arch/sh/kernel/process_64.c

   1 /*
   2  * arch/sh/kernel/process_64.c
   3  *
   4  * This file handles the architecture-dependent parts of process handling..
   5  *
   6  * Copyright (C) 2000, 2001  Paolo Alberelli
   7  * Copyright (C) 2003 - 2007  Paul Mundt
   8  * Copyright (C) 2003, 2004 Richard Curnow
   9  *
  10  * Started from SH3/4 version:
  11  *   Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
  12  *
  13  *   In turn started from i386 version:
  14  *     Copyright (C) 1995  Linus Torvalds
  15  *
  16  * This file is subject to the terms and conditions of the GNU General Public
  17  * License.  See the file "COPYING" in the main directory of this archive
  18  * for more details.
  19  */
  20 #include <linux/mm.h>
  21 #include <linux/fs.h>
  22 #include <linux/ptrace.h>
  23 #include <linux/reboot.h>
  24 #include <linux/init.h>
  25 #include <linux/module.h>
  26 #include <linux/io.h>
  27 #include <asm/syscalls.h>
  28 #include <asm/uaccess.h>
  29 #include <asm/pgtable.h>
  30 #include <asm/mmu_context.h>
  31 #include <asm/fpu.h>
  32
  33 struct task_struct *last_task_used_math = NULL;
  34
  35 void machine_restart(char * __unused)
  36 {
  37         extern void phys_stext(void);
  38
  39         phys_stext();
  40 }
  41
  42 void machine_halt(void)
  43 {
  44         for (;;);
  45 }
  46
  47 void machine_power_off(void)
  48 {
  49         __asm__ __volatile__ (
  50                 "sleep\n\t"
  51                 "synci\n\t"
  52                 "nop;nop;nop;nop\n\t"
  53         );
  54
  55         panic("Unexpected wakeup!\n");
  56 }
  57
  58 void show_regs(struct pt_regs * regs)
  59 {
  60         unsigned long long ah, al, bh, bl, ch, cl;
  61
  62         printk("\n");
  63
  64         ah = (regs->pc) >> 32;
  65         al = (regs->pc) & 0xffffffff;
  66         bh = (regs->regs[18]) >> 32;
  67         bl = (regs->regs[18]) & 0xffffffff;
  68         ch = (regs->regs[15]) >> 32;
  69         cl = (regs->regs[15]) & 0xffffffff;
  70         printk("PC  : %08Lx%08Lx LINK: %08Lx%08Lx SP  : %08Lx%08Lx\n",
  71                ah, al, bh, bl, ch, cl);
  72
  73         ah = (regs->sr) >> 32;
  74         al = (regs->sr) & 0xffffffff;
  75         asm volatile ("getcon   " __TEA ", %0" : "=r" (bh));
  76         asm volatile ("getcon   " __TEA ", %0" : "=r" (bl));
  77         bh = (bh) >> 32;
  78         bl = (bl) & 0xffffffff;
  79         asm volatile ("getcon   " __KCR0 ", %0" : "=r" (ch));
  80         asm volatile ("getcon   " __KCR0 ", %0" : "=r" (cl));
  81         ch = (ch) >> 32;
  82         cl = (cl) & 0xffffffff;
  83         printk("SR  : %08Lx%08Lx TEA : %08Lx%08Lx KCR0: %08Lx%08Lx\n",
  84                ah, al, bh, bl, ch, cl);
  85
  86         ah = (regs->regs[0]) >> 32;
  87         al = (regs->regs[0]) & 0xffffffff;
  88         bh = (regs->regs[1]) >> 32;
  89         bl = (regs->regs[1]) & 0xffffffff;
  90         ch = (regs->regs[2]) >> 32;
  91         cl = (regs->regs[2]) & 0xffffffff;
  92         printk("R0  : %08Lx%08Lx R1  : %08Lx%08Lx R2  : %08Lx%08Lx\n",
  93                ah, al, bh, bl, ch, cl);
  94
  95         ah = (regs->regs[3]) >> 32;
  96         al = (regs->regs[3]) & 0xffffffff;
  97         bh = (regs->regs[4]) >> 32;
  98         bl = (regs->regs[4]) & 0xffffffff;
  99         ch = (regs->regs[5]) >> 32;
 100         cl = (regs->regs[5]) & 0xffffffff;
