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 <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_thread_info()->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 k_sigaction *ka, struct pt_regs *regs, int framesize)
 131 {
 132         unsigned long sp = regs->sp;
 133
 134         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 135                 sp = current->sas_ss_sp + current->sas_ss_size;
 136
 137         return (void __user *)((sp - framesize) & ~3);
 138 }
 139
 140 static int
 141 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 142                sigset_t *set, struct pt_regs *regs)
 143 {
 144         struct rt_sigframe __user *frame;
 145         int err = 0;
 146
 147         frame = get_sigframe(ka, regs, sizeof(*frame));
 148         err = -EFAULT;
 149         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 150                 goto out;
 151
 152         /*
 153          * Set up the return code:
 154          *
 155          *      mov     r8, __NR_rt_sigreturn
 156          *      scall
 157          *
 158          * Note: This will blow up since we're using a non-executable
 159          * stack. Better use SA_RESTORER.
 160          */
 161 #if __NR_rt_sigreturn > 127
 162 # error __NR_rt_sigreturn must be < 127 to fit in a short mov
 163 #endif
 164         err = __put_user(0x3008d733 | (__NR_rt_sigreturn << 20),
 165                          &frame->retcode);
 166
 167         err |= copy_siginfo_to_user(&frame->info, info);
 168
 169         /* Set up the ucontext */
 170         err |= __put_user(0, &frame->uc.uc_flags);
 171         err |= __put_user(NULL, &frame->uc.uc_link);
 172         err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 173         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 174         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 175
 176         if (err)
 177                 goto out;
 178
 179         regs->r12 = sig;
 180         regs->r11 = (unsigned long) &frame->info;
 181         regs->r10 = (unsigned long) &frame->uc;
 182         regs->sp = (unsigned long) frame;
 183         if (ka->sa.sa_flags & SA_RESTORER)
 184                 regs->lr = (unsigned long)ka->sa.sa_restorer;
 185         else {
 186                 printk(KERN_NOTICE "[%s:%d] did not set SA_RESTORER\n",
 187                        current->comm, current->pid);
 188                 regs->lr = (unsigned long) &frame->retcode;
 189         }
 190
 191         pr_debug("SIG deliver [%s:%d]: sig=%d sp=0x%lx pc=0x%lx->0x%p lr=0x%lx\n",
 192                  current->comm, current->pid, sig, regs->sp,
 193                  regs->pc, ka->sa.sa_handler, regs->lr);
 194
 195         regs->pc = (unsigned long) ka->sa.sa_handler;
 196
 197 out:
 198         return err;
 199 }
 200
 201 static inline void setup_syscall_restart(struct pt_regs *regs)
 202 {
 203         if (regs->r12 == -ERESTART_RESTARTBLOCK)
 204                 regs->r8 = __NR_restart_syscall;
 205         else
 206                 regs->r12 = regs->r12_orig;
 207         regs->pc -= 2;
 208 }
 209
 210 static inline void
 211 handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
 212               struct pt_regs *regs, int syscall)
 213 {
 214         int ret;
 215
 216         /*
 217          * Set up the stack frame
 218          */
 219         ret = setup_rt_frame(sig, ka, info, sigmask_to_save(), regs);
 220
 221         /*
 222          * Check that the resulting registers are sane
 223          */
 224         ret |= !valid_user_regs(regs);
 225
 226         /*
 227          * Block the signal if we were successful.
 228          */
 229         if (ret != 0)
 230                 force_sigsegv(sig, current);
 231         else
 232                 signal_delivered(sig, info, ka, regs, 0);
 233 }
 234
 235 /*
 236  * Note that 'init' is a special process: it doesn't get signals it
 237  * doesn't want to handle. Thus you cannot kill init even with a
 238  * SIGKILL even by mistake.
 239  */
 240 static void do_signal(struct pt_regs *regs, int syscall)
 241 {
 242         siginfo_t info;
 243         int signr;
 244         struct k_sigaction ka;
 245
 246         /*
 247          * We want the common case to go fast, which is why we may in
 248          * certain cases get here from kernel mode. Just return
 249          * without doing anything if so.
 250          */
 251         if (!user_mode(regs))
 252                 return;
 253
 254         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 255         if (syscall) {
 256                 switch (regs->r12) {
 257                 case -ERESTART_RESTARTBLOCK:
 258                 case -ERESTARTNOHAND:
 259                         if (signr > 0) {
 260                                 regs->r12 = -EINTR;
 261                                 break;
 262                         }
 263                         /* fall through */
 264                 case -ERESTARTSYS:
 265                         if (signr > 0 && !(ka.sa.sa_flags & SA_RESTART)) {
 266                                 regs->r12 = -EINTR;
 267                                 break;
 268                         }
 269                         /* fall through */
 270                 case -ERESTARTNOINTR:
 271                         setup_syscall_restart(regs);
 272                 }
 273         }
 274
 275         if (signr == 0) {
 276                 /* No signal to deliver -- put the saved sigmask back */
 277                 restore_saved_sigmask();
 278                 return;
 279         }
 280
 281         handle_signal(signr, &ka, &info, regs, syscall);
 282 }
 283
 284 asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
 285 {
 286         int syscall = 0;
 287
 288         if ((sysreg_read(SR) & MODE_MASK) == MODE_SUPERVISOR)
 289                 syscall = 1;
 290
 291         if (ti->flags & _TIF_SIGPENDING)
 292                 do_signal(regs, syscall);
 293
 294         if (ti->flags & _TIF_NOTIFY_RESUME) {
 295                 clear_thread_flag(TIF_NOTIFY_RESUME);
 296                 tracehook_notify_resume(regs);
 297         }
 298 }