arch/frv/kernel/break.S

   1 /* break.S: Break interrupt handling (kept separate from entry.S)
   2  *
   3  * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/linkage.h>
  13 #include <asm/setup.h>
  14 #include <asm/segment.h>
  15 #include <asm/ptrace.h>
  16 #include <asm/thread_info.h>
  17 #include <asm/spr-regs.h>
  18
  19 #include <asm/errno.h>
  20
  21 #
  22 # the break handler has its own stack
  23 #
  24         .section        .bss.stack
  25         .globl          __break_user_context
  26         .balign         THREAD_SIZE
  27 __break_stack:
  28         .space          THREAD_SIZE - FRV_FRAME0_SIZE
  29 __break_frame_0:
  30         .space          FRV_FRAME0_SIZE
  31
  32 #
  33 # miscellaneous variables
  34 #
  35         .section        .bss
  36 #ifdef CONFIG_MMU
  37         .globl          __break_tlb_miss_real_return_info
  38 __break_tlb_miss_real_return_info:
  39         .balign         8
  40         .space          2*4                     /* saved PCSR, PSR for TLB-miss handler fixup */
  41 #endif
  42
  43 __break_trace_through_exceptions:
  44         .space          4
  45
  46 #define CS2_ECS1        0xe1200000
  47 #define CS2_USERLED     0x4
  48
  49 .macro LEDS val,reg
  50 #       sethi.p         %hi(CS2_ECS1+CS2_USERLED),gr30
  51 #       setlo           %lo(CS2_ECS1+CS2_USERLED),gr30
  52 #       setlos          #~\val,\reg
  53 #       st              \reg,@(gr30,gr0)
  54 #       setlos          #0x5555,\reg
  55 #       sethi.p         %hi(0xffc00100),gr30
  56 #       setlo           %lo(0xffc00100),gr30
  57 #       sth             \reg,@(gr30,gr0)
  58 #       membar
  59 .endm
  60
  61 ###############################################################################
  62 #
  63 # entry point for Break Exceptions/Interrupts
  64 #
  65 ###############################################################################
  66         .section        .text.break
  67         .balign         4
  68         .globl          __entry_break
  69 __entry_break:
  70 #ifdef CONFIG_MMU
  71         movgs           gr31,scr3
  72 #endif
  73         LEDS            0x1001,gr31
  74
  75         sethi.p         %hi(__break_frame_0),gr31
  76         setlo           %lo(__break_frame_0),gr31
  77
  78         stdi            gr2,@(gr31,#REG_GR(2))
  79         movsg           ccr,gr3
  80         sti             gr3,@(gr31,#REG_CCR)
  81
  82         # catch the return from a TLB-miss handler that had single-step disabled
  83         # traps will be enabled, so we have to do this now
  84 #ifdef CONFIG_MMU
  85         movsg           bpcsr,gr3
  86         sethi.p         %hi(__break_tlb_miss_return_breaks_here),gr2
  87         setlo           %lo(__break_tlb_miss_return_breaks_here),gr2
  88         subcc           gr2,gr3,gr0,icc0
  89         beq             icc0,#2,__break_return_singlestep_tlbmiss
  90 #endif
  91
  92         # determine whether we have stepped through into an exception
  93         # - we need to take special action to suspend h/w single stepping if we've done
  94         #   that, so that the gdbstub doesn't get bogged down endlessly stepping through
  95         #   external interrupt handling
  96         movsg           bpsr,gr3
  97         andicc          gr3,#BPSR_BET,gr0,icc0
  98         bne             icc0,#2,__break_maybe_userspace /* jump if PSR.ET was 1 */
  99
 100         LEDS            0x1003,gr2
 101
 102         movsg           brr,gr3
 103         andicc          gr3,#BRR_ST,gr0,icc0
 104         andicc.p        gr3,#BRR_SB,gr0,icc1
 105         bne             icc0,#2,__break_step            /* jump if single-step caused break */
 106         beq             icc1,#2,__break_continue        /* jump if BREAK didn't cause break */
 107
 108         LEDS            0x1007,gr2
 109
 110         # handle special breaks
 111         movsg           bpcsr,gr3
 112
 113         sethi.p         %hi(__entry_return_singlestep_breaks_here),gr2
 114         setlo           %lo(__entry_return_singlestep_breaks_here),gr2
 115         subcc           gr2,gr3,gr0,icc0
 116         beq             icc0,#2,__break_return_singlestep
 117
 118         bra             __break_continue
 119
 120
 121 ###############################################################################
 122 #
 123 # handle BREAK instruction in kernel-mode exception epilogue
 124 #
 125 ###############################################################################
 126 __break_return_singlestep:
 127         LEDS            0x100f,gr2
 128
 129         # special break insn requests single-stepping to be turned back on
 130         #               HERE            RETT
 131         # PSR.ET        0               0
 132         # PSR.PS        old PSR.S       ?
