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 <linux/tracehook.h>
  35 #include <asm/entry.h>
  36 #include <asm/ucontext.h>
  37 #include <linux/uaccess.h>
  38 #include <asm/pgtable.h>
  39 #include <asm/pgalloc.h>
  40 #include <linux/syscalls.h>
  41 #include <asm/cacheflush.h>
  42 #include <asm/syscalls.h>
  43
  44 /*
  45  * Do a signal return; undo the signal stack.
  46  */
  47 struct sigframe {
  48         struct sigcontext sc;
  49         unsigned long extramask[_NSIG_WORDS-1];
  50         unsigned long tramp[2]; /* signal trampoline */
  51 };
  52
  53 struct rt_sigframe {
  54         struct siginfo info;
  55         struct ucontext uc;
  56         unsigned long tramp[2]; /* signal trampoline */
  57 };
  58
  59 static int restore_sigcontext(struct pt_regs *regs,
  60                                 struct sigcontext __user *sc, int *rval_p)
  61 {
  62         unsigned int err = 0;
  63
  64 #define COPY(x)         {err |= __get_user(regs->x, &sc->regs.x); }
  65         COPY(r0);
  66         COPY(r1);
  67         COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
  68         COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
  69         COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
  70         COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
  71         COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
  72         COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
  73         COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
  74         COPY(r30);      COPY(r31);
  75         COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
  76 #undef COPY
  77
  78         *rval_p = regs->r3;
  79
  80         return err;
  81 }
  82
  83 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
  84 {
  85         struct rt_sigframe __user *frame =
  86                 (struct rt_sigframe __user *)(regs->r1);
  87
  88         sigset_t set;
  89         int rval;
  90
  91         /* Always make any pending restarted system calls return -EINTR */
  92         current->restart_block.fn = do_no_restart_syscall;
  93
  94         if (!access_ok(frame, sizeof(*frame)))
  95                 goto badframe;
  96
  97         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  98                 goto badframe;
  99
 100         set_current_blocked(&set);
 101
 102         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval))
 103                 goto badframe;
 104
 105         if (restore_altstack(&frame->uc.uc_stack))
 106                 goto badframe;
 107
 108         return rval;
 109
 110 badframe:
 111         force_sig(SIGSEGV);
 112         return 0;
 113 }
 114
 115 /*
 116  * Set up a signal frame.
 117  */
 118
 119 static int
 120 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 121                 unsigned long mask)
 122 {
 123         int err = 0;
 124
 125 #define COPY(x)         {err |= __put_user(regs->x, &sc->regs.x); }
 126         COPY(r0);
 127         COPY(r1);
 128         COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
 129         COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
 130         COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
 131         COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
 132         COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
 133         COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
 134         COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
 135         COPY(r30);      COPY(r31);
 136         COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
 137 #undef COPY
 138
 139         err |= __put_user(mask, &sc->oldmask);
 140
 141         return err;
 142 }
 143
 144 /*
 145  * Determine which stack to use..
 146  */
 147 static inline void __user *
 148 get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t frame_size)
 149 {
 150         /* Default to using normal stack */
 151         unsigned long sp = sigsp(regs->r1, ksig);
 152
 153         return (void __user *)((sp - frame_size) & -8UL);
 154 }
 155
 156 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 157                           struct pt_regs *regs)
 158 {
 159         struct rt_sigframe __user *frame;
 160         int err = 0, sig = ksig->sig;
 161         unsigned long address = 0;
 162 #ifdef CONFIG_MMU
 163         pgd_t *pgdp;
 164         p4d_t *p4dp;
 165         pud_t *pudp;
 166         pmd_t *pmdp;
 167         pte_t *ptep;
 168 #endif
 169
 170         frame = get_sigframe(ksig, regs, sizeof(*frame));
 171
 172         if (!access_ok(frame, sizeof(*frame)))
 173                 return -EFAULT;
 174
 175         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 176                 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 177
 178         /* Create the ucontext. */
 179         err |= __put_user(0, &frame->uc.uc_flags);
 180         err |= __put_user(NULL, &frame->uc.uc_link);
 181         err |= __save_altstack(&frame->uc.uc_stack, regs->r1);
 182         err |= setup_sigcontext(&frame->uc.uc_mcontext,
 183                         regs, set->sig[0]);
 184         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 185
 186         /* Set up to return from userspace. If provided, use a stub
 187          already in userspace. */
 188         /* minus 8 is offset to cater for "rtsd r15,8" */
 189         /* addi r12, r0, __NR_sigreturn */
 190         err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
 191                         frame->tramp + 0);
 192         /* brki r14, 0x8 */
 193         err |= __put_user(0xb9cc0008, frame->tramp + 1);
 194
 195         /* Return from sighandler will jump to the tramp.
