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         struct siginfo si;
 300         int err = 0;
 301 #ifdef __LP64__
 302         compat_int_t compat_val;
 303         struct compat_rt_sigframe __user * compat_frame;
 304         compat_sigset_t compat_set;
 305 #endif
 306
 307         usp = (regs->gr[30] & ~(0x01UL));
 308         /*FIXME: frame_size parameter is unused, remove it. */
 309         frame = get_sigframe(ka, usp, sizeof(*frame));
 310
 311         DBG(1,"SETUP_RT_FRAME: START\n");
 312         DBG(1,"setup_rt_frame: frame %p info %p\n", frame, info);
 313
 314
 315 #ifdef __LP64__
 316
 317         compat_frame = (struct compat_rt_sigframe __user *)frame;
 318
 319         if(personality(current->personality) == PER_LINUX32) {
 320                 DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &compat_frame->info);
 321                 err |= compat_copy_siginfo_to_user(&compat_frame->info, info);
 322                 DBG(1,"SETUP_RT_FRAME: 1\n");
 323                 compat_val = (compat_int_t)current->sas_ss_sp;
 324                 err |= __put_user(compat_val, &compat_frame->uc.uc_stack.ss_sp);
 325                 DBG(1,"SETUP_RT_FRAME: 2\n");
 326                 compat_val = (compat_int_t)current->sas_ss_size;
 327                 err |= __put_user(compat_val, &compat_frame->uc.uc_stack.ss_size);
 328                 DBG(1,"SETUP_RT_FRAME: 3\n");
 329                 compat_val = sas_ss_flags(regs->gr[30]);
 330                 err |= __put_user(compat_val, &compat_frame->uc.uc_stack.ss_flags);
 331                 DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &compat_frame->uc);
 332                 DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &compat_frame->uc.uc_mcontext);
 333                 err |= setup_sigcontext32(&compat_frame->uc.uc_mcontext,
 334                                         &compat_frame->regs, regs, in_syscall);
 335                 sigset_64to32(&compat_set,set);
 336                 err |= __copy_to_user(&compat_frame->uc.uc_sigmask, &compat_set, sizeof(compat_set));
 337         } else
 338 #endif
 339         {
 340                 DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &frame->info);
 341                 err |= copy_siginfo_to_user(&frame->info, info);
 342                 err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 343                 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 344                 err |= __put_user(sas_ss_flags(regs->gr[30]),
 345                                   &frame->uc.uc_stack.ss_flags);
 346                 DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &frame->uc);
 347                 DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &frame->uc.uc_mcontext);
 348                 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, in_syscall);
 349                 /* FIXME: Should probably be converted aswell for the compat case */
 350                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 351         }
 352
 353         if (err)
 354                 goto give_sigsegv;
 355
 356         /* Set up to return from userspace.  If provided, use a stub
 357            already in userspace. The first words of tramp are used to
 358            save the previous sigrestartblock trampoline that might be
 359            on the stack. We start the sigreturn trampoline at
 360            SIGRESTARTBLOCK_TRAMP+X. */
 361         err |= __put_user(in_syscall ? INSN_LDI_R25_1 : INSN_LDI_R25_0,
 362                         &frame->tramp[SIGRESTARTBLOCK_TRAMP+0]);
 363         err |= __put_user(INSN_LDI_R20,
 364                         &frame->tramp[SIGRESTARTBLOCK_TRAMP+1]);
 365         err |= __put_user(INSN_BLE_SR2_R0,
 366                         &frame->tramp[SIGRESTARTBLOCK_TRAMP+2]);
 367         err |= __put_user(INSN_NOP, &frame->tramp[SIGRESTARTBLOCK_TRAMP+3]);
 368
 369 #if DEBUG_SIG
 370         /* Assert that we're flushing in the correct space... */
 371         {
 372                 int sid;
 373                 asm ("mfsp %%sr3,%0" : "=r" (sid));
 374                 DBG(1,"setup_rt_frame: Flushing 64 bytes at space %#x offset %p\n",
 375                        sid, frame->tramp);
 376         }
 377 #endif
 378
 379         flush_user_dcache_range((unsigned long) &frame->tramp[0],
 380                            (unsigned long) &frame->tramp[TRAMP_SIZE]);
 381         flush_user_icache_range((unsigned long) &frame->tramp[0],
 382                            (unsigned long) &frame->tramp[TRAMP_SIZE]);
 383
 384         /* TRAMP Words 0-4, Lenght 5 = SIGRESTARTBLOCK_TRAMP