 133         # PSR.S         1               1
 134         # BPSR.ET       0               1 (can't have caused orig excep otherwise)
 135         # BPSR.BS       1               old PSR.S
 136         movsg           dcr,gr2
 137         sethi.p         %hi(DCR_SE),gr3
 138         setlo           %lo(DCR_SE),gr3
 139         or              gr2,gr3,gr2
 140         movgs           gr2,dcr
 141
 142         movsg           psr,gr2
 143         andi            gr2,#PSR_PS,gr2
 144         slli            gr2,#11,gr2                     /* PSR.PS -> BPSR.BS */
 145         ori             gr2,#BPSR_BET,gr2               /* 1 -> BPSR.BET */
 146         movgs           gr2,bpsr
 147
 148         # return to the invoker of the original kernel exception
 149         movsg           pcsr,gr2
 150         movgs           gr2,bpcsr
 151
 152         LEDS            0x101f,gr2
 153
 154         ldi             @(gr31,#REG_CCR),gr3
 155         movgs           gr3,ccr
 156         lddi.p          @(gr31,#REG_GR(2)),gr2
 157         xor             gr31,gr31,gr31
 158         movgs           gr0,brr
 159 #ifdef CONFIG_MMU
 160         movsg           scr3,gr31
 161 #endif
 162         rett            #1
 163
 164 ###############################################################################
 165 #
 166 # handle BREAK instruction in TLB-miss handler return path
 167 #
 168 ###############################################################################
 169 #ifdef CONFIG_MMU
 170 __break_return_singlestep_tlbmiss:
 171         LEDS            0x1100,gr2
 172
 173         sethi.p         %hi(__break_tlb_miss_real_return_info),gr3
 174         setlo           %lo(__break_tlb_miss_real_return_info),gr3
 175         lddi            @(gr3,#0),gr2
 176         movgs           gr2,pcsr
 177         movgs           gr3,psr
 178
 179         bra             __break_return_singlestep
 180 #endif
 181
 182
 183 ###############################################################################
 184 #
 185 # handle single stepping into an exception prologue from kernel mode
 186 # - we try and catch it whilst it is still in the main vector table
 187 # - if we catch it there, we have to jump to the fixup handler
 188 #   - there is a fixup table that has a pointer for every 16b slot in the trap
 189 #     table
 190 #
 191 ###############################################################################
 192 __break_step:
 193         LEDS            0x2003,gr2
 194
 195         # external interrupts seem to escape from the trap table before single
 196         # step catches up with them
 197         movsg           bpcsr,gr2
 198         sethi.p         %hi(__entry_kernel_external_interrupt),gr3
 199         setlo           %lo(__entry_kernel_external_interrupt),gr3
 200         subcc.p         gr2,gr3,gr0,icc0
 201         sethi           %hi(__entry_uspace_external_interrupt),gr3
 202         setlo.p         %lo(__entry_uspace_external_interrupt),gr3
 203         beq             icc0,#2,__break_step_kernel_external_interrupt
 204         subcc.p         gr2,gr3,gr0,icc0
 205         sethi           %hi(__entry_kernel_external_interrupt_virtually_disabled),gr3
 206         setlo.p         %lo(__entry_kernel_external_interrupt_virtually_disabled),gr3
 207         beq             icc0,#2,__break_step_uspace_external_interrupt
 208         subcc.p         gr2,gr3,gr0,icc0
 209         sethi           %hi(__entry_kernel_external_interrupt_virtual_reenable),gr3
 210         setlo.p         %lo(__entry_kernel_external_interrupt_virtual_reenable),gr3
 211         beq             icc0,#2,__break_step_kernel_external_interrupt_virtually_disabled
 212         subcc           gr2,gr3,gr0,icc0
 213         beq             icc0,#2,__break_step_kernel_external_interrupt_virtual_reenable
 214
 215         LEDS            0x2007,gr2
 216
 217         # the two main vector tables are adjacent on one 8Kb slab