 196          Negative 8 offset because return is rtsd r15, 8 */
 197         regs->r15 = ((unsigned long)frame->tramp)-8;
 198
 199         address = ((unsigned long)frame->tramp);
 200 #ifdef CONFIG_MMU
 201         pgdp = pgd_offset(current->mm, address);
 202         p4dp = p4d_offset(pgdp, address);
 203         pudp = pud_offset(p4dp, address);
 204         pmdp = pmd_offset(pudp, address);
 205
 206         preempt_disable();
 207         ptep = pte_offset_map(pmdp, address);
 208         if (pte_present(*ptep)) {
 209                 address = (unsigned long) page_address(pte_page(*ptep));
 210                 /* MS: I need add offset in page */
 211                 address += ((unsigned long)frame->tramp) & ~PAGE_MASK;
 212                 /* MS address is virtual */
 213                 address = __virt_to_phys(address);
 214                 invalidate_icache_range(address, address + 8);
 215                 flush_dcache_range(address, address + 8);
 216         }
 217         pte_unmap(ptep);
 218         preempt_enable();
 219 #else
 220         flush_icache_range(address, address + 8);
 221         flush_dcache_range(address, address + 8);
 222 #endif
 223         if (err)
 224                 return -EFAULT;
 225
 226         /* Set up registers for signal handler */
 227         regs->r1 = (unsigned long) frame;
 228
 229         /* Signal handler args: */
 230         regs->r5 = sig; /* arg 0: signum */
 231         regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */
 232         regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */
 233         /* Offset to handle microblaze rtid r14, 0 */
 234         regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
 235
 236 #ifdef DEBUG_SIG
 237         pr_info("SIG deliver (%s:%d): sp=%p pc=%08lx\n",
 238                 current->comm, current->pid, frame, regs->pc);
 239 #endif
 240
 241         return 0;
 242 }
 243
 244 /* Handle restarting system calls */
 245 static inline void
 246 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 247 {
 248         switch (regs->r3) {
 249         case -ERESTART_RESTARTBLOCK:
 250         case -ERESTARTNOHAND:
 251                 if (!has_handler)
 252                         goto do_restart;
 253                 regs->r3 = -EINTR;
 254                 break;
 255         case -ERESTARTSYS:
 256                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 257                         regs->r3 = -EINTR;
 258                         break;
 259         }
 260         /* fallthrough */
 261         case -ERESTARTNOINTR:
 262 do_restart:
 263                 /* offset of 4 bytes to re-execute trap (brki) instruction */
 264                 regs->pc -= 4;
 265                 break;
 266         }
 267 }
 268
 269 /*
 270  * OK, we're invoking a handler
 271  */
 272
 273 static void
 274 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 275 {
 276         sigset_t *oldset = sigmask_to_save();
 277         int ret;
 278
 279         /* Set up the stack frame */
 280         ret = setup_rt_frame(ksig, oldset, regs);
 281
 282         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 283 }
 284
 285 /*
 286  * Note that 'init' is a special process: it doesn't get signals it doesn't
 287  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 288  * mistake.
 289  *
 290  * Note that we go through the signals twice: once to check the signals that
 291  * the kernel can handle, and then we build all the user-level signal handling
 292  * stack-frames in one go after that.
 293  */
 294 static void do_signal(struct pt_regs *regs, int in_syscall)
 295 {
 296         struct ksignal ksig;
 297
 298 #ifdef DEBUG_SIG
 299         pr_info("do signal: %p %d\n", regs, in_syscall);
 300         pr_info("do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1,
 301                         regs->r12, current_thread_info()->flags);
 302 #endif
 303
 304         if (get_signal(&ksig)) {
 305                 /* Whee! Actually deliver the signal. */
 306                 if (in_syscall)
 307                         handle_restart(regs, &ksig.ka, 1);
 308                 handle_signal(&ksig, regs);
 309                 return;
 310         }
 311
 312         if (in_syscall)
 313                 handle_restart(regs, NULL, 0);
 314
 315         /*
 316          * If there's no signal to deliver, we just put the saved sigmask
 317          * back.
 318          */
 319         restore_saved_sigmask();
 320 }
 321
 322 asmlinkage void do_notify_resume(struct pt_regs *regs, int in_syscall)
 323 {
 324         if (test_thread_flag(TIF_SIGPENDING))
 325                 do_signal(regs, in_syscall);
 326
 327         if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
 328                 tracehook_notify_resume(regs);
 329 }