmask;
312 	else
313 		oldset = &current->blocked;
314 
315 	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
316 	if (signr > 0) {
317 		if (handle_signal(signr, &info, &ka, oldset,
318 				  regs, syscall) == 0) {
319 			/* a signal was successfully delivered; the saved
320 			 * sigmask will have been stored in the signal frame,
321 			 * and will be restored by sigreturn, so we can simply
322 			 * clear the TIF_RESTORE_SIGMASK flag */
323 			if (test_thread_flag(TIF_RESTORE_SIGMASK))
324 				clear_thread_flag(TIF_RESTORE_SIGMASK);
325 
326 			tracehook_signal_handler(signr, &info, &ka, regs, 0);
327 		}
328 
329 		return;
330 	}
331 
332 	/* did we come from a system call? */
333 	if (syscall) {
334 		/* restart the system call - no handlers present */
335 		switch (regs->a4) {
336 		case -ERESTARTNOHAND:
337 		case -ERESTARTSYS:
338 		case -ERESTARTNOINTR:
339 			regs->a4 = regs->orig_a4;
340 			regs->pc -= 4;
341 			break;
342 
343 		case -ERESTART_RESTARTBLOCK:
344 			regs->a4 = regs->orig_a4;
345 			regs->b0 = __NR_restart_syscall;
346 			regs->pc -= 4;
347 			break;
348 		}
349 	}
350 
351 	/* if there's no signal to deliver, we just put the saved sigmask
352 	 * back */
353 	if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
354 		clear_thread_flag(TIF_RESTORE_SIGMASK);
355 		sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
356 	}
357 }
358 
359 /*
360  * notification of userspace execution resumption
361  * - triggered by current->work.notify_resume
362  */
do_notify_resume(struct pt_regs * regs,u32 thread_info_flags,int syscall)363 asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags,
364 				 int syscall)
365 {
366 	/* deal with pending signal delivery */
367 	if (thread_info_flags & ((1 << TIF_SIGPENDING) |
368 				 (1 << TIF_RESTORE_SIGMASK)))
369 		do_signal(regs, syscall);
370 
371 	if (thread_info_flags & (1 << TIF_NOTIFY_RESUME)) {
372 		clear_thread_flag(TIF_NOTIFY_RESUME);
373 		tracehook_notify_resume(regs);
374 		if (current->replacement_session_keyring)
375 			key_replace_session_keyring();
376 	}
377 }
378