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
  23 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  24
  25 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  26                                struct pt_regs *regs)
  27 {
  28         return do_sigaltstack(uss, uoss, regs->sp);
  29 }
  30
  31 struct rt_sigframe
  32 {
  33         struct siginfo info;
  34         struct ucontext uc;
  35         unsigned long retcode;
  36 };
  37
  38 static int
  39 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
  40 {
  41         int err = 0;
  42
  43 #define COPY(x)         err |= __get_user(regs->x, &sc->x)
  44         COPY(sr);
  45         COPY(pc);
  46         COPY(lr);
  47         COPY(sp);
  48         COPY(r12);
  49         COPY(r11);
  50         COPY(r10);
  51         COPY(r9);
  52         COPY(r8);
  53         COPY(r7);
  54         COPY(r6);
  55         COPY(r5);
  56         COPY(r4);
  57         COPY(r3);
  58         COPY(r2);
  59         COPY(r1);
  60         COPY(r0);
  61 #undef  COPY
  62
  63         /*
  64          * Don't allow anyone to pretend they're running in supervisor
  65          * mode or something...
  66          */
  67         err |= !valid_user_regs(regs);
  68
  69         return err;
  70 }
  71
  72
  73 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
  74 {
  75         struct rt_sigframe __user *frame;
  76         sigset_t set;
  77
  78         frame = (struct rt_sigframe __user *)regs->sp;
  79         pr_debug("SIG return: frame = %p\n", frame);
  80
  81         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  82                 goto badframe;
  83
  84         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  85                 goto badframe;
  86
  87         sigdelsetmask(&set, ~_BLOCKABLE);
  88         spin_lock_irq(&current->sighand->siglock);
  89         current->blocked = set;
  90         recalc_sigpending();
  91         spin_unlock_irq(&current->sighand->siglock);
  92
  93         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  94                 goto badframe;
  95
  96         pr_debug("Context restored: pc = %08lx, lr = %08lx, sp = %08lx\n",
  97                  regs->pc, regs->lr, regs->sp);
  98
  99         return regs->r12;
 100
 101 badframe:
 102         force_sig(SIGSEGV, current);
 103         return 0;
 104 }
 105
 106 static int
 107 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 108 {
 109         int err = 0;
 110
 111 #define COPY(x)         err |= __put_user(regs->x, &sc->x)
 112         COPY(sr);
 113         COPY(pc);
 114         COPY(lr);
 115         COPY(sp);
 116         COPY(r12);
 117         COPY(r11);
 118         COPY(r10);
 119         COPY(r9);
 120         COPY(r8);
 121         COPY(r7);
 122         COPY(r6);
 123         COPY(r5);
 124         COPY(r4);
 125         COPY(r3);
 126         COPY(r2);
 127         COPY(r1);
 128         COPY(r0);
 129 #undef  COPY
 130
 131         return err;
 132 }
 133
 134 static inline void __user *
 135 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 136 {
 137         unsigned long sp = regs->sp;
 138
 139         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 140                 sp = current->sas_ss_sp + current->sas_ss_size;
 141
 142         return (void __user *)((sp - framesize) & ~3);
 143 }
 144
 145 static int
 146 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 147                sigset_t *set, struct pt_regs *regs)
 148 {
 149         struct rt_sigframe __user *frame;
 150         int err = 0;
 151
 152         frame = get_sigframe(ka, regs, sizeof(*frame));
 153         err = -EFAULT;
 154         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 155                 goto out;
 156
 157         /*
 158          * Set up the return code:
 159          *
 160          *      mov     r8, __NR_rt_sigreturn
 161          *      scall
 162          *
 163          * Note: This will blow up since we're using a non-executable
 164          * stack. Better use SA_RESTORER.
