root/arch/m68k/kernel/entry.S

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   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/segment.h>
  40 #include <asm/traps.h>
  41 #include <asm/unistd.h>
  42 #include <asm/asm-offsets.h>
  43 #include <asm/entry.h>
  44 
  45 .globl system_call, buserr, trap, resume
  46 .globl sys_call_table
  47 .globl __sys_fork, __sys_clone, __sys_vfork
  48 .globl bad_interrupt
  49 .globl auto_irqhandler_fixup
  50 .globl user_irqvec_fixup
  51 
  52 .text
  53 ENTRY(__sys_fork)
  54         SAVE_SWITCH_STACK
  55         jbsr    sys_fork
  56         lea     %sp@(24),%sp
  57         rts
  58 
  59 ENTRY(__sys_clone)
  60         SAVE_SWITCH_STACK
  61         pea     %sp@(SWITCH_STACK_SIZE)
  62         jbsr    m68k_clone
  63         lea     %sp@(28),%sp
  64         rts
  65 
  66 ENTRY(__sys_vfork)
  67         SAVE_SWITCH_STACK
  68         jbsr    sys_vfork
  69         lea     %sp@(24),%sp
  70         rts
  71 
  72 ENTRY(sys_sigreturn)
  73         SAVE_SWITCH_STACK
  74         movel   %sp,%sp@-                 | switch_stack pointer
  75         pea     %sp@(SWITCH_STACK_SIZE+4) | pt_regs pointer
  76         jbsr    do_sigreturn
  77         addql   #8,%sp
  78         RESTORE_SWITCH_STACK
  79         rts
  80 
  81 ENTRY(sys_rt_sigreturn)
  82         SAVE_SWITCH_STACK
  83         movel   %sp,%sp@-                 | switch_stack pointer
  84         pea     %sp@(SWITCH_STACK_SIZE+4) | pt_regs pointer
  85         jbsr    do_rt_sigreturn
  86         addql   #8,%sp
  87         RESTORE_SWITCH_STACK
  88         rts
  89 
  90 ENTRY(buserr)
  91         SAVE_ALL_INT
  92         GET_CURRENT(%d0)
  93         movel   %sp,%sp@-               | stack frame pointer argument
  94         jbsr    buserr_c
  95         addql   #4,%sp
  96         jra     ret_from_exception
  97 
  98 ENTRY(trap)
  99         SAVE_ALL_INT
 100         GET_CURRENT(%d0)
 101         movel   %sp,%sp@-               | stack frame pointer argument
 102         jbsr    trap_c
 103         addql   #4,%sp
 104         jra     ret_from_exception
 105 
 106         | After a fork we jump here directly from resume,
 107         | so that %d1 contains the previous task
 108         | schedule_tail now used regardless of CONFIG_SMP
 109 ENTRY(ret_from_fork)
 110         movel   %d1,%sp@-
 111         jsr     schedule_tail
 112         addql   #4,%sp
 113         jra     ret_from_exception
 114 
 115 ENTRY(ret_from_kernel_thread)
 116         | a3 contains the kernel thread payload, d7 - its argument
 117         movel   %d1,%sp@-
 118         jsr     schedule_tail
 119         movel   %d7,(%sp)
 120         jsr     %a3@
 121         addql   #4,%sp
 122         jra     ret_from_exception
 123 
 124 #if defined(CONFIG_COLDFIRE) || !defined(CONFIG_MMU)
 125 
 126 #ifdef TRAP_DBG_INTERRUPT
 127 
 128 .globl dbginterrupt
 129 ENTRY(dbginterrupt)
 130         SAVE_ALL_INT
 131         GET_CURRENT(%d0)
 132         movel   %sp,%sp@-               /* stack frame pointer argument */
 133         jsr     dbginterrupt_c
 134         addql   #4,%sp
 135         jra     ret_from_exception
 136 #endif