 101         printk("R3  : %08Lx%08Lx R4  : %08Lx%08Lx R5  : %08Lx%08Lx\n",
 102                ah, al, bh, bl, ch, cl);
 103
 104         ah = (regs->regs[6]) >> 32;
 105         al = (regs->regs[6]) & 0xffffffff;
 106         bh = (regs->regs[7]) >> 32;
 107         bl = (regs->regs[7]) & 0xffffffff;
 108         ch = (regs->regs[8]) >> 32;
 109         cl = (regs->regs[8]) & 0xffffffff;
 110         printk("R6  : %08Lx%08Lx R7  : %08Lx%08Lx R8  : %08Lx%08Lx\n",
 111                ah, al, bh, bl, ch, cl);
 112
 113         ah = (regs->regs[9]) >> 32;
 114         al = (regs->regs[9]) & 0xffffffff;
 115         bh = (regs->regs[10]) >> 32;
 116         bl = (regs->regs[10]) & 0xffffffff;
 117         ch = (regs->regs[11]) >> 32;
 118         cl = (regs->regs[11]) & 0xffffffff;
 119         printk("R9  : %08Lx%08Lx R10 : %08Lx%08Lx R11 : %08Lx%08Lx\n",
 120                ah, al, bh, bl, ch, cl);
 121
 122         ah = (regs->regs[12]) >> 32;
 123         al = (regs->regs[12]) & 0xffffffff;
 124         bh = (regs->regs[13]) >> 32;
 125         bl = (regs->regs[13]) & 0xffffffff;
 126         ch = (regs->regs[14]) >> 32;
 127         cl = (regs->regs[14]) & 0xffffffff;
 128         printk("R12 : %08Lx%08Lx R13 : %08Lx%08Lx R14 : %08Lx%08Lx\n",
 129                ah, al, bh, bl, ch, cl);
 130
 131         ah = (regs->regs[16]) >> 32;
 132         al = (regs->regs[16]) & 0xffffffff;
 133         bh = (regs->regs[17]) >> 32;
 134         bl = (regs->regs[17]) & 0xffffffff;
 135         ch = (regs->regs[19]) >> 32;
 136         cl = (regs->regs[19]) & 0xffffffff;
 137         printk("R16 : %08Lx%08Lx R17 : %08Lx%08Lx R19 : %08Lx%08Lx\n",
 138                ah, al, bh, bl, ch, cl);
 139
 140         ah = (regs->regs[20]) >> 32;
 141         al = (regs->regs[20]) & 0xffffffff;
 142         bh = (regs->regs[21]) >> 32;
 143         bl = (regs->regs[21]) & 0xffffffff;
 144         ch = (regs->regs[22]) >> 32;
 145         cl = (regs->regs[22]) & 0xffffffff;
 146         printk("R20 : %08Lx%08Lx R21 : %08Lx%08Lx R22 : %08Lx%08Lx\n",
 147                ah, al, bh, bl, ch, cl);
 148
 149         ah = (regs->regs[23]) >> 32;
 150         al = (regs->regs[23]) & 0xffffffff;
 151         bh = (regs->regs[24]) >> 32;
 152         bl = (regs->regs[24]) & 0xffffffff;
 153         ch = (regs->regs[25]) >> 32;
 154         cl = (regs->regs[25]) & 0xffffffff;
 155         printk("R23 : %08Lx%08Lx R24 : %08Lx%08Lx R25 : %08Lx%08Lx\n",
 156                ah, al, bh, bl, ch, cl);
 157
 158         ah = (regs->regs[26]) >> 32;
 159         al = (regs->regs[26]) & 0xffffffff;
 160         bh = (regs->regs[27]) >> 32;
 161         bl = (regs->regs[27]) & 0xffffffff;
 162         ch = (regs->regs[28]) >> 32;
 163         cl = (regs->regs[28]) & 0xffffffff;
 164         printk("R26 : %08Lx%08Lx R27 : %08Lx%08Lx R28 : %08Lx%08Lx\n",
 165                ah, al, bh, bl, ch, cl);
 166
 167         ah = (regs->regs[29]) >> 32;
 168         al = (regs->regs[29]) & 0xffffffff;
 169         bh = (regs->regs[30]) >> 32;
 170         bl = (regs->regs[30]) & 0xffffffff;
 171         ch = (regs->regs[31]) >> 32;
 172         cl = (regs->regs[31]) & 0xffffffff;
 173         printk("R29 : %08Lx%08Lx R30 : %08Lx%08Lx R31 : %08Lx%08Lx\n",
 174                ah, al, bh, bl, ch, cl);
 175
 176         ah = (regs->regs[32]) >> 32;
