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Linux/arch/c6x/kernel/signal.c

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  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 /*
 24  * Do a signal return, undo the signal stack.
 25  */
 26 
 27 #define RETCODE_SIZE (9 << 2)   /* 9 instructions = 36 bytes */
 28 
 29 struct rt_sigframe {
 30         struct siginfo __user *pinfo;
 31         void __user *puc;
 32         struct siginfo info;
 33         struct ucontext uc;
 34         unsigned long retcode[RETCODE_SIZE >> 2];
 35 };
 36 
 37 static int restore_sigcontext(struct pt_regs *regs,
 38                               struct sigcontext __user *sc)
 39 {
 40         int err = 0;
 41 
 42         /* The access_ok check was done by caller, so use __get_user here */
 43 #define COPY(x)  (err |= __get_user(regs->x, &sc->sc_##x))
 44 
 45         COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
 46         COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
 47         COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
 48 
 49         COPY(a16); COPY(a17); COPY(a18); COPY(a19);
 50         COPY(a20); COPY(a21); COPY(a22); COPY(a23);
 51         COPY(a24); COPY(a25); COPY(a26); COPY(a27);
 52         COPY(a28); COPY(a29); COPY(a30); COPY(a31);
 53         COPY(b16); COPY(b17); COPY(b18); COPY(b19);
 54         COPY(b20); COPY(b21); COPY(b22); COPY(b23);
 55         COPY(b24); COPY(b25); COPY(b26); COPY(b27);
 56         COPY(b28); COPY(b29); COPY(b30); COPY(b31);
 57 
 58         COPY(csr); COPY(pc);
 59 
 60 #undef COPY
 61 
 62         return err;
 63 }
 64 
 65 asmlinkage int do_rt_sigreturn(struct pt_regs *regs)
 66 {
 67         struct rt_sigframe __user *frame;
 68         sigset_t set;
 69 
 70         /* Always make any pending restarted system calls return -EINTR */
 71         current->restart_block.fn = do_no_restart_syscall;
 72 
 73         /*
 74          * Since we stacked the signal on a dword boundary,
 75          * 'sp' should be dword aligned here.  If it's
 76          * not, then the user is trying to mess with us.
 77          */
 78         if (regs->sp & 7)
 79                 goto badframe;
 80 
 81         frame = (struct rt_sigframe __user *) ((unsigned long) regs->sp + 8);
 82 
 83         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 84                 goto badframe;
 85         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 86                 goto badframe;
 87 
 88         set_current_blocked(&set);
 89 
 90         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 91                 goto badframe;
 92 
 93         return regs->a4;
 94 
 95 badframe:
 96         force_sig(SIGSEGV, current);
 97         return 0;
 98 }
 99 
100 static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
101                             unsigned long mask)
102 {
103         int err = 0;
104 
105         err |= __put_user(mask, &sc->sc_mask);
106 
107         /* The access_ok check was done by caller, so use __put_user here */
108 #define COPY(x) (err |= __put_user(regs->x, &sc->sc_##x))
109 
110         COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
111         COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
112         COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
113 
114         COPY(a16); COPY(a17); COPY(a18); COPY(a19);
115         COPY(a20); COPY(a21); COPY(a22); COPY(a23);
116         COPY(a24); COPY(a25); COPY(a26); COPY(a27);
117         COPY(a28); COPY(a29); COPY(a30); COPY(a31);
118         COPY(b16); COPY(b17); COPY(b18); COPY(b19);
119         COPY(b20); COPY(b21); COPY(b22); COPY(b23);
120         COPY(b24); COPY(b25); COPY(b26); COPY(b27);
121         COPY(b28); COPY(b29); COPY(b30); COPY(b31);
122 
123         COPY(csr); COPY(pc);
124 
125 #undef COPY
126 
127         return err;
128 }
129 
130 static inline void __user *get_sigframe(struct ksignal *ksig,
131                                         struct pt_regs *regs,
132                                         unsigned long framesize)
133 {
134         unsigned long sp = sigsp(regs->sp, ksig);
135 
136         /*
137          * No matter what happens, 'sp' must be dword
138          * aligned. Otherwise, nasty things will happen
139          */
140         return (void __user *)((sp - framesize) & ~7);
141 }
142 
143 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
144                           struct pt_regs *regs)
145 {
146         struct rt_sigframe __user *frame;
147         unsigned long __user *retcode;
148         int err = 0;
149 
150         frame = get_sigframe(ksig, regs, sizeof(*frame));
151 
152         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
153                 return -EFAULT;
154 
155         err |= __put_user(&frame->info, &frame->pinfo);
156         err |= __put_user(&frame->uc, &frame->puc);
157         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
158 
159         /* Clear all the bits of the ucontext we don't use.  */
160         err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
161 
162         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
163         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
164 
165         /* Set up to return from userspace */
166         retcode = (unsigned long __user *) &frame->retcode;
167 
168         /* The access_ok check was done above, so use __put_user here */
169 #define COPY(x) (err |= __put_user(x, retcode++))
