arch/microblaze/kernel/signal.c

   1 /*
   2  * Signal handling
   3  *
   4  * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
   5  * Copyright (C) 2008-2009 PetaLogix
   6  * Copyright (C) 2003,2004 John Williams <jwilliams@itee.uq.edu.au>
   7  * Copyright (C) 2001 NEC Corporation
   8  * Copyright (C) 2001 Miles Bader <miles@gnu.org>
   9  * Copyright (C) 1999,2000 Niibe Yutaka & Kaz Kojima
  10  * Copyright (C) 1991,1992 Linus Torvalds
  11  *
  12  * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
  13  *
  14  * This file was was derived from the sh version, arch/sh/kernel/signal.c
  15  *
  16  * This file is subject to the terms and conditions of the GNU General
  17  * Public License. See the file COPYING in the main directory of this
  18  * archive for more details.
  19  */
  20
  21 #include <linux/sched.h>
  22 #include <linux/mm.h>
  23 #include <linux/smp.h>
  24 #include <linux/kernel.h>
  25 #include <linux/signal.h>
  26 #include <linux/errno.h>
  27 #include <linux/wait.h>
  28 #include <linux/ptrace.h>
  29 #include <linux/unistd.h>
  30 #include <linux/stddef.h>
  31 #include <linux/personality.h>
  32 #include <linux/percpu.h>
  33 #include <linux/linkage.h>
  34 #include <asm/entry.h>
  35 #include <asm/ucontext.h>
  36 #include <linux/uaccess.h>
  37 #include <asm/pgtable.h>
  38 #include <asm/pgalloc.h>
  39 #include <linux/syscalls.h>
  40 #include <asm/cacheflush.h>
  41 #include <asm/syscalls.h>
  42
  43 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  44
  45 asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_sycall);
  46
  47
  48 asmlinkage long
  49 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  50                 struct pt_regs *regs)
  51 {
  52         return do_sigaltstack(uss, uoss, regs->r1);
  53 }
  54
  55 /*
  56  * Do a signal return; undo the signal stack.
  57  */
  58 struct sigframe {
  59         struct sigcontext sc;
  60         unsigned long extramask[_NSIG_WORDS-1];
  61         unsigned long tramp[2]; /* signal trampoline */
  62 };
  63
  64 struct rt_sigframe {
  65         struct siginfo info;
  66         struct ucontext uc;
  67         unsigned long tramp[2]; /* signal trampoline */
  68 };
  69
  70 static int restore_sigcontext(struct pt_regs *regs,
  71                                 struct sigcontext __user *sc, int *rval_p)
  72 {
  73         unsigned int err = 0;
  74
  75 #define COPY(x)         {err |= __get_user(regs->x, &sc->regs.x); }
  76         COPY(r0);
  77         COPY(r1);
  78         COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
  79         COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
  80         COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
  81         COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
  82         COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
  83         COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
  84         COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
  85         COPY(r30);      COPY(r31);
  86         COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
  87 #undef COPY
  88
  89         *rval_p = regs->r3;
  90
  91         return err;
  92 }
  93
  94 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
  95 {
  96         struct rt_sigframe __user *frame =
  97                 (struct rt_sigframe __user *)(regs->r1 + STATE_SAVE_ARG_SPACE);
  98
  99         sigset_t set;
 100         int rval;
 101
 102         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 103                 goto badframe;
 104
 105         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 106                 goto badframe;
 107
 108         sigdelsetmask(&set, ~_BLOCKABLE);
 109         spin_lock_irq(&current->sighand->siglock);
 110         current->blocked = set;
 111         recalc_sigpending();
 112         spin_unlock_irq(&current->sighand->siglock);
 113
 114         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval))
 115                 goto badframe;
 116
 117         /* It is more difficult to avoid calling this function than to
 118          call it and ignore errors. */
 119         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->r1))
 120                 goto badframe;
 121
 122         return rval;
 123
 124 badframe:
 125         force_sig(SIGSEGV, current);
 126         return 0;
 127 }
 128
 129 /*
 130  * Set up a signal frame.
