arch/sh/kernel/cpu/sh3/entry.S

   1 /*
   2  * arch/sh/kernel/cpu/sh3/entry.S
   3  *
   4  *  Copyright (C) 1999, 2000, 2002  Niibe Yutaka
   5  *  Copyright (C) 2003 - 2006  Paul Mundt
   6  *
   7  * This file is subject to the terms and conditions of the GNU General Public
   8  * License.  See the file "COPYING" in the main directory of this archive
   9  * for more details.
  10  */
  11 #include <linux/sys.h>
  12 #include <linux/errno.h>
  13 #include <linux/linkage.h>
  14 #include <asm/asm-offsets.h>
  15 #include <asm/thread_info.h>
  16 #include <asm/unistd.h>
  17 #include <cpu/mmu_context.h>
  18 #include <asm/page.h>
  19 #include <asm/cache.h>
  20
  21 ! NOTE:
  22 ! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address
  23 ! to be jumped is too far, but it causes illegal slot exception.
  24
  25 /*
  26  * entry.S contains the system-call and fault low-level handling routines.
  27  * This also contains the timer-interrupt handler, as well as all interrupts
  28  * and faults that can result in a task-switch.
  29  *
  30  * NOTE: This code handles signal-recognition, which happens every time
  31  * after a timer-interrupt and after each system call.
  32  *
  33  * NOTE: This code uses a convention that instructions in the delay slot
  34  * of a transfer-control instruction are indented by an extra space, thus:
  35  *
  36  *    jmp       @k0         ! control-transfer instruction
  37  *     ldc      k1, ssr     ! delay slot
  38  *
  39  * Stack layout in 'ret_from_syscall':
  40  *      ptrace needs to have all regs on the stack.
  41  *      if the order here is changed, it needs to be
  42  *      updated in ptrace.c and ptrace.h
  43  *
  44  *      r0
  45  *      ...
  46  *      r15 = stack pointer
  47  *      spc
  48  *      pr
  49  *      ssr
  50  *      gbr
  51  *      mach
  52  *      macl
  53  *      syscall #
  54  *
  55  */
  56 #if defined(CONFIG_KGDB)
  57 NMI_VEC = 0x1c0                 ! Must catch early for debounce
  58 #endif
  59
  60 /* Offsets to the stack */
  61 OFF_R0  =  0            /* Return value. New ABI also arg4 */
  62 OFF_R1  =  4            /* New ABI: arg5 */
  63 OFF_R2  =  8            /* New ABI: arg6 */
  64 OFF_R3  =  12           /* New ABI: syscall_nr */
  65 OFF_R4  =  16           /* New ABI: arg0 */
  66 OFF_R5  =  20           /* New ABI: arg1 */
  67 OFF_R6  =  24           /* New ABI: arg2 */
  68 OFF_R7  =  28           /* New ABI: arg3 */
  69 OFF_SP  =  (15*4)
  70 OFF_PC  =  (16*4)
  71 OFF_SR  =  (16*4+8)
  72 OFF_TRA =  (16*4+6*4)
  73
  74
  75 #define k0      r0
  76 #define k1      r1
  77 #define k2      r2
  78 #define k3      r3
  79 #define k4      r4
  80
  81 #define g_imask         r6      /* r6_bank1 */
  82 #define k_g_imask       r6_bank /* r6_bank1 */
  83 #define current         r7      /* r7_bank1 */
  84
  85 #include <asm/entry-macros.S>
  86
  87 /*
  88  * Kernel mode register usage:
  89  *      k0      scratch
  90  *      k1      scratch
  91  *      k2      scratch (Exception code)
  92  *      k3      scratch (Return address)
  93  *      k4      scratch
  94  *      k5      reserved
  95  *      k6      Global Interrupt Mask (0--15 << 4)
  96  *      k7      CURRENT_THREAD_INFO (pointer to current thread info)
  97  */
  98
  99 !
 100 ! TLB Miss / Initial Page write exception handling
 101 !                       _and_
 102 ! TLB hits, but the access violate the protection.
 103 ! It can be valid access, such as stack grow and/or C-O-W.
 104 !
 105 !
 106 ! Find the pmd/pte entry and loadtlb
 107 ! If it's not found, cause address error (SEGV)
 108 !
 109 ! Although this could be written in assembly language (and it'd be faster),
 110 ! this first version depends *much* on C implementation.
 111 !
