git.oblomov.eu Git - linux-2.6/blob - 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/smp_lock.h>
  20 #include <linux/kernel.h>
  21 #include <linux/signal.h>
  22 #include <linux/errno.h>
  23 #include <linux/wait.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/unistd.h>
  26 #include <linux/stddef.h>
  27 #include <linux/compat.h>
  28 #include <linux/elf.h>
  29 #include <linux/personality.h>
  30 #include <asm/ucontext.h>
  31 #include <asm/rt_sigframe.h>
  32 #include <asm/uaccess.h>
  33 #include <asm/pgalloc.h>
  34 #include <asm/cacheflush.h>
  35 #include <asm/asm-offsets.h>
  36
  37 #ifdef CONFIG_COMPAT
  38 #include <linux/compat.h>
  39 #include "signal32.h"
  40 #endif
  41
  42 #define DEBUG_SIG 0
  43 #define DEBUG_SIG_LEVEL 2
  44
  45 #if DEBUG_SIG
  46 #define DBG(LEVEL, ...) \
  47         ((DEBUG_SIG_LEVEL >= LEVEL) \
  48         ? printk(__VA_ARGS__) : (void) 0)
  49 #else
  50 #define DBG(LEVEL, ...)
  51 #endif
  52
  53
  54 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  55
  56 /* gcc will complain if a pointer is cast to an integer of different
  57  * size.  If you really need to do this (and we do for an ELF32 user
  58  * application in an ELF64 kernel) then you have to do a cast to an
  59  * integer of the same size first.  The A() macro accomplishes
  60  * this. */
  61 #define A(__x)  ((unsigned long)(__x))
  62
  63 int do_signal(sigset_t *oldset, struct pt_regs *regs, int in_syscall);
  64
  65 /*
  66  * Atomically swap in the new signal mask, and wait for a signal.
  67  */
  68 #ifdef __LP64__
  69 #include "sys32.h"
  70 #endif
  71
  72 asmlinkage int
  73 sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
  74 {
  75         sigset_t saveset, newset;
  76 #ifdef __LP64__
  77         compat_sigset_t newset32;
  78
  79         if(personality(current->personality) == PER_LINUX32){
  80                 /* XXX: Don't preclude handling different sized sigset_t's.  */
  81                 if (sigsetsize != sizeof(compat_sigset_t))
  82                         return -EINVAL;
  83                 if (copy_from_user(&newset32, (compat_sigset_t __user *)unewset, sizeof(newset32)))
  84                         return -EFAULT;
  85                 sigset_32to64(&newset,&newset32);
  86
  87         } else
  88 #endif
  89         {
  90                 /* XXX: Don't preclude handling different sized sigset_t's.  */
  91                 if (sigsetsize != sizeof(sigset_t))
  92                         return -EINVAL;
  93
  94                 if (copy_from_user(&newset, unewset, sizeof(newset)))
  95                         return -EFAULT;
  96         }
  97
  98         sigdelsetmask(&newset, ~_BLOCKABLE);
  99
 100         spin_lock_irq(&current->sighand->siglock);
 101         saveset = current->blocked;
 102         current->blocked = newset;
 103         recalc_sigpending();
 104         spin_unlock_irq(&current->sighand->siglock);
 105
 106         regs->gr[28] = -EINTR;
 107         while (1) {
 108                 current->state = TASK_INTERRUPTIBLE;
 109                 schedule();
 110                 if (do_signal(&saveset, regs, 1))
 111                         return -EINTR;
 112         }
 113 }
 114
 115 /*
 116  * Do a signal return - restore sigcontext.