 177         al = (regs->regs[32]) & 0xffffffff;
 178         bh = (regs->regs[33]) >> 32;
 179         bl = (regs->regs[33]) & 0xffffffff;
 180         ch = (regs->regs[34]) >> 32;
 181         cl = (regs->regs[34]) & 0xffffffff;
 182         printk("R32 : %08Lx%08Lx R33 : %08Lx%08Lx R34 : %08Lx%08Lx\n",
 183                ah, al, bh, bl, ch, cl);
 184
 185         ah = (regs->regs[35]) >> 32;
 186         al = (regs->regs[35]) & 0xffffffff;
 187         bh = (regs->regs[36]) >> 32;
 188         bl = (regs->regs[36]) & 0xffffffff;
 189         ch = (regs->regs[37]) >> 32;
 190         cl = (regs->regs[37]) & 0xffffffff;
 191         printk("R35 : %08Lx%08Lx R36 : %08Lx%08Lx R37 : %08Lx%08Lx\n",
 192                ah, al, bh, bl, ch, cl);
 193
 194         ah = (regs->regs[38]) >> 32;
 195         al = (regs->regs[38]) & 0xffffffff;
 196         bh = (regs->regs[39]) >> 32;
 197         bl = (regs->regs[39]) & 0xffffffff;
 198         ch = (regs->regs[40]) >> 32;
 199         cl = (regs->regs[40]) & 0xffffffff;
 200         printk("R38 : %08Lx%08Lx R39 : %08Lx%08Lx R40 : %08Lx%08Lx\n",
 201                ah, al, bh, bl, ch, cl);
 202
 203         ah = (regs->regs[41]) >> 32;
 204         al = (regs->regs[41]) & 0xffffffff;
 205         bh = (regs->regs[42]) >> 32;
 206         bl = (regs->regs[42]) & 0xffffffff;
 207         ch = (regs->regs[43]) >> 32;
 208         cl = (regs->regs[43]) & 0xffffffff;
 209         printk("R41 : %08Lx%08Lx R42 : %08Lx%08Lx R43 : %08Lx%08Lx\n",
 210                ah, al, bh, bl, ch, cl);
 211
 212         ah = (regs->regs[44]) >> 32;
 213         al = (regs->regs[44]) & 0xffffffff;
 214         bh = (regs->regs[45]) >> 32;
 215         bl = (regs->regs[45]) & 0xffffffff;
 216         ch = (regs->regs[46]) >> 32;
 217         cl = (regs->regs[46]) & 0xffffffff;
 218         printk("R44 : %08Lx%08Lx R45 : %08Lx%08Lx R46 : %08Lx%08Lx\n",
 219                ah, al, bh, bl, ch, cl);
 220
 221         ah = (regs->regs[47]) >> 32;
 222         al = (regs->regs[47]) & 0xffffffff;
 223         bh = (regs->regs[48]) >> 32;
 224         bl = (regs->regs[48]) & 0xffffffff;
 225         ch = (regs->regs[49]) >> 32;
 226         cl = (regs->regs[49]) & 0xffffffff;
 227         printk("R47 : %08Lx%08Lx R48 : %08Lx%08Lx R49 : %08Lx%08Lx\n",
 228                ah, al, bh, bl, ch, cl);
 229
 230         ah = (regs->regs[50]) >> 32;
 231         al = (regs->regs[50]) & 0xffffffff;
 232         bh = (regs->regs[51]) >> 32;
 233         bl = (regs->regs[51]) & 0xffffffff;
 234         ch = (regs->regs[52]) >> 32;
 235         cl = (regs->regs[52]) & 0xffffffff;
 236         printk("R50 : %08Lx%08Lx R51 : %08Lx%08Lx R52 : %08Lx%08Lx\n",
 237                ah, al, bh, bl, ch, cl);
 238
 239         ah = (regs->regs[53]) >> 32;
 240         al = (regs->regs[53]) & 0xffffffff;
 241         bh = (regs->regs[54]) >> 32;
 242         bl = (regs->regs[54]) & 0xffffffff;
 243         ch = (regs->regs[55]) >> 32;
 244         cl = (regs->regs[55]) & 0xffffffff;
 245         printk("R53 : %08Lx%08Lx R54 : %08Lx%08Lx R55 : %08Lx%08Lx\n",
 246                ah, al, bh, bl, ch, cl);
 247
 248         ah = (regs->regs[56]) >> 32;
 249         al = (regs->regs[56]) & 0xffffffff;
 250         bh = (regs->regs[57]) >> 32;
 251         bl = (regs->regs[57]) & 0xffffffff;
 252         ch = (regs->regs[58]) >> 32;
 253         cl = (regs->regs[58]) & 0xffffffff;