 218         movsg           bpcsr,gr2
 219         setlos          #0xffffe000,gr3
 220         and             gr2,gr3,gr2
 221         sethi.p         %hi(__trap_tables),gr3
 222         setlo           %lo(__trap_tables),gr3
 223         subcc           gr2,gr3,gr0,icc0
 224         bne             icc0,#2,__break_continue
 225
 226         LEDS            0x200f,gr2
 227
 228         # skip workaround if so requested by GDB
 229         sethi.p         %hi(__break_trace_through_exceptions),gr3
 230         setlo           %lo(__break_trace_through_exceptions),gr3
 231         ld              @(gr3,gr0),gr3
 232         subcc           gr3,gr0,gr0,icc0
 233         bne             icc0,#0,__break_continue
 234
 235         LEDS            0x201f,gr2
 236
 237         # access the fixup table - there's a 1:1 mapping between the slots in the trap tables and
 238         # the slots in the trap fixup tables allowing us to simply divide the offset into the
 239         # former by 4 to access the latter
 240         sethi.p         %hi(__trap_tables),gr3
 241         setlo           %lo(__trap_tables),gr3
 242         movsg           bpcsr,gr2
 243         sub             gr2,gr3,gr2
 244         srli.p          gr2,#2,gr2
 245
 246         sethi           %hi(__trap_fixup_tables),gr3
 247         setlo.p         %lo(__trap_fixup_tables),gr3
 248         andi            gr2,#~3,gr2
 249         ld              @(gr2,gr3),gr2
 250         jmpil           @(gr2,#0)
 251
 252 # step through an internal exception from kernel mode
 253         .globl          __break_step_kernel_softprog_interrupt
 254 __break_step_kernel_softprog_interrupt:
 255         sethi.p         %hi(__entry_kernel_softprog_interrupt_reentry),gr3
 256         setlo           %lo(__entry_kernel_softprog_interrupt_reentry),gr3
 257         bra             __break_return_as_kernel_prologue
 258
 259 # step through an external interrupt from kernel mode
 260         .globl          __break_step_kernel_external_interrupt
 261 __break_step_kernel_external_interrupt:
 262         # deal with virtual interrupt disablement
 263         beq             icc2,#0,__break_step_kernel_external_interrupt_virtually_disabled
 264
 265         sethi.p         %hi(__entry_kernel_external_interrupt_reentry),gr3
 266         setlo           %lo(__entry_kernel_external_interrupt_reentry),gr3
 267
 268 __break_return_as_kernel_prologue:
 269         LEDS            0x203f,gr2
 270
 271         movgs           gr3,bpcsr
 272
 273         # do the bit we had to skip
 274 #ifdef CONFIG_MMU
 275         movsg           ear0,gr2                /* EAR0 can get clobbered by gdb-stub (ICI/ICEI) */
 276         movgs           gr2,scr2
 277 #endif
 278
 279         or.p            sp,gr0,gr2              /* set up the stack pointer */
 280         subi            sp,#REG__END,sp
 281         sti.p           gr2,@(sp,#REG_SP)
 282
 283         setlos          #REG__STATUS_STEP,gr2
 284         sti             gr2,@(sp,#REG__STATUS)          /* record single step status */
 285
 286         # cancel single-stepping mode
 287         movsg           dcr,gr2
 288         sethi.p         %hi(~DCR_SE),gr3
 289         setlo           %lo(~DCR_SE),gr3
 290         and             gr2,gr3,gr2
 291         movgs           gr2,dcr
 292
 293         LEDS            0x207f,gr2
 294
 295         ldi             @(gr31,#REG_CCR),gr3
 296         movgs           gr3,ccr
 297         lddi.p          @(gr31,#REG_GR(2)),gr2
 298         xor             gr31,gr31,gr31
 299         movgs           gr0,brr
 300 #ifdef CONFIG_MMU
 301         movsg           scr3,gr31
 302 #endif
 303         rett            #1
 304
 305 # we single-stepped into an interrupt handler whilst interrupts were merely virtually disabled
 306 # need to really disable interrupts, set flag, fix up and return
 307 __break_step_kernel_external_interrupt_virtually_disabled:
 308         movsg           psr,gr2
 309         andi            gr2,#~PSR_PIL,gr2
 310         ori             gr2,#PSR_PIL_14,gr2     /* debugging interrupts only */
 311         movgs           gr2,psr
 312
 313         ldi             @(gr31,#REG_CCR),gr3
 314         movgs           gr3,ccr
 315         subcc.p         gr0,gr0,gr0,icc2        /* leave Z set, clear C */
 316
 317         # exceptions must've been enabled and we must've been in supervisor mode
 318         setlos          BPSR_BET|BPSR_BS,gr3
 319         movgs           gr3,bpsr
 320
 321         # return to where the interrupt happened
 322         movsg           pcsr,gr2
 323         movgs           gr2,bpcsr
 324
 325         lddi.p          @(gr31,#REG_GR(2)),gr2
 326
 327         xor             gr31,gr31,gr31
 328         movgs           gr0,brr
 329 #ifdef CONFIG_MMU
 330         movsg           scr3,gr31
 331 #endif
 332         rett            #1
 333
 334 # we stepped through into the virtual interrupt reenablement trap
 335 #
 336 # we also want to single step anyway, but after fixing up so that we get an event on the
 337 # instruction after the broken-into exception returns
 338         .globl          __break_step_kernel_external_interrupt_virtual_reenable
 339 __break_step_kernel_external_interrupt_virtual_reenable:
 340         movsg           psr,gr2
 341         andi            gr2,#~PSR_PIL,gr2
 342         movgs           gr2,psr
 343
 344         ldi             @(gr31,#REG_CCR),gr3
 345         movgs           gr3,ccr
 346         subicc          gr0,#1,gr0,icc2         /* clear Z, set C */
 347
 348         # save the adjusted ICC2
 349         movsg           ccr,gr3
 350         sti             gr3,@(gr31,#REG_CCR)
 351
 352         # exceptions must've been enabled and we must've been in supervisor mode
 353         setlos          BPSR_BET|BPSR_BS,gr3
 354         movgs           gr3,bpsr
 355
 356         # return to where the trap happened
 357         movsg           pcsr,gr2
 358         movgs           gr2,bpcsr
 359
 360         # and then process the single step
 361         bra             __break_continue
 362
 363 # step through an internal exception from uspace mode
 364         .globl          __break_step_uspace_softprog_interrupt
 365 __break_step_uspace_softprog_interrupt:
 366         sethi.p         %hi(__entry_uspace_softprog_interrupt_reentry),gr3
 367         setlo           %lo(__entry_uspace_softprog_interrupt_reentry),gr3
 368         bra             __break_return_as_uspace_prologue
 369
 370 # step through an external interrupt from kernel mode
 371         .globl          __break_step_uspace_external_interrupt
 372 __break_step_uspace_external_interrupt:
 373         sethi.p         %hi(__entry_uspace_external_interrupt_reentry),gr3
 374         setlo           %lo(__entry_uspace_external_interrupt_reentry),gr3
 375
 376 __break_return_as_uspace_prologue:
 377         LEDS            0x20ff,gr2
 378
 379         movgs           gr3,bpcsr
 380
 381         # do the bit we had to skip
 382         sethi.p         %hi(__kernel_frame0_ptr),gr28
 383         setlo           %lo(__kernel_frame0_ptr),gr28
 384         ldi.p           @(gr28,#0),gr28
 385
 386         setlos          #REG__STATUS_STEP,gr2
 387         sti             gr2,@(gr28,#REG__STATUS)        /* record single step status */
 388
 389         # cancel single-stepping mode
 390         movsg           dcr,gr2
 391         sethi.p         %hi(~DCR_SE),gr3
 392         setlo           %lo(~DCR_SE),gr3
 393         and             gr2,gr3,gr2
 394         movgs           gr2,dcr
 395
 396         LEDS            0x20fe,gr2
 397
 398         ldi             @(gr31,#REG_CCR),gr3
 399         movgs           gr3,ccr
 400         lddi.p          @(gr31,#REG_GR(2)),gr2
 401         xor             gr31,gr31,gr31
 402         movgs           gr0,brr
