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 asmlinkage long
  48 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  49                 struct pt_regs *regs)
  50 {
  51         return do_sigaltstack(uss, uoss, regs->r1);
  52 }
  53
  54 /*
  55  * Do a signal return; undo the signal stack.
  56  */
  57 struct sigframe {
  58         struct sigcontext sc;
  59         unsigned long extramask[_NSIG_WORDS-1];
  60         unsigned long tramp[2]; /* signal trampoline */
  61 };
  62
  63 struct rt_sigframe {
  64         struct siginfo info;
  65         struct ucontext uc;
  66         unsigned long tramp[2]; /* signal trampoline */
  67 };
  68
  69 static int restore_sigcontext(struct pt_regs *regs,
  70                                 struct sigcontext __user *sc, int *rval_p)
  71 {
  72         unsigned int err = 0;
  73
  74 #define COPY(x)         {err |= __get_user(regs->x, &sc->regs.x); }
  75         COPY(r0);
  76         COPY(r1);
  77         COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
  78         COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
  79         COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
  80         COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
  81         COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
  82         COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
  83         COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
  84         COPY(r30);      COPY(r31);
  85         COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
  86 #undef COPY
  87
  88         *rval_p = regs->r3;
  89
  90         return err;
  91 }
  92
  93 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
  94 {
  95         struct rt_sigframe __user *frame =
  96                 (struct rt_sigframe __user *)(regs->r1);
  97
  98         sigset_t set;
  99         int rval;
 100
 101         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 102                 goto badframe;
 103
 104         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 105                 goto badframe;
 106
 107         sigdelsetmask(&set, ~_BLOCKABLE);
 108         spin_lock_irq(&current->sighand->siglock);
 109         current->blocked = set;
 110         recalc_sigpending();
 111         spin_unlock_irq(&current->sighand->siglock);
 112
 113         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval))
 114                 goto badframe;
 115
 116         /* It is more difficult to avoid calling this function than to
 117          call it and ignore errors. */
 118         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->r1))
 119                 goto badframe;
 120
 121         return rval;
 122
 123 badframe:
 124         force_sig(SIGSEGV, current);
 125         return 0;
 126 }
 127
 128 /*
 129  * Set up a signal frame.
 130  */
 131
 132 static int
 133 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 134                 unsigned long mask)
 135 {
 136         int err = 0;
 137
 138 #define COPY(x)         {err |= __put_user(regs->x, &sc->regs.x); }
 139         COPY(r0);
 140         COPY(r1);
 141         COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
 142         COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
 143         COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
 144         COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
 145         COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
 146         COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
 147         COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
 148         COPY(r30);      COPY(r31);
 149         COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
 150 #undef COPY
 151
 152         err |= __put_user(mask, &sc->oldmask);
 153
 154         return err;
 155 }
 156
 157 /*
 158  * Determine which stack to use..
 159  */
 160 static inline void __user *
 161 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
 162 {
 163         /* Default to using normal stack */
 164         unsigned long sp = regs->r1;
 165
 166         if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && !on_sig_stack(sp))
 167                 sp = current->sas_ss_sp + current->sas_ss_size;
 168
 169         return (void __user *)((sp - frame_size) & -8UL);
 170 }
 171
 172 static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 173                         sigset_t *set, struct pt_regs *regs)
 174 {
 175         struct rt_sigframe __user *frame;
 176         int err = 0;
 177         int signal;
 178         unsigned long address = 0;
 179 #ifdef CONFIG_MMU
 180         pmd_t *pmdp;
 181         pte_t *ptep;
 182 #endif
 183
 184         frame = get_sigframe(ka, regs, sizeof(*frame));
 185
 186         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 187                 goto give_sigsegv;
 188
 189         signal = current_thread_info()->exec_domain
 190                 && current_thread_info()->exec_domain->signal_invmap
 191                 && sig < 32
 192                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 193                 : sig;
 194
 195         if (info)
 196                 err |= copy_siginfo_to_user(&frame->info, info);
 197
 198         /* Create the ucontext. */
 199         err |= __put_user(0, &frame->uc.uc_flags);
 200         err |= __put_user(NULL, &frame->uc.uc_link);
 201         err |= __put_user((void __user *)current->sas_ss_sp,
 202                         &frame->uc.uc_stack.ss_sp);
 203         err |= __put_user(sas_ss_flags(regs->r1),
 204                         &frame->uc.uc_stack.ss_flags);
 205         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 206         err |= setup_sigcontext(&frame->uc.uc_mcontext,
 207                         regs, set->sig[0]);
 208         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 209
 210         /* Set up to return from userspace. If provided, use a stub
 211          already in userspace. */
 212         /* minus 8 is offset to cater for "rtsd r15,8" */
 213         /* addi r12, r0, __NR_sigreturn */
 214         err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
 215                         frame->tramp + 0);
 216         /* brki r14, 0x8 */
 217         err |= __put_user(0xb9cc0008, frame->tramp + 1);
 218
 219         /* Return from sighandler will jump to the tramp.