 112
 113 #if defined(CONFIG_MMU)
 114         .align  2
 115 ENTRY(tlb_miss_load)
 116         bra     call_dpf
 117          mov    #0, r5
 118
 119         .align  2
 120 ENTRY(tlb_miss_store)
 121         bra     call_dpf
 122          mov    #1, r5
 123
 124         .align  2
 125 ENTRY(initial_page_write)
 126         bra     call_dpf
 127          mov    #1, r5
 128
 129         .align  2
 130 ENTRY(tlb_protection_violation_load)
 131         bra     call_dpf
 132          mov    #0, r5
 133
 134         .align  2
 135 ENTRY(tlb_protection_violation_store)
 136         bra     call_dpf
 137          mov    #1, r5
 138
 139 call_dpf:
 140         mov.l   1f, r0
 141         mov     r5, r8
 142         mov.l   @r0, r6
 143         mov     r6, r9
 144         mov.l   2f, r0
 145         sts     pr, r10
 146         jsr     @r0
 147          mov    r15, r4
 148         !
 149         tst     r0, r0
 150         bf/s    0f
 151          lds    r10, pr
 152         rts
 153          nop
 154 0:      mov.l   3f, r0
 155         mov     r9, r6
 156         mov     r8, r5
 157         jmp     @r0
 158          mov    r15, r4
 159
 160         .align 2
 161 1:      .long   MMU_TEA
 162 2:      .long   __do_page_fault
 163 3:      .long   do_page_fault
 164
 165         .align  2
 166 ENTRY(address_error_load)
 167         bra     call_dae
 168          mov    #0,r5           ! writeaccess = 0
 169
 170         .align  2
 171 ENTRY(address_error_store)
 172         bra     call_dae
 173          mov    #1,r5           ! writeaccess = 1
 174
 175         .align  2
 176 call_dae:
 177         mov.l   1f, r0
 178         mov.l   @r0, r6         ! address
 179         mov.l   2f, r0
 180         jmp     @r0
 181          mov    r15, r4         ! regs
 182
 183         .align 2
 184 1:      .long   MMU_TEA
 185 2:      .long   do_address_error
 186 #endif /* CONFIG_MMU */
 187
 188 #if defined(CONFIG_SH_STANDARD_BIOS)
 189         /* Unwind the stack and jmp to the debug entry */
 190 ENTRY(sh_bios_handler)
 191         mov.l   1f, r8
 192         bsr     restore_regs
 193          nop
 194
 195         lds     k2, pr                  ! restore pr
 196         mov     k4, r15
 197         !
 198         mov.l   2f, k0
 199         mov.l   @k0, k0
 200         jmp     @k0
 201          ldc    k3, ssr
 202         .align  2
 203 1:      .long   0x300000f0
 204 2:      .long   gdb_vbr_vector
 205 #endif /* CONFIG_SH_STANDARD_BIOS */
 206
 207 ! restore_regs()
 208 ! - restore r0, r1, r2, r3, r4, r5, r6, r7 from the stack
 209 ! - switch bank
 210 ! - restore r8, r9, r10, r11, r12, r13, r14, r15 from the stack
 211 ! - restore spc, pr*, ssr, gbr, mach, macl, skip default tra
 212 ! k2 returns original pr
 213 ! k3 returns original sr
 214 ! k4 returns original stack pointer
 215 ! r8 passes SR bitmask, overwritten with restored data on return
 216 ! r9 trashed
 217 ! BL=0 on entry, on exit BL=1 (depending on r8).
 218
 219 ENTRY(restore_regs)
 220         mov.l   @r15+, r0
 221         mov.l   @r15+, r1
 222         mov.l   @r15+, r2
 223         mov.l   @r15+, r3
 224         mov.l   @r15+, r4
 225         mov.l   @r15+, r5
 226         mov.l   @r15+, r6
 227         mov.l   @r15+, r7
 228         !
 229         stc     sr, r9
 230         or      r8, r9
 231         ldc     r9, sr
 232         !
 233         mov.l   @r15+, r8
 234         mov.l   @r15+, r9
 235         mov.l   @r15+, r10
 236         mov.l   @r15+, r11
 237         mov.l   @r15+, r12
 238         mov.l   @r15+, r13
 239         mov.l   @r15+, r14
 240         mov.l   @r15+, k4               ! original stack pointer
 241         ldc.l   @r15+, spc
 242         mov.l   @r15+, k2               ! original PR
 243         mov.l   @r15+, k3               ! original SR
 244         ldc.l   @r15+, gbr
 245         lds.l   @r15+, mach
 246         lds.l   @r15+, macl
 247         rts
 248          add    #4, r15                 ! Skip syscall number
 249
 250 restore_all:
 251         mov.l   7f, r8
 252         bsr     restore_regs
 253          nop
 254
 255         lds     k2, pr                  ! restore pr
 256         !