 117  */
 118
 119 /* Trampoline for calling rt_sigreturn() */
 120 #define INSN_LDI_R25_0   0x34190000 /* ldi  0,%r25 (in_syscall=0) */
 121 #define INSN_LDI_R25_1   0x34190002 /* ldi  1,%r25 (in_syscall=1) */
 122 #define INSN_LDI_R20     0x3414015a /* ldi  __NR_rt_sigreturn,%r20 */
 123 #define INSN_BLE_SR2_R0  0xe4008200 /* be,l 0x100(%sr2,%r0),%sr0,%r31 */
 124 #define INSN_NOP         0x08000240 /* nop */
 125 /* For debugging */
 126 #define INSN_DIE_HORRIBLY 0x68000ccc /* stw %r0,0x666(%sr0,%r0) */
 127
 128 static long
 129 restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 130 {
 131         long err = 0;
 132
 133         err |= __copy_from_user(regs->gr, sc->sc_gr, sizeof(regs->gr));
 134         err |= __copy_from_user(regs->fr, sc->sc_fr, sizeof(regs->fr));
 135         err |= __copy_from_user(regs->iaoq, sc->sc_iaoq, sizeof(regs->iaoq));
 136         err |= __copy_from_user(regs->iasq, sc->sc_iasq, sizeof(regs->iasq));
 137         err |= __get_user(regs->sar, &sc->sc_sar);
 138         DBG(2,"restore_sigcontext: iaoq is 0x%#lx / 0x%#lx\n",
 139                         regs->iaoq[0],regs->iaoq[1]);
 140         DBG(2,"restore_sigcontext: r28 is %ld\n", regs->gr[28]);
 141         return err;
 142 }
 143
 144 void
 145 sys_rt_sigreturn(struct pt_regs *regs, int in_syscall)
 146 {
 147         struct rt_sigframe __user *frame;
 148         struct siginfo si;
 149         sigset_t set;
 150         unsigned long usp = (regs->gr[30] & ~(0x01UL));
 151         unsigned long sigframe_size = PARISC_RT_SIGFRAME_SIZE;
 152 #ifdef __LP64__
 153         compat_sigset_t compat_set;
 154         struct compat_rt_sigframe __user * compat_frame;
 155
 156         if(personality(current->personality) == PER_LINUX32)
 157                 sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
 158 #endif
 159
 160
 161         /* Unwind the user stack to get the rt_sigframe structure. */
 162         frame = (struct rt_sigframe __user *)
 163                 (usp - sigframe_size);
 164         DBG(2,"sys_rt_sigreturn: frame is %p\n", frame);
 165
 166 #ifdef __LP64__
 167         compat_frame = (struct compat_rt_sigframe __user *)frame;
 168
 169         if(personality(current->personality) == PER_LINUX32){
 170                 DBG(2,"sys_rt_sigreturn: ELF32 process.\n");
 171                 if (__copy_from_user(&compat_set, &compat_frame->uc.uc_sigmask, sizeof(compat_set)))
 172                         goto give_sigsegv;
 173                 sigset_32to64(&set,&compat_set);
 174         } else
 175 #endif
 176         {
 177                 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 178                         goto give_sigsegv;
 179         }
 180
 181         sigdelsetmask(&set, ~_BLOCKABLE);
 182         spin_lock_irq(&current->sighand->siglock);
 183         current->blocked = set;
 184         recalc_sigpending();
 185         spin_unlock_irq(&current->sighand->siglock);
 186
 187         /* Good thing we saved the old gr[30], eh? */
 188 #ifdef __LP64__
 189         if(personality(current->personality) == PER_LINUX32){
 190                 DBG(1,"sys_rt_sigreturn: compat_frame->uc.uc_mcontext 0x%p\n",
 191                                 &compat_frame->uc.uc_mcontext);
 192 // FIXME: Load upper half from register file
 193                 if (restore_sigcontext32(&compat_frame->uc.uc_mcontext,
 194                                         &compat_frame->regs, regs))
 195                         goto give_sigsegv;
 196                 DBG(1,"sys_rt_sigreturn: usp %#08lx stack 0x%p\n",
 197                                 usp, &compat_frame->uc.uc_stack);
 198                 if (do_sigaltstack32(&compat_frame->uc.uc_stack, NULL, usp) == -EFAULT)
 199                         goto give_sigsegv;
 200         } else
 201 #endif
 202         {
 203                 DBG(1,"sys_rt_sigreturn: frame->uc.uc_mcontext 0x%p\n",
 204                                 &frame->uc.uc_mcontext);
 205                 if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
 206                         goto give_sigsegv;
 207                 DBG(1,"sys_rt_sigreturn: usp %#08lx stack 0x%p\n",
 208                                 usp, &frame->uc.uc_stack);
 209                 if (do_sigaltstack(&frame->uc.uc_stack, NULL, usp) == -EFAULT)
 210                         goto give_sigsegv;
 211         }
 212
 213
 214
 215         /* If we are on the syscall path IAOQ will not be restored, and
 216          * if we are on the interrupt path we must not corrupt gr31.
