arch/parisc/kernel/signal.c

   1 /*
   2  *  linux/arch/parisc/kernel/signal.c: Architecture-specific signal
   3  *  handling support.
   4  *
   5  *  Copyright (C) 2000 David Huggins-Daines <dhd@debian.org>
   6  *  Copyright (C) 2000 Linuxcare, Inc.
   7  *
   8  *  Based on the ia64, i386, and alpha versions.
   9  *
  10  *  Like the IA-64, we are a recent enough port (we are *starting*
  11  *  with glibc2.2) that we do not need to support the old non-realtime
  12  *  Linux signals.  Therefore we don't.  HP/UX signals will go in
  13  *  arch/parisc/hpux/signal.c when we figure out how to do them.
  14  */
  15
  16 #include <linux/sched.h>
  17 #include <linux/mm.h>
  18 #include <linux/smp.h>
  19 #include <linux/kernel.h>
  20 #include <linux/signal.h>
  21 #include <linux/errno.h>
  22 #include <linux/wait.h>
  23 #include <linux/ptrace.h>
  24 #include <linux/tracehook.h>
  25 #include <linux/unistd.h>
  26 #include <linux/stddef.h>
  27 #include <linux/compat.h>
  28 #include <linux/elf.h>
  29 #include <asm/ucontext.h>
  30 #include <asm/rt_sigframe.h>
  31 #include <asm/uaccess.h>
  32 #include <asm/pgalloc.h>
  33 #include <asm/cacheflush.h>
  34 #include <asm/asm-offsets.h>
  35
  36 #ifdef CONFIG_COMPAT
  37 #include "signal32.h"
  38 #endif
  39
  40 #define DEBUG_SIG 0
  41 #define DEBUG_SIG_LEVEL 2
  42
  43 #if DEBUG_SIG
  44 #define DBG(LEVEL, ...) \
  45         ((DEBUG_SIG_LEVEL >= LEVEL) \
  46         ? printk(__VA_ARGS__) : (void) 0)
  47 #else
  48 #define DBG(LEVEL, ...)
  49 #endif
  50
  51 /* gcc will complain if a pointer is cast to an integer of different
  52  * size.  If you really need to do this (and we do for an ELF32 user
  53  * application in an ELF64 kernel) then you have to do a cast to an
  54  * integer of the same size first.  The A() macro accomplishes
  55  * this. */
  56 #define A(__x)  ((unsigned long)(__x))
  57
  58 /*
  59  * Atomically swap in the new signal mask, and wait for a signal.
  60  */
  61 #ifdef CONFIG_64BIT
  62 #include "sys32.h"
  63 #endif
  64
  65 /*
  66  * Do a signal return - restore sigcontext.
  67  */
  68
  69 /* Trampoline for calling rt_sigreturn() */
  70 #define INSN_LDI_R25_0   0x34190000 /* ldi  0,%r25 (in_syscall=0) */
  71 #define INSN_LDI_R25_1   0x34190002 /* ldi  1,%r25 (in_syscall=1) */
  72 #define INSN_LDI_R20     0x3414015a /* ldi  __NR_rt_sigreturn,%r20 */
  73 #define INSN_BLE_SR2_R0  0xe4008200 /* be,l 0x100(%sr2,%r0),%sr0,%r31 */
  74 #define INSN_NOP         0x08000240 /* nop */
  75 /* For debugging */
  76 #define INSN_DIE_HORRIBLY 0x68000ccc /* stw %r0,0x666(%sr0,%r0) */
  77
  78 static long
  79 restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
  80 {
  81         long err = 0;
  82
  83         err |= __copy_from_user(regs->gr, sc->sc_gr, sizeof(regs->gr));
  84         err |= __copy_from_user(regs->fr, sc->sc_fr, sizeof(regs->fr));
  85         err |= __copy_from_user(regs->iaoq, sc->sc_iaoq, sizeof(regs->iaoq));
  86         err |= __copy_from_user(regs->iasq, sc->sc_iasq, sizeof(regs->iasq));
  87         err |= __get_user(regs->sar, &sc->sc_sar);
  88         DBG(2,"restore_sigcontext: iaoq is 0x%#lx / 0x%#lx\n",
  89                         regs->iaoq[0],regs->iaoq[1]);
  90         DBG(2,"restore_sigcontext: r28 is %ld\n", regs->gr[28]);
  91         return err;
  92 }
  93
  94 void
  95 sys_rt_sigreturn(struct pt_regs *regs, int in_syscall)
  96 {
  97         struct rt_sigframe __user *frame;
