release/src-rt-6.x.4708/linux/linux-2.6.36/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/slab.h>
  25 #include <linux/init.h>
  26 #include <linux/module.h>
  27 #include <linux/io.h>
  28 #include <asm/syscalls.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/pgtable.h>
  31 #include <asm/mmu_context.h>
  32 #include <asm/fpu.h>
  33
  34 struct task_struct *last_task_used_math = NULL;
  35
  36 void show_regs(struct pt_regs *regs)
  37 {
  38         unsigned long long ah, al, bh, bl, ch, cl;
  39
  40         printk("\n");
  41
  42         ah = (regs->pc) >> 32;
  43         al = (regs->pc) & 0xffffffff;
  44         bh = (regs->regs[18]) >> 32;
  45         bl = (regs->regs[18]) & 0xffffffff;
  46         ch = (regs->regs[15]) >> 32;
  47         cl = (regs->regs[15]) & 0xffffffff;
  48         printk("PC  : %08Lx%08Lx LINK: %08Lx%08Lx SP  : %08Lx%08Lx\n",
  49                ah, al, bh, bl, ch, cl);
  50
  51         ah = (regs->sr) >> 32;
  52         al = (regs->sr) & 0xffffffff;
  53         asm volatile ("getcon   " __TEA ", %0" : "=r" (bh));
  54         asm volatile ("getcon   " __TEA ", %0" : "=r" (bl));
  55         bh = (bh) >> 32;
  56         bl = (bl) & 0xffffffff;
  57         asm volatile ("getcon   " __KCR0 ", %0" : "=r" (ch));
  58         asm volatile ("getcon   " __KCR0 ", %0" : "=r" (cl));
  59         ch = (ch) >> 32;
  60         cl = (cl) & 0xffffffff;
  61         printk("SR  : %08Lx%08Lx TEA : %08Lx%08Lx KCR0: %08Lx%08Lx\n",
  62                ah, al, bh, bl, ch, cl);
  63
  64         ah = (regs->regs[0]) >> 32;
  65         al = (regs->regs[0]) & 0xffffffff;
  66         bh = (regs->regs[1]) >> 32;
  67         bl = (regs->regs[1]) & 0xffffffff;
  68         ch = (regs->regs[2]) >> 32;
  69         cl = (regs->regs[2]) & 0xffffffff;
  70         printk("R0  : %08Lx%08Lx R1  : %08Lx%08Lx R2  : %08Lx%08Lx\n",
  71                ah, al, bh, bl, ch, cl);
  72
  73         ah = (regs->regs[3]) >> 32;
  74         al = (regs->regs[3]) & 0xffffffff;
  75         bh = (regs->regs[4]) >> 32;
  76         bl = (regs->regs[4]) & 0xffffffff;
  77         ch = (regs->regs[5]) >> 32;
  78         cl = (regs->regs[5]) & 0xffffffff;
  79         printk("R3  : %08Lx%08Lx R4  : %08Lx%08Lx R5  : %08Lx%08Lx\n",
  80                ah, al, bh, bl, ch, cl);
  81
  82         ah = (regs->regs[6]) >> 32;
  83         al = (regs->regs[6]) & 0xffffffff;
  84         bh = (regs->regs[7]) >> 32;
  85         bl = (regs->regs[7]) & 0xffffffff;
  86         ch = (regs->regs[8]) >> 32;
  87         cl = (regs->regs[8]) & 0xffffffff;
  88         printk("R6  : %08Lx%08Lx R7  : %08Lx%08Lx R8  : %08Lx%08Lx\n",
  89                ah, al, bh, bl, ch, cl);
  90
  91         ah = (regs->regs[9]) >> 32;
  92         al = (regs->regs[9]) & 0xffffffff;
  93         bh = (regs->regs[10]) >> 32;
  94         bl = (regs->regs[10]) & 0xffffffff;
  95         ch = (regs->regs[11]) >> 32;
  96         cl = (regs->regs[11]) & 0xffffffff;
  97         printk("R9  : %08Lx%08Lx R10 : %08Lx%08Lx R11 : %08Lx%08Lx\n",
  98                ah, al, bh, bl, ch, cl);
  99