 165          */
 166 #if __NR_rt_sigreturn > 127
 167 # error __NR_rt_sigreturn must be < 127 to fit in a short mov
 168 #endif
 169         err = __put_user(0x3008d733 | (__NR_rt_sigreturn << 20),
 170                          &frame->retcode);
 171
 172         err |= copy_siginfo_to_user(&frame->info, info);
 173
 174         /* Set up the ucontext */
 175         err |= __put_user(0, &frame->uc.uc_flags);
 176         err |= __put_user(NULL, &frame->uc.uc_link);
 177         err |= __put_user((void __user *)current->sas_ss_sp,
 178                           &frame->uc.uc_stack.ss_sp);
 179         err |= __put_user(sas_ss_flags(regs->sp),
 180                           &frame->uc.uc_stack.ss_flags);
 181         err |= __put_user(current->sas_ss_size,
 182                           &frame->uc.uc_stack.ss_size);
 183         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 184         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 185
 186         if (err)
 187                 goto out;
 188
 189         regs->r12 = sig;
 190         regs->r11 = (unsigned long) &frame->info;
 191         regs->r10 = (unsigned long) &frame->uc;
 192         regs->sp = (unsigned long) frame;
 193         if (ka->sa.sa_flags & SA_RESTORER)
 194                 regs->lr = (unsigned long)ka->sa.sa_restorer;
 195         else {
 196                 printk(KERN_NOTICE "[%s:%d] did not set SA_RESTORER\n",
 197                        current->comm, current->pid);
 198                 regs->lr = (unsigned long) &frame->retcode;
 199         }
 200
 201         pr_debug("SIG deliver [%s:%d]: sig=%d sp=0x%lx pc=0x%lx->0x%p lr=0x%lx\n",
 202                  current->comm, current->pid, sig, regs->sp,
 203                  regs->pc, ka->sa.sa_handler, regs->lr);
 204
 205         regs->pc = (unsigned long) ka->sa.sa_handler;
 206
 207 out:
 208         return err;
 209 }
 210
 211 static inline void restart_syscall(struct pt_regs *regs)
 212 {
 213         if (regs->r12 == -ERESTART_RESTARTBLOCK)
 214                 regs->r8 = __NR_restart_syscall;
 215         else
 216                 regs->r12 = regs->r12_orig;
 217         regs->pc -= 2;
 218 }
 219
 220 static inline void
 221 handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
 222               sigset_t *oldset, struct pt_regs *regs, int syscall)
 223 {
 224         int ret;
 225
 226         /*
 227          * Set up the stack frame
 228          */
 229         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 230
 231         /*
 232          * Check that the resulting registers are sane
 233          */
 234         ret |= !valid_user_regs(regs);
 235
 236         /*
 237          * Block the signal if we were unsuccessful.
 238          */
 239         if (ret != 0 || !(ka->sa.sa_flags & SA_NODEFER)) {
 240                 spin_lock_irq(&current->sighand->siglock);
 241                 sigorsets(&current->blocked, &current->blocked,
 242                           &ka->sa.sa_mask);
 243                 sigaddset(&current->blocked, sig);
 244                 recalc_sigpending();
 245                 spin_unlock_irq(&current->sighand->siglock);
 246         }
 247
 248         if (ret == 0)
 249                 return;
 250
 251         force_sigsegv(sig, current);
 252 }
 253
 254 /*
 255  * Note that 'init' is a special process: it doesn't get signals it
 256  * doesn't want to handle. Thus you cannot kill init even with a
 257  * SIGKILL even by mistake.
 258  */
 259 int do_signal(struct pt_regs *regs, sigset_t *oldset, int syscall)
 260 {
 261         siginfo_t info;
 262         int signr;
 263         struct k_sigaction ka;
 264
 265         /*
 266          * We want the common case to go fast, which is why we may in
 267          * certain cases get here from kernel mode. Just return
 268          * without doing anything if so.
 269          */
 270         if (!user_mode(regs))
 271                 return 0;
 272
 273         if (try_to_freeze()) {
 274                 signr = 0;
 275                 if (!signal_pending(current))
 276                         goto no_signal;
 277         }
 278
 279         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 280                 oldset = &current->saved_sigmask;
 281         else if (!oldset)
 282                 oldset = &current->blocked;
 283
 284         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 285 no_signal:
 286         if (syscall) {
 287                 switch (regs->r12) {
 288                 case -ERESTART_RESTARTBLOCK:
 289                 case -ERESTARTNOHAND:
 290                         if (signr > 0) {
 291                                 regs->r12 = -EINTR;
 292                                 break;
 293                         }
 294                         /* fall through */
 295                 case -ERESTARTSYS:
 296                         if (signr > 0 && !(ka.sa.sa_flags & SA_RESTART)) {
 297                                 regs->r12 = -EINTR;
 298                                 break;
 299                         }
 300                         /* fall through */
 301                 case -ERESTARTNOINTR:
 302                         restart_syscall(regs);
 303                 }
 304         }
 305
 306         if (signr == 0) {
 307                 /* No signal to deliver -- put the saved sigmask back */
 308                 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 309                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 310                         sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 311                 }
 312                 return 0;
 313         }
 314
 315         handle_signal(signr, &ka, &info, oldset, regs, syscall);
 316         return 1;
 317 }
 318
 319 asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
 320 {
 321         int syscall = 0;
 322
 323         if ((sysreg_read(SR) & MODE_MASK) == MODE_SUPERVISOR)
 324                 syscall = 1;
 325
 326         if (ti->flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 327                 do_signal(regs, &current->blocked, syscall);
 328 }