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 #include <linux/tracehook.h>
  20
  21 #include <asm/uaccess.h>
  22 #include <asm/ucontext.h>
  23 #include <asm/syscalls.h>
  24
  25 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  26
  27 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  28                                struct pt_regs *regs)
  29 {
  30         return do_sigaltstack(uss, uoss, regs->sp);
  31 }
  32
  33 struct rt_sigframe
  34 {
  35         struct siginfo info;
  36         struct ucontext uc;
  37         unsigned long retcode;
  38 };
  39
  40 static int
  41 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
  42 {
  43         int err = 0;
  44
  45 #define COPY(x)         err |= __get_user(regs->x, &sc->x)
  46         COPY(sr);
  47         COPY(pc);
  48         COPY(lr);
  49         COPY(sp);
  50         COPY(r12);
  51         COPY(r11);
  52         COPY(r10);
  53         COPY(r9);
  54         COPY(r8);
  55         COPY(r7);
  56         COPY(r6);
  57         COPY(r5);
  58         COPY(r4);
  59         COPY(r3);
  60         COPY(r2);
  61         COPY(r1);
  62         COPY(r0);
  63 #undef  COPY
  64
  65         /*
  66          * Don't allow anyone to pretend they're running in supervisor
  67          * mode or something...
  68          */
  69         err |= !valid_user_regs(regs);
  70
  71         return err;
  72 }
  73
  74
  75 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
  76 {
  77         struct rt_sigframe __user *frame;
  78         sigset_t set;
  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         sigdelsetmask(&set, ~_BLOCKABLE);
  90         spin_lock_irq(&current->sighand->siglock);
  91         current->blocked = set;
  92         recalc_sigpending();
  93         spin_unlock_irq(&current->sighand->siglock);
  94
  95         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  96                 goto badframe;
  97
  98         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
  99                 goto badframe;
 100
 101         pr_debug("Context restored: pc = %08lx, lr = %08lx, sp = %08lx\n",
 102                  regs->pc, regs->lr, regs->sp);
 103
 104         return regs->r12;
 105
 106 badframe:
 107         force_sig(SIGSEGV, current);
 108         return 0;
 109 }
 110
 111 static int
 112 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 113 {
 114         int err = 0;
 115
 116 #define COPY(x)         err |= __put_user(regs->x, &sc->x)
 117         COPY(sr);
 118         COPY(pc);
 119         COPY(lr);
 120         COPY(sp);
 121         COPY(r12);
 122         COPY(r11);
 123         COPY(r10);
 124         COPY(r9);
 125         COPY(r8);
 126         COPY(r7);
 127         COPY(r6);
 128         COPY(r5);
 129         COPY(r4);
 130         COPY(r3);
 131         COPY(r2);
 132         COPY(r1);
 133         COPY(r0);
 134 #undef  COPY
 135
 136         return err;
 137 }
 138
 139 static inline void __user *
 140 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 141 {
 142         unsigned long sp = regs->sp;
 143
 144         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 145                 sp = current->sas_ss_sp + current->sas_ss_size;
 146
 147         return (void __user *)((sp - framesize) & ~3);
 148 }
 149
 150 static int
 151 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 152                sigset_t *set, struct pt_regs *regs)
 153 {
 154         struct rt_sigframe __user *frame;
 155         int err = 0;
 156
 157         frame = get_sigframe(ka, regs, sizeof(*frame));
 158         err = -EFAULT;
 159         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 160                 goto out;
 161
 162         /*
 163          * Set up the return code:
 164          *
 165          *      mov     r8, __NR_rt_sigreturn
 166          *      scall
 167          *
 168          * Note: This will blow up since we're using a non-executable
 169          * stack. Better use SA_RESTORER.
