arch/powerpc/kernel/misc_64.S

   1 /*
   2  * This file contains miscellaneous low-level functions.
   3  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   4  *
   5  * Largely rewritten by Cort Dougan (cort@cs.nmt.edu)
   6  * and Paul Mackerras.
   7  * Adapted for iSeries by Mike Corrigan (mikejc@us.ibm.com)
   8  * PPC64 updates by Dave Engebretsen (engebret@us.ibm.com)
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version
  13  * 2 of the License, or (at your option) any later version.
  14  *
  15  */
  16
  17 #include <linux/sys.h>
  18 #include <asm/unistd.h>
  19 #include <asm/errno.h>
  20 #include <asm/processor.h>
  21 #include <asm/page.h>
  22 #include <asm/cache.h>
  23 #include <asm/ppc_asm.h>
  24 #include <asm/asm-offsets.h>
  25 #include <asm/cputable.h>
  26 #include <asm/thread_info.h>
  27
  28         .text
  29
  30 #ifdef CONFIG_IRQSTACKS
  31 _GLOBAL(call_do_softirq)
  32         mflr    r0
  33         std     r0,16(r1)
  34         stdu    r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r3)
  35         mr      r1,r3
  36         bl      .__do_softirq
  37         ld      r1,0(r1)
  38         ld      r0,16(r1)
  39         mtlr    r0
  40         blr
  41
  42 _GLOBAL(call_handle_irq)
  43         ld      r8,0(r6)
  44         mflr    r0
  45         std     r0,16(r1)
  46         mtctr   r8
  47         stdu    r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r5)
  48         mr      r1,r5
  49         bctrl
  50         ld      r1,0(r1)
  51         ld      r0,16(r1)
  52         mtlr    r0
  53         blr
  54 #endif /* CONFIG_IRQSTACKS */
  55
  56         .section        ".toc","aw"
  57 PPC64_CACHES:
  58         .tc             ppc64_caches[TC],ppc64_caches
  59         .section        ".text"
  60
  61 /*
  62  * Write any modified data cache blocks out to memory
  63  * and invalidate the corresponding instruction cache blocks.
  64  *
  65  * flush_icache_range(unsigned long start, unsigned long stop)
  66  *
  67  *   flush all bytes from start through stop-1 inclusive
  68  */
  69
  70 _KPROBE(__flush_icache_range)
  71
  72 /*
  73  * Flush the data cache to memory
  74  *
  75  * Different systems have different cache line sizes
  76  * and in some cases i-cache and d-cache line sizes differ from
  77  * each other.
  78  */
  79         ld      r10,PPC64_CACHES@toc(r2)
  80         lwz     r7,DCACHEL1LINESIZE(r10)/* Get cache line size */
  81         addi    r5,r7,-1
  82         andc    r6,r3,r5                /* round low to line bdy */
  83         subf    r8,r6,r4                /* compute length */
  84         add     r8,r8,r5                /* ensure we get enough */
  85         lwz     r9,DCACHEL1LOGLINESIZE(r10)     /* Get log-2 of cache line size */
  86         srw.    r8,r8,r9                /* compute line count */
  87         beqlr                           /* nothing to do? */
  88         mtctr   r8
  89 1:      dcbst   0,r6
  90         add     r6,r6,r7
  91         bdnz    1b
  92         sync
  93
  94 /* Now invalidate the instruction cache */
  95
  96         lwz     r7,ICACHEL1LINESIZE(r10)        /* Get Icache line size */
  97         addi    r5,r7,-1
  98         andc    r6,r3,r5                /* round low to line bdy */
  99         subf    r8,r6,r4                /* compute length */
 100         add     r8,r8,r5
 101         lwz     r9,ICACHEL1LOGLINESIZE(r10)     /* Get log-2 of Icache line size */
 102         srw.    r8,r8,r9                /* compute line count */
 103         beqlr                           /* nothing to do? */
 104         mtctr   r8
 105 2:      icbi    0,r6
 106         add     r6,r6,r7
 107         bdnz    2b
 108         isync
 109         blr
 110         .previous .text
 111 /*
 112  * Like above, but only do the D-cache.