 254         printk("R56 : %08Lx%08Lx R57 : %08Lx%08Lx R58 : %08Lx%08Lx\n",
 255                ah, al, bh, bl, ch, cl);
 256
 257         ah = (regs->regs[59]) >> 32;
 258         al = (regs->regs[59]) & 0xffffffff;
 259         bh = (regs->regs[60]) >> 32;
 260         bl = (regs->regs[60]) & 0xffffffff;
 261         ch = (regs->regs[61]) >> 32;
 262         cl = (regs->regs[61]) & 0xffffffff;
 263         printk("R59 : %08Lx%08Lx R60 : %08Lx%08Lx R61 : %08Lx%08Lx\n",
 264                ah, al, bh, bl, ch, cl);
 265
 266         ah = (regs->regs[62]) >> 32;
 267         al = (regs->regs[62]) & 0xffffffff;
 268         bh = (regs->tregs[0]) >> 32;
 269         bl = (regs->tregs[0]) & 0xffffffff;
 270         ch = (regs->tregs[1]) >> 32;
 271         cl = (regs->tregs[1]) & 0xffffffff;
 272         printk("R62 : %08Lx%08Lx T0  : %08Lx%08Lx T1  : %08Lx%08Lx\n",
 273                ah, al, bh, bl, ch, cl);
 274
 275         ah = (regs->tregs[2]) >> 32;
 276         al = (regs->tregs[2]) & 0xffffffff;
 277         bh = (regs->tregs[3]) >> 32;
 278         bl = (regs->tregs[3]) & 0xffffffff;
 279         ch = (regs->tregs[4]) >> 32;
 280         cl = (regs->tregs[4]) & 0xffffffff;
 281         printk("T2  : %08Lx%08Lx T3  : %08Lx%08Lx T4  : %08Lx%08Lx\n",
 282                ah, al, bh, bl, ch, cl);
 283
 284         ah = (regs->tregs[5]) >> 32;
 285         al = (regs->tregs[5]) & 0xffffffff;
 286         bh = (regs->tregs[6]) >> 32;
 287         bl = (regs->tregs[6]) & 0xffffffff;
 288         ch = (regs->tregs[7]) >> 32;
 289         cl = (regs->tregs[7]) & 0xffffffff;
 290         printk("T5  : %08Lx%08Lx T6  : %08Lx%08Lx T7  : %08Lx%08Lx\n",
 291                ah, al, bh, bl, ch, cl);
 292
 293         /*
 294          * If we're in kernel mode, dump the stack too..
 295          */
 296         if (!user_mode(regs)) {
 297                 void show_stack(struct task_struct *tsk, unsigned long *sp);
 298                 unsigned long sp = regs->regs[15] & 0xffffffff;
 299                 struct task_struct *tsk = get_current();
 300
 301                 tsk->thread.kregs = regs;
 302
 303                 show_stack(tsk, (unsigned long *)sp);
 304         }
 305 }
 306
 307 /*
 308  * Create a kernel thread
 309  */
 310 ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *))
 311 {
 312         do_exit(fn(arg));
 313 }
 314
 315 /*
 316  * This is the mechanism for creating a new kernel thread.
 317  *
 318  * NOTE! Only a kernel-only process(ie the swapper or direct descendants
 319  * who haven't done an "execve()") should use this: it will work within
 320  * a system call from a "real" process, but the process memory space will
 321  * not be freed until both the parent and the child have exited.
 322  */
 323 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 324 {
 325         struct pt_regs regs;
 326
 327         memset(&regs, 0, sizeof(regs));
 328         regs.regs[2] = (unsigned long)arg;
 329         regs.regs[3] = (unsigned long)fn;
 330
 331         regs.pc = (unsigned long)kernel_thread_helper;
 332         regs.sr = (1 << 30);
 333
 334         /* Ok, create the new process.. */
 335         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0,
 336                       &regs, 0, NULL, NULL);
 337 }
 338 EXPORT_SYMBOL(kernel_thread);
 339
 340 /*
 341  * Free current thread data structures etc..
