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Linux/arch/blackfin/kernel/signal.c

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  1 /*
  2  * Copyright 2004-2010 Analog Devices Inc.
  3  *
  4  * Licensed under the GPL-2 or later
  5  */
  6 
  7 #include <linux/signal.h>
  8 #include <linux/syscalls.h>
  9 #include <linux/ptrace.h>
 10 #include <linux/tty.h>
 11 #include <linux/personality.h>
 12 #include <linux/binfmts.h>
 13 #include <linux/uaccess.h>
 14 #include <linux/tracehook.h>
 15 
 16 #include <asm/cacheflush.h>
 17 #include <asm/ucontext.h>
 18 #include <asm/fixed_code.h>
 19 #include <asm/syscall.h>
 20 
 21 /* Location of the trace bit in SYSCFG. */
 22 #define TRACE_BITS 0x0001
 23 
 24 struct fdpic_func_descriptor {
 25         unsigned long   text;
 26         unsigned long   GOT;
 27 };
 28 
 29 struct rt_sigframe {
 30         int sig;
 31         struct siginfo *pinfo;
 32         void *puc;
 33         /* This is no longer needed by the kernel, but unfortunately userspace
 34          * code expects it to be there.  */
 35         char retcode[8];
 36         struct siginfo info;
 37         struct ucontext uc;
 38 };
 39 
 40 static inline int
 41 rt_restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *pr0)
 42 {
 43         unsigned long usp = 0;
 44         int err = 0;
 45 
 46         /* Always make any pending restarted system calls return -EINTR */
 47         current->restart_block.fn = do_no_restart_syscall;
 48 
 49 #define RESTORE(x) err |= __get_user(regs->x, &sc->sc_##x)
 50 
 51         /* restore passed registers */
 52         RESTORE(r0); RESTORE(r1); RESTORE(r2); RESTORE(r3);
 53         RESTORE(r4); RESTORE(r5); RESTORE(r6); RESTORE(r7);
 54         RESTORE(p0); RESTORE(p1); RESTORE(p2); RESTORE(p3);
 55         RESTORE(p4); RESTORE(p5);
 56         err |= __get_user(usp, &sc->sc_usp);
 57         wrusp(usp);
 58         RESTORE(a0w); RESTORE(a1w);
 59         RESTORE(a0x); RESTORE(a1x);
 60         RESTORE(astat);
 61         RESTORE(rets);
 62         RESTORE(pc);
 63         RESTORE(retx);
 64         RESTORE(fp);
 65         RESTORE(i0); RESTORE(i1); RESTORE(i2); RESTORE(i3);
 66         RESTORE(m0); RESTORE(m1); RESTORE(m2); RESTORE(m3);
 67         RESTORE(l0); RESTORE(l1); RESTORE(l2); RESTORE(l3);
 68         RESTORE(b0); RESTORE(b1); RESTORE(b2); RESTORE(b3);
 69         RESTORE(lc0); RESTORE(lc1);
 70         RESTORE(lt0); RESTORE(lt1);
 71         RESTORE(lb0); RESTORE(lb1);
 72         RESTORE(seqstat);
 73 
 74         regs->orig_p0 = -1;     /* disable syscall checks */
 75 
 76         *pr0 = regs->r0;
 77         return err;
 78 }
 79 
 80 asmlinkage int sys_rt_sigreturn(void)
 81 {
 82         struct pt_regs *regs = current_pt_regs();
 83         unsigned long usp = rdusp();
 84         struct rt_sigframe *frame = (struct rt_sigframe *)(usp);
 85         sigset_t set;
 86         int r0;
 87 
 88         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 89                 goto badframe;
 90         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 91                 goto badframe;
 92 
 93         set_current_blocked(&set);
 94 
 95         if (rt_restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
 96                 goto badframe;
 97 
 98         if (restore_altstack(&frame->uc.uc_stack))
 99                 goto badframe;
100 
101         return r0;
102 
103  badframe:
104         force_sig(SIGSEGV, current);
105         return 0;
106 }
107 
108 static inline int rt_setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs)
109 {
110         int err = 0;
111 
112 #define SETUP(x) err |= __put_user(regs->x, &sc->sc_##x)
113 
114         SETUP(r0); SETUP(r1); SETUP(r2); SETUP(r3);
115         SETUP(r4); SETUP(r5); SETUP(r6); SETUP(r7);
116         SETUP(p0); SETUP(p1); SETUP(p2); SETUP(p3);
117         SETUP(p4); SETUP(p5);
118         err |= __put_user(rdusp(), &sc->sc_usp);
119         SETUP(a0w); SETUP(a1w);
120         SETUP(a0x); SETUP(a1x);
121         SETUP(astat);
122         SETUP(rets);
123         SETUP(pc);
124         SETUP(retx);
125         SETUP(fp);
126         SETUP(i0); SETUP(i1); SETUP(i2); SETUP(i3);
127         SETUP(m0); SETUP(m1); SETUP(m2); SETUP(m3);
128         SETUP(l0); SETUP(l1); SETUP(l2); SETUP(l3);
129         SETUP(b0); SETUP(b1); SETUP(b2); SETUP(b3);
130         SETUP(lc0); SETUP(lc1);
131         SETUP(lt0); SETUP(lt1);
132         SETUP(lb0); SETUP(lb1);
133         SETUP(seqstat);
134 
135         return err;
136 }
137 
138 static inline void *get_sigframe(struct ksignal *ksig,
139                                  size_t frame_size)
140 {
141         unsigned long usp = sigsp(rdusp(), ksig);
142 
143         return (void *)((usp - frame_size) & -8UL);
144 }
145 
146 static int
147 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