 113  *
 114  * flush_dcache_range(unsigned long start, unsigned long stop)
 115  *
 116  *    flush all bytes from start to stop-1 inclusive
 117  */
 118 _GLOBAL(flush_dcache_range)
 119
 120 /*
 121  * Flush the data cache to memory
 122  *
 123  * Different systems have different cache line sizes
 124  */
 125         ld      r10,PPC64_CACHES@toc(r2)
 126         lwz     r7,DCACHEL1LINESIZE(r10)        /* Get dcache line size */
 127         addi    r5,r7,-1
 128         andc    r6,r3,r5                /* round low to line bdy */
 129         subf    r8,r6,r4                /* compute length */
 130         add     r8,r8,r5                /* ensure we get enough */
 131         lwz     r9,DCACHEL1LOGLINESIZE(r10)     /* Get log-2 of dcache line size */
 132         srw.    r8,r8,r9                /* compute line count */
 133         beqlr                           /* nothing to do? */
 134         mtctr   r8
 135 0:      dcbst   0,r6
 136         add     r6,r6,r7
 137         bdnz    0b
 138         sync
 139         blr
 140
 141 /*
 142  * Like above, but works on non-mapped physical addresses.
 143  * Use only for non-LPAR setups ! It also assumes real mode
 144  * is cacheable. Used for flushing out the DART before using
 145  * it as uncacheable memory
 146  *
 147  * flush_dcache_phys_range(unsigned long start, unsigned long stop)
 148  *
 149  *    flush all bytes from start to stop-1 inclusive
 150  */
 151 _GLOBAL(flush_dcache_phys_range)
 152         ld      r10,PPC64_CACHES@toc(r2)
 153         lwz     r7,DCACHEL1LINESIZE(r10)        /* Get dcache line size */
 154         addi    r5,r7,-1
 155         andc    r6,r3,r5                /* round low to line bdy */
 156         subf    r8,r6,r4                /* compute length */
 157         add     r8,r8,r5                /* ensure we get enough */
 158         lwz     r9,DCACHEL1LOGLINESIZE(r10)     /* Get log-2 of dcache line size */
 159         srw.    r8,r8,r9                /* compute line count */
 160         beqlr                           /* nothing to do? */
 161         mfmsr   r5                      /* Disable MMU Data Relocation */
 162         ori     r0,r5,MSR_DR
 163         xori    r0,r0,MSR_DR
 164         sync
 165         mtmsr   r0
 166         sync
 167         isync
 168         mtctr   r8
 169 0:      dcbst   0,r6
 170         add     r6,r6,r7
 171         bdnz    0b
 172         sync
 173         isync
 174         mtmsr   r5                      /* Re-enable MMU Data Relocation */
 175         sync
 176         isync
 177         blr
 178
 179 _GLOBAL(flush_inval_dcache_range)
 180         ld      r10,PPC64_CACHES@toc(r2)
 181         lwz     r7,DCACHEL1LINESIZE(r10)        /* Get dcache line size */
 182         addi    r5,r7,-1
 183         andc    r6,r3,r5                /* round low to line bdy */
 184         subf    r8,r6,r4                /* compute length */
 185         add     r8,r8,r5                /* ensure we get enough */
 186         lwz     r9,DCACHEL1LOGLINESIZE(r10)/* Get log-2 of dcache line size */
 187         srw.    r8,r8,r9                /* compute line count */
 188         beqlr                           /* nothing to do? */
 189         sync
 190         isync
 191         mtctr   r8
 192 0:      dcbf    0,r6
 193         add     r6,r6,r7
 194         bdnz    0b
 195         sync
 196         isync
 197         blr
 198
 199
 200 /*
 201  * Flush a particular page from the data cache to RAM.
