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/freezer.h>
  19
  20 #include <asm/uaccess.h>
  21 #include <asm/ucontext.h>
  22 #include <asm/syscalls.h>
  23
  24 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  25
  26 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  27                                struct pt_regs *regs)
  28 {
  29         return do_sigaltstack(uss, uoss, regs->sp);
  30 }
  31
  32 struct rt_sigframe
  33 {
  34         struct siginfo info;
  35         struct ucontext uc;
  36         unsigned long retcode;
  37 };
  38
  39 static int
  40 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
  41 {
  42         int err = 0;
  43
  44 #define COPY(x)         err |= __get_user(regs->x, &sc->x)
  45         COPY(sr);
  46         COPY(pc);
  47         COPY(lr);
  48         COPY(sp);
  49         COPY(r12);
  50         COPY(r11);
  51         COPY(r10);
  52         COPY(r9);
  53         COPY(r8);
  54         COPY(r7);
  55         COPY(r6);
  56         COPY(r5);
  57         COPY(r4);
  58         COPY(r3);
  59         COPY(r2);
  60         COPY(r1);
  61         COPY(r0);
  62 #undef  COPY
  63
  64         /*
  65          * Don't allow anyone to pretend they're running in supervisor
  66          * mode or something...
  67          */
  68         err |= !valid_user_regs(regs);
  69
  70         return err;
  71 }
  72
  73
  74 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
  75 {
  76         struct rt_sigframe __user *frame;
  77         sigset_t set;
  78
  79         frame = (struct rt_sigframe __user *)regs->sp;
  80         pr_debug("SIG return: frame = %p\n", frame);
  81
  82         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  83                 goto badframe;
  84
  85         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  86                 goto badframe;
  87
  88         sigdelsetmask(&set, ~_BLOCKABLE);
  89         spin_lock_irq(&current->sighand->siglock);
  90         current->blocked = set;
  91         recalc_sigpending();
  92         spin_unlock_irq(&current->sighand->siglock);
  93
  94         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  95                 goto badframe;
  96
  97         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
  98                 goto badframe;
  99
 100         pr_debug("Context restored: pc = %08lx, lr = %08lx, sp = %08lx\n",
 101                  regs->pc, regs->lr, regs->sp);
 102
 103         return regs->r12;
 104
 105 badframe:
 106         force_sig(SIGSEGV, current);
 107         return 0;
 108 }
 109
 110 static int
 111 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 112 {
 113         int err = 0;
 114
 115 #define COPY(x)         err |= __put_user(regs->x, &sc->x)
 116         COPY(sr);
 117         COPY(pc);
 118         COPY(lr);
 119         COPY(sp);
 120         COPY(r12);
 121         COPY(r11);
 122         COPY(r10);
 123         COPY(r9);
 124         COPY(r8);
 125         COPY(r7);
 126         COPY(r6);
 127         COPY(r5);
 128         COPY(r4);
 129         COPY(r3);
 130         COPY(r2);
 131         COPY(r1);
 132         COPY(r0);
 133 #undef  COPY
 134
 135         return err;
 136 }
 137
 138 static inline void __user *
 139 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 140 {
 141         unsigned long sp = regs->sp;
 142
 143         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 144                 sp = current->sas_ss_sp + current->sas_ss_size;
 145
 146         return (void __user *)((sp - framesize) & ~3);
 147 }
 148
 149 static int
 150 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 151                sigset_t *set, struct pt_regs *regs)
 152 {
 153         struct rt_sigframe __user *frame;
 154         int err = 0;
 155
 156         frame = get_sigframe(ka, regs, sizeof(*frame));
 157         err = -EFAULT;
 158         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 159                 goto out;
 160
 161         /*
 162          * Set up the return code:
 163          *
 164          *      mov     r8, __NR_rt_sigreturn
 165          *      scall
 166          *
 167          * Note: This will blow up since we're using a non-executable
 168          * stack. Better use SA_RESTORER.
