arch/avr32/kernel/entry-avr32b.S

   1 /*
   2  * Copyright (C) 2004-2006 Atmel Corporation
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 /*
  10  * This file contains the low-level entry-points into the kernel, that is,
  11  * exception handlers, debug trap handlers, interrupt handlers and the
  12  * system call handler.
  13  */
  14 #include <linux/errno.h>
  15
  16 #include <asm/asm.h>
  17 #include <asm/hardirq.h>
  18 #include <asm/irq.h>
  19 #include <asm/ocd.h>
  20 #include <asm/page.h>
  21 #include <asm/pgtable.h>
  22 #include <asm/ptrace.h>
  23 #include <asm/sysreg.h>
  24 #include <asm/thread_info.h>
  25 #include <asm/unistd.h>
  26
  27 #ifdef CONFIG_PREEMPT
  28 # define preempt_stop           mask_interrupts
  29 #else
  30 # define preempt_stop
  31 # define fault_resume_kernel    fault_restore_all
  32 #endif
  33
  34 #define __MASK(x)       ((1 << (x)) - 1)
  35 #define IRQ_MASK        ((__MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT) | \
  36                          (__MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT))
  37
  38         .section .ex.text,"ax",@progbits
  39         .align  2
  40 exception_vectors:
  41         bral    handle_critical
  42         .align  2
  43         bral    handle_critical
  44         .align  2
  45         bral    do_bus_error_write
  46         .align  2
  47         bral    do_bus_error_read
  48         .align  2
  49         bral    do_nmi_ll
  50         .align  2
  51         bral    handle_address_fault
  52         .align  2
  53         bral    handle_protection_fault
  54         .align  2
  55         bral    handle_debug
  56         .align  2
  57         bral    do_illegal_opcode_ll
  58         .align  2
  59         bral    do_illegal_opcode_ll
  60         .align  2
  61         bral    do_illegal_opcode_ll
  62         .align  2
  63         bral    do_fpe_ll
  64         .align  2
  65         bral    do_illegal_opcode_ll
  66         .align  2
  67         bral    handle_address_fault
  68         .align  2
  69         bral    handle_address_fault
  70         .align  2
  71         bral    handle_protection_fault
  72         .align  2
  73         bral    handle_protection_fault
  74         .align  2
  75         bral    do_dtlb_modified
  76
  77 #define tlbmiss_save    pushm   r0-r3
  78 #define tlbmiss_restore popm    r0-r3
  79
  80         .org    0x50
  81         .global itlb_miss
  82 itlb_miss:
  83         tlbmiss_save
  84         rjmp    tlb_miss_common
  85
  86         .org    0x60
  87 dtlb_miss_read:
  88         tlbmiss_save
  89         rjmp    tlb_miss_common
  90
  91         .org    0x70
  92 dtlb_miss_write:
  93         tlbmiss_save
  94
  95         .global tlb_miss_common
  96         .align  2
  97 tlb_miss_common:
  98         mfsr    r0, SYSREG_TLBEAR
  99         mfsr    r1, SYSREG_PTBR
 100
 101         /*
 102          * First level lookup: The PGD contains virtual pointers to
 103          * the second-level page tables, but they may be NULL if not
 104          * present.