 202  * Note: this is necessary because the instruction cache does *not*
 203  * snoop from the data cache.
 204  *
 205  *      void __flush_dcache_icache(void *page)
 206  */
 207 _GLOBAL(__flush_dcache_icache)
 208 /*
 209  * Flush the data cache to memory
 210  *
 211  * Different systems have different cache line sizes
 212  */
 213
 214 /* Flush the dcache */
 215         ld      r7,PPC64_CACHES@toc(r2)
 216         clrrdi  r3,r3,PAGE_SHIFT                    /* Page align */
 217         lwz     r4,DCACHEL1LINESPERPAGE(r7)     /* Get # dcache lines per page */
 218         lwz     r5,DCACHEL1LINESIZE(r7)         /* Get dcache line size */
 219         mr      r6,r3
 220         mtctr   r4
 221 0:      dcbst   0,r6
 222         add     r6,r6,r5
 223         bdnz    0b
 224         sync
 225
 226 /* Now invalidate the icache */
 227
 228         lwz     r4,ICACHEL1LINESPERPAGE(r7)     /* Get # icache lines per page */
 229         lwz     r5,ICACHEL1LINESIZE(r7)         /* Get icache line size */
 230         mtctr   r4
 231 1:      icbi    0,r3
 232         add     r3,r3,r5
 233         bdnz    1b
 234         isync
 235         blr
 236
 237
 238 #if defined(CONFIG_PPC_PMAC) || defined(CONFIG_PPC_MAPLE)
 239 /*
 240  * Do an IO access in real mode
 241  */
 242 _GLOBAL(real_readb)
 243         mfmsr   r7
 244         ori     r0,r7,MSR_DR
 245         xori    r0,r0,MSR_DR
 246         sync
 247         mtmsrd  r0
 248         sync
 249         isync
 250         mfspr   r6,SPRN_HID4
 251         rldicl  r5,r6,32,0
 252         ori     r5,r5,0x100
 253         rldicl  r5,r5,32,0
 254         sync
 255         mtspr   SPRN_HID4,r5
 256         isync
 257         slbia
 258         isync
 259         lbz     r3,0(r3)
 260         sync
 261         mtspr   SPRN_HID4,r6
 262         isync
 263         slbia
 264         isync
 265         mtmsrd  r7
 266         sync
 267         isync
 268         blr
 269
 270         /*
 271  * Do an IO access in real mode
 272  */
 273 _GLOBAL(real_writeb)
 274         mfmsr   r7
 275         ori     r0,r7,MSR_DR
 276         xori    r0,r0,MSR_DR
 277         sync
 278         mtmsrd  r0
 279         sync
 280         isync
 281         mfspr   r6,SPRN_HID4
 282         rldicl  r5,r6,32,0
 283         ori     r5,r5,0x100
 284         rldicl  r5,r5,32,0
 285         sync
 286         mtspr   SPRN_HID4,r5
 287         isync
 288         slbia
 289         isync
 290         stb     r3,0(r4)
 291         sync
 292         mtspr   SPRN_HID4,r6
 293         isync
 294         slbia
 295         isync
 296         mtmsrd  r7
 297         sync
 298         isync
 299         blr
 300 #endif /* defined(CONFIG_PPC_PMAC) || defined(CONFIG_PPC_MAPLE) */
 301
 302 #ifdef CONFIG_PPC_PASEMI
 303
