LXR linux/arch/m68k/kernel/entry.S

   1/* -*- mode: asm -*-
   2 *
   3 *  linux/arch/m68k/kernel/entry.S
   4 *
   5 *  Copyright (C) 1991, 1992  Linus Torvalds
   6 *
   7 * This file is subject to the terms and conditions of the GNU General Public
   8 * License.  See the file README.legal in the main directory of this archive
   9 * for more details.
  10 *
  11 * Linux/m68k support by Hamish Macdonald
  12 *
  13 * 68060 fixes by Jesper Skov
  14 *
  15 */
  16
  17/*
  18 * entry.S  contains the system-call and fault low-level handling routines.
  19 * This also contains the timer-interrupt handler, as well as all interrupts
  20 * and faults that can result in a task-switch.
  21 *
  22 * NOTE: This code handles signal-recognition, which happens every time
  23 * after a timer-interrupt and after each system call.
  24 *
  25 */
  26
  27/*
  28 * 12/03/96 Jes: Currently we only support m68k single-cpu systems, so
  29 *               all pointers that used to be 'current' are now entry
  30 *               number 0 in the 'current_set' list.
  31 *
  32 *  6/05/00 RZ:  addedd writeback completion after return from sighandler
  33 *               for 68040
  34 */
  35
  36#include <linux/linkage.h>
  37#include <asm/errno.h>
  38#include <asm/setup.h>
  39#include <asm/traps.h>
  40#include <asm/unistd.h>
  41#include <asm/asm-offsets.h>
  42#include <asm/entry.h>
  43
  44.globl system_call, buserr, trap, resume
  45.globl sys_call_table
  46.globl __sys_fork, __sys_clone, __sys_vfork
  47.globl bad_interrupt
  48.globl auto_irqhandler_fixup
  49.globl user_irqvec_fixup
  50
  51.text
  52ENTRY(__sys_fork)
  53        SAVE_SWITCH_STACK
  54        jbsr    sys_fork
  55        lea     %sp@(24),%sp
  56        rts
  57
  58ENTRY(__sys_clone)
  59        SAVE_SWITCH_STACK
  60        pea     %sp@(SWITCH_STACK_SIZE)
  61        jbsr    m68k_clone
  62        lea     %sp@(28),%sp
  63        rts
  64
  65ENTRY(__sys_vfork)
  66        SAVE_SWITCH_STACK
  67        jbsr    sys_vfork
  68        lea     %sp@(24),%sp
  69        rts
  70
  71ENTRY(__sys_clone3)
  72        SAVE_SWITCH_STACK
  73        pea     %sp@(SWITCH_STACK_SIZE)
  74        jbsr    m68k_clone3
  75        lea     %sp@(28),%sp
  76        rts
  77
  78ENTRY(sys_sigreturn)
  79        SAVE_SWITCH_STACK
  80        movel   %sp,%a1                         | switch_stack pointer
  81        lea     %sp@(SWITCH_STACK_SIZE),%a0     | pt_regs pointer
  82        lea     %sp@(-84),%sp                   | leave a gap
  83        movel   %a1,%sp@-
  84        movel   %a0,%sp@-
  85        jbsr    do_sigreturn
  86        jra     1f                              | shared with rt_sigreturn()
  87
  88ENTRY(sys_rt_sigreturn)
  89        SAVE_SWITCH_STACK
  90        movel   %sp,%a1                         | switch_stack pointer
  91        lea     %sp@(SWITCH_STACK_SIZE),%a0     | pt_regs pointer
  92        lea     %sp@(-84),%sp                   | leave a gap
  93        movel   %a1,%sp@-
  94        movel   %a0,%sp@-
  95        | stack contents:
  96        |   [original pt_regs address] [original switch_stack address]
  97        |   [gap] [switch_stack] [pt_regs] [exception frame]
  98        jbsr    do_rt_sigreturn
  99
 1001:
 101        | stack contents now:
 102        |   [original pt_regs address] [original switch_stack address]
 103        |   [unused part of the gap] [moved switch_stack] [moved pt_regs]
 104        |   [replacement exception frame]
 105        | return value of do_{rt_,}sigreturn() points to moved switch_stack.