 105          */
 106 pgtbl_lookup:
 107         lsr     r2, r0, PGDIR_SHIFT
 108         ld.w    r3, r1[r2 << 2]
 109         bfextu  r1, r0, PAGE_SHIFT, PGDIR_SHIFT - PAGE_SHIFT
 110         cp.w    r3, 0
 111         breq    page_table_not_present
 112
 113         /* Second level lookup */
 114         ld.w    r2, r3[r1 << 2]
 115         mfsr    r0, SYSREG_TLBARLO
 116         bld     r2, _PAGE_BIT_PRESENT
 117         brcc    page_not_present
 118
 119         /* Mark the page as accessed */
 120         sbr     r2, _PAGE_BIT_ACCESSED
 121         st.w    r3[r1 << 2], r2
 122
 123         /* Drop software flags */
 124         andl    r2, _PAGE_FLAGS_HARDWARE_MASK & 0xffff
 125         mtsr    SYSREG_TLBELO, r2
 126
 127         /* Figure out which entry we want to replace */
 128         mfsr    r1, SYSREG_MMUCR
 129         clz     r2, r0
 130         brcc    1f
 131         mov     r3, -1                  /* All entries have been accessed, */
 132         mov     r2, 0                   /* so start at 0 */
 133         mtsr    SYSREG_TLBARLO, r3      /* and reset TLBAR */
 134
 135 1:      bfins   r1, r2, SYSREG_DRP_OFFSET, SYSREG_DRP_SIZE
 136         mtsr    SYSREG_MMUCR, r1
 137         tlbw
 138
 139         tlbmiss_restore
 140         rete
 141
 142         /* The slow path of the TLB miss handler */
 143         .align  2
 144 page_table_not_present:
 145         /* Do we need to synchronize with swapper_pg_dir? */
 146         bld     r0, 31
 147         brcs    sync_with_swapper_pg_dir
 148
 149 page_not_present:
 150         tlbmiss_restore
 151         sub     sp, 4
 152         stmts   --sp, r0-lr
 153         call    save_full_context_ex
 154         mfsr    r12, SYSREG_ECR
 155         mov     r11, sp
 156         call    do_page_fault
 157         rjmp    ret_from_exception
 158
 159         .align  2
 160 sync_with_swapper_pg_dir:
 161         /*
 162          * If swapper_pg_dir contains a non-NULL second-level page
 163          * table pointer, copy it into the current PGD. If not, we
 164          * must handle it as a full-blown page fault.
 165          *
 166          * Jumping back to pgtbl_lookup causes an unnecessary lookup,
 167          * but it is guaranteed to be a cache hit, it won't happen
 168          * very often, and we absolutely do not want to sacrifice any
 169          * performance in the fast path in order to improve this.
 170          */
 171         mov     r1, lo(swapper_pg_dir)
 172         orh     r1, hi(swapper_pg_dir)
 173         ld.w    r3, r1[r2 << 2]
 174         cp.w    r3, 0
 175         breq    page_not_present
 176         mfsr    r1, SYSREG_PTBR
 177         st.w    r1[r2 << 2], r3
 178         rjmp    pgtbl_lookup
 179
 180         /*
 181          * We currently have two bytes left at this point until we
 182          * crash into the system call handler...
 183          *
 184          * Don't worry, the assembler will let us know.
 185          */
 186
 187
 188         /* ---                    System Call                    --- */
 189
 190         .org    0x100
 191 system_call:
 192 #ifdef CONFIG_PREEMPT
 193         mask_interrupts
 194 #endif
 195         pushm   r12             /* r12_orig */
 196         stmts   --sp, r0-lr
 197
 198         mfsr    r0, SYSREG_RAR_SUP
 199         mfsr    r1, SYSREG_RSR_SUP
 200 #ifdef CONFIG_PREEMPT
 201         unmask_interrupts
 202 #endif
 203         zero_fp
 204         stm     --sp, r0-r1
 205
 206         /* check for syscall tracing */
 207         get_thread_info r0
 208         ld.w    r1, r0[TI_flags]
 209         bld     r1, TIF_SYSCALL_TRACE
 210         brcs    syscall_trace_enter
 211
 212 syscall_trace_cont:
 213         cp.w    r8, NR_syscalls
 214         brhs    syscall_badsys
 215
 216         lddpc   lr, syscall_table_addr
 217         ld.w    lr, lr[r8 << 2]
 218         mov     r8, r5          /* 5th argument (6th is pushed by stub) */
 219         icall   lr
 220
 221         .global syscall_return
 222 syscall_return:
 223         get_thread_info r0
 224         mask_interrupts         /* make sure we don't miss an interrupt