 217          */
 218         if (in_syscall)
 219                 regs->gr[31] = regs->iaoq[0];
 220 #if DEBUG_SIG
 221         DBG(1,"sys_rt_sigreturn: returning to %#lx, DUMPING REGS:\n", regs->iaoq[0]);
 222         show_regs(regs);
 223 #endif
 224         return;
 225
 226 give_sigsegv:
 227         DBG(1,"sys_rt_sigreturn: Sending SIGSEGV\n");
 228         si.si_signo = SIGSEGV;
 229         si.si_errno = 0;
 230         si.si_code = SI_KERNEL;
 231         si.si_pid = current->pid;
 232         si.si_uid = current->uid;
 233         si.si_addr = &frame->uc;
 234         force_sig_info(SIGSEGV, &si, current);
 235         return;
 236 }
 237
 238 /*
 239  * Set up a signal frame.
 240  */
 241
 242 static inline void __user *
 243 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
 244 {
 245         /*FIXME: ELF32 vs. ELF64 has different frame_size, but since we
 246           don't use the parameter it doesn't matter */
 247
 248         DBG(1,"get_sigframe: ka = %#lx, sp = %#lx, frame_size = %#lx\n",
 249                         (unsigned long)ka, sp, frame_size);
 250
 251         if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp))
 252                 sp = current->sas_ss_sp; /* Stacks grow up! */
 253
 254         DBG(1,"get_sigframe: Returning sp = %#lx\n", (unsigned long)sp);
 255         return (void __user *) sp; /* Stacks grow up.  Fun. */
 256 }
 257
 258 static long
 259 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, int in_syscall)
 260
 261 {
 262         unsigned long flags = 0;
 263         long err = 0;
 264
 265         if (on_sig_stack((unsigned long) sc))
 266                 flags |= PARISC_SC_FLAG_ONSTACK;
 267         if (in_syscall) {
 268                 flags |= PARISC_SC_FLAG_IN_SYSCALL;
 269                 /* regs->iaoq is undefined in the syscall return path */
 270                 err |= __put_user(regs->gr[31], &sc->sc_iaoq[0]);
 271                 err |= __put_user(regs->gr[31]+4, &sc->sc_iaoq[1]);
 272                 err |= __put_user(regs->sr[3], &sc->sc_iasq[0]);
 273                 err |= __put_user(regs->sr[3], &sc->sc_iasq[1]);
 274                 DBG(1,"setup_sigcontext: iaoq %#lx / %#lx (in syscall)\n",
 275                         regs->gr[31], regs->gr[31]+4);
 276         } else {
 277                 err |= __copy_to_user(sc->sc_iaoq, regs->iaoq, sizeof(regs->iaoq));
 278                 err |= __copy_to_user(sc->sc_iasq, regs->iasq, sizeof(regs->iasq));
 279                 DBG(1,"setup_sigcontext: iaoq %#lx / %#lx (not in syscall)\n",
 280                         regs->iaoq[0], regs->iaoq[1]);
 281         }
 282
 283         err |= __put_user(flags, &sc->sc_flags);
 284         err |= __copy_to_user(sc->sc_gr, regs->gr, sizeof(regs->gr));
 285         err |= __copy_to_user(sc->sc_fr, regs->fr, sizeof(regs->fr));
 286         err |= __put_user(regs->sar, &sc->sc_sar);
 287         DBG(1,"setup_sigcontext: r28 is %ld\n", regs->gr[28]);
 288
 289         return err;
 290 }
 291
 292 static long
 293 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 294                sigset_t *set, struct pt_regs *regs, int in_syscall)
 295 {
 296         struct rt_sigframe __user *frame;
 297         unsigned long rp, usp;
 298         unsigned long haddr, sigframe_size;
 299         int err = 0;
 300 #ifdef __LP64__
 301         compat_int_t compat_val;
 302         struct compat_rt_sigframe __user * compat_frame;
 303         compat_sigset_t compat_set;
 304 #endif
 305
 306         usp = (regs->gr[30] & ~(0x01UL));
 307         /*FIXME: frame_size parameter is unused, remove it. */
 308         frame = get_sigframe(ka, usp, sizeof(*frame));
 309
 310         DBG(1,"SETUP_RT_FRAME: START\n");
 311         DBG(1,"setup_rt_frame: frame %p info %p\n", frame, info);
 312
 313
 314 #ifdef __LP64__
 315
 316         compat_frame = (struct compat_rt_sigframe __user *)frame;
 317
 318         if(personality(current->personality) == PER_LINUX32) {
