arch/powerpc/kernel/head_44x.S

   1 /*
   2  * Kernel execution entry point code.
   3  *
   4  *    Copyright (c) 1995-1996 Gary Thomas <gdt@linuxppc.org>
   5  *      Initial PowerPC version.
   6  *    Copyright (c) 1996 Cort Dougan <cort@cs.nmt.edu>
   7  *      Rewritten for PReP
   8  *    Copyright (c) 1996 Paul Mackerras <paulus@cs.anu.edu.au>
   9  *      Low-level exception handers, MMU support, and rewrite.
  10  *    Copyright (c) 1997 Dan Malek <dmalek@jlc.net>
  11  *      PowerPC 8xx modifications.
  12  *    Copyright (c) 1998-1999 TiVo, Inc.
  13  *      PowerPC 403GCX modifications.
  14  *    Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu>
  15  *      PowerPC 403GCX/405GP modifications.
  16  *    Copyright 2000 MontaVista Software Inc.
  17  *      PPC405 modifications
  18  *      PowerPC 403GCX/405GP modifications.
  19  *      Author: MontaVista Software, Inc.
  20  *              frank_rowand@mvista.com or source@mvista.com
  21  *              debbie_chu@mvista.com
  22  *    Copyright 2002-2005 MontaVista Software, Inc.
  23  *      PowerPC 44x support, Matt Porter <mporter@kernel.crashing.org>
  24  *
  25  * This program is free software; you can redistribute  it and/or modify it
  26  * under  the terms of  the GNU General  Public License as published by the
  27  * Free Software Foundation;  either version 2 of the  License, or (at your
  28  * option) any later version.
  29  */
  30
  31 #include <asm/processor.h>
  32 #include <asm/page.h>
  33 #include <asm/mmu.h>
  34 #include <asm/pgtable.h>
  35 #include <asm/cputable.h>
  36 #include <asm/thread_info.h>
  37 #include <asm/ppc_asm.h>
  38 #include <asm/asm-offsets.h>
  39 #include "head_booke.h"
  40
  41
  42 /* As with the other PowerPC ports, it is expected that when code
  43  * execution begins here, the following registers contain valid, yet
  44  * optional, information:
  45  *
  46  *   r3 - Board info structure pointer (DRAM, frequency, MAC address, etc.)
  47  *   r4 - Starting address of the init RAM disk
  48  *   r5 - Ending address of the init RAM disk
  49  *   r6 - Start of kernel command line string (e.g. "mem=128")
  50  *   r7 - End of kernel command line string
  51  *
  52  */
  53         .section        .text.head, "ax"
  54 _ENTRY(_stext);
  55 _ENTRY(_start);
  56         /*
  57          * Reserve a word at a fixed location to store the address
  58          * of abatron_pteptrs
  59          */
  60         nop
  61 /*
  62  * Save parameters we are passed
  63  */
  64         mr      r31,r3
  65         mr      r30,r4
  66         mr      r29,r5
  67         mr      r28,r6
  68         mr      r27,r7
  69         li      r24,0           /* CPU number */
  70
  71 /*
  72  * In case the firmware didn't do it, we apply some workarounds
  73  * that are good for all 440 core variants here
  74  */
  75         mfspr   r3,SPRN_CCR0
  76         rlwinm  r3,r3,0,0,27    /* disable icache prefetch */
  77         isync
  78         mtspr   SPRN_CCR0,r3
  79         isync
  80         sync
  81
  82 /*
  83  * Set up the initial MMU state
  84  *
  85  * We are still executing code at the virtual address
  86  * mappings set by the firmware for the base of RAM.
  87  *
  88  * We first invalidate all TLB entries but the one
  89  * we are running from.  We then load the KERNELBASE
  90  * mappings so we can begin to use kernel addresses
  91  * natively and so the interrupt vector locations are
  92  * permanently pinned (necessary since Book E
  93  * implementations always have translation enabled).
  94  *
  95  * TODO: Use the known TLB entry we are running from to
  96  *       determine which physical region we are located
  97  *       in.  This can be used to determine where in RAM
  98  *       (on a shared CPU system) or PCI memory space
  99  *       (on a DRAMless system) we are located.