 403 #ifdef CONFIG_MMU
 404         movsg           scr3,gr31
 405 #endif
 406         rett            #1
 407
 408 #ifdef CONFIG_MMU
 409 # step through an ITLB-miss handler from user mode
 410         .globl          __break_user_insn_tlb_miss
 411 __break_user_insn_tlb_miss:
 412         # we'll want to try the trap stub again
 413         sethi.p         %hi(__trap_user_insn_tlb_miss),gr2
 414         setlo           %lo(__trap_user_insn_tlb_miss),gr2
 415         movgs           gr2,bpcsr
 416
 417 __break_tlb_miss_common:
 418         LEDS            0x2101,gr2
 419
 420         # cancel single-stepping mode
 421         movsg           dcr,gr2
 422         sethi.p         %hi(~DCR_SE),gr3
 423         setlo           %lo(~DCR_SE),gr3
 424         and             gr2,gr3,gr2
 425         movgs           gr2,dcr
 426
 427         # we'll swap the real return address for one with a BREAK insn so that we can re-enable
 428         # single stepping on return
 429         movsg           pcsr,gr2
 430         sethi.p         %hi(__break_tlb_miss_real_return_info),gr3
 431         setlo           %lo(__break_tlb_miss_real_return_info),gr3
 432         sti             gr2,@(gr3,#0)
 433
 434         sethi.p         %hi(__break_tlb_miss_return_break),gr2
 435         setlo           %lo(__break_tlb_miss_return_break),gr2
 436         movgs           gr2,pcsr
 437
 438         # we also have to fudge PSR because the return BREAK is in kernel space and we want
 439         # to get a BREAK fault not an access violation should the return be to userspace
 440         movsg           psr,gr2
 441         sti.p           gr2,@(gr3,#4)
 442         ori             gr2,#PSR_PS,gr2
 443         movgs           gr2,psr
 444
 445         LEDS            0x2102,gr2
 446
 447         ldi             @(gr31,#REG_CCR),gr3
 448         movgs           gr3,ccr
 449         lddi            @(gr31,#REG_GR(2)),gr2
 450         movsg           scr3,gr31
 451         movgs           gr0,brr
 452         rett            #1
 453
 454 # step through a DTLB-miss handler from user mode
 455         .globl          __break_user_data_tlb_miss
 456 __break_user_data_tlb_miss:
 457         # we'll want to try the trap stub again
 458         sethi.p         %hi(__trap_user_data_tlb_miss),gr2
 459         setlo           %lo(__trap_user_data_tlb_miss),gr2
 460         movgs           gr2,bpcsr
 461         bra             __break_tlb_miss_common
 462
 463 # step through an ITLB-miss handler from kernel mode
 464         .globl          __break_kernel_insn_tlb_miss
 465 __break_kernel_insn_tlb_miss:
 466         # we'll want to try the trap stub again
 467         sethi.p         %hi(__trap_kernel_insn_tlb_miss),gr2
 468         setlo           %lo(__trap_kernel_insn_tlb_miss),gr2
 469         movgs           gr2,bpcsr
 470         bra             __break_tlb_miss_common
 471
 472 # step through a DTLB-miss handler from kernel mode
 473         .globl          __break_kernel_data_tlb_miss
 474 __break_kernel_data_tlb_miss:
 475         # we'll want to try the trap stub again
 476         sethi.p         %hi(__trap_kernel_data_tlb_miss),gr2
 477         setlo           %lo(__trap_kernel_data_tlb_miss),gr2
 478         movgs           gr2,bpcsr
 479         bra             __break_tlb_miss_common
 480 #endif
 481
 482 ###############################################################################
 483 #
 484 # handle debug events originating with userspace
 485 #
 486 ###############################################################################
 487 __break_maybe_userspace:
 488         LEDS            0x3003,gr2
 489
 490         setlos          #BPSR_BS,gr2
 491         andcc           gr3,gr2,gr0,icc0
 492         bne             icc0,#0,__break_continue        /* skip if PSR.S was 1 */
 493
 494         movsg           brr,gr2
 495         andicc          gr2,#BRR_ST|BRR_SB,gr0,icc0