 225                                    setting need_resched or sigpending
 226                                    between sampling and the rets */
 227
 228         /* Store the return value so that the correct value is loaded below */
 229         stdsp   sp[REG_R12], r12
 230
 231         ld.w    r1, r0[TI_flags]
 232         andl    r1, _TIF_ALLWORK_MASK, COH
 233         brne    syscall_exit_work
 234
 235 syscall_exit_cont:
 236         popm    r8-r9
 237         mtsr    SYSREG_RAR_SUP, r8
 238         mtsr    SYSREG_RSR_SUP, r9
 239         ldmts   sp++, r0-lr
 240         sub     sp, -4          /* r12_orig */
 241         rets
 242
 243         .align  2
 244 syscall_table_addr:
 245         .long   sys_call_table
 246
 247 syscall_badsys:
 248         mov     r12, -ENOSYS
 249         rjmp    syscall_return
 250
 251         .global ret_from_fork
 252 ret_from_fork:
 253         call   schedule_tail
 254
 255         /* check for syscall tracing */
 256         get_thread_info r0
 257         ld.w    r1, r0[TI_flags]
 258         andl    r1, _TIF_ALLWORK_MASK, COH
 259         brne    syscall_exit_work
 260         rjmp    syscall_exit_cont
 261
 262 syscall_trace_enter:
 263         pushm   r8-r12
 264         call    syscall_trace
 265         popm    r8-r12
 266         rjmp    syscall_trace_cont
 267
 268 syscall_exit_work:
 269         bld     r1, TIF_SYSCALL_TRACE
 270         brcc    1f
 271         unmask_interrupts
 272         call    syscall_trace
 273         mask_interrupts
 274         ld.w    r1, r0[TI_flags]
 275
 276 1:      bld     r1, TIF_NEED_RESCHED
 277         brcc    2f
 278         unmask_interrupts
 279         call    schedule
 280         mask_interrupts
 281         ld.w    r1, r0[TI_flags]
 282         rjmp    1b
 283
 284 2:      mov     r2, _TIF_SIGPENDING | _TIF_RESTORE_SIGMASK | _TIF_NOTIFY_RESUME
 285         tst     r1, r2
 286         breq    3f
 287         unmask_interrupts
 288         mov     r12, sp
 289         mov     r11, r0
 290         call    do_notify_resume
 291         mask_interrupts
 292         ld.w    r1, r0[TI_flags]
 293         rjmp    1b
 294
 295 3:      bld     r1, TIF_BREAKPOINT
 296         brcc    syscall_exit_cont
 297         rjmp    enter_monitor_mode
 298
 299         /* This function expects to find offending PC in SYSREG_RAR_EX */
 300         .type   save_full_context_ex, @function
 301         .align  2
 302 save_full_context_ex:
 303         mfsr    r11, SYSREG_RAR_EX
 304         sub     r9, pc, . - debug_trampoline
 305         mfsr    r8, SYSREG_RSR_EX
 306         cp.w    r9, r11
 307         breq    3f
 308         mov     r12, r8
 309         andh    r8, (MODE_MASK >> 16), COH
 310         brne    2f
 311
 312 1:      pushm   r11, r12        /* PC and SR */
 313         unmask_exceptions
 314         ret     r12
 315
 316 2:      sub     r10, sp, -(FRAME_SIZE_FULL - REG_LR)
 317         stdsp   sp[4], r10      /* replace saved SP */
 318         rjmp    1b
 319
 320         /*
 321          * The debug handler set up a trampoline to make us
 322          * automatically enter monitor mode upon return, but since
 323          * we're saving the full context, we must assume that the
 324          * exception handler might want to alter the return address
 325          * and/or status register. So we need to restore the original
 326          * context and enter monitor mode manually after the exception
 327          * has been handled.
 328          */
 329 3:      get_thread_info r8
 330         ld.w    r11, r8[TI_rar_saved]
 331         ld.w    r12, r8[TI_rsr_saved]
 332         rjmp    1b
 333         .size   save_full_context_ex, . - save_full_context_ex
 334
 335         /* Low-level exception handlers */
 336 handle_critical:
 337         /*
 338          * AT32AP700x errata:
 339          *
 340          * After a Java stack overflow or underflow trap, any CPU
 341          * memory access may cause erratic behavior. This will happen
 342          * when the four least significant bits of the JOSP system
 343          * register contains any value between 9 and 15 (inclusive).