 385          * TRAMP Words 5-9, Length 4 = SIGRETURN_TRAMP
 386          * So the SIGRETURN_TRAMP is at the end of SIGRESTARTBLOCK_TRAMP
 387          */
 388         rp = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP];
 389
 390         if (err)
 391                 goto give_sigsegv;
 392
 393         haddr = A(ka->sa.sa_handler);
 394         /* The sa_handler may be a pointer to a function descriptor */
 395 #ifdef __LP64__
 396         if(personality(current->personality) == PER_LINUX32) {
 397 #endif
 398                 if (haddr & PA_PLABEL_FDESC) {
 399                         Elf32_Fdesc fdesc;
 400                         Elf32_Fdesc __user *ufdesc = (Elf32_Fdesc __user *)A(haddr & ~3);
 401
 402                         err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
 403
 404                         if (err)
 405                                 goto give_sigsegv;
 406
 407                         haddr = fdesc.addr;
 408                         regs->gr[19] = fdesc.gp;
 409                 }
 410 #ifdef __LP64__
 411         } else {
 412                 Elf64_Fdesc fdesc;
 413                 Elf64_Fdesc __user *ufdesc = (Elf64_Fdesc __user *)A(haddr & ~3);
 414
 415                 err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
 416
 417                 if (err)
 418                         goto give_sigsegv;
 419
 420                 haddr = fdesc.addr;
 421                 regs->gr[19] = fdesc.gp;
 422                 DBG(1,"setup_rt_frame: 64 bit signal, exe=%#lx, r19=%#lx, in_syscall=%d\n",
 423                      haddr, regs->gr[19], in_syscall);
 424         }
 425 #endif
 426
 427         /* The syscall return path will create IAOQ values from r31.
 428          */
 429         sigframe_size = PARISC_RT_SIGFRAME_SIZE;
 430 #ifdef __LP64__
 431         if(personality(current->personality) == PER_LINUX32)
 432                 sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
 433 #endif
 434         if (in_syscall) {
 435                 regs->gr[31] = haddr;
 436 #ifdef __LP64__
 437                 if(personality(current->personality) == PER_LINUX)
 438                         sigframe_size |= 1;
 439 #endif
 440         } else {
 441                 unsigned long psw = USER_PSW;
 442 #ifdef __LP64__
 443                 if(personality(current->personality) == PER_LINUX)
 444                         psw |= PSW_W;
 445 #endif
 446
 447                 /* If we are singlestepping, arrange a trap to be delivered
 448                    when we return to userspace. Note the semantics -- we
 449                    should trap before the first insn in the handler is
 450                    executed. Ref:
 451                         http://sources.redhat.com/ml/gdb/2004-11/msg00245.html
 452                  */
 453                 if (pa_psw(current)->r) {
 454                         pa_psw(current)->r = 0;
 455                         psw |= PSW_R;
 456                         mtctl(-1, 0);
 457                 }
 458
 459                 regs->gr[0] = psw;
 460                 regs->iaoq[0] = haddr | 3;
 461                 regs->iaoq[1] = regs->iaoq[0] + 4;
 462         }
 463
 464         regs->gr[2]  = rp;                /* userland return pointer */
 465         regs->gr[26] = sig;               /* signal number */
 466
 467 #ifdef __LP64__
 468         if(personality(current->personality) == PER_LINUX32){
 469                 regs->gr[25] = A(&compat_frame->info); /* siginfo pointer */
 470                 regs->gr[24] = A(&compat_frame->uc);   /* ucontext pointer */
 471         } else
 472 #endif
 473         {
 474                 regs->gr[25] = A(&frame->info); /* siginfo pointer */
 475                 regs->gr[24] = A(&frame->uc);   /* ucontext pointer */
 476         }
 477
 478         DBG(1,"setup_rt_frame: making sigreturn frame: %#lx + %#lx = %#lx\n",
 479                regs->gr[30], sigframe_size,
 480                regs->gr[30] + sigframe_size);
 481         /* Raise the user stack pointer to make a proper call frame. */
 482         regs->gr[30] = (A(frame) + sigframe_size);
 483
 484
 485         DBG(1,"setup_rt_frame: sig deliver (%s,%d) frame=0x%p sp=%#lx iaoq=%#lx/%#lx rp=%#lx\n",
 486                current->comm, current->pid, frame, regs->gr[30],
 487                regs->iaoq[0], regs->iaoq[1], rp);
 488
 489         return 1;
 490
 491 give_sigsegv:
 492         DBG(1,"setup_rt_frame: sending SIGSEGV\n");
 493         force_sigsegv(sig, current);
 494         return 0;
 495 }
 496
 497 /*
 498  * OK, we're invoking a handler.