 496         beq             icc0,#0,__break_continue        /* jump if not BREAK or single-step */
 497
 498         LEDS            0x3007,gr2
 499
 500         # do the first part of the exception prologue here
 501         sethi.p         %hi(__kernel_frame0_ptr),gr28
 502         setlo           %lo(__kernel_frame0_ptr),gr28
 503         ldi             @(gr28,#0),gr28
 504         andi            gr28,#~7,gr28
 505
 506         # set up the kernel stack pointer
 507         sti             sp  ,@(gr28,#REG_SP)
 508         ori             gr28,0,sp
 509         sti             gr0 ,@(gr28,#REG_GR(28))
 510
 511         stdi            gr20,@(gr28,#REG_GR(20))
 512         stdi            gr22,@(gr28,#REG_GR(22))
 513
 514         movsg           tbr,gr20
 515         movsg           bpcsr,gr21
 516         movsg           psr,gr22
 517
 518         # determine the exception type and cancel single-stepping mode
 519         or              gr0,gr0,gr23
 520
 521         movsg           dcr,gr2
 522         sethi.p         %hi(DCR_SE),gr3
 523         setlo           %lo(DCR_SE),gr3
 524         andcc           gr2,gr3,gr0,icc0
 525         beq             icc0,#0,__break_no_user_sstep   /* must have been a BREAK insn */
 526
 527         not             gr3,gr3
 528         and             gr2,gr3,gr2
 529         movgs           gr2,dcr
 530         ori             gr23,#REG__STATUS_STEP,gr23
 531
 532 __break_no_user_sstep:
 533         LEDS            0x300f,gr2
 534
 535         movsg           brr,gr2
 536         andi            gr2,#BRR_ST|BRR_SB,gr2
 537         slli            gr2,#1,gr2
 538         or              gr23,gr2,gr23
 539         sti.p           gr23,@(gr28,#REG__STATUS)       /* record single step status */
 540
 541         # adjust the value acquired from TBR - this indicates the exception
 542         setlos          #~TBR_TT,gr2
 543         and.p           gr20,gr2,gr20
 544         setlos          #TBR_TT_BREAK,gr2
 545         or.p            gr20,gr2,gr20
 546
 547         # fudge PSR.PS and BPSR.BS to return to kernel mode through the trap
 548         # table as trap 126
 549         andi            gr22,#~PSR_PS,gr22              /* PSR.PS should be 0 */
 550         movgs           gr22,psr
 551
 552         setlos          #BPSR_BS,gr2                    /* BPSR.BS should be 1 and BPSR.BET 0 */
 553         movgs           gr2,bpsr
 554
 555         # return through remainder of the exception prologue
 556         # - need to load gr23 with return handler address
 557         sethi.p         %hi(__entry_return_from_user_exception),gr23
 558         setlo           %lo(__entry_return_from_user_exception),gr23
 559         sethi.p         %hi(__entry_common),gr3
 560         setlo           %lo(__entry_common),gr3
 561         movgs           gr3,bpcsr
 562
 563         LEDS            0x301f,gr2
 564
 565         ldi             @(gr31,#REG_CCR),gr3
 566         movgs           gr3,ccr
 567         lddi.p          @(gr31,#REG_GR(2)),gr2
 568         xor             gr31,gr31,gr31
 569         movgs           gr0,brr
 570 #ifdef CONFIG_MMU
 571         movsg           scr3,gr31
 572 #endif
 573         rett            #1
 574
 575 ###############################################################################
 576 #
 577 # resume normal debug-mode entry
 578 #
 579 ###############################################################################
 580 __break_continue:
 581         LEDS            0x4003,gr2
 582
 583         # set up the kernel stack pointer
 584         sti             sp,@(gr31,#REG_SP)
 585
 586         sethi.p         %hi(__break_frame_0),sp
 587         setlo           %lo(__break_frame_0),sp
 588
 589         # finish building the exception frame
 590         stdi            gr4 ,@(gr31,#REG_GR(4))
 591         stdi            gr6 ,@(gr31,#REG_GR(6))
 592         stdi            gr8 ,@(gr31,#REG_GR(8))
