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