 344          *
 345          * Possible workarounds:
 346          *   - Don't use the Java Extension Module
 347          *   - Ensure that the stack overflow and underflow trap
 348          *     handlers do not do any memory access or trigger any
 349          *     exceptions before the overflow/underflow condition is
 350          *     cleared (by incrementing or decrementing the JOSP)
 351          *   - Make sure that JOSP does not contain any problematic
 352          *     value before doing any exception or interrupt
 353          *     processing.
 354          *   - Set up a critical exception handler which writes a
 355          *     known-to-be-safe value, e.g. 4, to JOSP before doing
 356          *     any further processing.
 357          *
 358          * We'll use the last workaround for now since we cannot
 359          * guarantee that user space processes don't use Java mode.
 360          * Non-well-behaving userland will be terminated with extreme
 361          * prejudice.
 362          */
 363 #ifdef CONFIG_CPU_AT32AP700X
 364         /*
 365          * There's a chance we can't touch memory, so temporarily
 366          * borrow PTBR to save the stack pointer while we fix things
 367          * up...
 368          */
 369         mtsr    SYSREG_PTBR, sp
 370         mov     sp, 4
 371         mtsr    SYSREG_JOSP, sp
 372         mfsr    sp, SYSREG_PTBR
 373         sub     pc, -2
 374
 375         /* Push most of pt_regs on stack. We'll do the rest later */
 376         sub     sp, 4
 377         pushm   r0-r12
 378
 379         /* PTBR mirrors current_thread_info()->task->active_mm->pgd */
 380         get_thread_info r0
 381         ld.w    r1, r0[TI_task]
 382         ld.w    r2, r1[TSK_active_mm]
 383         ld.w    r3, r2[MM_pgd]
 384         mtsr    SYSREG_PTBR, r3
 385 #else
 386         sub     sp, 4
 387         pushm   r0-r12
 388 #endif
 389         sub     r0, sp, -(14 * 4)
 390         mov     r1, lr
 391         mfsr    r2, SYSREG_RAR_EX
 392         mfsr    r3, SYSREG_RSR_EX
 393         pushm   r0-r3
 394
 395         mfsr    r12, SYSREG_ECR
 396         mov     r11, sp
 397         call    do_critical_exception
 398
 399         /* We should never get here... */
 400 bad_return:
 401         sub     r12, pc, (. - 1f)
 402         bral    panic
 403         .align  2
 404 1:      .asciz  "Return from critical exception!"
 405
 406         .align  1
 407 do_bus_error_write:
 408         sub     sp, 4
 409         stmts   --sp, r0-lr
 410         call    save_full_context_ex
 411         mov     r11, 1
 412         rjmp    1f
 413
 414 do_bus_error_read:
 415         sub     sp, 4
 416         stmts   --sp, r0-lr
 417         call    save_full_context_ex
 418         mov     r11, 0
 419 1:      mfsr    r12, SYSREG_BEAR
 420         mov     r10, sp
 421         call    do_bus_error
 422         rjmp    ret_from_exception
 423
 424         .align  1
 425 do_nmi_ll:
 426         sub     sp, 4
 427         stmts   --sp, r0-lr
 428         mfsr    r9, SYSREG_RSR_NMI
 429         mfsr    r8, SYSREG_RAR_NMI
 430         bfextu  r0, r9, MODE_SHIFT, 3
 431         brne    2f
 432
 433 1:      pushm   r8, r9  /* PC and SR */
 434         mfsr    r12, SYSREG_ECR
 435         mov     r11, sp
 436         call    do_nmi
 437         popm    r8-r9
 438         mtsr    SYSREG_RAR_NMI, r8
 439         tst     r0, r0
 440         mtsr    SYSREG_RSR_NMI, r9
 441         brne    3f
 442
 443         ldmts   sp++, r0-lr