 257 #ifdef CONFIG_SH_DSP
 258         mov.l   @r15+, k0               ! DSP mode marker
 259         mov.l   5f, k1
 260         cmp/eq  k0, k1                  ! Do we have a DSP stack frame?
 261         bf      skip_restore
 262
 263         stc     sr, k0                  ! Enable CPU DSP mode
 264         or      k1, k0                  ! (within kernel it may be disabled)
 265         ldc     k0, sr
 266         mov     r2, k0                  ! Backup r2
 267
 268         ! Restore DSP registers from stack
 269         mov     r15, r2
 270         movs.l  @r2+, a1
 271         movs.l  @r2+, a0g
 272         movs.l  @r2+, a1g
 273         movs.l  @r2+, m0
 274         movs.l  @r2+, m1
 275         mov     r2, r15
 276
 277         lds.l   @r15+, a0
 278         lds.l   @r15+, x0
 279         lds.l   @r15+, x1
 280         lds.l   @r15+, y0
 281         lds.l   @r15+, y1
 282         lds.l   @r15+, dsr
 283         ldc.l   @r15+, rs
 284         ldc.l   @r15+, re
 285         ldc.l   @r15+, mod
 286
 287         mov     k0, r2                  ! Restore r2
 288 skip_restore:
 289 #endif
 290         !
 291         ! Calculate new SR value
 292         mov     k3, k2                  ! original SR value
 293         mov     #0xf0, k1
 294         extu.b  k1, k1
 295         not     k1, k1
 296         and     k1, k2                  ! Mask original SR value
 297         !
 298         mov     k3, k0                  ! Calculate IMASK-bits
 299         shlr2   k0
 300         and     #0x3c, k0
 301         cmp/eq  #0x3c, k0
 302         bt/s    6f
 303          shll2  k0
 304         mov     g_imask, k0
 305         !
 306 6:      or      k0, k2                  ! Set the IMASK-bits
 307         ldc     k2, ssr
 308         !
 309 #if defined(CONFIG_KGDB)
 310         ! Clear in_nmi
 311         mov.l   6f, k0
 312         mov     #0, k1
 313         mov.b   k1, @k0
 314 #endif
 315         mov     k4, r15
 316         rte
 317          nop
 318
 319         .align  2
 320 5:      .long   0x00001000      ! DSP
 321 #ifdef CONFIG_KGDB
 322 6:      .long   in_nmi
 323 #endif
 324 7:      .long   0x30000000
 325
 326 ! common exception handler
 327 #include "../../entry-common.S"
 328
 329 ! Exception Vector Base
 330 !
 331 !       Should be aligned page boundary.
 332 !
 333         .balign         4096,0,4096
 334 ENTRY(vbr_base)
 335         .long   0
 336 !
 337 ! 0x100: General exception vector
 338 !
 339         .balign         256,0,256
 340 general_exception:
 341 #ifndef CONFIG_CPU_SUBTYPE_SHX3
 342         bra     handle_exception
 343          sts    pr, k3          ! save original pr value in k3
 344 #else
 345         mov.l   1f, k4
 346         mov.l   @k4, k4
 347
 348         ! Is EXPEVT larger than 0x800?