 100  *       For now, we assume a perfect world which means
 101  *       we are located at the base of DRAM (physical 0).
 102  */
 103
 104 /*
 105  * Search TLB for entry that we are currently using.
 106  * Invalidate all entries but the one we are using.
 107  */
 108         /* Load our current PID->MMUCR TID and MSR IS->MMUCR STS */
 109         mfspr   r3,SPRN_PID                     /* Get PID */
 110         mfmsr   r4                              /* Get MSR */
 111         andi.   r4,r4,MSR_IS@l                  /* TS=1? */
 112         beq     wmmucr                          /* If not, leave STS=0 */
 113         oris    r3,r3,PPC44x_MMUCR_STS@h        /* Set STS=1 */
 114 wmmucr: mtspr   SPRN_MMUCR,r3                   /* Put MMUCR */
 115         sync
 116
 117         bl      invstr                          /* Find our address */
 118 invstr: mflr    r5                              /* Make it accessible */
 119         tlbsx   r23,0,r5                        /* Find entry we are in */
 120         li      r4,0                            /* Start at TLB entry 0 */
 121         li      r3,0                            /* Set PAGEID inval value */
 122 1:      cmpw    r23,r4                          /* Is this our entry? */
 123         beq     skpinv                          /* If so, skip the inval */
 124         tlbwe   r3,r4,PPC44x_TLB_PAGEID         /* If not, inval the entry */
 125 skpinv: addi    r4,r4,1                         /* Increment */
 126         cmpwi   r4,64                           /* Are we done? */
 127         bne     1b                              /* If not, repeat */
 128         isync                                   /* If so, context change */
 129
 130 /*
 131  * Configure and load pinned entry into TLB slot 63.
 132  */
 133
 134         lis     r3,PAGE_OFFSET@h
 135         ori     r3,r3,PAGE_OFFSET@l
 136
 137         /* Kernel is at the base of RAM */
 138         li r4, 0                        /* Load the kernel physical address */
 139
 140         /* Load the kernel PID = 0 */
 141         li      r0,0
 142         mtspr   SPRN_PID,r0
 143         sync
 144
 145         /* Initialize MMUCR */
 146         li      r5,0
 147         mtspr   SPRN_MMUCR,r5
 148         sync
 149
 150         /* pageid fields */
 151         clrrwi  r3,r3,10                /* Mask off the effective page number */
 152         ori     r3,r3,PPC44x_TLB_VALID | PPC44x_TLB_256M
 153
 154         /* xlat fields */
 155         clrrwi  r4,r4,10                /* Mask off the real page number */
 156                                         /* ERPN is 0 for first 4GB page */
 157
 158         /* attrib fields */
 159         /* Added guarded bit to protect against speculative loads/stores */
 160         li      r5,0
 161         ori     r5,r5,(PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G)
 162
 163         li      r0,63                    /* TLB slot 63 */
 164
 165         tlbwe   r3,r0,PPC44x_TLB_PAGEID /* Load the pageid fields */
 166         tlbwe   r4,r0,PPC44x_TLB_XLAT   /* Load the translation fields */
 167         tlbwe   r5,r0,PPC44x_TLB_ATTRIB /* Load the attrib/access fields */
 168
 169         /* Force context change */
 170         mfmsr   r0
 171         mtspr   SPRN_SRR1, r0
 172         lis     r0,3f@h
 173         ori     r0,r0,3f@l
 174         mtspr   SPRN_SRR0,r0
 175         sync
 176         rfi
 177
 178         /* If necessary, invalidate original entry we used */
 179 3:      cmpwi   r23,63
 180         beq     4f
 181         li      r6,0
 182         tlbwe   r6,r23,PPC44x_TLB_PAGEID
 183         isync
 184
 185 4:
 186 #ifdef CONFIG_PPC_EARLY_DEBUG_44x