 220          Negative 8 offset because return is rtsd r15, 8 */
 221         regs->r15 = ((unsigned long)frame->tramp)-8;
 222
 223         address = ((unsigned long)frame->tramp);
 224 #ifdef CONFIG_MMU
 225         pmdp = pmd_offset(pud_offset(
 226                         pgd_offset(current->mm, address),
 227                                         address), address);
 228
 229         preempt_disable();
 230         ptep = pte_offset_map(pmdp, address);
 231         if (pte_present(*ptep)) {
 232                 address = (unsigned long) page_address(pte_page(*ptep));
 233                 /* MS: I need add offset in page */
 234                 address += ((unsigned long)frame->tramp) & ~PAGE_MASK;
 235                 /* MS address is virtual */
 236                 address = virt_to_phys(address);
 237                 invalidate_icache_range(address, address + 8);
 238                 flush_dcache_range(address, address + 8);
 239         }
 240         pte_unmap(ptep);
 241         preempt_enable();
 242 #else
 243         flush_icache_range(address, address + 8);
 244         flush_dcache_range(address, address + 8);
 245 #endif
 246         if (err)
 247                 goto give_sigsegv;
 248
 249         /* Set up registers for signal handler */
 250         regs->r1 = (unsigned long) frame;
 251
 252         /* Signal handler args: */
 253         regs->r5 = signal; /* arg 0: signum */
 254         regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */
 255         regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */
 256         /* Offset to handle microblaze rtid r14, 0 */
 257         regs->pc = (unsigned long)ka->sa.sa_handler;
 258
 259         set_fs(USER_DS);
 260
 261         /* the tracer may want to single-step inside the handler */
 262         if (test_thread_flag(TIF_SINGLESTEP))
 263                 ptrace_notify(SIGTRAP);
 264
 265 #ifdef DEBUG_SIG
 266         printk(KERN_INFO "SIG deliver (%s:%d): sp=%p pc=%08lx\n",
 267                 current->comm, current->pid, frame, regs->pc);
 268 #endif
 269
 270         return;
 271
 272 give_sigsegv:
 273         if (sig == SIGSEGV)
 274                 ka->sa.sa_handler = SIG_DFL;
 275         force_sig(SIGSEGV, current);
 276 }
 277
 278 /* Handle restarting system calls */
 279 static inline void
 280 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 281 {
 282         switch (regs->r3) {
 283         case -ERESTART_RESTARTBLOCK:
 284         case -ERESTARTNOHAND:
 285                 if (!has_handler)
 286                         goto do_restart;
 287                 regs->r3 = -EINTR;
 288                 break;
 289         case -ERESTARTSYS:
 290                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 291                         regs->r3 = -EINTR;
 292                         break;
 293         }
 294         /* fallthrough */
 295         case -ERESTARTNOINTR:
 296 do_restart:
 297                 /* offset of 4 bytes to re-execute trap (brki) instruction */
 298 #ifndef CONFIG_MMU
 299                 regs->pc -= 4;
 300 #else
 301                 /* offset of 8 bytes required = 4 for rtbd
 302                    offset, plus 4 for size of
 303                         "brki r14,8"
 304                    instruction. */
 305                 regs->pc -= 8;
 306 #endif
 307                 break;
 308         }
 309 }
 310
 311 /*
 312  * OK, we're invoking a handler
 313  */
 314
 315 static int
 316 handle_signal(unsigned long sig, struct k_sigaction *ka,
 317                 siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
 318 {
 319         /* Set up the stack frame */
 320         if (ka->sa.sa_flags & SA_SIGINFO)
 321                 setup_rt_frame(sig, ka, info, oldset, regs);
 322         else
 323                 setup_rt_frame(sig, ka, NULL, oldset, regs);
 324
 325         if (ka->sa.sa_flags & SA_ONESHOT)
 326                 ka->sa.sa_handler = SIG_DFL;
 327
 328         if (!(ka->sa.sa_flags & SA_NODEFER)) {
 329                 spin_lock_irq(&current->sighand->siglock);
 330                 sigorsets(&current->blocked,
 331                                 &current->blocked, &ka->sa.sa_mask);
 332                 sigaddset(&current->blocked, sig);
 333                 recalc_sigpending();
 334                 spin_unlock_irq(&current->sighand->siglock);
 335         }
 336         return 1;
 337 }
 338
 339 /*
 340  * Note that 'init' is a special process: it doesn't get signals it doesn't
 341  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 342  * mistake.
 343  *
 344  * Note that we go through the signals twice: once to check the signals that
 345  * the kernel can handle, and then we build all the user-level signal handling
 346  * stack-frames in one go after that.
 347  */
 348 int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_syscall)
 349 {
 350         siginfo_t info;
 351         int signr;
 352         struct k_sigaction ka;
 353 #ifdef DEBUG_SIG
 354         printk(KERN_INFO "do signal: %p %p %d\n", regs, oldset, in_syscall);
 355         printk(KERN_INFO "do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1,
 356                         regs->r12, current_thread_info()->flags);
 357 #endif
 358         /*
 359          * We want the common case to go fast, which
 360          * is why we may in certain cases get here from
 361          * kernel mode. Just return without doing anything
 362          * if so.
 363          */
 364         if (kernel_mode(regs))
 365                 return 1;
 366
 367         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 368                 oldset = &current->saved_sigmask;
 369         else
 370                 oldset = &current->blocked;
 371
 372         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 373         if (signr > 0) {
 374                 /* Whee! Actually deliver the signal. */
 375                 if (in_syscall)
 376                         handle_restart(regs, &ka, 1);
 377                 if (handle_signal(signr, &ka, &info, oldset, regs)) {
 378                         /*
 379                          * A signal was successfully delivered; the saved
 380                          * sigmask will have been stored in the signal frame,
 381                          * and will be restored by sigreturn, so we can simply
 382                          * clear the TS_RESTORE_SIGMASK flag.
 383                          */
 384                         current_thread_info()->status &=
 385                             ~TS_RESTORE_SIGMASK;
 386                 }
 387                 return 1;
 388         }
 389
 390         if (in_syscall)
 391                 handle_restart(regs, NULL, 0);
 392
 393         /*
 394          * If there's no signal to deliver, we just put the saved sigmask
 395          * back.
 396          */
 397         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 398                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 399                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 400         }
 401
 402         /* Did we come from a system call? */
 403         return 0;
 404 }