 106
 107        movel   %d0,%sp                         | discard the leftover junk
 108        RESTORE_SWITCH_STACK
 109        | stack contents now is just [syscall return address] [pt_regs] [frame]
 110        | return pt_regs.d0
 111        movel   %sp@(PT_OFF_D0+4),%d0
 112        rts
 113
 114ENTRY(buserr)
 115        SAVE_ALL_INT
 116        GET_CURRENT(%d0)
 117        movel   %sp,%sp@-               | stack frame pointer argument
 118        jbsr    buserr_c
 119        addql   #4,%sp
 120        jra     ret_from_exception
 121
 122ENTRY(trap)
 123        SAVE_ALL_INT
 124        GET_CURRENT(%d0)
 125        movel   %sp,%sp@-               | stack frame pointer argument
 126        jbsr    trap_c
 127        addql   #4,%sp
 128        jra     ret_from_exception
 129
 130        | After a fork we jump here directly from resume,
 131        | so that %d1 contains the previous task
 132        | schedule_tail now used regardless of CONFIG_SMP
 133ENTRY(ret_from_fork)
 134        movel   %d1,%sp@-
 135        jsr     schedule_tail
 136        addql   #4,%sp
 137        jra     ret_from_exception
 138
 139ENTRY(ret_from_kernel_thread)
 140        | a3 contains the kernel thread payload, d7 - its argument
 141        movel   %d1,%sp@-
 142        jsr     schedule_tail
 143        movel   %d7,(%sp)
 144        jsr     %a3@
 145        addql   #4,%sp
 146        jra     ret_from_exception
 147
 148#if defined(CONFIG_COLDFIRE) || !defined(CONFIG_MMU)
 149
 150#ifdef TRAP_DBG_INTERRUPT
 151
 152.globl dbginterrupt
 153ENTRY(dbginterrupt)
 154        SAVE_ALL_INT
 155        GET_CURRENT(%d0)
 156        movel   %sp,%sp@-               /* stack frame pointer argument */
 157        jsr     dbginterrupt_c
 158        addql   #4,%sp
 159        jra     ret_from_exception
 160#endif
 161
 162ENTRY(reschedule)
 163        /* save top of frame */
 164        pea     %sp@
 165        jbsr    set_esp0
 166        addql   #4,%sp
 167        pea     ret_from_exception
 168        jmp     schedule
 169
 170ENTRY(ret_from_user_signal)
 171        moveq #__NR_sigreturn,%d0
 172        trap #0
 173
 174ENTRY(ret_from_user_rt_signal)
 175        movel #__NR_rt_sigreturn,%d0
 176        trap #0
 177
 178#else
 179
 180do_trace_entry:
 181        movel   #-ENOSYS,%sp@(PT_OFF_D0)| needed for strace
 182        subql   #4,%sp
 183        SAVE_SWITCH_STACK
 184        jbsr    syscall_trace
 185        RESTORE_SWITCH_STACK
 186        addql   #4,%sp
 187        movel   %sp@(PT_OFF_ORIG_D0),%d0
 188        cmpl    #NR_syscalls,%d0
 189        jcs     syscall
 190badsys:
 191        movel   #-ENOSYS,%sp@(PT_OFF_D0)
 192        jra     ret_from_syscall
 193
 194do_trace_exit:
 195        subql   #4,%sp
 196        SAVE_SWITCH_STACK
 197        jbsr    syscall_trace
 198        RESTORE_SWITCH_STACK
 199        addql   #4,%sp
 200        jra     .Lret_from_exception
 201
 202ENTRY(system_call)
 203        SAVE_ALL_SYS
 204
 205        GET_CURRENT(%d1)
 206        movel   %d1,%a1
 207
 208        | save top of frame
 209        movel   %sp,%curptr@(TASK_THREAD+THREAD_ESP0)
 210
 211        | syscall trace?
