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 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         /* Always make any pending restarted system calls return -EINTR */
  79         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  80
  81         frame = (struct rt_sigframe __user *)regs->sp;
  82         pr_debug("SIG return: frame = %p\n", frame);
  83
  84         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  85                 goto badframe;
  86
  87         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  88                 goto badframe;
  89
  90         set_current_blocked(&set);
  91
  92         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  93                 goto badframe;
  94
  95         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
  96                 goto badframe;
  97
  98         pr_debug("Context restored: pc = %08lx, lr = %08lx, sp = %08lx\n",
  99                  regs->pc, regs->lr, regs->sp);
 100
 101         return regs->r12;
 102
 103 badframe:
 104         force_sig(SIGSEGV, current);
 105         return 0;
 106 }
 107
 108 static int
 109 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 110 {
 111         int err = 0;
 112
 113 #define COPY(x)         err |= __put_user(regs->x, &sc->x)
 114         COPY(sr);
 115         COPY(pc);
 116         COPY(lr);
 117         COPY(sp);
 118         COPY(r12);
 119         COPY(r11);
 120         COPY(r10);
 121         COPY(r9);
 122         COPY(r8);
 123         COPY(r7);
 124         COPY(r6);
 125         COPY(r5);
 126         COPY(r4);
 127         COPY(r3);
 128         COPY(r2);
 129         COPY(r1);
 130         COPY(r0);
 131 #undef  COPY
 132
 133         return err;
 134 }
 135
 136 static inline void __user *
 137 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 138 {
 139         unsigned long sp = regs->sp;
 140
 141         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 142                 sp = current->sas_ss_sp + current->sas_ss_size;
 143
 144         return (void __user *)((sp - framesize) & ~3);
 145 }
 146
 147 static int
 148 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 149                sigset_t *set, struct pt_regs *regs)
 150 {
 151         struct rt_sigframe __user *frame;
 152         int err = 0;
 153
 154         frame = get_sigframe(ka, regs, sizeof(*frame));
 155         err = -EFAULT;
 156         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 157                 goto out;
 158
 159         /*
 160          * Set up the return code:
 161          *
 162          *      mov     r8, __NR_rt_sigreturn
 163          *      scall
 164          *
 165          * Note: This will blow up since we're using a non-executable
 166          * stack. Better use SA_RESTORER.
 167          */
 168 #if __NR_rt_sigreturn > 127
 169 # error __NR_rt_sigreturn must be < 127 to fit in a short mov
 170 #endif
 171         err = __put_user(0x3008d733 | (__NR_rt_sigreturn << 20),
 172                          &frame->retcode);
 173
 174         err |= copy_siginfo_to_user(&frame->info, info);
 175
 176         /* Set up the ucontext */
 177         err |= __put_user(0, &frame->uc.uc_flags);
 178         err |= __put_user(NULL, &frame->uc.uc_link);
 179         err |= __put_user((void __user *)current->sas_ss_sp,
 180                           &frame->uc.uc_stack.ss_sp);
 181         err |= __put_user(sas_ss_flags(regs->sp),
 182                           &frame->uc.uc_stack.ss_flags);
 183         err |= __put_user(current->sas_ss_size,
 184                           &frame->uc.uc_stack.ss_size);
 185         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 186         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 187
 188         if (err)
 189                 goto out;
 190
 191         regs->r12 = sig;
 192         regs->r11 = (unsigned long) &frame->info;
 193         regs->r10 = (unsigned long) &frame->uc;
 194         regs->sp = (unsigned long) frame;
 195         if (ka->sa.sa_flags & SA_RESTORER)
 196                 regs->lr = (unsigned long)ka->sa.sa_restorer;
 197         else {
 198                 printk(KERN_NOTICE "[%s:%d] did not set SA_RESTORER\n",
 199                        current->comm, current->pid);
 200                 regs->lr = (unsigned long) &frame->retcode;
 201         }
 202
 203         pr_debug("SIG deliver [%s:%d]: sig=%d sp=0x%lx pc=0x%lx->0x%p lr=0x%lx\n",
 204                  current->comm, current->pid, sig, regs->sp,
 205                  regs->pc, ka->sa.sa_handler, regs->lr);
 206
 207         regs->pc = (unsigned long) ka->sa.sa_handler;
 208
 209 out:
 210         return err;
 211 }
 212
 213 static inline void setup_syscall_restart(struct pt_regs *regs)
 214 {
 215         if (regs->r12 == -ERESTART_RESTARTBLOCK)
 216                 regs->r8 = __NR_restart_syscall;
 217         else
 218                 regs->r12 = regs->r12_orig;
 219         regs->pc -= 2;
 220 }
 221
 222 static inline void
 223 handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
 224               struct pt_regs *regs, int syscall)
 225 {
 226         int ret;
 227
 228         /*
 229          * Set up the stack frame
 230          */
 231         ret = setup_rt_frame(sig, ka, info, sigmask_to_save(), regs);
 232
 233         /*
 234          * Check that the resulting registers are sane
 235          */
 236         ret |= !valid_user_regs(regs);
 237
 238         /*
 239          * Block the signal if we were successful.
 240          */
 241         if (ret != 0)
 242                 force_sigsegv(sig, current);
 243         else
 244                 signal_delivered(sig, info, ka, regs, 0);
 245 }
 246
 247 /*
 248  * Note that 'init' is a special process: it doesn't get signals it
 249  * doesn't want to handle. Thus you cannot kill init even with a
 250  * SIGKILL even by mistake.
 251  */
 252 static void do_signal(struct pt_regs *regs, int syscall)
 253 {
 254         siginfo_t info;
 255         int signr;
 256         struct k_sigaction ka;
 257
 258         /*
 259          * We want the common case to go fast, which is why we may in
 260          * certain cases get here from kernel mode. Just return
 261          * without doing anything if so.
 262          */
 263         if (!user_mode(regs))
 264                 return;
 265
 266         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 267         if (syscall) {
 268                 switch (regs->r12) {
 269                 case -ERESTART_RESTARTBLOCK:
 270                 case -ERESTARTNOHAND:
 271                         if (signr > 0) {
 272                                 regs->r12 = -EINTR;
 273                                 break;
 274                         }
 275                         /* fall through */
 276                 case -ERESTARTSYS:
 277                         if (signr > 0 && !(ka.sa.sa_flags & SA_RESTART)) {
 278                                 regs->r12 = -EINTR;
 279                                 break;
 280                         }
 281                         /* fall through */
 282                 case -ERESTARTNOINTR:
 283                         setup_syscall_restart(regs);
 284                 }
 285         }
 286
 287         if (signr == 0) {
 288                 /* No signal to deliver -- put the saved sigmask back */
 289                 restore_saved_sigmask();
 290                 return;
 291         }
 292
 293         handle_signal(signr, &ka, &info, regs, syscall);
 294 }
 295
 296 asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
 297 {
 298         int syscall = 0;
 299
 300         if ((sysreg_read(SR) & MODE_MASK) == MODE_SUPERVISOR)
 301                 syscall = 1;
 302
 303         if (ti->flags & _TIF_SIGPENDING))
 304                 do_signal(regs, syscall);
 305
 306         if (ti->flags & _TIF_NOTIFY_RESUME) {
 307                 clear_thread_flag(TIF_NOTIFY_RESUME);
 308                 tracehook_notify_resume(regs);
 309         }
 310 }