 304 /* No support in all binutils for these yet, so use defines */
 305 #define LBZCIX(RT,RA,RB)  .long (0x7c0006aa|(RT<<21)|(RA<<16)|(RB << 11))
 306 #define STBCIX(RS,RA,RB)  .long (0x7c0007aa|(RS<<21)|(RA<<16)|(RB << 11))
 307
 308
 309 _GLOBAL(real_205_readb)
 310         mfmsr   r7
 311         ori     r0,r7,MSR_DR
 312         xori    r0,r0,MSR_DR
 313         sync
 314         mtmsrd  r0
 315         sync
 316         isync
 317         LBZCIX(r3,0,r3)
 318         isync
 319         mtmsrd  r7
 320         sync
 321         isync
 322         blr
 323
 324 _GLOBAL(real_205_writeb)
 325         mfmsr   r7
 326         ori     r0,r7,MSR_DR
 327         xori    r0,r0,MSR_DR
 328         sync
 329         mtmsrd  r0
 330         sync
 331         isync
 332         STBCIX(r3,0,r4)
 333         isync
 334         mtmsrd  r7
 335         sync
 336         isync
 337         blr
 338
 339 #endif /* CONFIG_PPC_PASEMI */
 340
 341
 342 #ifdef CONFIG_CPU_FREQ_PMAC64
 343 /*
 344  * SCOM access functions for 970 (FX only for now)
 345  *
 346  * unsigned long scom970_read(unsigned int address);
 347  * void scom970_write(unsigned int address, unsigned long value);
 348  *
 349  * The address passed in is the 24 bits register address. This code
 350  * is 970 specific and will not check the status bits, so you should
 351  * know what you are doing.
 352  */
 353 _GLOBAL(scom970_read)
 354         /* interrupts off */
 355         mfmsr   r4
 356         ori     r0,r4,MSR_EE
 357         xori    r0,r0,MSR_EE
 358         mtmsrd  r0,1
 359
 360         /* rotate 24 bits SCOM address 8 bits left and mask out it's low 8 bits
 361          * (including parity). On current CPUs they must be 0'd,
 362          * and finally or in RW bit
 363          */
 364         rlwinm  r3,r3,8,0,15
 365         ori     r3,r3,0x8000
 366
 367         /* do the actual scom read */
 368         sync
 369         mtspr   SPRN_SCOMC,r3
 370         isync
 371         mfspr   r3,SPRN_SCOMD
 372         isync
 373         mfspr   r0,SPRN_SCOMC
 374         isync
 375
 376         /* XXX: fixup result on some buggy 970's (ouch ! we lost a bit, bah
 377          * that's the best we can do). Not implemented yet as we don't use
 378          * the scom on any of the bogus CPUs yet, but may have to be done
 379          * ultimately
 380          */
 381
 382         /* restore interrupts */
 383         mtmsrd  r4,1
 384         blr
 385
 386
 387 _GLOBAL(scom970_write)
 388         /* interrupts off */
 389         mfmsr   r5
 390         ori     r0,r5,MSR_EE
 391         xori    r0,r0,MSR_EE
 392         mtmsrd  r0,1
 393
 394         /* rotate 24 bits SCOM address 8 bits left and mask out it's low 8 bits
 395          * (including parity). On current CPUs they must be 0'd.
