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 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  25                                struct pt_regs *regs)
  26 {
  27         return do_sigaltstack(uss, uoss, regs->sp);
  28 }
  29
  30 struct rt_sigframe
  31 {
  32         struct siginfo info;
  33         struct ucontext uc;
  34         unsigned long retcode;
  35 };
  36
  37 static int
  38 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
  39 {
  40         int err = 0;
  41
  42 #define COPY(x)         err |= __get_user(regs->x, &sc->x)
  43         COPY(sr);
  44         COPY(pc);
  45         COPY(lr);
  46         COPY(sp);
  47         COPY(r12);
  48         COPY(r11);
  49         COPY(r10);
  50         COPY(r9);
  51         COPY(r8);
  52         COPY(r7);
  53         COPY(r6);
  54         COPY(r5);
  55         COPY(r4);
  56         COPY(r3);
  57         COPY(r2);
  58         COPY(r1);
  59         COPY(r0);
  60 #undef  COPY
  61
  62         /*
  63          * Don't allow anyone to pretend they're running in supervisor
  64          * mode or something...
  65          */
  66         err |= !valid_user_regs(regs);
  67
  68         return err;
  69 }
  70
  71
  72 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
  73 {
  74         struct rt_sigframe __user *frame;
  75         sigset_t set;
  76
  77         /* Always make any pending restarted system calls return -EINTR */
  78         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  79
  80         frame = (struct rt_sigframe __user *)regs->sp;
  81         pr_debug("SIG return: frame = %p\n", frame);
  82
  83         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  84                 goto badframe;
  85
  86         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  87                 goto badframe;
  88
  89         set_current_blocked(&set);
  90
  91         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  92                 goto badframe;
  93
  94         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
  95                 goto badframe;
  96
  97         pr_debug("Context restored: pc = %08lx, lr = %08lx, sp = %08lx\n",
  98                  regs->pc, regs->lr, regs->sp);
  99
 100         return regs->r12;
 101
 102 badframe:
 103         force_sig(SIGSEGV, current);
 104         return 0;
 105 }
 106
 107 static int
 108 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 109 {
 110         int err = 0;
 111
 112 #define COPY(x)         err |= __put_user(regs->x, &sc->x)
 113         COPY(sr);
 114         COPY(pc);
 115         COPY(lr);
 116         COPY(sp);
 117         COPY(r12);
 118         COPY(r11);
 119         COPY(r10);
 120         COPY(r9);
 121         COPY(r8);
 122         COPY(r7);
 123         COPY(r6);
 124         COPY(r5);
 125         COPY(r4);
 126         COPY(r3);
 127         COPY(r2);
 128         COPY(r1);
 129         COPY(r0);
 130 #undef  COPY
 131
 132         return err;
 133 }
 134
 135 static inline void __user *
 136 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 137 {
 138         unsigned long sp = regs->sp;
 139
 140         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 141                 sp = current->sas_ss_sp + current->sas_ss_size;
 142
 143         return (void __user *)((sp - framesize) & ~3);
 144 }
 145
 146 static int
 147 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 148                sigset_t *set, struct pt_regs *regs)
 149 {
 150         struct rt_sigframe __user *frame;
 151         int err = 0;
 152
 153         frame = get_sigframe(ka, regs, sizeof(*frame));
 154         err = -EFAULT;
 155         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 156                 goto out;
 157
 158         /*
 159          * Set up the return code:
 160          *
 161          *      mov     r8, __NR_rt_sigreturn
 162          *      scall
 163          *
 164          * Note: This will blow up since we're using a non-executable
 165          * stack. Better use SA_RESTORER.
