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Linux/arch/avr32/kernel/signal.c

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  1 /*
  2  * Copyright (C) 2004-2006 Atmel Corporation
  3  *
  4  * Based on linux/arch/sh/kernel/signal.c
  5  *  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
  6  *  Copyright (C) 1991, 1992  Linus Torvalds
  7  *
  8  * This program is free software; you can redistribute it and/or modify
  9  * it under the terms of the GNU General Public License version 2 as
 10  * published by the Free Software Foundation.
 11  */
 12 
 13 #include <linux/sched.h>
 14 #include <linux/mm.h>
 15 #include <linux/errno.h>
 16 #include <linux/ptrace.h>
 17 #include <linux/unistd.h>
 18 #include <linux/tracehook.h>
 19 
 20 #include <asm/uaccess.h>
 21 #include <asm/ucontext.h>
 22 #include <asm/syscalls.h>
 23 
 24 struct rt_sigframe
 25 {
 26         struct siginfo info;
 27         struct ucontext uc;
 28         unsigned long retcode;
 29 };
 30 
 31 static int
 32 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 33 {
 34         int err = 0;
 35 
 36 #define COPY(x)         err |= __get_user(regs->x, &sc->x)
 37         COPY(sr);
 38         COPY(pc);
 39         COPY(lr);
 40         COPY(sp);
 41         COPY(r12);
 42         COPY(r11);
 43         COPY(r10);
 44         COPY(r9);
 45         COPY(r8);
 46         COPY(r7);
 47         COPY(r6);
 48         COPY(r5);
 49         COPY(r4);
 50         COPY(r3);
 51         COPY(r2);
 52         COPY(r1);
 53         COPY(r0);
 54 #undef  COPY
 55 
 56         /*
 57          * Don't allow anyone to pretend they're running in supervisor
 58          * mode or something...
 59          */
 60         err |= !valid_user_regs(regs);
 61 
 62         return err;
 63 }
 64 
 65 
 66 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 67 {
 68         struct rt_sigframe __user *frame;
 69         sigset_t set;
 70 
 71         /* Always make any pending restarted system calls return -EINTR */
 72         current->restart_block.fn = do_no_restart_syscall;
 73 
 74         frame = (struct rt_sigframe __user *)regs->sp;
 75         pr_debug("SIG return: frame = %p\n", frame);
 76 
 77         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 78                 goto badframe;
 79 
 80         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 81                 goto badframe;
 82 
 83         set_current_blocked(&set);
 84 
 85         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 86                 goto badframe;
 87 
 88         if (restore_altstack(&frame->uc.uc_stack))
 89                 goto badframe;
 90 
 91         pr_debug("Context restored: pc = %08lx, lr = %08lx, sp = %08lx\n",
 92                  regs->pc, regs->lr, regs->sp);
 93 
 94         return regs->r12;
 95 
 96 badframe:
 97         force_sig(SIGSEGV, current);
 98         return 0;
 99 }
100 
101 static int
102 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
103 {
104         int err = 0;
105 
106 #define COPY(x)         err |= __put_user(regs->x, &sc->x)
107         COPY(sr);
108         COPY(pc);
109         COPY(lr);
110         COPY(sp);
111         COPY(r12);
112         COPY(r11);
113         COPY(r10);
114         COPY(r9);
115         COPY(r8);
116         COPY(r7);
117         COPY(r6);
118         COPY(r5);
119         COPY(r4);
120         COPY(r3);
121         COPY(r2);
122         COPY(r1);
123         COPY(r0);
124 #undef  COPY
125 
126         return err;
127 }
128 
129 static inline void __user *
130 get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize)
131 {
132         unsigned long sp = sigsp(regs->sp, ksig);
133 
134         return (void __user *)((sp - framesize) & ~3);
135 }
136 
137 static int
138 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
139 {
140         struct rt_sigframe __user *frame;
141         int err = 0;
142 
143         frame = get_sigframe(ksig, regs, sizeof(*frame));
144         err = -EFAULT;
145         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
146                 goto out;
147 
148         /*
149          * Set up the return code:
150          *
151          *      mov     r8, __NR_rt_sigreturn
152          *      scall
153          *
154          * Note: This will blow up since we're using a non-executable
155          * stack. Better use SA_RESTORER.