 319                 DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &compat_frame->info);
 320                 err |= copy_siginfo_to_user32(&compat_frame->info, info);
 321                 DBG(1,"SETUP_RT_FRAME: 1\n");
 322                 compat_val = (compat_int_t)current->sas_ss_sp;
 323                 err |= __put_user(compat_val, &compat_frame->uc.uc_stack.ss_sp);
 324                 DBG(1,"SETUP_RT_FRAME: 2\n");
 325                 compat_val = (compat_int_t)current->sas_ss_size;
 326                 err |= __put_user(compat_val, &compat_frame->uc.uc_stack.ss_size);
 327                 DBG(1,"SETUP_RT_FRAME: 3\n");
 328                 compat_val = sas_ss_flags(regs->gr[30]);
 329                 err |= __put_user(compat_val, &compat_frame->uc.uc_stack.ss_flags);
 330                 DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &compat_frame->uc);
 331                 DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &compat_frame->uc.uc_mcontext);
 332                 err |= setup_sigcontext32(&compat_frame->uc.uc_mcontext,
 333                                         &compat_frame->regs, regs, in_syscall);
 334                 sigset_64to32(&compat_set,set);
 335                 err |= __copy_to_user(&compat_frame->uc.uc_sigmask, &compat_set, sizeof(compat_set));
 336         } else
 337 #endif
 338         {
 339                 DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &frame->info);
 340                 err |= copy_siginfo_to_user(&frame->info, info);
 341                 err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 342                 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 343                 err |= __put_user(sas_ss_flags(regs->gr[30]),
 344                                   &frame->uc.uc_stack.ss_flags);
 345                 DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &frame->uc);
 346                 DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &frame->uc.uc_mcontext);
 347                 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, in_syscall);
 348                 /* FIXME: Should probably be converted aswell for the compat case */
 349                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 350         }
 351
 352         if (err)
 353                 goto give_sigsegv;
 354
 355         /* Set up to return from userspace.  If provided, use a stub
 356            already in userspace. The first words of tramp are used to
 357            save the previous sigrestartblock trampoline that might be
 358            on the stack. We start the sigreturn trampoline at
 359            SIGRESTARTBLOCK_TRAMP+X. */
 360         err |= __put_user(in_syscall ? INSN_LDI_R25_1 : INSN_LDI_R25_0,
 361                         &frame->tramp[SIGRESTARTBLOCK_TRAMP+0]);
 362         err |= __put_user(INSN_LDI_R20,
 363                         &frame->tramp[SIGRESTARTBLOCK_TRAMP+1]);
 364         err |= __put_user(INSN_BLE_SR2_R0,
 365                         &frame->tramp[SIGRESTARTBLOCK_TRAMP+2]);
 366         err |= __put_user(INSN_NOP, &frame->tramp[SIGRESTARTBLOCK_TRAMP+3]);
 367
 368 #if DEBUG_SIG
 369         /* Assert that we're flushing in the correct space... */
 370         {
 371                 int sid;
 372                 asm ("mfsp %%sr3,%0" : "=r" (sid));
 373                 DBG(1,"setup_rt_frame: Flushing 64 bytes at space %#x offset %p\n",
 374                        sid, frame->tramp);
 375         }
 376 #endif
 377
 378         flush_user_dcache_range((unsigned long) &frame->tramp[0],
 379                            (unsigned long) &frame->tramp[TRAMP_SIZE]);
 380         flush_user_icache_range((unsigned long) &frame->tramp[0],
 381                            (unsigned long) &frame->tramp[TRAMP_SIZE]);
 382
 383         /* TRAMP Words 0-4, Lenght 5 = SIGRESTARTBLOCK_TRAMP
 384          * TRAMP Words 5-9, Length 4 = SIGRETURN_TRAMP
 385          * So the SIGRETURN_TRAMP is at the end of SIGRESTARTBLOCK_TRAMP
 386          */