170 
171         COPY(0x0000002AUL | (__NR_rt_sigreturn << 7));
172                                 /* MVK __NR_rt_sigreturn,B0 */
173         COPY(0x10000000UL);     /* SWE */
174         COPY(0x00006000UL);     /* NOP 4 */
175         COPY(0x00006000UL);     /* NOP 4 */
176         COPY(0x00006000UL);     /* NOP 4 */
177         COPY(0x00006000UL);     /* NOP 4 */
178         COPY(0x00006000UL);     /* NOP 4 */
179         COPY(0x00006000UL);     /* NOP 4 */
180         COPY(0x00006000UL);     /* NOP 4 */
181 
182 #undef COPY
183 
184         if (err)
185                 return -EFAULT;
186 
187         flush_icache_range((unsigned long) &frame->retcode,
188                            (unsigned long) &frame->retcode + RETCODE_SIZE);
189 
190         retcode = (unsigned long __user *) &frame->retcode;
191 
192         /* Change user context to branch to signal handler */
193         regs->sp = (unsigned long) frame - 8;
194         regs->b3 = (unsigned long) retcode;
195         regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
196 
197         /* Give the signal number to the handler */
198         regs->a4 = ksig->sig;
199 
200         /*
201          * For realtime signals we must also set the second and third
202          * arguments for the signal handler.
203          *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
204          */
205         regs->b4 = (unsigned long)&frame->info;
206         regs->a6 = (unsigned long)&frame->uc;
207 
208         return 0;
209 }
210 
211 static inline void
212 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
213 {
214         switch (regs->a4) {
215         case -ERESTARTNOHAND:
216                 if (!has_handler)
217                         goto do_restart;
218                 regs->a4 = -EINTR;
219                 break;
220 
221         case -ERESTARTSYS:
222                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
223                         regs->a4 = -EINTR;
224                         break;
225                 }
226         /* fallthrough */
227         case -ERESTARTNOINTR:
228 do_restart:
229                 regs->a4 = regs->orig_a4;
230                 regs->pc -= 4;
231                 break;
232         }
233 }
234 
235 /*
236  * handle the actual delivery of a signal to userspace
237  */
238 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs,
239                           int syscall)
240 {
241         int ret;
242 
243         /* Are we from a system call? */
244         if (syscall) {
245                 /* If so, check system call restarting.. */
246                 switch (regs->a4) {
247                 case -ERESTART_RESTARTBLOCK:
248                 case -ERESTARTNOHAND:
249                         regs->a4 = -EINTR;
250                         break;
251 
252                 case -ERESTARTSYS:
253                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
254                                 regs->a4 = -EINTR;
255                                 break;
256                         }
257 
258                         /* fallthrough */
259                 case -ERESTARTNOINTR:
260                         regs->a4 = regs->orig_a4;
261                         regs->pc -= 4;
262                 }
263         }
264 
265         /* Set up the stack frame */
266         ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
267         signal_setup_done(ret, ksig, 0);
268 }
269 
270 /*
271  * handle a potential signal
272  */
273 static void do_signal(struct pt_regs *regs, int syscall)
274 {
275         struct ksignal ksig;
276 
277         /* we want the common case to go fast, which is why we may in certain
278          * cases get here from kernel mode */
279         if (!user_mode(regs))
280                 return;
281 
282         if (get_signal(&ksig)) {
283                 handle_signal(&ksig, regs, syscall);
284                 return;
285         }
286 
287         /* did we come from a system call? */
288         if (syscall) {
289                 /* restart the system call - no handlers present */
290                 switch (regs->a4) {
291                 case -ERESTARTNOHAND:
292                 case -ERESTARTSYS:
293                 case -ERESTARTNOINTR:
294                         regs->a4 = regs->orig_a4;
295                         regs->pc -= 4;
296                         break;
297 
298                 case -ERESTART_RESTARTBLOCK:
299                         regs->a4 = regs->orig_a4;
300                         regs->b0 = __NR_restart_syscall;
301                         regs->pc -= 4;
302                         break;
303                 }
304         }
305 
306         /* if there's no signal to deliver, we just put the saved sigmask
307          * back */
308         restore_saved_sigmask();
309 }
310 
311 /*
312  * notification of userspace execution resumption
313  * - triggered by current->work.notify_resume
314  */
315 asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags,
316                                  int syscall)
317 {
318         /* deal with pending signal delivery */
319         if (thread_info_flags & (1 << TIF_SIGPENDING))
320                 do_signal(regs, syscall);
321 
322         if (thread_info_flags & (1 << TIF_NOTIFY_RESUME)) {
323                 clear_thread_flag(TIF_NOTIFY_RESUME);
324                 tracehook_notify_resume(regs);
325         }
326 }
327 

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