 499  */
 500
 501 static long
 502 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 503                 sigset_t *oldset, struct pt_regs *regs, int in_syscall)
 504 {
 505         DBG(1,"handle_signal: sig=%ld, ka=%p, info=%p, oldset=%p, regs=%p\n",
 506                sig, ka, info, oldset, regs);
 507
 508         /* Set up the stack frame */
 509         if (!setup_rt_frame(sig, ka, info, oldset, regs, in_syscall))
 510                 return 0;
 511
 512         spin_lock_irq(&current->sighand->siglock);
 513         sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 514         if (!(ka->sa.sa_flags & SA_NODEFER))
 515                 sigaddset(&current->blocked,sig);
 516         recalc_sigpending();
 517         spin_unlock_irq(&current->sighand->siglock);
 518         return 1;
 519 }
 520
 521 /*
 522  * Note that 'init' is a special process: it doesn't get signals it doesn't
 523  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 524  * mistake.
 525  *
 526  * We need to be able to restore the syscall arguments (r21-r26) to
 527  * restart syscalls.  Thus, the syscall path should save them in the
 528  * pt_regs structure (it's okay to do so since they are caller-save
 529  * registers).  As noted below, the syscall number gets restored for
 530  * us due to the magic of delayed branching.
 531  */
 532
 533 asmlinkage int
 534 do_signal(sigset_t *oldset, struct pt_regs *regs, int in_syscall)
 535 {
 536         siginfo_t info;
 537         struct k_sigaction ka;
 538         int signr;
 539
 540         DBG(1,"\ndo_signal: oldset=0x%p, regs=0x%p, sr7 %#lx, in_syscall=%d\n",
 541                oldset, regs, regs->sr[7], in_syscall);
 542
 543         /* Everyone else checks to see if they are in kernel mode at
 544            this point and exits if that's the case.  I'm not sure why
 545            we would be called in that case, but for some reason we
 546            are. */
 547
 548         if (!oldset)
 549                 oldset = &current->blocked;
 550
 551         DBG(1,"do_signal: oldset %08lx / %08lx\n",
 552                 oldset->sig[0], oldset->sig[1]);
 553
 554
 555         /* May need to force signal if handle_signal failed to deliver */
 556         while (1) {
 557
 558                 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 559                 DBG(3,"do_signal: signr = %d, regs->gr[28] = %ld\n", signr, regs->gr[28]);
 560
 561                 if (signr <= 0)
 562                   break;
 563
 564                 /* Restart a system call if necessary. */
 565                 if (in_syscall) {
 566                         /* Check the return code */
 567                         switch (regs->gr[28]) {
 568                         case -ERESTART_RESTARTBLOCK:
 569                                 current_thread_info()->restart_block.fn = do_no_restart_syscall;
 570                         case -ERESTARTNOHAND:
 571                                 DBG(1,"ERESTARTNOHAND: returning -EINTR\n");
 572                                 regs->gr[28] = -EINTR;
 573                                 break;
 574
 575                         case -ERESTARTSYS:
 576                                 if (!(ka.sa.sa_flags & SA_RESTART)) {
 577                                         DBG(1,"ERESTARTSYS: putting -EINTR\n");
 578                                         regs->gr[28] = -EINTR;
 579                                         break;
 580                                 }
 581                         /* fallthrough */
 582                         case -ERESTARTNOINTR:
 583                                 /* A syscall is just a branch, so all
 584                                    we have to do is fiddle the return pointer. */