 342  */
 343 void exit_thread(void)
 344 {
 345         /*
 346          * See arch/sparc/kernel/process.c for the precedent for doing
 347          * this -- RPC.
 348          *
 349          * The SH-5 FPU save/restore approach relies on
 350          * last_task_used_math pointing to a live task_struct.  When
 351          * another task tries to use the FPU for the 1st time, the FPUDIS
 352          * trap handling (see arch/sh/kernel/cpu/sh5/fpu.c) will save the
 353          * existing FPU state to the FP regs field within
 354          * last_task_used_math before re-loading the new task's FPU state
 355          * (or initialising it if the FPU has been used before).  So if
 356          * last_task_used_math is stale, and its page has already been
 357          * re-allocated for another use, the consequences are rather
 358          * grim. Unless we null it here, there is no other path through
 359          * which it would get safely nulled.
 360          */
 361 #ifdef CONFIG_SH_FPU
 362         if (last_task_used_math == current) {
 363                 last_task_used_math = NULL;
 364         }
 365 #endif
 366 }
 367
 368 void flush_thread(void)
 369 {
 370
 371         /* Called by fs/exec.c (flush_old_exec) to remove traces of a
 372          * previously running executable. */
 373 #ifdef CONFIG_SH_FPU
 374         if (last_task_used_math == current) {
 375                 last_task_used_math = NULL;
 376         }
 377         /* Force FPU state to be reinitialised after exec */
 378         clear_used_math();
 379 #endif
 380
 381         /* if we are a kernel thread, about to change to user thread,
 382          * update kreg
 383          */
 384         if(current->thread.kregs==&fake_swapper_regs) {
 385           current->thread.kregs =
 386              ((struct pt_regs *)(THREAD_SIZE + (unsigned long) current) - 1);
 387           current->thread.uregs = current->thread.kregs;
 388         }
 389 }
 390
 391 void release_thread(struct task_struct *dead_task)
 392 {
 393         /* do nothing */
 394 }
 395
 396 /* Fill in the fpu structure for a core dump.. */
 397 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 398 {
 399 #ifdef CONFIG_SH_FPU
 400         int fpvalid;
 401         struct task_struct *tsk = current;
 402
 403         fpvalid = !!tsk_used_math(tsk);
 404         if (fpvalid) {
 405                 if (current == last_task_used_math) {
 406                         enable_fpu();
 407                         save_fpu(tsk);
 408                         disable_fpu();
 409                         last_task_used_math = 0;
 410                         regs->sr |= SR_FD;
 411                 }
 412
 413                 memcpy(fpu, &tsk->thread.fpu.hard, sizeof(*fpu));
 414         }
 415
 416         return fpvalid;
 417 #else
 418         return 0; /* Task didn't use the fpu at all. */
 419 #endif
 420 }
 421 EXPORT_SYMBOL(dump_fpu);
 422
 423 asmlinkage void ret_from_fork(void);
 424
 425 int copy_thread(unsigned long clone_flags, unsigned long usp,
 426                 unsigned long unused,
 427                 struct task_struct *p, struct pt_regs *regs)
 428 {
 429         struct pt_regs *childregs;
 430
 431 #ifdef CONFIG_SH_FPU
 432         if(last_task_used_math == current) {
 433                 enable_fpu();
 434                 save_fpu(current);
 435                 disable_fpu();
 436                 last_task_used_math = NULL;
 437                 regs->sr |= SR_FD;
 438         }
 439 #endif
 440         /* Copy from sh version */
 441         childregs = (struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1;
 442
 443         *childregs = *regs;
 444
 445         /*
 446          * Sign extend the edited stack.
 447          * Note that thread.pc and thread.pc will stay
 448          * 32-bit wide and context switch must take care
 449          * of NEFF sign extension.