 212        tstb    %a1@(TINFO_FLAGS+2)
 213        jmi     do_trace_entry
 214        cmpl    #NR_syscalls,%d0
 215        jcc     badsys
 216syscall:
 217        jbsr    @(sys_call_table,%d0:l:4)@(0)
 218        movel   %d0,%sp@(PT_OFF_D0)     | save the return value
 219ret_from_syscall:
 220        |oriw   #0x0700,%sr
 221        movel   %curptr@(TASK_STACK),%a1
 222        movew   %a1@(TINFO_FLAGS+2),%d0
 223        jne     syscall_exit_work
 2241:      RESTORE_ALL
 225
 226syscall_exit_work:
 227        btst    #5,%sp@(PT_OFF_SR)      | check if returning to kernel
 228        bnes    1b                      | if so, skip resched, signals
 229        lslw    #1,%d0
 230        jcs     do_trace_exit
 231        jmi     do_delayed_trace
 232        lslw    #8,%d0
 233        jne     do_signal_return
 234        pea     resume_userspace
 235        jra     schedule
 236
 237
 238ENTRY(ret_from_exception)
 239.Lret_from_exception:
 240        btst    #5,%sp@(PT_OFF_SR)      | check if returning to kernel
 241        bnes    1f                      | if so, skip resched, signals
 242        | only allow interrupts when we are really the last one on the
 243        | kernel stack, otherwise stack overflow can occur during
 244        | heavy interrupt load
 245        andw    #ALLOWINT,%sr
 246
 247resume_userspace:
 248        movel   %curptr@(TASK_STACK),%a1
 249        moveb   %a1@(TINFO_FLAGS+3),%d0
 250        jne     exit_work
 2511:      RESTORE_ALL
 252
 253exit_work:
 254        | save top of frame
 255        movel   %sp,%curptr@(TASK_THREAD+THREAD_ESP0)
 256        lslb    #1,%d0
 257        jne     do_signal_return
 258        pea     resume_userspace
 259        jra     schedule
 260
 261
 262do_signal_return:
 263        |andw   #ALLOWINT,%sr
 264        subql   #4,%sp                  | dummy return address
 265        SAVE_SWITCH_STACK
 266        pea     %sp@(SWITCH_STACK_SIZE)
 267        bsrl    do_notify_resume
 268        addql   #4,%sp
 269        RESTORE_SWITCH_STACK
 270        addql   #4,%sp
 271        jbra    resume_userspace
 272
 273do_delayed_trace:
 274        bclr    #7,%sp@(PT_OFF_SR)      | clear trace bit in SR
 275        pea     1                       | send SIGTRAP
 276        movel   %curptr,%sp@-
 277        pea     LSIGTRAP
 278        jbsr    send_sig
 279        addql   #8,%sp
 280        addql   #4,%sp
 281        jbra    resume_userspace
 282
 283
 284/* This is the main interrupt handler for autovector interrupts */
 285
 286ENTRY(auto_inthandler)
 287        SAVE_ALL_INT
 288        GET_CURRENT(%d0)
 289                                        |  put exception # in d0
 290        bfextu  %sp@(PT_OFF_FORMATVEC){#4,#10},%d0
 291        subw    #VEC_SPUR,%d0
 292
 293        movel   %sp,%sp@-
 294        movel   %d0,%sp@-               |  put vector # on stack
 295auto_irqhandler_fixup = . + 2
 296        jsr     do_IRQ                  |  process the IRQ
 297        addql   #8,%sp                  |  pop parameters off stack
 298        jra     ret_from_exception
 299
 300/* Handler for user defined interrupt vectors */
 301
 302ENTRY(user_inthandler)
 303        SAVE_ALL_INT
 304        GET_CURRENT(%d0)
 305                                        |  put exception # in d0
 306        bfextu  %sp@(PT_OFF_FORMATVEC){#4,#10},%d0
 307user_irqvec_fixup = . + 2
 308        subw    #VEC_USER,%d0
 309
 310        movel   %sp,%sp@-
 311        movel   %d0,%sp@-               |  put vector # on stack
 312        jsr     do_IRQ                  |  process the IRQ
 313        addql   #8,%sp                  |  pop parameters off stack
 314        jra     ret_from_exception
 315
 316/* Handler for uninitialized and spurious interrupts */
 317
 318ENTRY(bad_inthandler)
 319        SAVE_ALL_INT
 320        GET_CURRENT(%d0)
 321
 322        movel   %sp,%sp@-
 323        jsr     handle_badint
 324        addql   #4,%sp
 325        jra     ret_from_exception
 326
 327resume:
 328        /*
 329         * Beware - when entering resume, prev (the current task) is
 330         * in a0, next (the new task) is in a1,so don't change these
 331         * registers until their contents are no longer needed.