 166          */
 167 #if __NR_rt_sigreturn > 127
 168 # error __NR_rt_sigreturn must be < 127 to fit in a short mov
 169 #endif
 170         err = __put_user(0x3008d733 | (__NR_rt_sigreturn << 20),
 171                          &frame->retcode);
 172
 173         err |= copy_siginfo_to_user(&frame->info, info);
 174
 175         /* Set up the ucontext */
 176         err |= __put_user(0, &frame->uc.uc_flags);
 177         err |= __put_user(NULL, &frame->uc.uc_link);
 178         err |= __put_user((void __user *)current->sas_ss_sp,
 179                           &frame->uc.uc_stack.ss_sp);
 180         err |= __put_user(sas_ss_flags(regs->sp),
 181                           &frame->uc.uc_stack.ss_flags);
 182         err |= __put_user(current->sas_ss_size,
 183                           &frame->uc.uc_stack.ss_size);
 184         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 185         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 186
 187         if (err)
 188                 goto out;
 189
 190         regs->r12 = sig;
 191         regs->r11 = (unsigned long) &frame->info;
 192         regs->r10 = (unsigned long) &frame->uc;
 193         regs->sp = (unsigned long) frame;
 194         if (ka->sa.sa_flags & SA_RESTORER)
 195                 regs->lr = (unsigned long)ka->sa.sa_restorer;
 196         else {
 197                 printk(KERN_NOTICE "[%s:%d] did not set SA_RESTORER\n",
 198                        current->comm, current->pid);
 199                 regs->lr = (unsigned long) &frame->retcode;
 200         }
 201
 202         pr_debug("SIG deliver [%s:%d]: sig=%d sp=0x%lx pc=0x%lx->0x%p lr=0x%lx\n",
 203                  current->comm, current->pid, sig, regs->sp,
 204                  regs->pc, ka->sa.sa_handler, regs->lr);
 205
 206         regs->pc = (unsigned long) ka->sa.sa_handler;
 207
 208 out:
 209         return err;
 210 }
 211
 212 static inline void setup_syscall_restart(struct pt_regs *regs)
 213 {
 214         if (regs->r12 == -ERESTART_RESTARTBLOCK)
 215                 regs->r8 = __NR_restart_syscall;
 216         else
 217                 regs->r12 = regs->r12_orig;
 218         regs->pc -= 2;
 219 }
 220
 221 static inline void
 222 handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
 223               struct pt_regs *regs, int syscall)
 224 {
 225         int ret;
 226
 227         /*
 228          * Set up the stack frame
 229          */
 230         ret = setup_rt_frame(sig, ka, info, sigmask_to_save(), regs);
 231
 232         /*
 233          * Check that the resulting registers are sane
 234          */
 235         ret |= !valid_user_regs(regs);
 236
 237         /*
 238          * Block the signal if we were successful.
 239          */
 240         if (ret != 0)
 241                 force_sigsegv(sig, current);
 242         else
 243                 signal_delivered(sig, info, ka, regs, 0);
 244 }
 245
 246 /*
 247  * Note that 'init' is a special process: it doesn't get signals it
 248  * doesn't want to handle. Thus you cannot kill init even with a
 249  * SIGKILL even by mistake.
 250  */
 251 static void do_signal(struct pt_regs *regs, int syscall)
 252 {
 253         siginfo_t info;
 254         int signr;
 255         struct k_sigaction ka;
 256
 257         /*
 258          * We want the common case to go fast, which is why we may in
 259          * certain cases get here from kernel mode. Just return
 260          * without doing anything if so.
 261          */
 262         if (!user_mode(regs))
 263                 return;
 264
 265         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 266         if (syscall) {
 267                 switch (regs->r12) {
 268                 case -ERESTART_RESTARTBLOCK:
 269                 case -ERESTARTNOHAND:
 270                         if (signr > 0) {
 271                                 regs->r12 = -EINTR;
 272                                 break;
 273                         }
 274                         /* fall through */
 275                 case -ERESTARTSYS:
 276                         if (signr > 0 && !(ka.sa.sa_flags & SA_RESTART)) {
 277                                 regs->r12 = -EINTR;
 278                                 break;
 279                         }
 280                         /* fall through */
 281                 case -ERESTARTNOINTR:
 282                         setup_syscall_restart(regs);
 283                 }
 284         }
 285
 286         if (signr == 0) {
 287                 /* No signal to deliver -- put the saved sigmask back */
 288                 restore_saved_sigmask();
 289                 return;
 290         }
 291
 292         handle_signal(signr, &ka, &info, regs, syscall);
 293 }
 294
 295 asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
 296 {
 297         int syscall = 0;
 298
 299         if ((sysreg_read(SR) & MODE_MASK) == MODE_SUPERVISOR)
 300                 syscall = 1;
 301
 302         if (ti->flags & _TIF_SIGPENDING)
 303                 do_signal(regs, syscall);
 304
 305         if (ti->flags & _TIF_NOTIFY_RESUME) {
 306                 clear_thread_flag(TIF_NOTIFY_RESUME);
 307                 tracehook_notify_resume(regs);
 308         }
 309 }