 444         sub     sp, -4          /* skip r12_orig */
 445         rete
 446
 447 2:      sub     r10, sp, -(FRAME_SIZE_FULL - REG_LR)
 448         stdsp   sp[4], r10      /* replace saved SP */
 449         rjmp    1b
 450
 451 3:      popm    lr
 452         sub     sp, -4          /* skip sp */
 453         popm    r0-r12
 454         sub     sp, -4          /* skip r12_orig */
 455         rete
 456
 457 handle_address_fault:
 458         sub     sp, 4
 459         stmts   --sp, r0-lr
 460         call    save_full_context_ex
 461         mfsr    r12, SYSREG_ECR
 462         mov     r11, sp
 463         call    do_address_exception
 464         rjmp    ret_from_exception
 465
 466 handle_protection_fault:
 467         sub     sp, 4
 468         stmts   --sp, r0-lr
 469         call    save_full_context_ex
 470         mfsr    r12, SYSREG_ECR
 471         mov     r11, sp
 472         call    do_page_fault
 473         rjmp    ret_from_exception
 474
 475         .align  1
 476 do_illegal_opcode_ll:
 477         sub     sp, 4
 478         stmts   --sp, r0-lr
 479         call    save_full_context_ex
 480         mfsr    r12, SYSREG_ECR
 481         mov     r11, sp
 482         call    do_illegal_opcode
 483         rjmp    ret_from_exception
 484
 485 do_dtlb_modified:
 486         pushm   r0-r3
 487         mfsr    r1, SYSREG_TLBEAR
 488         mfsr    r0, SYSREG_PTBR
 489         lsr     r2, r1, PGDIR_SHIFT
 490         ld.w    r0, r0[r2 << 2]
 491         lsl     r1, (32 - PGDIR_SHIFT)
 492         lsr     r1, (32 - PGDIR_SHIFT) + PAGE_SHIFT
 493
 494         /* Translate to virtual address in P1 */
 495         andl    r0, 0xf000
 496         sbr     r0, 31
 497         add     r2, r0, r1 << 2
 498         ld.w    r3, r2[0]
 499         sbr     r3, _PAGE_BIT_DIRTY
 500         mov     r0, r3
 501         st.w    r2[0], r3
 502
 503         /* The page table is up-to-date. Update the TLB entry as well */
 504         andl    r0, lo(_PAGE_FLAGS_HARDWARE_MASK)
 505         mtsr    SYSREG_TLBELO, r0
 506
 507         /* MMUCR[DRP] is updated automatically, so let's go... */
 508         tlbw
 509
 510         popm    r0-r3
 511         rete
 512
 513 do_fpe_ll:
 514         sub     sp, 4
 515         stmts   --sp, r0-lr
 516         call    save_full_context_ex
 517         unmask_interrupts
 518         mov     r12, 26
 519         mov     r11, sp
 520         call    do_fpe
 521         rjmp    ret_from_exception
 522
 523 ret_from_exception:
 524         mask_interrupts
 525         lddsp   r4, sp[REG_SR]
 526
 527         andh    r4, (MODE_MASK >> 16), COH
 528         brne    fault_resume_kernel
 529
 530         get_thread_info r0
 531         ld.w    r1, r0[TI_flags]
 532         andl    r1, _TIF_WORK_MASK, COH
 533         brne    fault_exit_work
 534
 535 fault_resume_user:
 536         popm    r8-r9
 537         mask_exceptions
 538         mtsr    SYSREG_RAR_EX, r8
 539         mtsr    SYSREG_RSR_EX, r9
 540         ldmts   sp++, r0-lr
 541         sub     sp, -4
 542         rete
 543
 544 fault_resume_kernel:
 545 #ifdef CONFIG_PREEMPT
 546         get_thread_info r0
 547         ld.w    r2, r0[TI_preempt_count]
 548         cp.w    r2, 0
 549         brne    1f
 550         ld.w    r1, r0[TI_flags]
 551         bld     r1, TIF_NEED_RESCHED
 552         brcc    1f
 553         lddsp   r4, sp[REG_SR]
 554         bld     r4, SYSREG_GM_OFFSET
 555         brcs    1f
 556         call    preempt_schedule_irq
 557 1:
 558 #endif
 559