 137 
 138 ENTRY(reschedule)
 139         /* save top of frame */
 140         pea     %sp@
 141         jbsr    set_esp0
 142         addql   #4,%sp
 143         pea     ret_from_exception
 144         jmp     schedule
 145 
 146 ENTRY(ret_from_user_signal)
 147         moveq #__NR_sigreturn,%d0
 148         trap #0
 149 
 150 ENTRY(ret_from_user_rt_signal)
 151         movel #__NR_rt_sigreturn,%d0
 152         trap #0
 153 
 154 #else
 155 
 156 do_trace_entry:
 157         movel   #-ENOSYS,%sp@(PT_OFF_D0)| needed for strace
 158         subql   #4,%sp
 159         SAVE_SWITCH_STACK
 160         jbsr    syscall_trace
 161         RESTORE_SWITCH_STACK
 162         addql   #4,%sp
 163         movel   %sp@(PT_OFF_ORIG_D0),%d0
 164         cmpl    #NR_syscalls,%d0
 165         jcs     syscall
 166 badsys:
 167         movel   #-ENOSYS,%sp@(PT_OFF_D0)
 168         jra     ret_from_syscall
 169 
 170 do_trace_exit:
 171         subql   #4,%sp
 172         SAVE_SWITCH_STACK
 173         jbsr    syscall_trace
 174         RESTORE_SWITCH_STACK
 175         addql   #4,%sp
 176         jra     .Lret_from_exception
 177 
 178 ENTRY(ret_from_signal)
 179         movel   %curptr@(TASK_STACK),%a1
 180         tstb    %a1@(TINFO_FLAGS+2)
 181         jge     1f
 182         jbsr    syscall_trace
 183 1:      RESTORE_SWITCH_STACK
 184         addql   #4,%sp
 185 /* on 68040 complete pending writebacks if any */
 186 #ifdef CONFIG_M68040
 187         bfextu  %sp@(PT_OFF_FORMATVEC){#0,#4},%d0
 188         subql   #7,%d0                          | bus error frame ?
 189         jbne    1f
 190         movel   %sp,%sp@-
 191         jbsr    berr_040cleanup
 192         addql   #4,%sp
 193 1:
 194 #endif
 195         jra     .Lret_from_exception
 196 
 197 ENTRY(system_call)
 198         SAVE_ALL_SYS
 199 
 200         GET_CURRENT(%d1)
 201         movel   %d1,%a1
 202 
 203         | save top of frame
 204         movel   %sp,%curptr@(TASK_THREAD+THREAD_ESP0)
 205 
 206         | syscall trace?
 207         tstb    %a1@(TINFO_FLAGS+2)
 208         jmi     do_trace_entry
 209         cmpl    #NR_syscalls,%d0
 210         jcc     badsys
 211 syscall:
 212         jbsr    @(sys_call_table,%d0:l:4)@(0)
 213         movel   %d0,%sp@(PT_OFF_D0)     | save the return value
 214 ret_from_syscall:
 215         |oriw   #0x0700,%sr
 216         movel   %curptr@(TASK_STACK),%a1
 217         movew   %a1@(TINFO_FLAGS+2),%d0
 218         jne     syscall_exit_work
 219 1:      RESTORE_ALL
 220 
 221 syscall_exit_work:
 222         btst    #5,%sp@(PT_OFF_SR)      | check if returning to kernel
 223         bnes    1b                      | if so, skip resched, signals
 224         lslw    #1,%d0
 225         jcs     do_trace_exit
 226         jmi     do_delayed_trace
 227         lslw    #8,%d0
 228         jne     do_signal_return
 229         pea     resume_userspace
 230         jra     schedule
 231 
 232 
 233 ENTRY(ret_from_exception)
 234 .Lret_from_exception:
 235         btst    #5,%sp@(PT_OFF_SR)      | check if returning to kernel
 236         bnes    1f                      | if so, skip resched, signals