 396          */
 397
 398         rlwinm  r3,r3,8,0,15
 399
 400         sync
 401         mtspr   SPRN_SCOMD,r4      /* write data */
 402         isync
 403         mtspr   SPRN_SCOMC,r3      /* write command */
 404         isync
 405         mfspr   3,SPRN_SCOMC
 406         isync
 407
 408         /* restore interrupts */
 409         mtmsrd  r5,1
 410         blr
 411 #endif /* CONFIG_CPU_FREQ_PMAC64 */
 412
 413
 414 /*
 415  * Create a kernel thread
 416  *   kernel_thread(fn, arg, flags)
 417  */
 418 _GLOBAL(kernel_thread)
 419         std     r29,-24(r1)
 420         std     r30,-16(r1)
 421         stdu    r1,-STACK_FRAME_OVERHEAD(r1)
 422         mr      r29,r3
 423         mr      r30,r4
 424         ori     r3,r5,CLONE_VM  /* flags */
 425         oris    r3,r3,(CLONE_UNTRACED>>16)
 426         li      r4,0            /* new sp (unused) */
 427         li      r0,__NR_clone
 428         sc
 429         bns+    1f              /* did system call indicate error? */
 430         neg     r3,r3           /* if so, make return code negative */
 431 1:      cmpdi   0,r3,0          /* parent or child? */
 432         bne     2f              /* return if parent */
 433         li      r0,0
 434         stdu    r0,-STACK_FRAME_OVERHEAD(r1)
 435         ld      r2,8(r29)
 436         ld      r29,0(r29)
 437         mtlr    r29              /* fn addr in lr */
 438         mr      r3,r30          /* load arg and call fn */
 439         blrl
 440         li      r0,__NR_exit    /* exit after child exits */
 441         li      r3,0
 442         sc
 443 2:      addi    r1,r1,STACK_FRAME_OVERHEAD
 444         ld      r29,-24(r1)
 445         ld      r30,-16(r1)
 446         blr
 447
 448 /*
 449  * disable_kernel_fp()
 450  * Disable the FPU.
 451  */
 452 _GLOBAL(disable_kernel_fp)
 453         mfmsr   r3
 454         rldicl  r0,r3,(63-MSR_FP_LG),1
 455         rldicl  r3,r0,(MSR_FP_LG+1),0
 456         mtmsrd  r3                      /* disable use of fpu now */
 457         isync
 458         blr
 459
 460 #ifdef CONFIG_ALTIVEC
 461
 462 #if 0 /* this has no callers for now */
 463 /*
 464  * disable_kernel_altivec()
 465  * Disable the VMX.
 466  */
 467 _GLOBAL(disable_kernel_altivec)
 468         mfmsr   r3
 469         rldicl  r0,r3,(63-MSR_VEC_LG),1
 470         rldicl  r3,r0,(MSR_VEC_LG+1),0
 471         mtmsrd  r3                      /* disable use of VMX now */
 472         isync
 473         blr
 474 #endif /* 0 */
 475
 476 /*
 477  * giveup_altivec(tsk)
 478  * Disable VMX for the task given as the argument,
 479  * and save the vector registers in its thread_struct.
 480  * Enables the VMX for use in the kernel on return.
 481  */
 482 _GLOBAL(giveup_altivec)
 483         mfmsr   r5
 484         oris    r5,r5,MSR_VEC@h
 485         mtmsrd  r5                      /* enable use of VMX now */
 486         isync
 487         cmpdi   0,r3,0
 488         beqlr-                          /* if no previous owner, done */
 489         addi    r3,r3,THREAD            /* want THREAD of task */
 490         ld      r5,PT_REGS(r3)
 491         cmpdi   0,r5,0
 492         SAVE_32VRS(0,r4,r3)
 493         mfvscr  vr0
 494         li      r4,THREAD_VSCR
 495         stvx    vr0,r4,r3
 496         beq     1f
 497         ld      r4,_MSR-STACK_FRAME_OVERHEAD(r5)
 498 #ifdef CONFIG_VSX
 499 BEGIN_FTR_SECTION
 500         lis     r3,(MSR_VEC|MSR_VSX)@h
 501 FTR_SECTION_ELSE
 502         lis     r3,MSR_VEC@h
 503 ALT_FTR_SECTION_END_IFSET(CPU_FTR_VSX)
 504 #else
 505         lis     r3,MSR_VEC@h
 506 #endif
 507         andc    r4,r4,r3                /* disable FP for previous task */
 508         std     r4,_MSR-STACK_FRAME_OVERHEAD(r5)
 509 1:
 510 #ifndef CONFIG_SMP
 511         li      r5,0
 512         ld      r4,last_task_used_altivec@got(r2)
 513         std     r5,0(r4)
 514 #endif /* CONFIG_SMP */
 515         blr
 516
 517 #endif /* CONFIG_ALTIVEC */
 518
 519 #ifdef CONFIG_VSX
 520 /*
 521  * __giveup_vsx(tsk)
 522  * Disable VSX for the task given as the argument.