 131  */
 132
 133 static int
 134 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 135                 unsigned long mask)
 136 {
 137         int err = 0;
 138
 139 #define COPY(x)         {err |= __put_user(regs->x, &sc->regs.x); }
 140         COPY(r0);
 141         COPY(r1);
 142         COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
 143         COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
 144         COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
 145         COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
 146         COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
 147         COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
 148         COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
 149         COPY(r30);      COPY(r31);
 150         COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
 151 #undef COPY
 152
 153         err |= __put_user(mask, &sc->oldmask);
 154
 155         return err;
 156 }
 157
 158 /*
 159  * Determine which stack to use..
 160  */
 161 static inline void __user *
 162 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
 163 {
 164         /* Default to using normal stack */
 165         unsigned long sp = regs->r1;
 166
 167         if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && !on_sig_stack(sp))
 168                 sp = current->sas_ss_sp + current->sas_ss_size;
 169
 170         return (void __user *)((sp - frame_size) & -8UL);
 171 }
 172
 173 static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 174                         sigset_t *set, struct pt_regs *regs)
 175 {
 176         struct rt_sigframe __user *frame;
 177         int err = 0;
 178         int signal;
 179
 180         frame = get_sigframe(ka, regs, sizeof(*frame));
 181
 182         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 183                 goto give_sigsegv;
 184
 185         signal = current_thread_info()->exec_domain
 186                 && current_thread_info()->exec_domain->signal_invmap
 187                 && sig < 32
 188                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 189                 : sig;
 190
 191         if (info)
 192                 err |= copy_siginfo_to_user(&frame->info, info);
 193
 194         /* Create the ucontext. */
 195         err |= __put_user(0, &frame->uc.uc_flags);
 196         err |= __put_user(0, &frame->uc.uc_link);
 197         err |= __put_user((void *)current->sas_ss_sp,
 198                         &frame->uc.uc_stack.ss_sp);
 199         err |= __put_user(sas_ss_flags(regs->r1),
 200                         &frame->uc.uc_stack.ss_flags);
 201         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 202         err |= setup_sigcontext(&frame->uc.uc_mcontext,
 203                         regs, set->sig[0]);
 204         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 205
 206         /* Set up to return from userspace. If provided, use a stub
 207          already in userspace. */
 208         /* minus 8 is offset to cater for "rtsd r15,8" */
 209         /* addi r12, r0, __NR_sigreturn */
 210         err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
 211                         frame->tramp + 0);
 212         /* brki r14, 0x8 */
 213         err |= __put_user(0xb9cc0008, frame->tramp + 1);
 214
 215         /* Return from sighandler will jump to the tramp.
 216          Negative 8 offset because return is rtsd r15, 8 */
 217         regs->r15 = ((unsigned long)frame->tramp)-8;
 218
 219         __invalidate_cache_sigtramp((unsigned long)frame->tramp);
 220
 221         if (err)
 222                 goto give_sigsegv;
 223
 224         /* Set up registers for signal handler */
 225         regs->r1 = (unsigned long) frame - STATE_SAVE_ARG_SPACE;
 226
 227         /* Signal handler args: */
 228         regs->r5 = signal; /* arg 0: signum */
 229         regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */
 230         regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */
 231         /* Offset to handle microblaze rtid r14, 0 */
 232         regs->pc = (unsigned long)ka->sa.sa_handler;
 233
 234         set_fs(USER_DS);
 235
 236 #ifdef DEBUG_SIG
 237         printk(KERN_INFO "SIG deliver (%s:%d): sp=%p pc=%08lx\n",
 238                 current->comm, current->pid, frame, regs->pc);
 239 #endif
 240
 241         return;
 242
 243 give_sigsegv:
 244         if (sig == SIGSEGV)
 245                 ka->sa.sa_handler = SIG_DFL;
 246         force_sig(SIGSEGV, current);
 247 }
 248
 249 /* Handle restarting system calls */
 250 static inline void
 251 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 252 {
 253         switch (regs->r3) {