 100         ah = (regs->regs[12]) >> 32;
 101         al = (regs->regs[12]) & 0xffffffff;
 102         bh = (regs->regs[13]) >> 32;
 103         bl = (regs->regs[13]) & 0xffffffff;
 104         ch = (regs->regs[14]) >> 32;
 105         cl = (regs->regs[14]) & 0xffffffff;
 106         printk("R12 : %08Lx%08Lx R13 : %08Lx%08Lx R14 : %08Lx%08Lx\n",
 107                ah, al, bh, bl, ch, cl);
 108
 109         ah = (regs->regs[16]) >> 32;
 110         al = (regs->regs[16]) & 0xffffffff;
 111         bh = (regs->regs[17]) >> 32;
 112         bl = (regs->regs[17]) & 0xffffffff;
 113         ch = (regs->regs[19]) >> 32;
 114         cl = (regs->regs[19]) & 0xffffffff;
 115         printk("R16 : %08Lx%08Lx R17 : %08Lx%08Lx R19 : %08Lx%08Lx\n",
 116                ah, al, bh, bl, ch, cl);
 117
 118         ah = (regs->regs[20]) >> 32;
 119         al = (regs->regs[20]) & 0xffffffff;
 120         bh = (regs->regs[21]) >> 32;
 121         bl = (regs->regs[21]) & 0xffffffff;
 122         ch = (regs->regs[22]) >> 32;
 123         cl = (regs->regs[22]) & 0xffffffff;
 124         printk("R20 : %08Lx%08Lx R21 : %08Lx%08Lx R22 : %08Lx%08Lx\n",
 125                ah, al, bh, bl, ch, cl);
 126
 127         ah = (regs->regs[23]) >> 32;
 128         al = (regs->regs[23]) & 0xffffffff;
 129         bh = (regs->regs[24]) >> 32;
 130         bl = (regs->regs[24]) & 0xffffffff;
 131         ch = (regs->regs[25]) >> 32;
 132         cl = (regs->regs[25]) & 0xffffffff;
 133         printk("R23 : %08Lx%08Lx R24 : %08Lx%08Lx R25 : %08Lx%08Lx\n",
 134                ah, al, bh, bl, ch, cl);
 135
 136         ah = (regs->regs[26]) >> 32;
 137         al = (regs->regs[26]) & 0xffffffff;
 138         bh = (regs->regs[27]) >> 32;
 139         bl = (regs->regs[27]) & 0xffffffff;
 140         ch = (regs->regs[28]) >> 32;
 141         cl = (regs->regs[28]) & 0xffffffff;
 142         printk("R26 : %08Lx%08Lx R27 : %08Lx%08Lx R28 : %08Lx%08Lx\n",
 143                ah, al, bh, bl, ch, cl);
 144
 145         ah = (regs->regs[29]) >> 32;
 146         al = (regs->regs[29]) & 0xffffffff;
 147         bh = (regs->regs[30]) >> 32;
 148         bl = (regs->regs[30]) & 0xffffffff;
 149         ch = (regs->regs[31]) >> 32;
 150         cl = (regs->regs[31]) & 0xffffffff;
 151         printk("R29 : %08Lx%08Lx R30 : %08Lx%08Lx R31 : %08Lx%08Lx\n",
 152                ah, al, bh, bl, ch, cl);
 153
 154         ah = (regs->regs[32]) >> 32;
 155         al = (regs->regs[32]) & 0xffffffff;
 156         bh = (regs->regs[33]) >> 32;
 157         bl = (regs->regs[33]) & 0xffffffff;
 158         ch = (regs->regs[34]) >> 32;
 159         cl = (regs->regs[34]) & 0xffffffff;
 160         printk("R32 : %08Lx%08Lx R33 : %08Lx%08Lx R34 : %08Lx%08Lx\n",
 161                ah, al, bh, bl, ch, cl);
 162
 163         ah = (regs->regs[35]) >> 32;
 164         al = (regs->regs[35]) & 0xffffffff;
 165         bh = (regs->regs[36]) >> 32;
 166         bl = (regs->regs[36]) & 0xffffffff;
 167         ch = (regs->regs[37]) >> 32;
 168         cl = (regs->regs[37]) & 0xffffffff;
 169         printk("R35 : %08Lx%08Lx R36 : %08Lx%08Lx R37 : %08Lx%08Lx\n",