 560         popm    r8-r9
 561         mask_exceptions
 562         mfsr    r1, SYSREG_SR
 563         mtsr    SYSREG_RAR_EX, r8
 564         mtsr    SYSREG_RSR_EX, r9
 565         popm    lr
 566         sub     sp, -4          /* ignore SP */
 567         popm    r0-r12
 568         sub     sp, -4          /* ignore r12_orig */
 569         rete
 570
 571 irq_exit_work:
 572         /* Switch to exception mode so that we can share the same code. */
 573         mfsr    r8, SYSREG_SR
 574         cbr     r8, SYSREG_M0_OFFSET
 575         orh     r8, hi(SYSREG_BIT(M1) | SYSREG_BIT(M2))
 576         mtsr    SYSREG_SR, r8
 577         sub     pc, -2
 578         get_thread_info r0
 579         ld.w    r1, r0[TI_flags]
 580
 581 fault_exit_work:
 582         bld     r1, TIF_NEED_RESCHED
 583         brcc    1f
 584         unmask_interrupts
 585         call    schedule
 586         mask_interrupts
 587         ld.w    r1, r0[TI_flags]
 588         rjmp    fault_exit_work
 589
 590 1:      mov     r2, _TIF_SIGPENDING | _TIF_RESTORE_SIGMASK
 591         tst     r1, r2
 592         breq    2f
 593         unmask_interrupts
 594         mov     r12, sp
 595         mov     r11, r0
 596         call    do_notify_resume
 597         mask_interrupts
 598         ld.w    r1, r0[TI_flags]
 599         rjmp    fault_exit_work
 600
 601 2:      bld     r1, TIF_BREAKPOINT
 602         brcc    fault_resume_user
 603         rjmp    enter_monitor_mode
 604
 605         .section .kprobes.text, "ax", @progbits
 606         .type   handle_debug, @function
 607 handle_debug:
 608         sub     sp, 4           /* r12_orig */
 609         stmts   --sp, r0-lr
 610         mfsr    r8, SYSREG_RAR_DBG
 611         mfsr    r9, SYSREG_RSR_DBG
 612         unmask_exceptions
 613         pushm   r8-r9
 614         bfextu  r9, r9, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
 615         brne    debug_fixup_regs
 616
 617 .Ldebug_fixup_cont:
 618 #ifdef CONFIG_TRACE_IRQFLAGS
 619         call    trace_hardirqs_off
 620 #endif
 621         mov     r12, sp
 622         call    do_debug
 623         mov     sp, r12
 624
 625         lddsp   r2, sp[REG_SR]
 626         bfextu  r3, r2, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
 627         brne    debug_resume_kernel
 628
 629         get_thread_info r0
 630         ld.w    r1, r0[TI_flags]
 631         mov     r2, _TIF_DBGWORK_MASK
 632         tst     r1, r2
 633         brne    debug_exit_work
 634
 635         bld     r1, TIF_SINGLE_STEP
 636         brcc    1f
 637         mfdr    r4, OCD_DC
 638         sbr     r4, OCD_DC_SS_BIT
 639         mtdr    OCD_DC, r4
 640
 641 1:      popm    r10,r11
 642         mask_exceptions
 643         mtsr    SYSREG_RSR_DBG, r11
 644         mtsr    SYSREG_RAR_DBG, r10
 645 #ifdef CONFIG_TRACE_IRQFLAGS
 646         call    trace_hardirqs_on
 647 1:
 648 #endif
 649         ldmts   sp++, r0-lr
 650         sub     sp, -4
 651         retd
 652         .size   handle_debug, . - handle_debug
 653
 654         /* Mode of the trapped context is in r9 */
 655         .type   debug_fixup_regs, @function
 656 debug_fixup_regs:
 657         mfsr    r8, SYSREG_SR
 658         mov     r10, r8
 659         bfins   r8, r9, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
 660         mtsr    SYSREG_SR, r8
 661         sub     pc, -2
 662         stdsp   sp[REG_LR], lr
 663         mtsr    SYSREG_SR, r10
 664         sub     pc, -2
 665         sub     r8, sp, -FRAME_SIZE_FULL