 254         case -ERESTART_RESTARTBLOCK:
 255         case -ERESTARTNOHAND:
 256                 if (!has_handler)
 257                         goto do_restart;
 258                 regs->r3 = -EINTR;
 259                 break;
 260         case -ERESTARTSYS:
 261                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 262                         regs->r3 = -EINTR;
 263                         break;
 264         }
 265         /* fallthrough */
 266         case -ERESTARTNOINTR:
 267 do_restart:
 268                 /* offset of 4 bytes to re-execute trap (brki) instruction */
 269 #ifndef CONFIG_MMU
 270                 regs->pc -= 4;
 271 #else
 272                 /* offset of 8 bytes required = 4 for rtbd
 273                    offset, plus 4 for size of
 274                         "brki r14,8"
 275                    instruction. */
 276                 regs->pc -= 8;
 277 #endif
 278                 break;
 279         }
 280 }
 281
 282 /*
 283  * OK, we're invoking a handler
 284  */
 285
 286 static int
 287 handle_signal(unsigned long sig, struct k_sigaction *ka,
 288                 siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
 289 {
 290         /* Set up the stack frame */
 291         if (ka->sa.sa_flags & SA_SIGINFO)
 292                 setup_rt_frame(sig, ka, info, oldset, regs);
 293         else
 294                 setup_rt_frame(sig, ka, NULL, oldset, regs);
 295
 296         if (ka->sa.sa_flags & SA_ONESHOT)
 297                 ka->sa.sa_handler = SIG_DFL;
 298
 299         if (!(ka->sa.sa_flags & SA_NODEFER)) {
 300                 spin_lock_irq(&current->sighand->siglock);
 301                 sigorsets(&current->blocked,
 302                                 &current->blocked, &ka->sa.sa_mask);
 303                 sigaddset(&current->blocked, sig);
 304                 recalc_sigpending();
 305                 spin_unlock_irq(&current->sighand->siglock);
 306         }
 307         return 1;
 308 }
 309
 310 /*
 311  * Note that 'init' is a special process: it doesn't get signals it doesn't
 312  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 313  * mistake.
 314  *
 315  * Note that we go through the signals twice: once to check the signals that
 316  * the kernel can handle, and then we build all the user-level signal handling
 317  * stack-frames in one go after that.
 318  */
 319 int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_syscall)
 320 {
 321         siginfo_t info;
 322         int signr;
 323         struct k_sigaction ka;
 324 #ifdef DEBUG_SIG
 325         printk(KERN_INFO "do signal: %p %p %d\n", regs, oldset, in_syscall);
 326         printk(KERN_INFO "do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1,
 327                         regs->r12, current_thread_info()->flags);
 328 #endif
 329         /*
 330          * We want the common case to go fast, which
 331          * is why we may in certain cases get here from
 332          * kernel mode. Just return without doing anything
 333          * if so.
 334          */
 335         if (kernel_mode(regs))
 336                 return 1;
 337
 338         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 339                 oldset = &current->saved_sigmask;
 340         else
 341                 oldset = &current->blocked;
 342
 343         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 344         if (signr > 0) {
 345                 /* Whee! Actually deliver the signal. */
 346                 if (in_syscall)
 347                         handle_restart(regs, &ka, 1);
 348                 if (handle_signal(signr, &ka, &info, oldset, regs)) {
 349                         /*
 350                          * A signal was successfully delivered; the saved
 351                          * sigmask will have been stored in the signal frame,
 352                          * and will be restored by sigreturn, so we can simply
 353                          * clear the TS_RESTORE_SIGMASK flag.
 354                          */
 355                         current_thread_info()->status &=
 356                             ~TS_RESTORE_SIGMASK;
 357                 }
 358                 return 1;
 359         }
 360
 361         if (in_syscall)
 362                 handle_restart(regs, NULL, 0);
 363
 364         /*
 365          * If there's no signal to deliver, we just put the saved sigmask
 366          * back.
 367          */
 368         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 369                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 370                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 371         }
 372
 373         /* Did we come from a system call? */
 374         return 0;
 375 }