  98         sigset_t set;
  99         unsigned long usp = (regs->gr[30] & ~(0x01UL));
 100         unsigned long sigframe_size = PARISC_RT_SIGFRAME_SIZE;
 101 #ifdef CONFIG_64BIT
 102         compat_sigset_t compat_set;
 103         struct compat_rt_sigframe __user * compat_frame;
 104
 105         if (is_compat_task())
 106                 sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
 107 #endif
 108
 109         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 110
 111         /* Unwind the user stack to get the rt_sigframe structure. */
 112         frame = (struct rt_sigframe __user *)
 113                 (usp - sigframe_size);
 114         DBG(2,"sys_rt_sigreturn: frame is %p\n", frame);
 115
 116         regs->orig_r28 = 1; /* no restarts for sigreturn */
 117
 118 #ifdef CONFIG_64BIT
 119         compat_frame = (struct compat_rt_sigframe __user *)frame;
 120
 121         if (is_compat_task()) {
 122                 DBG(2,"sys_rt_sigreturn: ELF32 process.\n");
 123                 if (__copy_from_user(&compat_set, &compat_frame->uc.uc_sigmask, sizeof(compat_set)))
 124                         goto give_sigsegv;
 125                 sigset_32to64(&set,&compat_set);
 126         } else
 127 #endif
 128         {
 129                 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 130                         goto give_sigsegv;
 131         }
 132
 133         set_current_blocked(&set);
 134
 135         /* Good thing we saved the old gr[30], eh? */
 136 #ifdef CONFIG_64BIT
 137         if (is_compat_task()) {
 138                 DBG(1,"sys_rt_sigreturn: compat_frame->uc.uc_mcontext 0x%p\n",
 139                                 &compat_frame->uc.uc_mcontext);
 140 // FIXME: Load upper half from register file
 141                 if (restore_sigcontext32(&compat_frame->uc.uc_mcontext,
 142                                         &compat_frame->regs, regs))
 143                         goto give_sigsegv;
 144                 DBG(1,"sys_rt_sigreturn: usp %#08lx stack 0x%p\n",
 145                                 usp, &compat_frame->uc.uc_stack);
 146                 if (do_sigaltstack32(&compat_frame->uc.uc_stack, NULL, usp) == -EFAULT)
 147                         goto give_sigsegv;
 148         } else
 149 #endif
 150         {
 151                 DBG(1,"sys_rt_sigreturn: frame->uc.uc_mcontext 0x%p\n",
 152                                 &frame->uc.uc_mcontext);
 153                 if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
 154                         goto give_sigsegv;
 155                 DBG(1,"sys_rt_sigreturn: usp %#08lx stack 0x%p\n",
 156                                 usp, &frame->uc.uc_stack);
 157                 if (do_sigaltstack(&frame->uc.uc_stack, NULL, usp) == -EFAULT)
 158                         goto give_sigsegv;
 159         }
 160
 161
 162
 163         /* If we are on the syscall path IAOQ will not be restored, and
 164          * if we are on the interrupt path we must not corrupt gr31.
 165          */
 166         if (in_syscall)
 167                 regs->gr[31] = regs->iaoq[0];
 168 #if DEBUG_SIG
 169         DBG(1,"sys_rt_sigreturn: returning to %#lx, DUMPING REGS:\n", regs->iaoq[0]);
 170         show_regs(regs);
 171 #endif
 172         return;
 173
 174 give_sigsegv:
 175         DBG(1,"sys_rt_sigreturn: Sending SIGSEGV\n");
 176         force_sig(SIGSEGV, current);
 177         return;
 178 }
 179
 180 /*
 181  * Set up a signal frame.