 450          */
 451         if (user_mode(regs)) {
 452                 childregs->regs[15] = neff_sign_extend(usp);
 453                 p->thread.uregs = childregs;
 454         } else {
 455                 childregs->regs[15] =
 456                         neff_sign_extend((unsigned long)task_stack_page(p) +
 457                                          THREAD_SIZE);
 458         }
 459
 460         childregs->regs[9] = 0; /* Set return value for child */
 461         childregs->sr |= SR_FD; /* Invalidate FPU flag */
 462
 463         p->thread.sp = (unsigned long) childregs;
 464         p->thread.pc = (unsigned long) ret_from_fork;
 465
 466         return 0;
 467 }
 468
 469 asmlinkage int sys_fork(unsigned long r2, unsigned long r3,
 470                         unsigned long r4, unsigned long r5,
 471                         unsigned long r6, unsigned long r7,
 472                         struct pt_regs *pregs)
 473 {
 474         return do_fork(SIGCHLD, pregs->regs[15], pregs, 0, 0, 0);
 475 }
 476
 477 asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
 478                          unsigned long r4, unsigned long r5,
 479                          unsigned long r6, unsigned long r7,
 480                          struct pt_regs *pregs)
 481 {
 482         if (!newsp)
 483                 newsp = pregs->regs[15];
 484         return do_fork(clone_flags, newsp, pregs, 0, 0, 0);
 485 }
 486
 487 /*
 488  * This is trivial, and on the face of it looks like it
 489  * could equally well be done in user mode.
 490  *
 491  * Not so, for quite unobvious reasons - register pressure.
 492  * In user mode vfork() cannot have a stack frame, and if
 493  * done by calling the "clone()" system call directly, you
 494  * do not have enough call-clobbered registers to hold all
 495  * the information you need.
 496  */
 497 asmlinkage int sys_vfork(unsigned long r2, unsigned long r3,
 498                          unsigned long r4, unsigned long r5,
 499                          unsigned long r6, unsigned long r7,
 500                          struct pt_regs *pregs)
 501 {
 502         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, pregs->regs[15], pregs, 0, 0, 0);
 503 }
 504
 505 /*
 506  * sys_execve() executes a new program.
 507  */
 508 asmlinkage int sys_execve(char *ufilename, char **uargv,
 509                           char **uenvp, unsigned long r5,
 510                           unsigned long r6, unsigned long r7,
 511                           struct pt_regs *pregs)
 512 {
 513         int error;
 514         char *filename;
 515
 516         filename = getname((char __user *)ufilename);
 517         error = PTR_ERR(filename);
 518         if (IS_ERR(filename))
 519                 goto out;
 520
 521         error = do_execve(filename,
 522                           (char __user * __user *)uargv,
 523                           (char __user * __user *)uenvp,
 524                           pregs);
 525         putname(filename);
 526 out:
 527         return error;
 528 }
 529
 530 /*
 531  * These bracket the sleeping functions..
 532  */
 533 extern void interruptible_sleep_on(wait_queue_head_t *q);
 534
 535 #define mid_sched       ((unsigned long) interruptible_sleep_on)
 536
 537 #ifdef CONFIG_FRAME_POINTER
 538 static int in_sh64_switch_to(unsigned long pc)
 539 {
 540         extern char __sh64_switch_to_end;
 541         /* For a sleeping task, the PC is somewhere in the middle of the function,
 542            so we don't have to worry about masking the LSB off */
 543         return (pc >= (unsigned long) sh64_switch_to) &&
 544                (pc < (unsigned long) &__sh64_switch_to_end);
 545 }
 546 #endif
 547
 548 unsigned long get_wchan(struct task_struct *p)
 549 {
 550         unsigned long pc;
 551
 552         if (!p || p == current || p->state == TASK_RUNNING)
 553                 return 0;
 554
 555         /*
 556          * The same comment as on the Alpha applies here, too ...
 557          */
 558         pc = thread_saved_pc(p);
 559
 560 #ifdef CONFIG_FRAME_POINTER
 561         if (in_sh64_switch_to(pc)) {
 562                 unsigned long schedule_fp;
 563                 unsigned long sh64_switch_to_fp;
 564                 unsigned long schedule_caller_pc;
 565
 566                 sh64_switch_to_fp = (long) p->thread.sp;
 567                 /* r14 is saved at offset 4 in the sh64_switch_to frame */
 568                 schedule_fp = *(unsigned long *) (long)(sh64_switch_to_fp + 4);
 569
 570                 /* and the caller of 'schedule' is (currently!) saved at offset 24
 571                    in the frame of schedule (from disasm) */
 572                 schedule_caller_pc = *(unsigned long *) (long)(schedule_fp + 24);
 573                 return schedule_caller_pc;
 574         }
 575 #endif
 576         return pc;
 577 }