 237         | only allow interrupts when we are really the last one on the
 238         | kernel stack, otherwise stack overflow can occur during
 239         | heavy interrupt load
 240         andw    #ALLOWINT,%sr
 241 
 242 resume_userspace:
 243         movel   %curptr@(TASK_STACK),%a1
 244         moveb   %a1@(TINFO_FLAGS+3),%d0
 245         jne     exit_work
 246 1:      RESTORE_ALL
 247 
 248 exit_work:
 249         | save top of frame
 250         movel   %sp,%curptr@(TASK_THREAD+THREAD_ESP0)
 251         lslb    #1,%d0
 252         jne     do_signal_return
 253         pea     resume_userspace
 254         jra     schedule
 255 
 256 
 257 do_signal_return:
 258         |andw   #ALLOWINT,%sr
 259         subql   #4,%sp                  | dummy return address
 260         SAVE_SWITCH_STACK
 261         pea     %sp@(SWITCH_STACK_SIZE)
 262         bsrl    do_notify_resume
 263         addql   #4,%sp
 264         RESTORE_SWITCH_STACK
 265         addql   #4,%sp
 266         jbra    resume_userspace
 267 
 268 do_delayed_trace:
 269         bclr    #7,%sp@(PT_OFF_SR)      | clear trace bit in SR
 270         pea     1                       | send SIGTRAP
 271         movel   %curptr,%sp@-
 272         pea     LSIGTRAP
 273         jbsr    send_sig
 274         addql   #8,%sp
 275         addql   #4,%sp
 276         jbra    resume_userspace
 277 
 278 
 279 /* This is the main interrupt handler for autovector interrupts */
 280 
 281 ENTRY(auto_inthandler)
 282         SAVE_ALL_INT
 283         GET_CURRENT(%d0)
 284                                         |  put exception # in d0
 285         bfextu  %sp@(PT_OFF_FORMATVEC){#4,#10},%d0
 286         subw    #VEC_SPUR,%d0
 287 
 288         movel   %sp,%sp@-
 289         movel   %d0,%sp@-               |  put vector # on stack
 290 auto_irqhandler_fixup = . + 2
 291         jsr     do_IRQ                  |  process the IRQ
 292         addql   #8,%sp                  |  pop parameters off stack
 293         jra     ret_from_exception
 294 
 295 /* Handler for user defined interrupt vectors */
 296 
 297 ENTRY(user_inthandler)
 298         SAVE_ALL_INT
 299         GET_CURRENT(%d0)
 300                                         |  put exception # in d0
 301         bfextu  %sp@(PT_OFF_FORMATVEC){#4,#10},%d0
 302 user_irqvec_fixup = . + 2
 303         subw    #VEC_USER,%d0
 304 
 305         movel   %sp,%sp@-
 306         movel   %d0,%sp@-               |  put vector # on stack
 307         jsr     do_IRQ                  |  process the IRQ
 308         addql   #8,%sp                  |  pop parameters off stack
 309         jra     ret_from_exception
 310 
 311 /* Handler for uninitialized and spurious interrupts */
 312 
 313 ENTRY(bad_inthandler)
 314         SAVE_ALL_INT
 315         GET_CURRENT(%d0)
 316 
 317         movel   %sp,%sp@-
 318         jsr     handle_badint
 319         addql   #4,%sp
 320         jra     ret_from_exception
 321 
 322 resume:
 323         /*
 324          * Beware - when entering resume, prev (the current task) is
 325          * in a0, next (the new task) is in a1,so don't change these
 326          * registers until their contents are no longer needed.