 182  */
 183
 184 static inline void __user *
 185 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
 186 {
 187         /*FIXME: ELF32 vs. ELF64 has different frame_size, but since we
 188           don't use the parameter it doesn't matter */
 189
 190         DBG(1,"get_sigframe: ka = %#lx, sp = %#lx, frame_size = %#lx\n",
 191                         (unsigned long)ka, sp, frame_size);
 192
 193         /* Align alternate stack and reserve 64 bytes for the signal
 194            handler's frame marker.  */
 195         if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp))
 196                 sp = (current->sas_ss_sp + 0x7f) & ~0x3f; /* Stacks grow up! */
 197
 198         DBG(1,"get_sigframe: Returning sp = %#lx\n", (unsigned long)sp);
 199         return (void __user *) sp; /* Stacks grow up.  Fun. */
 200 }
 201
 202 static long
 203 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, int in_syscall)
 204
 205 {
 206         unsigned long flags = 0;
 207         long err = 0;
 208
 209         if (on_sig_stack((unsigned long) sc))
 210                 flags |= PARISC_SC_FLAG_ONSTACK;
 211         if (in_syscall) {
 212                 flags |= PARISC_SC_FLAG_IN_SYSCALL;
 213                 /* regs->iaoq is undefined in the syscall return path */
 214                 err |= __put_user(regs->gr[31], &sc->sc_iaoq[0]);
 215                 err |= __put_user(regs->gr[31]+4, &sc->sc_iaoq[1]);
 216                 err |= __put_user(regs->sr[3], &sc->sc_iasq[0]);
 217                 err |= __put_user(regs->sr[3], &sc->sc_iasq[1]);
 218                 DBG(1,"setup_sigcontext: iaoq %#lx / %#lx (in syscall)\n",
 219                         regs->gr[31], regs->gr[31]+4);
 220         } else {
 221                 err |= __copy_to_user(sc->sc_iaoq, regs->iaoq, sizeof(regs->iaoq));
 222                 err |= __copy_to_user(sc->sc_iasq, regs->iasq, sizeof(regs->iasq));
 223                 DBG(1,"setup_sigcontext: iaoq %#lx / %#lx (not in syscall)\n",
 224                         regs->iaoq[0], regs->iaoq[1]);
 225         }
 226
 227         err |= __put_user(flags, &sc->sc_flags);
 228         err |= __copy_to_user(sc->sc_gr, regs->gr, sizeof(regs->gr));
 229         err |= __copy_to_user(sc->sc_fr, regs->fr, sizeof(regs->fr));
 230         err |= __put_user(regs->sar, &sc->sc_sar);
 231         DBG(1,"setup_sigcontext: r28 is %ld\n", regs->gr[28]);
 232
 233         return err;
 234 }
 235
 236 static long
 237 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 238                sigset_t *set, struct pt_regs *regs, int in_syscall)
 239 {
 240         struct rt_sigframe __user *frame;
 241         unsigned long rp, usp;
 242         unsigned long haddr, sigframe_size;
 243         int err = 0;
 244 #ifdef CONFIG_64BIT
 245         compat_int_t compat_val;
 246         struct compat_rt_sigframe __user * compat_frame;
 247         compat_sigset_t compat_set;
 248 #endif
 249
 250         usp = (regs->gr[30] & ~(0x01UL));
 251         /*FIXME: frame_size parameter is unused, remove it. */
 252         frame = get_sigframe(ka, usp, sizeof(*frame));
 253
 254         DBG(1,"SETUP_RT_FRAME: START\n");
 255         DBG(1,"setup_rt_frame: frame %p info %p\n", frame, info);
 256
 257
 258 #ifdef CONFIG_64BIT
 259
 260         compat_frame = (struct compat_rt_sigframe __user *)frame;
 261
 262         if (is_compat_task()) {
 263                 DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &compat_frame->info);
 264                 err |= copy_siginfo_to_user32(&compat_frame->info, info);
 265                 DBG(1,"SETUP_RT_FRAME: 1\n");
 266                 compat_val = (compat_int_t)current->sas_ss_sp;
 267                 err |= __put_user(compat_val, &compat_frame->uc.uc_stack.ss_sp);
 268                 DBG(1,"SETUP_RT_FRAME: 2\n");
 269                 compat_val = (compat_int_t)current->sas_ss_size;
 270                 err |= __put_user(compat_val, &compat_frame->uc.uc_stack.ss_size);
 271                 DBG(1,"SETUP_RT_FRAME: 3\n");
 272                 compat_val = sas_ss_flags(regs->gr[30]);
 273                 err |= __put_user(compat_val, &compat_frame->uc.uc_stack.ss_flags);
 274                 DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &compat_frame->uc);
 275                 DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &compat_frame->uc.uc_mcontext);
 276                 err |= setup_sigcontext32(&compat_frame->uc.uc_mcontext,