 349         mov     #0x8, k0
 350         shll8   k0
 351         cmp/hs  k0, k4
 352         bf      0f
 353
 354         ! then add 0x580 (k2 is 0xd80 or 0xda0)
 355         mov     #0x58, k0
 356         shll2   k0
 357         shll2   k0
 358         add     k0, k4
 359 0:
 360         ! Setup stack and save DSP context (k0 contains original r15 on return)
 361         bsr     prepare_stack_save_dsp
 362          nop
 363
 364         ! Save registers / Switch to bank 0
 365         mov             k4, k2          ! keep vector in k2
 366         mov.l   1f, k4          ! SR bits to clear in k4
 367         bsr     save_regs       ! needs original pr value in k3
 368          nop
 369
 370         bra     handle_exception_special
 371          nop
 372
 373         .align  2
 374 1:      .long   EXPEVT
 375 #endif
 376
 377 ! prepare_stack_save_dsp()
 378 ! - roll back gRB
 379 ! - switch to kernel stack
 380 ! - save DSP
 381 ! k0 returns original sp (after roll back)
 382 ! k1 trashed
 383 ! k2 trashed
 384
 385 prepare_stack_save_dsp:
 386 #ifdef CONFIG_GUSA
 387         ! Check for roll back gRB (User and Kernel)
 388         mov     r15, k0
 389         shll    k0
 390         bf/s    1f
 391          shll   k0
 392         bf/s    1f
 393          stc    spc, k1
 394         stc     r0_bank, k0
 395         cmp/hs  k0, k1          ! test k1 (saved PC) >= k0 (saved r0)
 396         bt/s    2f
 397          stc    r1_bank, k1
 398
 399         add     #-2, k0
 400         add     r15, k0
 401         ldc     k0, spc         ! PC = saved r0 + r15 - 2
 402 2:      mov     k1, r15         ! SP = r1
 403 1:
 404 #endif
 405         ! Switch to kernel stack if needed
 406         stc     ssr, k0         ! Is it from kernel space?
 407         shll    k0              ! Check MD bit (bit30) by shifting it into...
 408         shll    k0              !       ...the T bit
 409         bt/s    1f              ! It's a kernel to kernel transition.
 410          mov    r15, k0         ! save original stack to k0
 411         /* User space to kernel */
 412         mov     #(THREAD_SIZE >> 10), k1
 413         shll8   k1              ! k1 := THREAD_SIZE
 414         shll2   k1
 415         add     current, k1
 416         mov     k1, r15         ! change to kernel stack
 417         !
 418 1:
 419 #ifdef CONFIG_SH_DSP
 420         ! Save DSP context if needed
 421         stc     sr, k1
 422         mov     #0x10, k2
 423         shll8   k2                      ! DSP=1 (0x00001000)
 424         tst     k2, k1                  ! Check if in DSP mode (passed in k2)
 425         bt/s    skip_save
 426          mov    #0, k1                  ! Set marker for no stack frame
 427
 428         mov     k2, k1                  ! Save has-frame marker
 429
 430         ! Save DSP registers on stack
 431         stc.l   mod, @-r15
 432         stc.l   re, @-r15
 433         stc.l   rs, @-r15
 434         sts.l   dsr, @-r15
 435         sts.l   y1, @-r15
 436         sts.l   y0, @-r15
 437         sts.l   x1, @-r15
 438         sts.l   x0, @-r15
 439         sts.l   a0, @-r15
 440
 441         ! GAS is broken, does not generate correct "movs.l Ds,@-As" instr.
 442
 443         ! FIXME: Make sure that this is still the case with newer toolchains,
 444         ! as we're not at all interested in supporting ancient toolchains at
 445         ! this point. -- PFM.
 446
 447         mov     r15, k2
 448         .word   0xf653                  ! movs.l        a1, @-r2
 449         .word   0xf6f3                  ! movs.l        a0g, @-r2
 450         .word   0xf6d3                  ! movs.l        a1g, @-r2
 451         .word   0xf6c3                  ! movs.l        m0, @-r2
 452         .word   0xf6e3                  ! movs.l        m1, @-r2
 453         mov     k2, r15
 454
 455 skip_save:
 456         mov.l   k1, @-r15               ! Push DSP mode marker onto stack
 457 #endif
 458         rts
 459          nop
 460 !
 461 ! 0x400: Instruction and Data TLB miss exception vector
 462 !
 463         .balign         1024,0,1024
 464 tlb_miss:
 465         sts     pr, k3          ! save original pr value in k3
 466
 467 handle_exception:
 468         mova    exception_data, k0
 469
 470         ! Setup stack and save DSP context (k0 contains original r15 on return)
 471         bsr     prepare_stack_save_dsp
 472          PREF(k0)
 473
 474         ! Save registers / Switch to bank 0
 475         mov.l   5f, k2          ! vector register address
 476         mov.l   1f, k4          ! SR bits to clear in k4
 477         bsr     save_regs       ! needs original pr value in k3
 478          mov.l  @k2, k2         ! read out vector and keep in k2
 479
 480 handle_exception_special:
 481         ! Setup return address and jump to exception handler
 482         mov.l   7f, r9          ! fetch return address
 483         stc     r2_bank, r0     ! k2 (vector)
 484         mov.l   6f, r10
 485         shlr2   r0
 486         shlr    r0
 487         mov.l   @(r0, r10), r10
 488         jmp     @r10
 489          lds    r9, pr          ! put return address in pr
 490
 491         .align  L1_CACHE_SHIFT
 492
 493 ! save_regs()
 494 ! - save default tra, macl, mach, gbr, ssr, pr* and spc on the stack
 495 ! - save r15*, r14, r13, r12, r11, r10, r9, r8 on the stack
 496 ! - switch bank
 497 ! - save r7, r6, r5, r4, r3, r2, r1, r0 on the stack
 498 ! k0 contains original stack pointer*
 499 ! k1 trashed
 500 ! k3 passes original pr*
 501 ! k4 passes SR bitmask
 502 ! BL=1 on entry, on exit BL=0.