 170                ah, al, bh, bl, ch, cl);
 171
 172         ah = (regs->regs[38]) >> 32;
 173         al = (regs->regs[38]) & 0xffffffff;
 174         bh = (regs->regs[39]) >> 32;
 175         bl = (regs->regs[39]) & 0xffffffff;
 176         ch = (regs->regs[40]) >> 32;
 177         cl = (regs->regs[40]) & 0xffffffff;
 178         printk("R38 : %08Lx%08Lx R39 : %08Lx%08Lx R40 : %08Lx%08Lx\n",
 179                ah, al, bh, bl, ch, cl);
 180
 181         ah = (regs->regs[41]) >> 32;
 182         al = (regs->regs[41]) & 0xffffffff;
 183         bh = (regs->regs[42]) >> 32;
 184         bl = (regs->regs[42]) & 0xffffffff;
 185         ch = (regs->regs[43]) >> 32;
 186         cl = (regs->regs[43]) & 0xffffffff;
 187         printk("R41 : %08Lx%08Lx R42 : %08Lx%08Lx R43 : %08Lx%08Lx\n",
 188                ah, al, bh, bl, ch, cl);
 189
 190         ah = (regs->regs[44]) >> 32;
 191         al = (regs->regs[44]) & 0xffffffff;
 192         bh = (regs->regs[45]) >> 32;
 193         bl = (regs->regs[45]) & 0xffffffff;
 194         ch = (regs->regs[46]) >> 32;
 195         cl = (regs->regs[46]) & 0xffffffff;
 196         printk("R44 : %08Lx%08Lx R45 : %08Lx%08Lx R46 : %08Lx%08Lx\n",
 197                ah, al, bh, bl, ch, cl);
 198
 199         ah = (regs->regs[47]) >> 32;
 200         al = (regs->regs[47]) & 0xffffffff;
 201         bh = (regs->regs[48]) >> 32;
 202         bl = (regs->regs[48]) & 0xffffffff;
 203         ch = (regs->regs[49]) >> 32;
 204         cl = (regs->regs[49]) & 0xffffffff;
 205         printk("R47 : %08Lx%08Lx R48 : %08Lx%08Lx R49 : %08Lx%08Lx\n",
 206                ah, al, bh, bl, ch, cl);
 207
 208         ah = (regs->regs[50]) >> 32;
 209         al = (regs->regs[50]) & 0xffffffff;
 210         bh = (regs->regs[51]) >> 32;
 211         bl = (regs->regs[51]) & 0xffffffff;
 212         ch = (regs->regs[52]) >> 32;
 213         cl = (regs->regs[52]) & 0xffffffff;
 214         printk("R50 : %08Lx%08Lx R51 : %08Lx%08Lx R52 : %08Lx%08Lx\n",
 215                ah, al, bh, bl, ch, cl);
 216
 217         ah = (regs->regs[53]) >> 32;
 218         al = (regs->regs[53]) & 0xffffffff;
 219         bh = (regs->regs[54]) >> 32;
 220         bl = (regs->regs[54]) & 0xffffffff;
 221         ch = (regs->regs[55]) >> 32;
 222         cl = (regs->regs[55]) & 0xffffffff;
 223         printk("R53 : %08Lx%08Lx R54 : %08Lx%08Lx R55 : %08Lx%08Lx\n",
 224                ah, al, bh, bl, ch, cl);
 225
 226         ah = (regs->regs[56]) >> 32;
 227         al = (regs->regs[56]) & 0xffffffff;
 228         bh = (regs->regs[57]) >> 32;
 229         bl = (regs->regs[57]) & 0xffffffff;
 230         ch = (regs->regs[58]) >> 32;
 231         cl = (regs->regs[58]) & 0xffffffff;
 232         printk("R56 : %08Lx%08Lx R57 : %08Lx%08Lx R58 : %08Lx%08Lx\n",
 233                ah, al, bh, bl, ch, cl);
 234
 235         ah = (regs->regs[59]) >> 32;
 236         al = (regs->regs[59]) & 0xffffffff;
 237         bh = (regs->regs[60]) >> 32;
 238         bl = (regs->regs[60]) & 0xffffffff;
 239         ch = (regs->regs[61]) >> 32;
 240         cl = (regs->regs[61]) & 0xffffffff;