 277                                         &compat_frame->regs, regs, in_syscall);
 278                 sigset_64to32(&compat_set,set);
 279                 err |= __copy_to_user(&compat_frame->uc.uc_sigmask, &compat_set, sizeof(compat_set));
 280         } else
 281 #endif
 282         {
 283                 DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &frame->info);
 284                 err |= copy_siginfo_to_user(&frame->info, info);
 285                 err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 286                 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 287                 err |= __put_user(sas_ss_flags(regs->gr[30]),
 288                                   &frame->uc.uc_stack.ss_flags);
 289                 DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &frame->uc);
 290                 DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &frame->uc.uc_mcontext);
 291                 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, in_syscall);
 292                 /* FIXME: Should probably be converted as well for the compat case */
 293                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 294         }
 295
 296         if (err)
 297                 goto give_sigsegv;
 298
 299         /* Set up to return from userspace.  If provided, use a stub
 300            already in userspace. The first words of tramp are used to
 301            save the previous sigrestartblock trampoline that might be
 302            on the stack. We start the sigreturn trampoline at
 303            SIGRESTARTBLOCK_TRAMP+X. */
 304         err |= __put_user(in_syscall ? INSN_LDI_R25_1 : INSN_LDI_R25_0,
 305                         &frame->tramp[SIGRESTARTBLOCK_TRAMP+0]);
 306         err |= __put_user(INSN_LDI_R20,
 307                         &frame->tramp[SIGRESTARTBLOCK_TRAMP+1]);
 308         err |= __put_user(INSN_BLE_SR2_R0,
 309                         &frame->tramp[SIGRESTARTBLOCK_TRAMP+2]);
 310         err |= __put_user(INSN_NOP, &frame->tramp[SIGRESTARTBLOCK_TRAMP+3]);
 311
 312 #if DEBUG_SIG
 313         /* Assert that we're flushing in the correct space... */
 314         {
 315                 int sid;
 316                 asm ("mfsp %%sr3,%0" : "=r" (sid));
 317                 DBG(1,"setup_rt_frame: Flushing 64 bytes at space %#x offset %p\n",
 318                        sid, frame->tramp);
 319         }
 320 #endif
 321
 322         flush_user_dcache_range((unsigned long) &frame->tramp[0],
 323                            (unsigned long) &frame->tramp[TRAMP_SIZE]);
 324         flush_user_icache_range((unsigned long) &frame->tramp[0],
 325                            (unsigned long) &frame->tramp[TRAMP_SIZE]);
 326
 327         /* TRAMP Words 0-4, Length 5 = SIGRESTARTBLOCK_TRAMP
 328          * TRAMP Words 5-9, Length 4 = SIGRETURN_TRAMP
 329          * So the SIGRETURN_TRAMP is at the end of SIGRESTARTBLOCK_TRAMP
 330          */
 331         rp = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP];
 332
 333         if (err)
 334                 goto give_sigsegv;
 335
 336         haddr = A(ka->sa.sa_handler);
 337         /* The sa_handler may be a pointer to a function descriptor */
 338 #ifdef CONFIG_64BIT
 339         if (is_compat_task()) {
 340 #endif
 341                 if (haddr & PA_PLABEL_FDESC) {
 342                         Elf32_Fdesc fdesc;
 343                         Elf32_Fdesc __user *ufdesc = (Elf32_Fdesc __user *)A(haddr & ~3);
 344
 345                         err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
 346
 347                         if (err)
 348                                 goto give_sigsegv;
 349
 350                         haddr = fdesc.addr;
 351                         regs->gr[19] = fdesc.gp;
 352                 }
 353 #ifdef CONFIG_64BIT
 354         } else {
 355                 Elf64_Fdesc fdesc;
 356                 Elf64_Fdesc __user *ufdesc = (Elf64_Fdesc __user *)A(haddr & ~3);
 357
 358                 err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
 359
 360                 if (err)
 361                         goto give_sigsegv;
 362
 363                 haddr = fdesc.addr;
 364                 regs->gr[19] = fdesc.gp;
 365                 DBG(1,"setup_rt_frame: 64 bit signal, exe=%#lx, r19=%#lx, in_syscall=%d\n",
 366                      haddr, regs->gr[19], in_syscall);
 367         }
 368 #endif
 369
 370         /* The syscall return path will create IAOQ values from r31.