 187         /* Add UART mapping for early debug. */
 188
 189         /* pageid fields */
 190         lis     r3,PPC44x_EARLY_DEBUG_VIRTADDR@h
 191         ori     r3,r3,PPC44x_TLB_VALID|PPC44x_TLB_TS|PPC44x_TLB_64K
 192
 193         /* xlat fields */
 194         lis     r4,CONFIG_PPC_EARLY_DEBUG_44x_PHYSLOW@h
 195         ori     r4,r4,CONFIG_PPC_EARLY_DEBUG_44x_PHYSHIGH
 196
 197         /* attrib fields */
 198         li      r5,(PPC44x_TLB_SW|PPC44x_TLB_SR|PPC44x_TLB_I|PPC44x_TLB_G)
 199         li      r0,62                    /* TLB slot 0 */
 200
 201         tlbwe   r3,r0,PPC44x_TLB_PAGEID
 202         tlbwe   r4,r0,PPC44x_TLB_XLAT
 203         tlbwe   r5,r0,PPC44x_TLB_ATTRIB
 204
 205         /* Force context change */
 206         isync
 207 #endif /* CONFIG_PPC_EARLY_DEBUG_44x */
 208
 209         /* Establish the interrupt vector offsets */
 210         SET_IVOR(0,  CriticalInput);
 211         SET_IVOR(1,  MachineCheck);
 212         SET_IVOR(2,  DataStorage);
 213         SET_IVOR(3,  InstructionStorage);
 214         SET_IVOR(4,  ExternalInput);
 215         SET_IVOR(5,  Alignment);
 216         SET_IVOR(6,  Program);
 217         SET_IVOR(7,  FloatingPointUnavailable);
 218         SET_IVOR(8,  SystemCall);
 219         SET_IVOR(9,  AuxillaryProcessorUnavailable);
 220         SET_IVOR(10, Decrementer);
 221         SET_IVOR(11, FixedIntervalTimer);
 222         SET_IVOR(12, WatchdogTimer);
 223         SET_IVOR(13, DataTLBError);
 224         SET_IVOR(14, InstructionTLBError);
 225         SET_IVOR(15, DebugCrit);
 226
 227         /* Establish the interrupt vector base */
 228         lis     r4,interrupt_base@h     /* IVPR only uses the high 16-bits */
 229         mtspr   SPRN_IVPR,r4
 230
 231         /*
 232          * This is where the main kernel code starts.
 233          */
 234
 235         /* ptr to current */
 236         lis     r2,init_task@h
 237         ori     r2,r2,init_task@l
 238
 239         /* ptr to current thread */
 240         addi    r4,r2,THREAD    /* init task's THREAD */
 241         mtspr   SPRN_SPRG3,r4
 242
 243         /* stack */
 244         lis     r1,init_thread_union@h
 245         ori     r1,r1,init_thread_union@l
 246         li      r0,0
 247         stwu    r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
 248
 249         bl      early_init
 250
 251 /*
 252  * Decide what sort of machine this is and initialize the MMU.
 253  */
 254         mr      r3,r31
 255         mr      r4,r30
 256         mr      r5,r29
 257         mr      r6,r28
 258         mr      r7,r27
 259         bl      machine_init
 260         bl      MMU_init
 261
 262         /* Setup PTE pointers for the Abatron bdiGDB */
 263         lis     r6, swapper_pg_dir@h
 264         ori     r6, r6, swapper_pg_dir@l
 265         lis     r5, abatron_pteptrs@h
 266         ori     r5, r5, abatron_pteptrs@l
 267         lis     r4, KERNELBASE@h
 268         ori     r4, r4, KERNELBASE@l
 269         stw     r5, 0(r4)       /* Save abatron_pteptrs at a fixed location */
 270         stw     r6, 0(r5)
 271
 272         /* Let's move on */
 273         lis     r4,start_kernel@h
 274         ori     r4,r4,start_kernel@l
 275         lis     r3,MSR_KERNEL@h
 276         ori     r3,r3,MSR_KERNEL@l
 277         mtspr   SPRN_SRR0,r4
 278         mtspr   SPRN_SRR1,r3
 279         rfi                     /* change context and jump to start_kernel */
 280
 281 /*
 282  * Interrupt vector entry code
 283  *
 284  * The Book E MMUs are always on so we don't need to handle
 285  * interrupts in real mode as with previous PPC processors. In
 286  * this case we handle interrupts in the kernel virtual address
 287  * space.