 503
 504 ENTRY(save_regs)
 505         mov     #-1, r1
 506         mov.l   k1, @-r15       ! set TRA (default: -1)
 507         sts.l   macl, @-r15
 508         sts.l   mach, @-r15
 509         stc.l   gbr, @-r15
 510         stc.l   ssr, @-r15
 511         mov.l   k3, @-r15       ! original pr in k3
 512         stc.l   spc, @-r15
 513
 514         mov.l   k0, @-r15       ! original stack pointer in k0
 515         mov.l   r14, @-r15
 516         mov.l   r13, @-r15
 517         mov.l   r12, @-r15
 518         mov.l   r11, @-r15
 519         mov.l   r10, @-r15
 520         mov.l   r9, @-r15
 521         mov.l   r8, @-r15
 522
 523         mov.l   0f, k3          ! SR bits to set in k3
 524
 525         ! fall-through
 526
 527 ! save_low_regs()
 528 ! - modify SR for bank switch
 529 ! - save r7, r6, r5, r4, r3, r2, r1, r0 on the stack
 530 ! k3 passes bits to set in SR
 531 ! k4 passes bits to clear in SR
 532
 533 ENTRY(save_low_regs)
 534         stc     sr, r8
 535         or      k3, r8
 536         and     k4, r8
 537         ldc     r8, sr
 538
 539         mov.l   r7, @-r15
 540         mov.l   r6, @-r15
 541         mov.l   r5, @-r15
 542         mov.l   r4, @-r15
 543         mov.l   r3, @-r15
 544         mov.l   r2, @-r15
 545         mov.l   r1, @-r15
 546         rts
 547          mov.l  r0, @-r15
 548
 549 !
 550 ! 0x600: Interrupt / NMI vector
 551 !
 552         .balign         512,0,512
 553 ENTRY(handle_interrupt)
 554 #if defined(CONFIG_KGDB)
 555         mov.l   2f, k2
 556         ! Debounce (filter nested NMI)
 557         mov.l   @k2, k0
 558         mov.l   9f, k1
 559         cmp/eq  k1, k0
 560         bf      11f
 561         mov.l   10f, k1
 562         tas.b   @k1
 563         bt      11f
 564         rte
 565          nop
 566         .align  2
 567 9:      .long   NMI_VEC
 568 10:     .long   in_nmi
 569 11:
 570 #endif /* defined(CONFIG_KGDB) */
 571         sts     pr, k3          ! save original pr value in k3
 572         mova    exception_data, k0
 573
 574         ! Setup stack and save DSP context (k0 contains original r15 on return)
 575         bsr     prepare_stack_save_dsp
 576          PREF(k0)
 577
 578         ! Save registers / Switch to bank 0
 579         mov.l   1f, k4          ! SR bits to clear in k4
 580         bsr     save_regs       ! needs original pr value in k3
 581          mov    #-1, k2         ! default vector kept in k2
 582
 583         ! Setup return address and jump to do_IRQ
 584         mov.l   4f, r9          ! fetch return address
 585         lds     r9, pr          ! put return address in pr
 586         mov.l   2f, r4
 587         mov.l   3f, r9
 588         mov.l   @r4, r4         ! pass INTEVT vector as arg0
 589         jmp     @r9
 590          mov    r15, r5         ! pass saved registers as arg1
 591
 592 ENTRY(exception_none)
 593         rts
 594          nop
 595
 596         .align  L1_CACHE_SHIFT
 597 exception_data:
 598 0:      .long   0x000080f0      ! FD=1, IMASK=15
 599 1:      .long   0xcfffffff      ! RB=0, BL=0
 600 2:      .long   INTEVT
 601 3:      .long   do_IRQ
 602 4:      .long   ret_from_irq
 603 5:      .long   EXPEVT
 604 6:      .long   exception_handling_table
 605 7:      .long   ret_from_exception