 371          */
 372         sigframe_size = PARISC_RT_SIGFRAME_SIZE;
 373 #ifdef CONFIG_64BIT
 374         if (is_compat_task())
 375                 sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
 376 #endif
 377         if (in_syscall) {
 378                 regs->gr[31] = haddr;
 379 #ifdef CONFIG_64BIT
 380                 if (!test_thread_flag(TIF_32BIT))
 381                         sigframe_size |= 1;
 382 #endif
 383         } else {
 384                 unsigned long psw = USER_PSW;
 385 #ifdef CONFIG_64BIT
 386                 if (!test_thread_flag(TIF_32BIT))
 387                         psw |= PSW_W;
 388 #endif
 389
 390                 /* If we are singlestepping, arrange a trap to be delivered
 391                    when we return to userspace. Note the semantics -- we
 392                    should trap before the first insn in the handler is
 393                    executed. Ref:
 394                         http://sources.redhat.com/ml/gdb/2004-11/msg00245.html
 395                  */
 396                 if (pa_psw(current)->r) {
 397                         pa_psw(current)->r = 0;
 398                         psw |= PSW_R;
 399                         mtctl(-1, 0);
 400                 }
 401
 402                 regs->gr[0] = psw;
 403                 regs->iaoq[0] = haddr | 3;
 404                 regs->iaoq[1] = regs->iaoq[0] + 4;
 405         }
 406
 407         regs->gr[2]  = rp;                /* userland return pointer */
 408         regs->gr[26] = sig;               /* signal number */
 409
 410 #ifdef CONFIG_64BIT
 411         if (is_compat_task()) {
 412                 regs->gr[25] = A(&compat_frame->info); /* siginfo pointer */
 413                 regs->gr[24] = A(&compat_frame->uc);   /* ucontext pointer */
 414         } else
 415 #endif
 416         {
 417                 regs->gr[25] = A(&frame->info); /* siginfo pointer */
 418                 regs->gr[24] = A(&frame->uc);   /* ucontext pointer */
 419         }
 420
 421         DBG(1,"setup_rt_frame: making sigreturn frame: %#lx + %#lx = %#lx\n",
 422                regs->gr[30], sigframe_size,
 423                regs->gr[30] + sigframe_size);
 424         /* Raise the user stack pointer to make a proper call frame. */
 425         regs->gr[30] = (A(frame) + sigframe_size);
 426
 427
 428         DBG(1,"setup_rt_frame: sig deliver (%s,%d) frame=0x%p sp=%#lx iaoq=%#lx/%#lx rp=%#lx\n",
 429                current->comm, current->pid, frame, regs->gr[30],
 430                regs->iaoq[0], regs->iaoq[1], rp);
 431
 432         return 1;
 433
 434 give_sigsegv:
 435         DBG(1,"setup_rt_frame: sending SIGSEGV\n");
 436         force_sigsegv(sig, current);
 437         return 0;
 438 }
 439
 440 /*
 441  * OK, we're invoking a handler.
 442  */
 443
 444 static void
 445 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 446                 struct pt_regs *regs, int in_syscall)
 447 {
 448         sigset_t *oldset = sigmask_to_save();
 449         DBG(1,"handle_signal: sig=%ld, ka=%p, info=%p, oldset=%p, regs=%p\n",
 450                sig, ka, info, oldset, regs);
 451
 452         /* Set up the stack frame */
 453         if (!setup_rt_frame(sig, ka, info, oldset, regs, in_syscall))
 454                 return;
 455
 456         signal_delivered(sig, info, ka, regs,
 457                 test_thread_flag(TIF_SINGLESTEP) ||
 458                 test_thread_flag(TIF_BLOCKSTEP));
 459
 460         DBG(1,KERN_DEBUG "do_signal: Exit (success), regs->gr[28] = %ld\n",
 461                 regs->gr[28]);
 462 }
 463
 464 static inline void
 465 syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
 466 {
 467         if (regs->orig_r28)
 468                 return;
 469         regs->orig_r28 = 1; /* no more restarts */
 470         /* Check the return code */
 471         switch (regs->gr[28]) {
 472         case -ERESTART_RESTARTBLOCK:
 473         case -ERESTARTNOHAND:
 474                 DBG(1,"ERESTARTNOHAND: returning -EINTR\n");
 475                 regs->gr[28] = -EINTR;
 476                 break;
 477
 478         case -ERESTARTSYS:
 479                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 480                         DBG(1,"ERESTARTSYS: putting -EINTR\n");
 481                         regs->gr[28] = -EINTR;
 482                         break;
 483                 }
 484                 /* fallthrough */
 485         case -ERESTARTNOINTR:
 486                 /* A syscall is just a branch, so all
 487                  * we have to do is fiddle the return pointer.