 241         printk("R59 : %08Lx%08Lx R60 : %08Lx%08Lx R61 : %08Lx%08Lx\n",
 242                ah, al, bh, bl, ch, cl);
 243
 244         ah = (regs->regs[62]) >> 32;
 245         al = (regs->regs[62]) & 0xffffffff;
 246         bh = (regs->tregs[0]) >> 32;
 247         bl = (regs->tregs[0]) & 0xffffffff;
 248         ch = (regs->tregs[1]) >> 32;
 249         cl = (regs->tregs[1]) & 0xffffffff;
 250         printk("R62 : %08Lx%08Lx T0  : %08Lx%08Lx T1  : %08Lx%08Lx\n",
 251                ah, al, bh, bl, ch, cl);
 252
 253         ah = (regs->tregs[2]) >> 32;
 254         al = (regs->tregs[2]) & 0xffffffff;
 255         bh = (regs->tregs[3]) >> 32;
 256         bl = (regs->tregs[3]) & 0xffffffff;
 257         ch = (regs->tregs[4]) >> 32;
 258         cl = (regs->tregs[4]) & 0xffffffff;
 259         printk("T2  : %08Lx%08Lx T3  : %08Lx%08Lx T4  : %08Lx%08Lx\n",
 260                ah, al, bh, bl, ch, cl);
 261
 262         ah = (regs->tregs[5]) >> 32;
 263         al = (regs->tregs[5]) & 0xffffffff;
 264         bh = (regs->tregs[6]) >> 32;
 265         bl = (regs->tregs[6]) & 0xffffffff;
 266         ch = (regs->tregs[7]) >> 32;
 267         cl = (regs->tregs[7]) & 0xffffffff;
 268         printk("T5  : %08Lx%08Lx T6  : %08Lx%08Lx T7  : %08Lx%08Lx\n",
 269                ah, al, bh, bl, ch, cl);
 270
 271         /*
 272          * If we're in kernel mode, dump the stack too..
 273          */
 274         if (!user_mode(regs)) {
 275                 void show_stack(struct task_struct *tsk, unsigned long *sp);
 276                 unsigned long sp = regs->regs[15] & 0xffffffff;
 277                 struct task_struct *tsk = get_current();
 278
 279                 tsk->thread.kregs = regs;
 280
 281                 show_stack(tsk, (unsigned long *)sp);
 282         }
 283 }
 284
 285 /*
 286  * Create a kernel thread
 287  */
 288 ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *))
 289 {
 290         do_exit(fn(arg));
 291 }
 292
 293 /*
 294  * This is the mechanism for creating a new kernel thread.
 295  *
 296  * NOTE! Only a kernel-only process(ie the swapper or direct descendants
 297  * who haven't done an "execve()") should use this: it will work within
 298  * a system call from a "real" process, but the process memory space will
 299  * not be freed until both the parent and the child have exited.
 300  */
 301 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 302 {
 303         struct pt_regs regs;
 304
 305         memset(&regs, 0, sizeof(regs));
 306         regs.regs[2] = (unsigned long)arg;
 307         regs.regs[3] = (unsigned long)fn;
 308
 309         regs.pc = (unsigned long)kernel_thread_helper;
 310         regs.sr = (1 << 30);
 311
 312         /* Ok, create the new process.. */
 313         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0,
 314                       &regs, 0, NULL, NULL);
 315 }
 316 EXPORT_SYMBOL(kernel_thread);
 317
 318 /*
 319  * Free current thread data structures etc..
 320  */
 321 void exit_thread(void)
 322 {
 323         /*
 324          * See arch/sparc/kernel/process.c for the precedent for doing
 325          * this -- RPC.
