arch/avr32/kernel/signal.c

   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 <linux/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 }