 288  *
 289  * Interrupt vectors are dynamically placed relative to the
 290  * interrupt prefix as determined by the address of interrupt_base.
 291  * The interrupt vectors offsets are programmed using the labels
 292  * for each interrupt vector entry.
 293  *
 294  * Interrupt vectors must be aligned on a 16 byte boundary.
 295  * We align on a 32 byte cache line boundary for good measure.
 296  */
 297
 298 interrupt_base:
 299         /* Critical Input Interrupt */
 300         CRITICAL_EXCEPTION(0x0100, CriticalInput, unknown_exception)
 301
 302         /* Machine Check Interrupt */
 303         CRITICAL_EXCEPTION(0x0200, MachineCheck, machine_check_exception)
 304         MCHECK_EXCEPTION(0x0210, MachineCheckA, machine_check_exception)
 305
 306         /* Data Storage Interrupt */
 307         DATA_STORAGE_EXCEPTION
 308
 309                 /* Instruction Storage Interrupt */
 310         INSTRUCTION_STORAGE_EXCEPTION
 311
 312         /* External Input Interrupt */
 313         EXCEPTION(0x0500, ExternalInput, do_IRQ, EXC_XFER_LITE)
 314
 315         /* Alignment Interrupt */
 316         ALIGNMENT_EXCEPTION
 317
 318         /* Program Interrupt */
 319         PROGRAM_EXCEPTION
 320
 321         /* Floating Point Unavailable Interrupt */
 322 #ifdef CONFIG_PPC_FPU
 323         FP_UNAVAILABLE_EXCEPTION
 324 #else
 325         EXCEPTION(0x2010, FloatingPointUnavailable, unknown_exception, EXC_XFER_EE)
 326 #endif
 327         /* System Call Interrupt */
 328         START_EXCEPTION(SystemCall)
 329         NORMAL_EXCEPTION_PROLOG
 330         EXC_XFER_EE_LITE(0x0c00, DoSyscall)
 331
 332         /* Auxillary Processor Unavailable Interrupt */
 333         EXCEPTION(0x2020, AuxillaryProcessorUnavailable, unknown_exception, EXC_XFER_EE)
 334
 335         /* Decrementer Interrupt */
 336         DECREMENTER_EXCEPTION
 337
 338         /* Fixed Internal Timer Interrupt */
 339         /* TODO: Add FIT support */
 340         EXCEPTION(0x1010, FixedIntervalTimer, unknown_exception, EXC_XFER_EE)
 341
 342         /* Watchdog Timer Interrupt */
 343         /* TODO: Add watchdog support */
 344 #ifdef CONFIG_BOOKE_WDT
 345         CRITICAL_EXCEPTION(0x1020, WatchdogTimer, WatchdogException)
 346 #else
 347         CRITICAL_EXCEPTION(0x1020, WatchdogTimer, unknown_exception)
 348 #endif
 349
 350         /* Data TLB Error Interrupt */
 351         START_EXCEPTION(DataTLBError)
 352         mtspr   SPRN_SPRG0, r10         /* Save some working registers */
 353         mtspr   SPRN_SPRG1, r11
 354         mtspr   SPRN_SPRG4W, r12
 355         mtspr   SPRN_SPRG5W, r13
 356         mfcr    r11
 357         mtspr   SPRN_SPRG7W, r11
 358         mfspr   r10, SPRN_DEAR          /* Get faulting address */
 359
 360         /* If we are faulting a kernel address, we have to use the
 361          * kernel page tables.