 170          */
 171 #if __NR_rt_sigreturn > 127
 172 # error __NR_rt_sigreturn must be < 127 to fit in a short mov
 173 #endif
 174         err = __put_user(0x3008d733 | (__NR_rt_sigreturn << 20),
 175                          &frame->retcode);
 176
 177         err |= copy_siginfo_to_user(&frame->info, info);
 178
 179         /* Set up the ucontext */
 180         err |= __put_user(0, &frame->uc.uc_flags);
 181         err |= __put_user(NULL, &frame->uc.uc_link);
 182         err |= __put_user((void __user *)current->sas_ss_sp,
 183                           &frame->uc.uc_stack.ss_sp);
 184         err |= __put_user(sas_ss_flags(regs->sp),
 185                           &frame->uc.uc_stack.ss_flags);
 186         err |= __put_user(current->sas_ss_size,
 187                           &frame->uc.uc_stack.ss_size);
 188         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 189         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 190
 191         if (err)
 192                 goto out;
 193
 194         regs->r12 = sig;
 195         regs->r11 = (unsigned long) &frame->info;
 196         regs->r10 = (unsigned long) &frame->uc;
 197         regs->sp = (unsigned long) frame;
 198         if (ka->sa.sa_flags & SA_RESTORER)
 199                 regs->lr = (unsigned long)ka->sa.sa_restorer;
 200         else {
 201                 printk(KERN_NOTICE "[%s:%d] did not set SA_RESTORER\n",
 202                        current->comm, current->pid);
 203                 regs->lr = (unsigned long) &frame->retcode;
 204         }
 205
 206         pr_debug("SIG deliver [%s:%d]: sig=%d sp=0x%lx pc=0x%lx->0x%p lr=0x%lx\n",
 207                  current->comm, current->pid, sig, regs->sp,
 208                  regs->pc, ka->sa.sa_handler, regs->lr);
 209
 210         regs->pc = (unsigned long) ka->sa.sa_handler;
 211
 212 out:
 213         return err;
 214 }
 215
 216 static inline void setup_syscall_restart(struct pt_regs *regs)
 217 {
 218         if (regs->r12 == -ERESTART_RESTARTBLOCK)
 219                 regs->r8 = __NR_restart_syscall;
 220         else
 221                 regs->r12 = regs->r12_orig;
 222         regs->pc -= 2;
 223 }
 224
 225 static inline void
 226 handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
 227               sigset_t *oldset, struct pt_regs *regs, int syscall)
 228 {
 229         int ret;
 230
 231         /*
 232          * Set up the stack frame
 233          */
 234         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 235
 236         /*
 237          * Check that the resulting registers are sane
 238          */
 239         ret |= !valid_user_regs(regs);
 240
 241         /*
 242          * Block the signal if we were unsuccessful.
 243          */
 244         if (ret != 0 || !(ka->sa.sa_flags & SA_NODEFER)) {
 245                 spin_lock_irq(&current->sighand->siglock);
 246                 sigorsets(&current->blocked, &current->blocked,
 247                           &ka->sa.sa_mask);
 248                 sigaddset(&current->blocked, sig);
 249                 recalc_sigpending();
 250                 spin_unlock_irq(&current->sighand->siglock);
 251         }
 252
 253         if (ret == 0)
 254                 return;
 255
 256         force_sigsegv(sig, current);
 257 }
 258
 259 /*
 260  * Note that 'init' is a special process: it doesn't get signals it
 261  * doesn't want to handle. Thus you cannot kill init even with a
 262  * SIGKILL even by mistake.
 263  */
 264 int do_signal(struct pt_regs *regs, sigset_t *oldset, int syscall)
 265 {
 266         siginfo_t info;
 267         int signr;
 268         struct k_sigaction ka;
 269
 270         /*
 271          * We want the common case to go fast, which is why we may in
 272          * certain cases get here from kernel mode. Just return
 273          * without doing anything if so.
 274          */
 275         if (!user_mode(regs))
 276                 return 0;
 277
 278         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 279                 oldset = &current->saved_sigmask;
 280         else if (!oldset)
 281                 oldset = &current->blocked;
 282
 283         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 284         if (syscall) {
 285                 switch (regs->r12) {
 286                 case -ERESTART_RESTARTBLOCK:
 287                 case -ERESTARTNOHAND:
 288                         if (signr > 0) {
 289                                 regs->r12 = -EINTR;
 290                                 break;
 291                         }
 292                         /* fall through */
 293                 case -ERESTARTSYS:
 294                         if (signr > 0 && !(ka.sa.sa_flags & SA_RESTART)) {
 295                                 regs->r12 = -EINTR;
 296                                 break;
 297                         }
 298                         /* fall through */
 299                 case -ERESTARTNOINTR:
 300                         setup_syscall_restart(regs);
 301                 }
 302         }
 303
 304         if (signr == 0) {
 305                 /* No signal to deliver -- put the saved sigmask back */
 306                 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 307                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 308                         sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 309                 }
 310                 return 0;
 311         }
 312
 313         handle_signal(signr, &ka, &info, oldset, regs, syscall);
 314         return 1;
 315 }
 316
 317 asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
 318 {
 319         int syscall = 0;
 320
 321         if ((sysreg_read(SR) & MODE_MASK) == MODE_SUPERVISOR)
 322                 syscall = 1;
 323
 324         if (ti->flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 325                 do_signal(regs, &current->blocked, syscall);
 326
 327         if (ti->flags & _TIF_NOTIFY_RESUME) {
 328                 clear_thread_flag(TIF_NOTIFY_RESUME);
 329                 tracehook_notify_resume(regs);
 330                 if (current->replacement_session_keyring)
 331                         key_replace_session_keyring();
 332         }
 333 }