 326          *
 327          * The SH-5 FPU save/restore approach relies on
 328          * last_task_used_math pointing to a live task_struct.  When
 329          * another task tries to use the FPU for the 1st time, the FPUDIS
 330          * trap handling (see arch/sh/kernel/cpu/sh5/fpu.c) will save the
 331          * existing FPU state to the FP regs field within
 332          * last_task_used_math before re-loading the new task's FPU state
 333          * (or initialising it if the FPU has been used before).  So if
 334          * last_task_used_math is stale, and its page has already been
 335          * re-allocated for another use, the consequences are rather
 336          * grim. Unless we null it here, there is no other path through
 337          * which it would get safely nulled.
 338          */
 339 #ifdef CONFIG_SH_FPU
 340         if (last_task_used_math == current) {
 341                 last_task_used_math = NULL;
 342         }
 343 #endif
 344 }
 345
 346 void flush_thread(void)
 347 {
 348
 349         /* Called by fs/exec.c (setup_new_exec) to remove traces of a
 350          * previously running executable. */
 351 #ifdef CONFIG_SH_FPU
 352         if (last_task_used_math == current) {
 353                 last_task_used_math = NULL;
 354         }
 355         /* Force FPU state to be reinitialised after exec */
 356         clear_used_math();
 357 #endif
 358
 359         /* if we are a kernel thread, about to change to user thread,
 360          * update kreg
 361          */
 362         if(current->thread.kregs==&fake_swapper_regs) {
 363           current->thread.kregs =
 364              ((struct pt_regs *)(THREAD_SIZE + (unsigned long) current) - 1);
 365           current->thread.uregs = current->thread.kregs;
 366         }
 367 }
 368
 369 void release_thread(struct task_struct *dead_task)
 370 {
 371         /* do nothing */
 372 }
 373
 374 /* Fill in the fpu structure for a core dump.. */
 375 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 376 {
 377 #ifdef CONFIG_SH_FPU
 378         int fpvalid;
 379         struct task_struct *tsk = current;
 380
 381         fpvalid = !!tsk_used_math(tsk);
 382         if (fpvalid) {
 383                 if (current == last_task_used_math) {
 384                         enable_fpu();
 385                         save_fpu(tsk);
 386                         disable_fpu();
 387                         last_task_used_math = 0;
 388                         regs->sr |= SR_FD;
 389                 }
 390
 391                 memcpy(fpu, &tsk->thread.xstate->hardfpu, sizeof(*fpu));
 392         }
 393
 394         return fpvalid;
 395 #else
 396         return 0; /* Task didn't use the fpu at all. */
 397 #endif
 398 }
 399 EXPORT_SYMBOL(dump_fpu);
 400
 401 asmlinkage void ret_from_fork(void);
 402
 403 int copy_thread(unsigned long clone_flags, unsigned long usp,
 404                 unsigned long unused,
 405                 struct task_struct *p, struct pt_regs *regs)
 406 {
 407         struct pt_regs *childregs;
 408
 409 #ifdef CONFIG_SH_FPU
 410         if(last_task_used_math == current) {
 411                 enable_fpu();
 412                 save_fpu(current);
 413                 disable_fpu();
 414                 last_task_used_math = NULL;
 415                 regs->sr |= SR_FD;
 416         }
 417 #endif
 418         /* Copy from sh version */
 419         childregs = (struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1;
 420
 421         *childregs = *regs;
 422
 423         /*
 424          * Sign extend the edited stack.
 425          * Note that thread.pc and thread.pc will stay
 426          * 32-bit wide and context switch must take care
 427          * of NEFF sign extension.