 387         rp = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP];
 388
 389         if (err)
 390                 goto give_sigsegv;
 391
 392         haddr = A(ka->sa.sa_handler);
 393         /* The sa_handler may be a pointer to a function descriptor */
 394 #ifdef __LP64__
 395         if(personality(current->personality) == PER_LINUX32) {
 396 #endif
 397                 if (haddr & PA_PLABEL_FDESC) {
 398                         Elf32_Fdesc fdesc;
 399                         Elf32_Fdesc __user *ufdesc = (Elf32_Fdesc __user *)A(haddr & ~3);
 400
 401                         err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
 402
 403                         if (err)
 404                                 goto give_sigsegv;
 405
 406                         haddr = fdesc.addr;
 407                         regs->gr[19] = fdesc.gp;
 408                 }
 409 #ifdef __LP64__
 410         } else {
 411                 Elf64_Fdesc fdesc;
 412                 Elf64_Fdesc __user *ufdesc = (Elf64_Fdesc __user *)A(haddr & ~3);
 413
 414                 err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
 415
 416                 if (err)
 417                         goto give_sigsegv;
 418
 419                 haddr = fdesc.addr;
 420                 regs->gr[19] = fdesc.gp;
 421                 DBG(1,"setup_rt_frame: 64 bit signal, exe=%#lx, r19=%#lx, in_syscall=%d\n",
 422                      haddr, regs->gr[19], in_syscall);
 423         }
 424 #endif
 425
 426         /* The syscall return path will create IAOQ values from r31.
 427          */
 428         sigframe_size = PARISC_RT_SIGFRAME_SIZE;
 429 #ifdef __LP64__
 430         if(personality(current->personality) == PER_LINUX32)
 431                 sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
 432 #endif
 433         if (in_syscall) {
 434                 regs->gr[31] = haddr;
 435 #ifdef __LP64__
 436                 if(personality(current->personality) == PER_LINUX)
 437                         sigframe_size |= 1;
 438 #endif
 439         } else {
 440                 unsigned long psw = USER_PSW;
 441 #ifdef __LP64__
 442                 if(personality(current->personality) == PER_LINUX)
 443                         psw |= PSW_W;
 444 #endif
 445
 446                 /* If we are singlestepping, arrange a trap to be delivered
 447                    when we return to userspace. Note the semantics -- we
 448                    should trap before the first insn in the handler is
 449                    executed. Ref:
 450                         http://sources.redhat.com/ml/gdb/2004-11/msg00245.html
 451                  */
 452                 if (pa_psw(current)->r) {
 453                         pa_psw(current)->r = 0;
 454                         psw |= PSW_R;
 455                         mtctl(-1, 0);
 456                 }
 457
 458                 regs->gr[0] = psw;
 459                 regs->iaoq[0] = haddr | 3;
 460                 regs->iaoq[1] = regs->iaoq[0] + 4;
 461         }
 462
 463         regs->gr[2]  = rp;                /* userland return pointer */
 464         regs->gr[26] = sig;               /* signal number */
 465
 466 #ifdef __LP64__
 467         if(personality(current->personality) == PER_LINUX32){
 468                 regs->gr[25] = A(&compat_frame->info); /* siginfo pointer */
 469                 regs->gr[24] = A(&compat_frame->uc);   /* ucontext pointer */
 470         } else
 471 #endif
 472         {
 473                 regs->gr[25] = A(&frame->info); /* siginfo pointer */
 474                 regs->gr[24] = A(&frame->uc);   /* ucontext pointer */
 475         }
 476
 477         DBG(1,"setup_rt_frame: making sigreturn frame: %#lx + %#lx = %#lx\n",
 478                regs->gr[30], sigframe_size,
 479                regs->gr[30] + sigframe_size);
 480         /* Raise the user stack pointer to make a proper call frame. */
 481         regs->gr[30] = (A(frame) + sigframe_size);
 482
 483