 327          */
 328 
 329         /* save sr */
 330         movew   %sr,%a0@(TASK_THREAD+THREAD_SR)
 331 
 332         /* save fs (sfc,%dfc) (may be pointing to kernel memory) */
 333         movec   %sfc,%d0
 334         movew   %d0,%a0@(TASK_THREAD+THREAD_FS)
 335 
 336         /* save usp */
 337         /* it is better to use a movel here instead of a movew 8*) */
 338         movec   %usp,%d0
 339         movel   %d0,%a0@(TASK_THREAD+THREAD_USP)
 340 
 341         /* save non-scratch registers on stack */
 342         SAVE_SWITCH_STACK
 343 
 344         /* save current kernel stack pointer */
 345         movel   %sp,%a0@(TASK_THREAD+THREAD_KSP)
 346 
 347         /* save floating point context */
 348 #ifndef CONFIG_M68KFPU_EMU_ONLY
 349 #ifdef CONFIG_M68KFPU_EMU
 350         tstl    m68k_fputype
 351         jeq     3f
 352 #endif
 353         fsave   %a0@(TASK_THREAD+THREAD_FPSTATE)
 354 
 355 #if defined(CONFIG_M68060)
 356 #if !defined(CPU_M68060_ONLY)
 357         btst    #3,m68k_cputype+3
 358         beqs    1f
 359 #endif
 360         /* The 060 FPU keeps status in bits 15-8 of the first longword */
 361         tstb    %a0@(TASK_THREAD+THREAD_FPSTATE+2)
 362         jeq     3f
 363 #if !defined(CPU_M68060_ONLY)
 364         jra     2f
 365 #endif
 366 #endif /* CONFIG_M68060 */
 367 #if !defined(CPU_M68060_ONLY)
 368 1:      tstb    %a0@(TASK_THREAD+THREAD_FPSTATE)
 369         jeq     3f
 370 #endif
 371 2:      fmovemx %fp0-%fp7,%a0@(TASK_THREAD+THREAD_FPREG)
 372         fmoveml %fpcr/%fpsr/%fpiar,%a0@(TASK_THREAD+THREAD_FPCNTL)
 373 3:
 374 #endif  /* CONFIG_M68KFPU_EMU_ONLY */
 375         /* Return previous task in %d1 */
 376         movel   %curptr,%d1
 377 
 378         /* switch to new task (a1 contains new task) */
 379         movel   %a1,%curptr
 380 
 381         /* restore floating point context */
 382 #ifndef CONFIG_M68KFPU_EMU_ONLY
 383 #ifdef CONFIG_M68KFPU_EMU
 384         tstl    m68k_fputype
 385         jeq     4f
 386 #endif
 387 #if defined(CONFIG_M68060)
 388 #if !defined(CPU_M68060_ONLY)
 389         btst    #3,m68k_cputype+3
 390         beqs    1f
 391 #endif
 392         /* The 060 FPU keeps status in bits 15-8 of the first longword */
 393         tstb    %a1@(TASK_THREAD+THREAD_FPSTATE+2)
 394         jeq     3f
 395 #if !defined(CPU_M68060_ONLY)
 396         jra     2f
 397 #endif
 398 #endif /* CONFIG_M68060 */
 399 #if !defined(CPU_M68060_ONLY)
 400 1:      tstb    %a1@(TASK_THREAD+THREAD_FPSTATE)
 401         jeq     3f
 402 #endif
 403 2:      fmovemx %a1@(TASK_THREAD+THREAD_FPREG),%fp0-%fp7
 404         fmoveml %a1@(TASK_THREAD+THREAD_FPCNTL),%fpcr/%fpsr/%fpiar
 405 3:      frestore %a1@(TASK_THREAD+THREAD_FPSTATE)
 406 4:
 407 #endif  /* CONFIG_M68KFPU_EMU_ONLY */
 408 
 409         /* restore the kernel stack pointer */
 410         movel   %a1@(TASK_THREAD+THREAD_KSP),%sp
 411 
 412         /* restore non-scratch registers */
 413         RESTORE_SWITCH_STACK
 414 
 415         /* restore user stack pointer */
 416         movel   %a1@(TASK_THREAD+THREAD_USP),%a0
 417         movel   %a0,%usp
 418 
 419         /* restore fs (sfc,%dfc) */
 420         movew   %a1@(TASK_THREAD+THREAD_FS),%a0
 421         movec   %a0,%sfc
 422         movec   %a0,%dfc
 423 
 424         /* restore status register */
 425         movew   %a1@(TASK_THREAD+THREAD_SR),%sr
 426 
 427         rts
 428 
 429 #endif /* CONFIG_MMU && !CONFIG_COLDFIRE */
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