 593         stdi            gr10,@(gr31,#REG_GR(10))
 594         stdi            gr12,@(gr31,#REG_GR(12))
 595         stdi            gr14,@(gr31,#REG_GR(14))
 596         stdi            gr16,@(gr31,#REG_GR(16))
 597         stdi            gr18,@(gr31,#REG_GR(18))
 598         stdi            gr20,@(gr31,#REG_GR(20))
 599         stdi            gr22,@(gr31,#REG_GR(22))
 600         stdi            gr24,@(gr31,#REG_GR(24))
 601         stdi            gr26,@(gr31,#REG_GR(26))
 602         sti             gr0 ,@(gr31,#REG_GR(28))        /* NULL frame pointer */
 603         sti             gr29,@(gr31,#REG_GR(29))
 604         sti             gr30,@(gr31,#REG_GR(30))
 605         sti             gr8 ,@(gr31,#REG_ORIG_GR8)
 606
 607 #ifdef CONFIG_MMU
 608         movsg           scr3,gr19
 609         sti             gr19,@(gr31,#REG_GR(31))
 610 #endif
 611
 612         movsg           bpsr ,gr19
 613         movsg           tbr  ,gr20
 614         movsg           bpcsr,gr21
 615         movsg           psr  ,gr22
 616         movsg           isr  ,gr23
 617         movsg           cccr ,gr25
 618         movsg           lr   ,gr26
 619         movsg           lcr  ,gr27
 620
 621         andi.p          gr22,#~(PSR_S|PSR_ET),gr5       /* rebuild PSR */
 622         andi            gr19,#PSR_ET,gr4
 623         or.p            gr4,gr5,gr5
 624         srli            gr19,#10,gr4
 625         andi            gr4,#PSR_S,gr4
 626         or.p            gr4,gr5,gr5
 627
 628         setlos          #-1,gr6
 629         sti             gr20,@(gr31,#REG_TBR)
 630         sti             gr21,@(gr31,#REG_PC)
 631         sti             gr5 ,@(gr31,#REG_PSR)
 632         sti             gr23,@(gr31,#REG_ISR)
 633         sti             gr25,@(gr31,#REG_CCCR)
 634         stdi            gr26,@(gr31,#REG_LR)
 635         sti             gr6 ,@(gr31,#REG_SYSCALLNO)
 636
 637         # store CPU-specific regs
 638         movsg           iacc0h,gr4
 639         movsg           iacc0l,gr5
 640         stdi            gr4,@(gr31,#REG_IACC0)
 641
 642         movsg           gner0,gr4
 643         movsg           gner1,gr5
 644         stdi            gr4,@(gr31,#REG_GNER0)
 645
 646         # build the debug register frame
 647         movsg           brr,gr4
 648         movgs           gr0,brr
 649         movsg           nmar,gr5
 650         movsg           dcr,gr6
 651
 652         sethi.p         %hi(__debug_status),gr7
 653         setlo           %lo(__debug_status),gr7
 654
 655         stdi            gr4 ,@(gr7,#DEBUG_BRR)
 656         sti             gr19,@(gr7,#DEBUG_BPSR)
 657         sti.p           gr6 ,@(gr7,#DEBUG_DCR)
 658
 659         # trap exceptions during break handling and disable h/w breakpoints/watchpoints
 660         sethi           %hi(DCR_EBE),gr5
 661         setlo.p         %lo(DCR_EBE),gr5
 662         sethi           %hi(__entry_breaktrap_table),gr4
 663         setlo           %lo(__entry_breaktrap_table),gr4
 664         movgs           gr5,dcr
 665         movgs           gr4,tbr
 666
 667         # set up kernel global registers
 668         sethi.p         %hi(__kernel_current_task),gr5
 669         setlo           %lo(__kernel_current_task),gr5
 670         ld              @(gr5,gr0),gr29
 671         ldi.p           @(gr29,#4),gr15         ; __current_thread_info = current->thread_info
 672
 673         sethi           %hi(_gp),gr16
 674         setlo.p         %lo(_gp),gr16
 675
 676         # make sure we (the kernel) get div-zero and misalignment exceptions
 677         setlos          #ISR_EDE|ISR_DTT_DIVBYZERO|ISR_EMAM_EXCEPTION,gr5
 678         movgs           gr5,isr
 679
 680         # enter the GDB stub
 681         LEDS            0x4007,gr2
 682
 683         or.p            gr0,gr0,fp
 684         call            debug_stub
 685
 686         LEDS            0x403f,gr2
 687