 484         DBG(1,"setup_rt_frame: sig deliver (%s,%d) frame=0x%p sp=%#lx iaoq=%#lx/%#lx rp=%#lx\n",
 485                current->comm, current->pid, frame, regs->gr[30],
 486                regs->iaoq[0], regs->iaoq[1], rp);
 487
 488         return 1;
 489
 490 give_sigsegv:
 491         DBG(1,"setup_rt_frame: sending SIGSEGV\n");
 492         force_sigsegv(sig, current);
 493         return 0;
 494 }
 495
 496 /*
 497  * OK, we're invoking a handler.
 498  */
 499
 500 static long
 501 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 502                 sigset_t *oldset, struct pt_regs *regs, int in_syscall)
 503 {
 504         DBG(1,"handle_signal: sig=%ld, ka=%p, info=%p, oldset=%p, regs=%p\n",
 505                sig, ka, info, oldset, regs);
 506
 507         /* Set up the stack frame */
 508         if (!setup_rt_frame(sig, ka, info, oldset, regs, in_syscall))
 509                 return 0;
 510
 511         spin_lock_irq(&current->sighand->siglock);
 512         sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 513         if (!(ka->sa.sa_flags & SA_NODEFER))
 514                 sigaddset(&current->blocked,sig);
 515         recalc_sigpending();
 516         spin_unlock_irq(&current->sighand->siglock);
 517         return 1;
 518 }
 519
 520 /*
 521  * Note that 'init' is a special process: it doesn't get signals it doesn't
 522  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 523  * mistake.
 524  *
 525  * We need to be able to restore the syscall arguments (r21-r26) to
 526  * restart syscalls.  Thus, the syscall path should save them in the
 527  * pt_regs structure (it's okay to do so since they are caller-save
 528  * registers).  As noted below, the syscall number gets restored for
 529  * us due to the magic of delayed branching.
 530  */
 531
 532 asmlinkage int
 533 do_signal(sigset_t *oldset, struct pt_regs *regs, int in_syscall)
 534 {
 535         siginfo_t info;
 536         struct k_sigaction ka;
 537         int signr;
 538
 539         DBG(1,"\ndo_signal: oldset=0x%p, regs=0x%p, sr7 %#lx, in_syscall=%d\n",
 540                oldset, regs, regs->sr[7], in_syscall);
 541
 542         /* Everyone else checks to see if they are in kernel mode at
 543            this point and exits if that's the case.  I'm not sure why
 544            we would be called in that case, but for some reason we
 545            are. */
 546
 547         if (!oldset)
 548                 oldset = &current->blocked;
 549
 550         DBG(1,"do_signal: oldset %08lx / %08lx\n",
 551                 oldset->sig[0], oldset->sig[1]);
 552
 553
 554         /* May need to force signal if handle_signal failed to deliver */
 555         while (1) {
 556
 557                 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 558                 DBG(3,"do_signal: signr = %d, regs->gr[28] = %ld\n", signr, regs->gr[28]);
 559
 560                 if (signr <= 0)
 561                   break;
 562
 563                 /* Restart a system call if necessary. */
 564                 if (in_syscall) {
 565                         /* Check the return code */
 566                         switch (regs->gr[28]) {
 567                         case -ERESTART_RESTARTBLOCK:
 568                                 current_thread_info()->restart_block.fn = do_no_restart_syscall;
 569                         case -ERESTARTNOHAND:
 570                                 DBG(1,"ERESTARTNOHAND: returning -EINTR\n");
 571                                 regs->gr[28] = -EINTR;
 572                                 break;
 573
 574                         case -ERESTARTSYS:
 575                                 if (!(ka.sa.sa_flags & SA_RESTART)) {
 576                                         DBG(1,"ERESTARTSYS: putting -EINTR\n");
 577                                         regs->gr[28] = -EINTR;
 578                                         break;
 579                                 }
 580                         /* fallthrough */