148 {
149         struct rt_sigframe *frame;
150         int err = 0;
151 
152         frame = get_sigframe(ksig, sizeof(*frame));
153 
154         err |= __put_user(ksig->sig, &frame->sig);
155 
156         err |= __put_user(&frame->info, &frame->pinfo);
157         err |= __put_user(&frame->uc, &frame->puc);
158         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
159 
160         /* Create the ucontext.  */
161         err |= __put_user(0, &frame->uc.uc_flags);
162         err |= __put_user(0, &frame->uc.uc_link);
163         err |= __save_altstack(&frame->uc.uc_stack, rdusp());
164         err |= rt_setup_sigcontext(&frame->uc.uc_mcontext, regs);
165         err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
166 
167         if (err)
168                 return -EFAULT;
169 
170         /* Set up registers for signal handler */
171         if (current->personality & FDPIC_FUNCPTRS) {
172                 struct fdpic_func_descriptor __user *funcptr =
173                         (struct fdpic_func_descriptor *) ksig->ka.sa.sa_handler;
174                 u32 pc, p3;
175                 err |= __get_user(pc, &funcptr->text);
176                 err |= __get_user(p3, &funcptr->GOT);
177                 if (err)
178                         return -EFAULT;
179                 regs->pc = pc;
180                 regs->p3 = p3;
181         } else
182                 regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
183         wrusp((unsigned long)frame);
184         regs->rets = SIGRETURN_STUB;
185 
186         regs->r0 = frame->sig;
187         regs->r1 = (unsigned long)(&frame->info);
188         regs->r2 = (unsigned long)(&frame->uc);
189 
190         return 0;
191 }
192 
193 static inline void
194 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
195 {
196         switch (regs->r0) {
197         case -ERESTARTNOHAND:
198                 if (!has_handler)
199                         goto do_restart;
200                 regs->r0 = -EINTR;
201                 break;
202 
203         case -ERESTARTSYS:
204                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
205                         regs->r0 = -EINTR;
206                         break;
207                 }
208                 /* fallthrough */
209         case -ERESTARTNOINTR:
210  do_restart:
211                 regs->p0 = regs->orig_p0;
212                 regs->r0 = regs->orig_r0;
213                 regs->pc -= 2;
214                 break;
215 
216         case -ERESTART_RESTARTBLOCK:
217                 regs->p0 = __NR_restart_syscall;
218                 regs->pc -= 2;
219                 break;
220         }
221 }
222 
223 /*
224  * OK, we're invoking a handler
225  */
226 static void
227 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
228 {
229         int ret;
230 
231         /* are we from a system call? to see pt_regs->orig_p0 */
232         if (regs->orig_p0 >= 0)
233                 /* If so, check system call restarting.. */
234                 handle_restart(regs, &ksig->ka, 1);
235 
236         /* set up the stack frame */
237         ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
238 
239         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
240 }
241 
242 /*
243  * Note that 'init' is a special process: it doesn't get signals it doesn't
244  * want to handle. Thus you cannot kill init even with a SIGKILL even by
245  * mistake.
246  *
247  * Note that we go through the signals twice: once to check the signals
248  * that the kernel can handle, and then we build all the user-level signal
249  * handling stack-frames in one go after that.
250  */
251 asmlinkage void do_signal(struct pt_regs *regs)
252 {
253         struct ksignal ksig;
254 
255         current->thread.esp0 = (unsigned long)regs;
256 
257         if (get_signal(&ksig)) {
258                 /* Whee!  Actually deliver the signal.  */
259                 handle_signal(&ksig, regs);
260                 return;
261         }
262 
263         /* Did we come from a system call? */
264         if (regs->orig_p0 >= 0)
265                 /* Restart the system call - no handlers present */
266                 handle_restart(regs, NULL, 0);
267 
268         /* if there's no signal to deliver, we just put the saved sigmask
269          * back */
270         restore_saved_sigmask();
271 }
272 
273 /*
274  * notification of userspace execution resumption
275  */
276 asmlinkage void do_notify_resume(struct pt_regs *regs)
277 {
278         if (test_thread_flag(TIF_SIGPENDING))
279                 do_signal(regs);
280 
281         if (test_thread_flag(TIF_NOTIFY_RESUME)) {
282                 clear_thread_flag(TIF_NOTIFY_RESUME);
283                 tracehook_notify_resume(regs);
284         }
285 }
286 
287 

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