 428          */
 429         if (user_mode(regs)) {
 430                 childregs->regs[15] = neff_sign_extend(usp);
 431                 p->thread.uregs = childregs;
 432         } else {
 433                 childregs->regs[15] =
 434                         neff_sign_extend((unsigned long)task_stack_page(p) +
 435                                          THREAD_SIZE);
 436         }
 437
 438         childregs->regs[9] = 0; /* Set return value for child */
 439         childregs->sr |= SR_FD; /* Invalidate FPU flag */
 440
 441         p->thread.sp = (unsigned long) childregs;
 442         p->thread.pc = (unsigned long) ret_from_fork;
 443
 444         return 0;
 445 }
 446
 447 asmlinkage int sys_fork(unsigned long r2, unsigned long r3,
 448                         unsigned long r4, unsigned long r5,
 449                         unsigned long r6, unsigned long r7,
 450                         struct pt_regs *pregs)
 451 {
 452         return do_fork(SIGCHLD, pregs->regs[15], pregs, 0, 0, 0);
 453 }
 454
 455 asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
 456                          unsigned long r4, unsigned long r5,
 457                          unsigned long r6, unsigned long r7,
 458                          struct pt_regs *pregs)
 459 {
 460         if (!newsp)
 461                 newsp = pregs->regs[15];
 462         return do_fork(clone_flags, newsp, pregs, 0, 0, 0);
 463 }
 464
 465 /*
 466  * This is trivial, and on the face of it looks like it
 467  * could equally well be done in user mode.
 468  *
 469  * Not so, for quite unobvious reasons - register pressure.
 470  * In user mode vfork() cannot have a stack frame, and if
 471  * done by calling the "clone()" system call directly, you
 472  * do not have enough call-clobbered registers to hold all
 473  * the information you need.
 474  */
 475 asmlinkage int sys_vfork(unsigned long r2, unsigned long r3,
 476                          unsigned long r4, unsigned long r5,
 477                          unsigned long r6, unsigned long r7,
 478                          struct pt_regs *pregs)
 479 {
 480         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, pregs->regs[15], pregs, 0, 0, 0);
 481 }
 482
 483 /*
 484  * sys_execve() executes a new program.
 485  */
 486 asmlinkage int sys_execve(const char *ufilename, char **uargv,
 487                           char **uenvp, unsigned long r5,
 488                           unsigned long r6, unsigned long r7,
 489                           struct pt_regs *pregs)
 490 {
 491         int error;
 492         char *filename;
 493
 494         filename = getname((char __user *)ufilename);
 495         error = PTR_ERR(filename);
 496         if (IS_ERR(filename))
 497                 goto out;
 498
 499         error = do_execve(filename,
 500                           (const char __user *const __user *)uargv,
 501                           (const char __user *const __user *)uenvp,
 502                           pregs);
 503         putname(filename);
 504 out:
 505         return error;
 506 }
 507
 508 #ifdef CONFIG_FRAME_POINTER
 509 static int in_sh64_switch_to(unsigned long pc)
 510 {
 511         extern char __sh64_switch_to_end;
 512         /* For a sleeping task, the PC is somewhere in the middle of the function,
 513            so we don't have to worry about masking the LSB off */
 514         return (pc >= (unsigned long) sh64_switch_to) &&
 515                (pc < (unsigned long) &__sh64_switch_to_end);
 516 }
 517 #endif
 518
 519 unsigned long get_wchan(struct task_struct *p)
 520 {
 521         unsigned long pc;
 522
 523         if (!p || p == current || p->state == TASK_RUNNING)
 524                 return 0;
 525
 526         /*
 527          * The same comment as on the Alpha applies here, too ...
 528          */
 529         pc = thread_saved_pc(p);
 530
 531 #ifdef CONFIG_FRAME_POINTER
 532         if (in_sh64_switch_to(pc)) {
 533                 unsigned long schedule_fp;
 534                 unsigned long sh64_switch_to_fp;
 535                 unsigned long schedule_caller_pc;
 536
 537                 sh64_switch_to_fp = (long) p->thread.sp;
 538                 /* r14 is saved at offset 4 in the sh64_switch_to frame */
 539                 schedule_fp = *(unsigned long *) (long)(sh64_switch_to_fp + 4);
 540
 541                 /* and the caller of 'schedule' is (currently!) saved at offset 24
 542                    in the frame of schedule (from disasm) */
 543                 schedule_caller_pc = *(unsigned long *) (long)(schedule_fp + 24);
 544                 return schedule_caller_pc;
 545         }
 546 #endif
 547         return pc;
 548 }