156          */
157 #if __NR_rt_sigreturn > 127
158 # error __NR_rt_sigreturn must be < 127 to fit in a short mov
159 #endif
160         err = __put_user(0x3008d733 | (__NR_rt_sigreturn << 20),
161                          &frame->retcode);
162 
163         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
164 
165         /* Set up the ucontext */
166         err |= __put_user(0, &frame->uc.uc_flags);
167         err |= __put_user(NULL, &frame->uc.uc_link);
168         err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
169         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
170         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
171 
172         if (err)
173                 goto out;
174 
175         regs->r12 = ksig->sig;
176         regs->r11 = (unsigned long) &frame->info;
177         regs->r10 = (unsigned long) &frame->uc;
178         regs->sp = (unsigned long) frame;
179         if (ksig->ka.sa.sa_flags & SA_RESTORER)
180                 regs->lr = (unsigned long)ksig->ka.sa.sa_restorer;
181         else {
182                 printk(KERN_NOTICE "[%s:%d] did not set SA_RESTORER\n",
183                        current->comm, current->pid);
184                 regs->lr = (unsigned long) &frame->retcode;
185         }
186 
187         pr_debug("SIG deliver [%s:%d]: sig=%d sp=0x%lx pc=0x%lx->0x%p lr=0x%lx\n",
188                  current->comm, current->pid, ksig->sig, regs->sp,
189                  regs->pc, ksig->ka.sa.sa_handler, regs->lr);
190 
191         regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
192 
193 out:
194         return err;
195 }
196 
197 static inline void setup_syscall_restart(struct pt_regs *regs)
198 {
199         if (regs->r12 == -ERESTART_RESTARTBLOCK)
200                 regs->r8 = __NR_restart_syscall;
201         else
202                 regs->r12 = regs->r12_orig;
203         regs->pc -= 2;
204 }
205 
206 static inline void
207 handle_signal(struct ksignal *ksig, struct pt_regs *regs, int syscall)
208 {
209         int ret;
210 
211         /*
212          * Set up the stack frame
213          */
214         ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
215 
216         /*
217          * Check that the resulting registers are sane
218          */
219         ret |= !valid_user_regs(regs);
220 
221         /*
222          * Block the signal if we were successful.
223          */
224         signal_setup_done(ret, ksig, 0);
225 }
226 
227 /*
228  * Note that 'init' is a special process: it doesn't get signals it
229  * doesn't want to handle. Thus you cannot kill init even with a
230  * SIGKILL even by mistake.
231  */
232 static void do_signal(struct pt_regs *regs, int syscall)
233 {
234         struct ksignal ksig;
235 
236         /*
237          * We want the common case to go fast, which is why we may in
238          * certain cases get here from kernel mode. Just return
239          * without doing anything if so.
240          */
241         if (!user_mode(regs))
242                 return;
243 
244         get_signal(&ksig);
245         if (syscall) {
246                 switch (regs->r12) {
247                 case -ERESTART_RESTARTBLOCK:
248                 case -ERESTARTNOHAND:
249                         if (ksig.sig > 0) {
250                                 regs->r12 = -EINTR;
251                                 break;
252                         }
253                         /* fall through */
254                 case -ERESTARTSYS:
255                         if (ksig.sig > 0 && !(ksig.ka.sa.sa_flags & SA_RESTART)) {
256                                 regs->r12 = -EINTR;
257                                 break;
258                         }
259                         /* fall through */
260                 case -ERESTARTNOINTR:
261                         setup_syscall_restart(regs);
262                 }
263         }
264 
265         if (!ksig.sig) {
266                 /* No signal to deliver -- put the saved sigmask back */
267                 restore_saved_sigmask();
268                 return;
269         }
270 
271         handle_signal(&ksig, regs, syscall);
272 }
273 
274 asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
275 {
276         int syscall = 0;
277 
278         if ((sysreg_read(SR) & MODE_MASK) == MODE_SUPERVISOR)
279                 syscall = 1;
280 
281         if (ti->flags & _TIF_SIGPENDING)
282                 do_signal(regs, syscall);
283 
284         if (ti->flags & _TIF_NOTIFY_RESUME) {
285                 clear_thread_flag(TIF_NOTIFY_RESUME);
286                 tracehook_notify_resume(regs);
287         }
288 }
289 

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