 688         # return from break
 689         lddi            @(gr31,#REG_IACC0),gr4
 690         movgs           gr4,iacc0h
 691         movgs           gr5,iacc0l
 692
 693         lddi            @(gr31,#REG_GNER0),gr4
 694         movgs           gr4,gner0
 695         movgs           gr5,gner1
 696
 697         lddi            @(gr31,#REG_LR)  ,gr26
 698         lddi            @(gr31,#REG_CCR) ,gr24
 699         lddi            @(gr31,#REG_PSR) ,gr22
 700         ldi             @(gr31,#REG_PC)  ,gr21
 701         ldi             @(gr31,#REG_TBR) ,gr20
 702
 703         sethi.p         %hi(__debug_status),gr6
 704         setlo           %lo(__debug_status),gr6
 705         ldi.p           @(gr6,#DEBUG_DCR) ,gr6
 706
 707         andi            gr22,#PSR_S,gr19                /* rebuild BPSR */
 708         andi.p          gr22,#PSR_ET,gr5
 709         slli            gr19,#10,gr19
 710         or              gr5,gr19,gr19
 711
 712         movgs           gr6 ,dcr
 713         movgs           gr19,bpsr
 714         movgs           gr20,tbr
 715         movgs           gr21,bpcsr
 716         movgs           gr23,isr
 717         movgs           gr24,ccr
 718         movgs           gr25,cccr
 719         movgs           gr26,lr
 720         movgs           gr27,lcr
 721
 722         LEDS            0x407f,gr2
 723
 724 #ifdef CONFIG_MMU
 725         ldi             @(gr31,#REG_GR(31)),gr2
 726         movgs           gr2,scr3
 727 #endif
 728
 729         ldi             @(gr31,#REG_GR(30)),gr30
 730         ldi             @(gr31,#REG_GR(29)),gr29
 731         lddi            @(gr31,#REG_GR(26)),gr26
 732         lddi            @(gr31,#REG_GR(24)),gr24
 733         lddi            @(gr31,#REG_GR(22)),gr22
 734         lddi            @(gr31,#REG_GR(20)),gr20
 735         lddi            @(gr31,#REG_GR(18)),gr18
 736         lddi            @(gr31,#REG_GR(16)),gr16
 737         lddi            @(gr31,#REG_GR(14)),gr14
 738         lddi            @(gr31,#REG_GR(12)),gr12
 739         lddi            @(gr31,#REG_GR(10)),gr10
 740         lddi            @(gr31,#REG_GR(8)) ,gr8
 741         lddi            @(gr31,#REG_GR(6)) ,gr6
 742         lddi            @(gr31,#REG_GR(4)) ,gr4
 743         lddi            @(gr31,#REG_GR(2)) ,gr2
 744         ldi.p           @(gr31,#REG_SP)    ,sp
 745
 746         xor             gr31,gr31,gr31
 747         movgs           gr0,brr
 748 #ifdef CONFIG_MMU
 749         movsg           scr3,gr31
 750 #endif
 751         rett            #1
 752
 753 ###################################################################################################
 754 #
 755 # GDB stub "system calls"
 756 #
 757 ###################################################################################################
 758
 759 #ifdef CONFIG_GDBSTUB
 760         # void gdbstub_console_write(struct console *con, const char *p, unsigned n)
 761         .globl          gdbstub_console_write
 762 gdbstub_console_write:
 763         break
 764         bralr
 765 #endif
 766
 767         # GDB stub BUG() trap
 768         # GR8 is the proposed signal number
 769         .globl          __debug_bug_trap
 770 __debug_bug_trap:
 771         break
 772         bralr
 773
 774         # transfer kernel exeception to GDB for handling
 775         .globl          __break_hijack_kernel_event
 776 __break_hijack_kernel_event:
 777         break
 778         .globl          __break_hijack_kernel_event_breaks_here
 779 __break_hijack_kernel_event_breaks_here:
 780         nop
 781
 782 #ifdef CONFIG_MMU
 783         # handle a return from TLB-miss that requires single-step reactivation
 784         .globl          __break_tlb_miss_return_break
 785 __break_tlb_miss_return_break:
 786         break
 787 __break_tlb_miss_return_breaks_here:
 788         nop
 789 #endif
 790
 791         # guard the first .text label in the next file from confusion
 792         nop