 523  * Does NOT save vsx registers.
 524  * Enables the VSX for use in the kernel on return.
 525  */
 526 _GLOBAL(__giveup_vsx)
 527         mfmsr   r5
 528         oris    r5,r5,MSR_VSX@h
 529         mtmsrd  r5                      /* enable use of VSX now */
 530         isync
 531
 532         cmpdi   0,r3,0
 533         beqlr-                          /* if no previous owner, done */
 534         addi    r3,r3,THREAD            /* want THREAD of task */
 535         ld      r5,PT_REGS(r3)
 536         cmpdi   0,r5,0
 537         beq     1f
 538         ld      r4,_MSR-STACK_FRAME_OVERHEAD(r5)
 539         lis     r3,MSR_VSX@h
 540         andc    r4,r4,r3                /* disable VSX for previous task */
 541         std     r4,_MSR-STACK_FRAME_OVERHEAD(r5)
 542 1:
 543 #ifndef CONFIG_SMP
 544         li      r5,0
 545         ld      r4,last_task_used_vsx@got(r2)
 546         std     r5,0(r4)
 547 #endif /* CONFIG_SMP */
 548         blr
 549
 550 #endif /* CONFIG_VSX */
 551
 552 /* kexec_wait(phys_cpu)
 553  *
 554  * wait for the flag to change, indicating this kernel is going away but
 555  * the slave code for the next one is at addresses 0 to 100.
 556  *
 557  * This is used by all slaves.
 558  *
 559  * Physical (hardware) cpu id should be in r3.
 560  */
 561 _GLOBAL(kexec_wait)
 562         bl      1f
 563 1:      mflr    r5
 564         addi    r5,r5,kexec_flag-1b
 565
 566 99:     HMT_LOW
 567 #ifdef CONFIG_KEXEC             /* use no memory without kexec */
 568         lwz     r4,0(r5)
 569         cmpwi   0,r4,0
 570         bnea    0x60
 571 #endif
 572         b       99b
 573
 574 /* this can be in text because we won't change it until we are
 575  * running in real anyways
 576  */
 577 kexec_flag:
 578         .long   0
 579
 580
 581 #ifdef CONFIG_KEXEC
 582
 583 /* kexec_smp_wait(void)
 584  *
 585  * call with interrupts off
 586  * note: this is a terminal routine, it does not save lr
 587  *
 588  * get phys id from paca
 589  * set paca id to -1 to say we got here
 590  * switch to real mode
 591  * join other cpus in kexec_wait(phys_id)
 592  */
 593 _GLOBAL(kexec_smp_wait)
 594         lhz     r3,PACAHWCPUID(r13)
 595         li      r4,-1
 596         sth     r4,PACAHWCPUID(r13)     /* let others know we left */
 597         bl      real_mode
 598         b       .kexec_wait
 599
 600 /*
 601  * switch to real mode (turn mmu off)
 602  * we use the early kernel trick that the hardware ignores bits
 603  * 0 and 1 (big endian) of the effective address in real mode
 604  *
 605  * don't overwrite r3 here, it is live for kexec_wait above.
 606  */
 607 real_mode:      /* assume normal blr return */
 608 1:      li      r9,MSR_RI
 609         li      r10,MSR_DR|MSR_IR
 610         mflr    r11             /* return address to SRR0 */
 611         mfmsr   r12
 612         andc    r9,r12,r9
 613         andc    r10,r12,r10
 614
 615         mtmsrd  r9,1
 616         mtspr   SPRN_SRR1,r10
 617         mtspr   SPRN_SRR0,r11
 618         rfid
 619
 620
 621 /*
 622  * kexec_sequence(newstack, start, image, control, clear_all())
 623  *
 624  * does the grungy work with stack switching and real mode switches
 625  * also does simple calls to other code
 626  */
 627
 628 _GLOBAL(kexec_sequence)
 629         mflr    r0
 630         std     r0,16(r1)
 631
 632         /* switch stacks to newstack -- &kexec_stack.stack */
 633         stdu    r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r3)
 634         mr      r1,r3
 635
 636         li      r0,0
 637         std     r0,16(r1)
 638
 639         /* save regs for local vars on new stack.