 666         stdsp   sp[REG_SP], r8
 667         rjmp    .Ldebug_fixup_cont
 668         .size   debug_fixup_regs, . - debug_fixup_regs
 669
 670         .type   debug_resume_kernel, @function
 671 debug_resume_kernel:
 672         mask_exceptions
 673         popm    r10, r11
 674         mtsr    SYSREG_RAR_DBG, r10
 675         mtsr    SYSREG_RSR_DBG, r11
 676 #ifdef CONFIG_TRACE_IRQFLAGS
 677         bld     r11, SYSREG_GM_OFFSET
 678         brcc    1f
 679         call    trace_hardirqs_on
 680 1:
 681 #endif
 682         mfsr    r2, SYSREG_SR
 683         mov     r1, r2
 684         bfins   r2, r3, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
 685         mtsr    SYSREG_SR, r2
 686         sub     pc, -2
 687         popm    lr
 688         mtsr    SYSREG_SR, r1
 689         sub     pc, -2
 690         sub     sp, -4          /* skip SP */
 691         popm    r0-r12
 692         sub     sp, -4
 693         retd
 694         .size   debug_resume_kernel, . - debug_resume_kernel
 695
 696         .type   debug_exit_work, @function
 697 debug_exit_work:
 698         /*
 699          * We must return from Monitor Mode using a retd, and we must
 700          * not schedule since that involves the D bit in SR getting
 701          * cleared by something other than the debug hardware. This
 702          * may cause undefined behaviour according to the Architecture
 703          * manual.
 704          *
 705          * So we fix up the return address and status and return to a
 706          * stub below in Exception mode. From there, we can follow the
 707          * normal exception return path.
 708          *
 709          * The real return address and status registers are stored on
 710          * the stack in the way the exception return path understands,
 711          * so no need to fix anything up there.
 712          */
 713         sub     r8, pc, . - fault_exit_work
 714         mtsr    SYSREG_RAR_DBG, r8
 715         mov     r9, 0
 716         orh     r9, hi(SR_EM | SR_GM | MODE_EXCEPTION)
 717         mtsr    SYSREG_RSR_DBG, r9
 718         sub     pc, -2
 719         retd
 720         .size   debug_exit_work, . - debug_exit_work
 721
 722         .set    rsr_int0,       SYSREG_RSR_INT0
 723         .set    rsr_int1,       SYSREG_RSR_INT1
 724         .set    rsr_int2,       SYSREG_RSR_INT2
 725         .set    rsr_int3,       SYSREG_RSR_INT3
 726         .set    rar_int0,       SYSREG_RAR_INT0
 727         .set    rar_int1,       SYSREG_RAR_INT1
 728         .set    rar_int2,       SYSREG_RAR_INT2
 729         .set    rar_int3,       SYSREG_RAR_INT3
 730
 731         .macro  IRQ_LEVEL level
 732         .type   irq_level\level, @function
 733 irq_level\level:
 734         sub     sp, 4           /* r12_orig */
 735         stmts   --sp,r0-lr
 736         mfsr    r8, rar_int\level
 737         mfsr    r9, rsr_int\level
 738
 739 #ifdef CONFIG_PREEMPT
 740         sub     r11, pc, (. - system_call)
 741         cp.w    r11, r8
 742         breq    4f
 743 #endif
 744
 745         pushm   r8-r9
 746
 747         mov     r11, sp
 748         mov     r12, \level
 749
 750         call    do_IRQ
 751
 752         lddsp   r4, sp[REG_SR]
 753         bfextu  r4, r4, SYSREG_M0_OFFSET, 3
 754         cp.w    r4, MODE_SUPERVISOR >> SYSREG_M0_OFFSET
 755         breq    2f
 756         cp.w    r4, MODE_USER >> SYSREG_M0_OFFSET
 757 #ifdef CONFIG_PREEMPT
 758         brne    3f
 759 #else
 760         brne    1f
 761 #endif
 762
 763         get_thread_info r0