 169          */
 170 #if __NR_rt_sigreturn > 127
 171 # error __NR_rt_sigreturn must be < 127 to fit in a short mov
 172 #endif
 173         err = __put_user(0x3008d733 | (__NR_rt_sigreturn << 20),
 174                          &frame->retcode);
 175
 176         err |= copy_siginfo_to_user(&frame->info, info);
 177
 178         /* Set up the ucontext */
 179         err |= __put_user(0, &frame->uc.uc_flags);
 180         err |= __put_user(NULL, &frame->uc.uc_link);
 181         err |= __put_user((void __user *)current->sas_ss_sp,
 182                           &frame->uc.uc_stack.ss_sp);
 183         err |= __put_user(sas_ss_flags(regs->sp),
 184                           &frame->uc.uc_stack.ss_flags);
 185         err |= __put_user(current->sas_ss_size,
 186                           &frame->uc.uc_stack.ss_size);
 187         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 188         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 189
 190         if (err)
 191                 goto out;
 192
 193         regs->r12 = sig;
 194         regs->r11 = (unsigned long) &frame->info;
 195         regs->r10 = (unsigned long) &frame->uc;
 196         regs->sp = (unsigned long) frame;
 197         if (ka->sa.sa_flags & SA_RESTORER)
 198                 regs->lr = (unsigned long)ka->sa.sa_restorer;
 199         else {
 200                 printk(KERN_NOTICE "[%s:%d] did not set SA_RESTORER\n",
 201                        current->comm, current->pid);
 202                 regs->lr = (unsigned long) &frame->retcode;
 203         }
 204
 205         pr_debug("SIG deliver [%s:%d]: sig=%d sp=0x%lx pc=0x%lx->0x%p lr=0x%lx\n",
 206                  current->comm, current->pid, sig, regs->sp,
 207                  regs->pc, ka->sa.sa_handler, regs->lr);
 208
 209         regs->pc = (unsigned long) ka->sa.sa_handler;
 210
 211 out:
 212         return err;
 213 }
 214
 215 static inline void setup_syscall_restart(struct pt_regs *regs)
 216 {
 217         if (regs->r12 == -ERESTART_RESTARTBLOCK)
 218                 regs->r8 = __NR_restart_syscall;
 219         else
 220                 regs->r12 = regs->r12_orig;
 221         regs->pc -= 2;
 222 }
 223
 224 static inline void
 225 handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
 226               sigset_t *oldset, struct pt_regs *regs, int syscall)
 227 {
 228         int ret;
 229
 230         /*
 231          * Set up the stack frame
 232          */
 233         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 234
 235         /*
 236          * Check that the resulting registers are sane
 237          */
 238         ret |= !valid_user_regs(regs);
 239
 240         /*
 241          * Block the signal if we were unsuccessful.
 242          */
 243         if (ret != 0 || !(ka->sa.sa_flags & SA_NODEFER)) {
 244                 spin_lock_irq(&current->sighand->siglock);
 245                 sigorsets(&current->blocked, &current->blocked,
 246                           &ka->sa.sa_mask);
 247                 sigaddset(&current->blocked, sig);
 248                 recalc_sigpending();
 249                 spin_unlock_irq(&current->sighand->siglock);
 250         }
 251
 252         if (ret == 0)
 253                 return;
 254
 255         force_sigsegv(sig, current);
 256 }
 257
 258 /*
 259  * Note that 'init' is a special process: it doesn't get signals it
 260  * doesn't want to handle. Thus you cannot kill init even with a
 261  * SIGKILL even by mistake.
 262  */
 263 int do_signal(struct pt_regs *regs, sigset_t *oldset, int syscall)
 264 {
 265         siginfo_t info;
 266         int signr;
 267         struct k_sigaction ka;
 268
 269         /*
 270          * We want the common case to go fast, which is why we may in
 271          * certain cases get here from kernel mode. Just return
 272          * without doing anything if so.
 273          */
 274         if (!user_mode(regs))
 275                 return 0;
 276
 277         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 278                 oldset = &current->saved_sigmask;
 279         else if (!oldset)
 280                 oldset = &current->blocked;
 281
 282         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 283         if (syscall) {
 284                 switch (regs->r12) {
 285                 case -ERESTART_RESTARTBLOCK:
 286                 case -ERESTARTNOHAND:
 287                         if (signr > 0) {
 288                                 regs->r12 = -EINTR;
 289                                 break;
 290                         }
 291                         /* fall through */
 292                 case -ERESTARTSYS:
 293                         if (signr > 0 && !(ka.sa.sa_flags & SA_RESTART)) {
 294                                 regs->r12 = -EINTR;
 295                                 break;
 296                         }
 297                         /* fall through */
 298                 case -ERESTARTNOINTR:
 299                         setup_syscall_restart(regs);
 300                 }
 301         }
 302
 303         if (signr == 0) {
 304                 /* No signal to deliver -- put the saved sigmask back */
 305                 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 306                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 307                         sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 308                 }
 309                 return 0;
 310         }
 311
 312         handle_signal(signr, &ka, &info, oldset, regs, syscall);
 313         return 1;
 314 }
 315
 316 asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
 317 {
 318         int syscall = 0;
 319
 320         if ((sysreg_read(SR) & MODE_MASK) == MODE_SUPERVISOR)
 321                 syscall = 1;
 322
 323         if (ti->flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 324                 do_signal(regs, &current->blocked, syscall);
 325 }