 640          * yes, we won't go back, but ...
 641          */
 642         std     r31,-8(r1)
 643         std     r30,-16(r1)
 644         std     r29,-24(r1)
 645         std     r28,-32(r1)
 646         std     r27,-40(r1)
 647         std     r26,-48(r1)
 648         std     r25,-56(r1)
 649
 650         stdu    r1,-STACK_FRAME_OVERHEAD-64(r1)
 651
 652         /* save args into preserved regs */
 653         mr      r31,r3                  /* newstack (both) */
 654         mr      r30,r4                  /* start (real) */
 655         mr      r29,r5                  /* image (virt) */
 656         mr      r28,r6                  /* control, unused */
 657         mr      r27,r7                  /* clear_all() fn desc */
 658         mr      r26,r8                  /* spare */
 659         lhz     r25,PACAHWCPUID(r13)    /* get our phys cpu from paca */
 660
 661         /* disable interrupts, we are overwriting kernel data next */
 662         mfmsr   r3
 663         rlwinm  r3,r3,0,17,15
 664         mtmsrd  r3,1
 665
 666         /* copy dest pages, flush whole dest image */
 667         mr      r3,r29
 668         bl      .kexec_copy_flush       /* (image) */
 669
 670         /* turn off mmu */
 671         bl      real_mode
 672
 673         /* copy  0x100 bytes starting at start to 0 */
 674         li      r3,0
 675         mr      r4,r30          /* start, aka phys mem offset */
 676         li      r5,0x100
 677         li      r6,0
 678         bl      .copy_and_flush /* (dest, src, copy limit, start offset) */
 679 1:      /* assume normal blr return */
 680
 681         /* release other cpus to the new kernel secondary start at 0x60 */
 682         mflr    r5
 683         li      r6,1
 684         stw     r6,kexec_flag-1b(5)
 685
 686         /* clear out hardware hash page table and tlb */
 687         ld      r5,0(r27)               /* deref function descriptor */
 688         mtctr   r5
 689         bctrl                           /* ppc_md.hpte_clear_all(void); */
 690
 691 /*
 692  *   kexec image calling is:
 693  *      the first 0x100 bytes of the entry point are copied to 0
 694  *
 695  *      all slaves branch to slave = 0x60 (absolute)
 696  *              slave(phys_cpu_id);
 697  *
 698  *      master goes to start = entry point
 699  *              start(phys_cpu_id, start, 0);
 700  *
 701  *
 702  *   a wrapper is needed to call existing kernels, here is an approximate
 703  *   description of one method:
 704  *
 705  * v2: (2.6.10)
 706  *   start will be near the boot_block (maybe 0x100 bytes before it?)
 707  *   it will have a 0x60, which will b to boot_block, where it will wait
 708  *   and 0 will store phys into struct boot-block and load r3 from there,
 709  *   copy kernel 0-0x100 and tell slaves to back down to 0x60 again
 710  *
 711  * v1: (2.6.9)
 712  *    boot block will have all cpus scanning device tree to see if they
 713  *    are the boot cpu ?????
 714  *    other device tree differences (prop sizes, va vs pa, etc)...
 715  */
 716         mr      r3,r25  # my phys cpu
 717         mr      r4,r30  # start, aka phys mem offset
 718         mtlr    4
 719         li      r5,0
 720         blr     /* image->start(physid, image->start, 0); */
 721 #endif /* CONFIG_KEXEC */