 332         */
 333
 334        /* save sr */
 335        movew   %sr,%a0@(TASK_THREAD+THREAD_SR)
 336
 337        /* save fs (sfc,%dfc) (may be pointing to kernel memory) */
 338        movec   %sfc,%d0
 339        movew   %d0,%a0@(TASK_THREAD+THREAD_FC)
 340
 341        /* save usp */
 342        /* it is better to use a movel here instead of a movew 8*) */
 343        movec   %usp,%d0
 344        movel   %d0,%a0@(TASK_THREAD+THREAD_USP)
 345
 346        /* save non-scratch registers on stack */
 347        SAVE_SWITCH_STACK
 348
 349        /* save current kernel stack pointer */
 350        movel   %sp,%a0@(TASK_THREAD+THREAD_KSP)
 351
 352        /* save floating point context */
 353#ifndef CONFIG_M68KFPU_EMU_ONLY
 354#ifdef CONFIG_M68KFPU_EMU
 355        tstl    m68k_fputype
 356        jeq     3f
 357#endif
 358        fsave   %a0@(TASK_THREAD+THREAD_FPSTATE)
 359
 360#if defined(CONFIG_M68060)
 361#if !defined(CPU_M68060_ONLY)
 362        btst    #3,m68k_cputype+3
 363        beqs    1f
 364#endif
 365        /* The 060 FPU keeps status in bits 15-8 of the first longword */
 366        tstb    %a0@(TASK_THREAD+THREAD_FPSTATE+2)
 367        jeq     3f
 368#if !defined(CPU_M68060_ONLY)
 369        jra     2f
 370#endif
 371#endif /* CONFIG_M68060 */
 372#if !defined(CPU_M68060_ONLY)
 3731:      tstb    %a0@(TASK_THREAD+THREAD_FPSTATE)
 374        jeq     3f
 375#endif
 3762:      fmovemx %fp0-%fp7,%a0@(TASK_THREAD+THREAD_FPREG)
 377        fmoveml %fpcr/%fpsr/%fpiar,%a0@(TASK_THREAD+THREAD_FPCNTL)
 3783:
 379#endif  /* CONFIG_M68KFPU_EMU_ONLY */
 380        /* Return previous task in %d1 */
 381        movel   %curptr,%d1
 382
 383        /* switch to new task (a1 contains new task) */
 384        movel   %a1,%curptr
 385
 386        /* restore floating point context */
 387#ifndef CONFIG_M68KFPU_EMU_ONLY
 388#ifdef CONFIG_M68KFPU_EMU
 389        tstl    m68k_fputype
 390        jeq     4f
 391#endif
 392#if defined(CONFIG_M68060)
 393#if !defined(CPU_M68060_ONLY)
 394        btst    #3,m68k_cputype+3
 395        beqs    1f
 396#endif
 397        /* The 060 FPU keeps status in bits 15-8 of the first longword */
 398        tstb    %a1@(TASK_THREAD+THREAD_FPSTATE+2)
 399        jeq     3f
 400#if !defined(CPU_M68060_ONLY)
 401        jra     2f
 402#endif
 403#endif /* CONFIG_M68060 */
 404#if !defined(CPU_M68060_ONLY)
 4051:      tstb    %a1@(TASK_THREAD+THREAD_FPSTATE)
 406        jeq     3f
 407#endif
 4082:      fmovemx %a1@(TASK_THREAD+THREAD_FPREG),%fp0-%fp7
 409        fmoveml %a1@(TASK_THREAD+THREAD_FPCNTL),%fpcr/%fpsr/%fpiar
 4103:      frestore %a1@(TASK_THREAD+THREAD_FPSTATE)
 4114:
 412#endif  /* CONFIG_M68KFPU_EMU_ONLY */
 413
 414        /* restore the kernel stack pointer */
 415        movel   %a1@(TASK_THREAD+THREAD_KSP),%sp
 416
 417        /* restore non-scratch registers */
 418        RESTORE_SWITCH_STACK
 419
 420        /* restore user stack pointer */
 421        movel   %a1@(TASK_THREAD+THREAD_USP),%a0
 422        movel   %a0,%usp
 423
 424        /* restore fs (sfc,%dfc) */
 425        movew   %a1@(TASK_THREAD+THREAD_FC),%a0
 426        movec   %a0,%sfc
 427        movec   %a0,%dfc
 428
 429        /* restore status register */
 430        movew   %a1@(TASK_THREAD+THREAD_SR),%sr
 431
 432        rts
 433
 434#endif /* CONFIG_MMU && !CONFIG_COLDFIRE */
 435