 581                         case -ERESTARTNOINTR:
 582                                 /* A syscall is just a branch, so all
 583                                    we have to do is fiddle the return pointer. */
 584                                 regs->gr[31] -= 8; /* delayed branching */
 585                                 /* Preserve original r28. */
 586                                 regs->gr[28] = regs->orig_r28;
 587                                 break;
 588                         }
 589                 }
 590                 /* Whee!  Actually deliver the signal.  If the
 591                    delivery failed, we need to continue to iterate in
 592                    this loop so we can deliver the SIGSEGV... */
 593                 if (handle_signal(signr, &info, &ka, oldset, regs, in_syscall)) {
 594                         DBG(1,KERN_DEBUG "do_signal: Exit (success), regs->gr[28] = %ld\n",
 595                                 regs->gr[28]);
 596                         return 1;
 597                 }
 598         }
 599         /* end of while(1) looping forever if we can't force a signal */
 600
 601         /* Did we come from a system call? */
 602         if (in_syscall) {
 603                 /* Restart the system call - no handlers present */
 604                 if (regs->gr[28] == -ERESTART_RESTARTBLOCK) {
 605                         unsigned int *usp = (unsigned int *)regs->gr[30];
 606
 607                         /* Setup a trampoline to restart the syscall
 608                          * with __NR_restart_syscall
 609                          *
 610                          *  0: <return address (orig r31)>
 611                          *  4: <2nd half for 64-bit>
 612                          *  8: ldw 0(%sp), %r31
 613                          * 12: be 0x100(%sr2, %r0)
 614                          * 16: ldi __NR_restart_syscall, %r20
 615                          */
 616 #ifndef __LP64__
 617                         put_user(regs->gr[31], &usp[0]);
 618                         put_user(0x0fc0109f, &usp[2]);
 619 #else
 620                         put_user(regs->gr[31] >> 32, &usp[0]);
 621                         put_user(regs->gr[31] & 0xffffffff, &usp[1]);
 622                         put_user(0x0fc010df, &usp[2]);
 623 #endif
 624                         put_user(0xe0008200, &usp[3]);
 625                         put_user(0x34140000, &usp[4]);
 626
 627                         /* Stack is 64-byte aligned, and we only need
 628                          * to flush 1 cache line.
 629                          * Flushing one cacheline is cheap.
 630                          * "sync" on bigger (> 4 way) boxes is not.
 631                          */
 632                         asm("fdc %%r0(%%sr3, %0)\n"
 633                             "sync\n"
 634                             "fic %%r0(%%sr3, %0)\n"
 635                             "sync\n"
 636                             : : "r"(regs->gr[30]));
 637
 638                         regs->gr[31] = regs->gr[30] + 8;
 639                         /* Preserve original r28. */
 640                         regs->gr[28] = regs->orig_r28;
 641                 } else if (regs->gr[28] == -ERESTARTNOHAND ||
 642                            regs->gr[28] == -ERESTARTSYS ||
 643                            regs->gr[28] == -ERESTARTNOINTR) {
 644                         /* Hooray for delayed branching.  We don't
 645                            have to restore %r20 (the system call
 646                            number) because it gets loaded in the delay
 647                            slot of the branch external instruction. */
 648                         regs->gr[31] -= 8;
 649                         /* Preserve original r28. */
 650                         regs->gr[28] = regs->orig_r28;
 651                 }
 652         }
 653
 654         DBG(1,"do_signal: Exit (not delivered), regs->gr[28] = %ld\n",
 655                 regs->gr[28]);
 656
 657         return 0;
 658 }