 362          */
 363         lis     r11, PAGE_OFFSET@h
 364         cmplw   r10, r11
 365         blt+    3f
 366         lis     r11, swapper_pg_dir@h
 367         ori     r11, r11, swapper_pg_dir@l
 368
 369         mfspr   r12,SPRN_MMUCR
 370         rlwinm  r12,r12,0,0,23          /* Clear TID */
 371
 372         b       4f
 373
 374         /* Get the PGD for the current thread */
 375 3:
 376         mfspr   r11,SPRN_SPRG3
 377         lwz     r11,PGDIR(r11)
 378
 379         /* Load PID into MMUCR TID */
 380         mfspr   r12,SPRN_MMUCR
 381         mfspr   r13,SPRN_PID            /* Get PID */
 382         rlwimi  r12,r13,0,24,31         /* Set TID */
 383
 384 4:
 385         mtspr   SPRN_MMUCR,r12
 386
 387         /* Mask of required permission bits. Note that while we
 388          * do copy ESR:ST to _PAGE_RW position as trying to write
 389          * to an RO page is pretty common, we don't do it with
 390          * _PAGE_DIRTY. We could do it, but it's a fairly rare
 391          * event so I'd rather take the overhead when it happens
 392          * rather than adding an instruction here. We should measure
 393          * whether the whole thing is worth it in the first place
 394          * as we could avoid loading SPRN_ESR completely in the first
 395          * place...
 396          *
 397          * TODO: Is it worth doing that mfspr & rlwimi in the first
 398          *       place or can we save a couple of instructions here ?
 399          */
 400         mfspr   r12,SPRN_ESR
 401         li      r13,_PAGE_PRESENT|_PAGE_ACCESSED
 402         rlwimi  r13,r12,10,30,30
 403
 404         /* Load the PTE */
 405         /* Compute pgdir/pmd offset */
 406         rlwinm  r12, r10, PPC44x_PGD_OFF_SHIFT, PPC44x_PGD_OFF_MASK_BIT, 29
 407         lwzx    r11, r12, r11           /* Get pgd/pmd entry */
 408         rlwinm. r12, r11, 0, 0, 20      /* Extract pt base address */
 409         beq     2f                      /* Bail if no table */
 410
 411         /* Compute pte address */
 412         rlwimi  r12, r10, PPC44x_PTE_ADD_SHIFT, PPC44x_PTE_ADD_MASK_BIT, 28
 413         lwz     r11, 0(r12)             /* Get high word of pte entry */
 414         lwz     r12, 4(r12)             /* Get low word of pte entry */
 415
 416         lis     r10,tlb_44x_index@ha
 417
 418         andc.   r13,r13,r12             /* Check permission */
 419
 420         /* Load the next available TLB index */
 421         lwz     r13,tlb_44x_index@l(r10)
 422
 423         bne     2f                      /* Bail if permission mismach */
 424
 425         /* Increment, rollover, and store TLB index */
 426         addi    r13,r13,1
 427
 428         /* Compare with watermark (instruction gets patched) */
 429         .globl tlb_44x_patch_hwater_D
 430 tlb_44x_patch_hwater_D:
 431         cmpwi   0,r13,1                 /* reserve entries */
 432         ble     5f
 433         li      r13,0
 434 5:
 435         /* Store the next available TLB index */
 436         stw     r13,tlb_44x_index@l(r10)
 437
 438         /* Re-load the faulting address */
 439         mfspr   r10,SPRN_DEAR
 440
 441          /* Jump to common tlb load */
 442         b       finish_tlb_load
 443
 444 2:
 445         /* The bailout.  Restore registers to pre-exception conditions
 446          * and call the heavyweights to help us out.
 447          */
 448         mfspr   r11, SPRN_SPRG7R
 449         mtcr    r11
 450         mfspr   r13, SPRN_SPRG5R
 451         mfspr   r12, SPRN_SPRG4R
 452         mfspr   r11, SPRN_SPRG1
 453         mfspr   r10, SPRN_SPRG0
 454         b       DataStorage
 455
 456         /* Instruction TLB Error Interrupt */
 457         /*
 458          * Nearly the same as above, except we get our
 459          * information from different registers and bailout
 460          * to a different point.