 488                  */
 489                 regs->gr[31] -= 8; /* delayed branching */
 490                 break;
 491         }
 492 }
 493
 494 static inline void
 495 insert_restart_trampoline(struct pt_regs *regs)
 496 {
 497         if (regs->orig_r28)
 498                 return;
 499         regs->orig_r28 = 1; /* no more restarts */
 500         switch(regs->gr[28]) {
 501         case -ERESTART_RESTARTBLOCK: {
 502                 /* Restart the system call - no handlers present */
 503                 unsigned int *usp = (unsigned int *)regs->gr[30];
 504
 505                 /* Setup a trampoline to restart the syscall
 506                  * with __NR_restart_syscall
 507                  *
 508                  *  0: <return address (orig r31)>
 509                  *  4: <2nd half for 64-bit>
 510                  *  8: ldw 0(%sp), %r31
 511                  * 12: be 0x100(%sr2, %r0)
 512                  * 16: ldi __NR_restart_syscall, %r20
 513                  */
 514 #ifdef CONFIG_64BIT
 515                 put_user(regs->gr[31] >> 32, &usp[0]);
 516                 put_user(regs->gr[31] & 0xffffffff, &usp[1]);
 517                 put_user(0x0fc010df, &usp[2]);
 518 #else
 519                 put_user(regs->gr[31], &usp[0]);
 520                 put_user(0x0fc0109f, &usp[2]);
 521 #endif
 522                 put_user(0xe0008200, &usp[3]);
 523                 put_user(0x34140000, &usp[4]);
 524
 525                 /* Stack is 64-byte aligned, and we only need
 526                  * to flush 1 cache line.
 527                  * Flushing one cacheline is cheap.
 528                  * "sync" on bigger (> 4 way) boxes is not.
 529                  */
 530                 flush_user_dcache_range(regs->gr[30], regs->gr[30] + 4);
 531                 flush_user_icache_range(regs->gr[30], regs->gr[30] + 4);
 532
 533                 regs->gr[31] = regs->gr[30] + 8;
 534                 return;
 535         }
 536         case -ERESTARTNOHAND:
 537         case -ERESTARTSYS:
 538         case -ERESTARTNOINTR: {
 539                 /* Hooray for delayed branching.  We don't
 540                  * have to restore %r20 (the system call
 541                  * number) because it gets loaded in the delay
 542                  * slot of the branch external instruction.
 543                  */
 544                 regs->gr[31] -= 8;
 545                 return;
 546         }
 547         default:
 548                 break;
 549         }
 550 }
 551
 552 /*
 553  * Note that 'init' is a special process: it doesn't get signals it doesn't
 554  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 555  * mistake.
 556  *
 557  * We need to be able to restore the syscall arguments (r21-r26) to
 558  * restart syscalls.  Thus, the syscall path should save them in the
 559  * pt_regs structure (it's okay to do so since they are caller-save
 560  * registers).  As noted below, the syscall number gets restored for
 561  * us due to the magic of delayed branching.
 562  */
 563 asmlinkage void
 564 do_signal(struct pt_regs *regs, long in_syscall)
 565 {
 566         siginfo_t info;
 567         struct k_sigaction ka;
 568         int signr;
 569
 570         DBG(1,"\ndo_signal: regs=0x%p, sr7 %#lx, in_syscall=%d\n",
 571                regs, regs->sr[7], in_syscall);
 572
 573         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 574         DBG(3,"do_signal: signr = %d, regs->gr[28] = %ld\n", signr, regs->gr[28]);
 575
 576         if (signr > 0) {
 577                 /* Restart a system call if necessary. */
 578                 if (in_syscall)
 579                         syscall_restart(regs, &ka);
 580
 581                 handle_signal(signr, &info, &ka, regs, in_syscall);
 582                 return;
 583         }
 584
 585         /* Did we come from a system call? */
 586         if (in_syscall)
 587                 insert_restart_trampoline(regs);
 588
 589         DBG(1,"do_signal: Exit (not delivered), regs->gr[28] = %ld\n",
 590                 regs->gr[28]);
 591
 592         restore_saved_sigmask();
 593 }
 594
 595 void do_notify_resume(struct pt_regs *regs, long in_syscall)
 596 {
 597         if (test_thread_flag(TIF_SIGPENDING))
 598                 do_signal(regs, in_syscall);
 599
 600         if (test_thread_flag(TIF_NOTIFY_RESUME)) {
 601                 clear_thread_flag(TIF_NOTIFY_RESUME);
 602                 tracehook_notify_resume(regs);
 603         }
 604 }