 585                                 regs->gr[31] -= 8; /* delayed branching */
 586                                 /* Preserve original r28. */
 587                                 regs->gr[28] = regs->orig_r28;
 588                                 break;
 589                         }
 590                 }
 591                 /* Whee!  Actually deliver the signal.  If the
 592                    delivery failed, we need to continue to iterate in
 593                    this loop so we can deliver the SIGSEGV... */
 594                 if (handle_signal(signr, &info, &ka, oldset, regs, in_syscall)) {
 595                         DBG(1,KERN_DEBUG "do_signal: Exit (success), regs->gr[28] = %ld\n",
 596                                 regs->gr[28]);
 597                         return 1;
 598                 }
 599         }
 600         /* end of while(1) looping forever if we can't force a signal */
 601
 602         /* Did we come from a system call? */
 603         if (in_syscall) {
 604                 /* Restart the system call - no handlers present */
 605                 if (regs->gr[28] == -ERESTART_RESTARTBLOCK) {
 606                         unsigned int *usp = (unsigned int *)regs->gr[30];
 607
 608                         /* Setup a trampoline to restart the syscall
 609                          * with __NR_restart_syscall
 610                          *
 611                          *  0: <return address (orig r31)>
 612                          *  4: <2nd half for 64-bit>
 613                          *  8: ldw 0(%sp), %r31
 614                          * 12: be 0x100(%sr2, %r0)
 615                          * 16: ldi __NR_restart_syscall, %r20
 616                          */
 617 #ifndef __LP64__
 618                         put_user(regs->gr[31], &usp[0]);
 619                         put_user(0x0fc0109f, &usp[2]);
 620 #else
 621                         put_user(regs->gr[31] >> 32, &usp[0]);
 622                         put_user(regs->gr[31] & 0xffffffff, &usp[1]);
 623                         put_user(0x0fc010df, &usp[2]);
 624 #endif
 625                         put_user(0xe0008200, &usp[3]);
 626                         put_user(0x34140000, &usp[4]);
 627
 628                         /* Stack is 64-byte aligned, and we only need
 629                          * to flush 1 cache line.
 630                          * Flushing one cacheline is cheap.
 631                          * "sync" on bigger (> 4 way) boxes is not.
 632                          */
 633                         asm("fdc %%r0(%%sr3, %0)\n"
 634                             "sync\n"
 635                             "fic %%r0(%%sr3, %0)\n"
 636                             "sync\n"
 637                             : : "r"(regs->gr[30]));
 638
 639                         regs->gr[31] = regs->gr[30] + 8;
 640                         /* Preserve original r28. */
 641                         regs->gr[28] = regs->orig_r28;
 642                 } else if (regs->gr[28] == -ERESTARTNOHAND ||
 643                            regs->gr[28] == -ERESTARTSYS ||
 644                            regs->gr[28] == -ERESTARTNOINTR) {
 645                         /* Hooray for delayed branching.  We don't
 646                            have to restore %r20 (the system call
 647                            number) because it gets loaded in the delay
 648                            slot of the branch external instruction. */
 649                         regs->gr[31] -= 8;
 650                         /* Preserve original r28. */
 651                         regs->gr[28] = regs->orig_r28;
 652                 }
 653         }
 654
 655         DBG(1,"do_signal: Exit (not delivered), regs->gr[28] = %ld\n",
 656                 regs->gr[28]);
 657
 658         return 0;
 659 }