 461          */
 462         START_EXCEPTION(InstructionTLBError)
 463         mtspr   SPRN_SPRG0, r10         /* Save some working registers */
 464         mtspr   SPRN_SPRG1, r11
 465         mtspr   SPRN_SPRG4W, r12
 466         mtspr   SPRN_SPRG5W, r13
 467         mfcr    r11
 468         mtspr   SPRN_SPRG7W, r11
 469         mfspr   r10, SPRN_SRR0          /* Get faulting address */
 470
 471         /* If we are faulting a kernel address, we have to use the
 472          * kernel page tables.
 473          */
 474         lis     r11, PAGE_OFFSET@h
 475         cmplw   r10, r11
 476         blt+    3f
 477         lis     r11, swapper_pg_dir@h
 478         ori     r11, r11, swapper_pg_dir@l
 479
 480         mfspr   r12,SPRN_MMUCR
 481         rlwinm  r12,r12,0,0,23          /* Clear TID */
 482
 483         b       4f
 484
 485         /* Get the PGD for the current thread */
 486 3:
 487         mfspr   r11,SPRN_SPRG3
 488         lwz     r11,PGDIR(r11)
 489
 490         /* Load PID into MMUCR TID */
 491         mfspr   r12,SPRN_MMUCR
 492         mfspr   r13,SPRN_PID            /* Get PID */
 493         rlwimi  r12,r13,0,24,31         /* Set TID */
 494
 495 4:
 496         mtspr   SPRN_MMUCR,r12
 497
 498         /* Make up the required permissions */
 499         li      r13,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_HWEXEC
 500
 501         /* Compute pgdir/pmd offset */
 502         rlwinm  r12, r10, PPC44x_PGD_OFF_SHIFT, PPC44x_PGD_OFF_MASK_BIT, 29
 503         lwzx    r11, r12, r11           /* Get pgd/pmd entry */
 504         rlwinm. r12, r11, 0, 0, 20      /* Extract pt base address */
 505         beq     2f                      /* Bail if no table */
 506
 507         /* Compute pte address */
 508         rlwimi  r12, r10, PPC44x_PTE_ADD_SHIFT, PPC44x_PTE_ADD_MASK_BIT, 28
 509         lwz     r11, 0(r12)             /* Get high word of pte entry */
 510         lwz     r12, 4(r12)             /* Get low word of pte entry */
 511
 512         lis     r10,tlb_44x_index@ha
 513
 514         andc.   r13,r13,r12             /* Check permission */
 515
 516         /* Load the next available TLB index */
 517         lwz     r13,tlb_44x_index@l(r10)
 518
 519         bne     2f                      /* Bail if permission mismach */
 520
 521         /* Increment, rollover, and store TLB index */
 522         addi    r13,r13,1
 523
 524         /* Compare with watermark (instruction gets patched) */
 525         .globl tlb_44x_patch_hwater_I
 526 tlb_44x_patch_hwater_I:
 527         cmpwi   0,r13,1                 /* reserve entries */
 528         ble     5f
 529         li      r13,0
 530 5:
 531         /* Store the next available TLB index */
 532         stw     r13,tlb_44x_index@l(r10)
 533
 534         /* Re-load the faulting address */
 535         mfspr   r10,SPRN_SRR0
 536
 537         /* Jump to common TLB load point */
 538         b       finish_tlb_load
 539
 540 2:
 541         /* The bailout.  Restore registers to pre-exception conditions
 542          * and call the heavyweights to help us out.
 543          */
 544         mfspr   r11, SPRN_SPRG7R
 545         mtcr    r11
 546         mfspr   r13, SPRN_SPRG5R
 547         mfspr   r12, SPRN_SPRG4R
 548         mfspr   r11, SPRN_SPRG1
 549         mfspr   r10, SPRN_SPRG0
 550         b       InstructionStorage
 551
 552         /* Debug Interrupt */
 553         DEBUG_CRIT_EXCEPTION
 554
 555 /*
 556  * Local functions
 557   */
 558
 559 /*
 560
 561  * Both the instruction and data TLB miss get to this
 562  * point to load the TLB.
 563  *      r10 - EA of fault
 564  *      r11 - PTE high word value
 565  *      r12 - PTE low word value
 566  *      r13 - TLB index
 567  *      MMUCR - loaded with proper value when we get here
 568  *      Upon exit, we reload everything and RFI.