 764         ld.w    r1, r0[TI_flags]
 765         andl    r1, _TIF_WORK_MASK, COH
 766         brne    irq_exit_work
 767
 768 1:
 769 #ifdef CONFIG_TRACE_IRQFLAGS
 770         call    trace_hardirqs_on
 771 #endif
 772         popm    r8-r9
 773         mtsr    rar_int\level, r8
 774         mtsr    rsr_int\level, r9
 775         ldmts   sp++,r0-lr
 776         sub     sp, -4          /* ignore r12_orig */
 777         rete
 778
 779 #ifdef CONFIG_PREEMPT
 780 4:      mask_interrupts
 781         mfsr    r8, rsr_int\level
 782         sbr     r8, 16
 783         mtsr    rsr_int\level, r8
 784         ldmts   sp++, r0-lr
 785         sub     sp, -4          /* ignore r12_orig */
 786         rete
 787 #endif
 788
 789 2:      get_thread_info r0
 790         ld.w    r1, r0[TI_flags]
 791         bld     r1, TIF_CPU_GOING_TO_SLEEP
 792 #ifdef CONFIG_PREEMPT
 793         brcc    3f
 794 #else
 795         brcc    1b
 796 #endif
 797         sub     r1, pc, . - cpu_idle_skip_sleep
 798         stdsp   sp[REG_PC], r1
 799 #ifdef CONFIG_PREEMPT
 800 3:      get_thread_info r0
 801         ld.w    r2, r0[TI_preempt_count]
 802         cp.w    r2, 0
 803         brne    1b
 804         ld.w    r1, r0[TI_flags]
 805         bld     r1, TIF_NEED_RESCHED
 806         brcc    1b
 807         lddsp   r4, sp[REG_SR]
 808         bld     r4, SYSREG_GM_OFFSET
 809         brcs    1b
 810         call    preempt_schedule_irq
 811 #endif
 812         rjmp    1b
 813         .endm
 814
 815         .section .irq.text,"ax",@progbits
 816
 817         .global irq_level0
 818         .global irq_level1
 819         .global irq_level2
 820         .global irq_level3
 821         IRQ_LEVEL 0
 822         IRQ_LEVEL 1
 823         IRQ_LEVEL 2
 824         IRQ_LEVEL 3
 825
 826         .section .kprobes.text, "ax", @progbits
 827         .type   enter_monitor_mode, @function
 828 enter_monitor_mode:
 829         /*
 830          * We need to enter monitor mode to do a single step. The
 831          * monitor code will alter the return address so that we
 832          * return directly to the user instead of returning here.
 833          */
 834         breakpoint
 835         rjmp    breakpoint_failed
 836
 837         .size   enter_monitor_mode, . - enter_monitor_mode
 838
 839         .type   debug_trampoline, @function
 840         .global debug_trampoline
 841 debug_trampoline:
 842         /*
 843          * Save the registers on the stack so that the monitor code
 844          * can find them easily.
 845          */
 846         sub     sp, 4           /* r12_orig */
 847         stmts   --sp, r0-lr
 848         get_thread_info r0
 849         ld.w    r8, r0[TI_rar_saved]
 850         ld.w    r9, r0[TI_rsr_saved]
 851         pushm   r8-r9
 852
 853         /*
 854          * The monitor code will alter the return address so we don't
 855          * return here.
 856          */
 857         breakpoint
 858         rjmp    breakpoint_failed
 859         .size   debug_trampoline, . - debug_trampoline
 860
 861         .type breakpoint_failed, @function
 862 breakpoint_failed:
 863         /*
 864          * Something went wrong. Perhaps the debug hardware isn't
 865          * enabled?
 866          */
 867         lda.w   r12, msg_breakpoint_failed
 868         mov     r11, sp
 869         mov     r10, 9          /* SIGKILL */
 870         call    die
 871 1:      rjmp    1b
 872
 873 msg_breakpoint_failed:
 874         .asciz  "Failed to enter Debug Mode"