 569  */
 570 finish_tlb_load:
 571         /* Combine RPN & ERPN an write WS 0 */
 572         rlwimi  r11,r12,0,0,31-PAGE_SHIFT
 573         tlbwe   r11,r13,PPC44x_TLB_XLAT
 574
 575         /*
 576          * Create WS1. This is the faulting address (EPN),
 577          * page size, and valid flag.
 578          */
 579         li      r11,PPC44x_TLB_VALID | PPC44x_TLBE_SIZE
 580         /* Insert valid and page size */
 581         rlwimi  r10,r11,0,PPC44x_PTE_ADD_MASK_BIT,31
 582         tlbwe   r10,r13,PPC44x_TLB_PAGEID       /* Write PAGEID */
 583
 584         /* And WS 2 */
 585         li      r10,0xf85                       /* Mask to apply from PTE */
 586         rlwimi  r10,r12,29,30,30                /* DIRTY -> SW position */
 587         and     r11,r12,r10                     /* Mask PTE bits to keep */
 588         andi.   r10,r12,_PAGE_USER              /* User page ? */
 589         beq     1f                              /* nope, leave U bits empty */
 590         rlwimi  r11,r11,3,26,28                 /* yes, copy S bits to U */
 591 1:      tlbwe   r11,r13,PPC44x_TLB_ATTRIB       /* Write ATTRIB */
 592
 593         /* Done...restore registers and get out of here.
 594         */
 595         mfspr   r11, SPRN_SPRG7R
 596         mtcr    r11
 597         mfspr   r13, SPRN_SPRG5R
 598         mfspr   r12, SPRN_SPRG4R
 599         mfspr   r11, SPRN_SPRG1
 600         mfspr   r10, SPRN_SPRG0
 601         rfi                                     /* Force context change */
 602
 603 /*
 604  * Global functions
 605  */
 606
 607 /*
 608  * Adjust the machine check IVOR on 440A cores
 609  */
 610 _GLOBAL(__fixup_440A_mcheck)
 611         li      r3,MachineCheckA@l
 612         mtspr   SPRN_IVOR1,r3
 613         sync
 614         blr
 615
 616 /*
 617  * extern void giveup_altivec(struct task_struct *prev)
 618  *
 619  * The 44x core does not have an AltiVec unit.
 620  */
 621 _GLOBAL(giveup_altivec)
 622         blr
 623
 624 /*
 625  * extern void giveup_fpu(struct task_struct *prev)
 626  *
 627  * The 44x core does not have an FPU.
 628  */
 629 #ifndef CONFIG_PPC_FPU
 630 _GLOBAL(giveup_fpu)
 631         blr
 632 #endif
 633
 634 _GLOBAL(set_context)
 635
 636 #ifdef CONFIG_BDI_SWITCH
 637         /* Context switch the PTE pointer for the Abatron BDI2000.
 638          * The PGDIR is the second parameter.
 639          */
 640         lis     r5, abatron_pteptrs@h
 641         ori     r5, r5, abatron_pteptrs@l
 642         stw     r4, 0x4(r5)
 643 #endif
 644         mtspr   SPRN_PID,r3
 645         isync                   /* Force context change */
 646         blr
 647
 648 /*
 649  * We put a few things here that have to be page-aligned. This stuff
 650  * goes at the beginning of the data segment, which is page-aligned.
 651  */
 652         .data
 653         .align  PAGE_SHIFT
 654         .globl  sdata
 655 sdata:
 656         .globl  empty_zero_page
 657 empty_zero_page:
 658         .space  PAGE_SIZE
 659
 660 /*
 661  * To support >32-bit physical addresses, we use an 8KB pgdir.
 662  */
 663         .globl  swapper_pg_dir
 664 swapper_pg_dir:
 665         .space  PGD_TABLE_SIZE
 666
 667 /*
 668  * Room for two PTE pointers, usually the kernel and current user pointers
 669  * to their respective root page table.
 670  */
 671 abatron_pteptrs:
 672         .space  8