/* $NetBSD: locore.s,v 1.69 2022/03/16 20:31:02 andvar Exp $ */
/*
* Copyright (c) 1988 University of Utah.
* Copyright (c) 1980, 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: Utah $Hdr: locore.s 1.66 92/12/22$
* @(#)locore.s 8.6 (Berkeley) 5/27/94
*/
#include "opt_compat_netbsd.h"
#include "opt_compat_sunos.h"
#include "opt_kgdb.h"
#include "opt_lockdebug.h"
#include "assym.h"
#include <machine/asm.h>
#include <machine/trap.h>
| Remember this is a fun project!
.data
GLOBAL(mon_crp)
.long 0,0
| This is for kvm_mkdb, and should be the address of the beginning
| of the kernel text segment (not necessarily the same as kernbase).
.text
GLOBAL(kernel_text)
| This is the entry point, as well as the end of the temporary stack
| used during process switch (one 8K page ending at start)
ASGLOBAL(tmpstk)
ASGLOBAL(start)
| The first step, after disabling interrupts, is to map enough of the kernel
| into high virtual address space so that we can use position dependent code.
| This is a tricky task on the sun3x because the MMU is already enabled and
| the ROM monitor provides no indication of where the root MMU table is mapped.
| Therefore we must use one of the 68030's 'transparent translation' registers
| to define a range in the address space where the MMU translation is
| turned off. Once this is complete we can modify the MMU table directly
| without the need for it to be mapped into virtual memory.
| All code must be position independent until otherwise noted, as the
| boot loader has loaded us into low memory but all the symbols in this
| code have been linked high.
movw #PSL_HIGHIPL,%sr | no interrupts
movl #KERNBASE3X,%a5 | for vtop conversion
lea _C_LABEL(mon_crp),%a0 | where to store the CRP
subl %a5,%a0
| Note: borrowing mon_crp for tt0 setup...
movl #0x3F8107,%a0@ | map the low 1GB v=p with the
.long 0xf0100800 | transparent translation reg0
| [ pmove a0@, tt0 ]
| In order to map the kernel into high memory we will copy the root table
| entry which maps the 16 megabytes of memory starting at 0x0 into the
| entry which maps the 16 megabytes starting at KERNBASE.
pmove %crp,%a0@ | Get monitor CPU root pointer
movl %a0@(4),%a1 | 2nd word is PA of level A table
movl %a1,%a0 | compute the descriptor address
addl #0x3e0,%a1 | for VA starting at KERNBASE
movl %a0@,%a1@ | copy descriptor type
movl %a0@(4),%a1@(4) | copy physical address
| Kernel is now double mapped at zero and KERNBASE.
| Force a long jump to the relocated code (high VA).
movl #IC_CLEAR,%d0 | Flush the I-cache
movc %d0,%cacr
jmp L_high_code:l | long jump
L_high_code:
| We are now running in the correctly relocated kernel, so
| we are no longer restricted to position-independent code.
| It is handy to leave transparent translation enabled while
| for the low 1GB while _bootstrap() is doing its thing.
| Do bootstrap stuff needed before main() gets called.
| Our boot loader leaves a copy of the kernel's exec header
| just before the start of the kernel text segment, so the
| kernel can sanity-check the DDB symbols at [end...esym].
| Pass the struct exec at tmpstk-32 to _bootstrap().
| Also, make sure the initial frame pointer is zero so that
| the backtrace algorithm used by KGDB terminates nicely.
lea _ASM_LABEL(tmpstk)-32,%sp
movl #0,%a6
jsr _C_LABEL(_bootstrap) | See locore2.c
| Now turn off the transparent translation of the low 1GB.
| (this also flushes the ATC)
clrl %sp@-
.long 0xf0170800 | pmove sp@,tt0
addql #4,%sp
| Now that _bootstrap() is done using the PROM functions,
| we can safely set the sfc/dfc to something != FC_CONTROL
moveq #FC_USERD,%d0 | make movs access "user data"
movc %d0,%sfc | space for copyin/copyout
movc %d0,%dfc
| Setup process zero user/kernel stacks.
lea _C_LABEL(lwp0),%a0 | get lwp0
movl %a0@(L_PCB),%a1 | XXXuvm_lwp_getuarea
lea %a1@(USPACE-4),%sp | set SSP to last word
movl #USRSTACK3X-4,%a2
movl %a2,%usp | init user SP
| Note curpcb was already set in _bootstrap().
| Will do fpu initialization during autoconfig (see fpu.c)
| The interrupt vector table and stack are now ready.
| Interrupts will be enabled later, AFTER autoconfiguration
| is finished, to avoid spurrious interrupts.
/*
* Create a fake exception frame so that cpu_lwp_fork() can copy it.
* main() nevers returns; we exit to user mode from a forked process
* later on.
*/
clrw %sp@- | tf_format,tf_vector
clrl %sp@- | tf_pc (filled in later)
movw #PSL_USER,%sp@- | tf_sr for user mode
clrl %sp@- | tf_stackadj
lea %sp@(-64),%sp | tf_regs[16]
movl %a1,%a0@(L_MD_REGS) | lwp0.l_md.md_regs = trapframe
jbsr _C_LABEL(main) | main(&trapframe)
PANIC("main() returned")
| That is all the assembly startup code we need on the sun3x!
| The rest of this is like the hp300/locore.s where possible.
/*
* Trap/interrupt vector routines
*/
#include <m68k/m68k/trap_subr.s>
GLOBAL(buserr)
tstl _C_LABEL(nofault) | device probe?
jeq _C_LABEL(addrerr) | no, handle as usual
movl _C_LABEL(nofault),%sp@- | yes,
jbsr _C_LABEL(longjmp) | longjmp(nofault)
GLOBAL(addrerr)
clrl %sp@- | stack adjust count
moveml #0xFFFF,%sp@- | save user registers
movl %usp,%a0 | save the user SP
movl %a0,%sp@(FR_SP) | in the savearea
lea %sp@(FR_HW),%a1 | grab base of HW berr frame
moveq #0,%d0
movw %a1@(10),%d0 | grab SSW for fault processing
btst #12,%d0 | RB set?
jeq LbeX0 | no, test RC
bset #14,%d0 | yes, must set FB
movw %d0,%a1@(10) | for hardware too
LbeX0:
btst #13,%d0 | RC set?
jeq LbeX1 | no, skip
bset #15,%d0 | yes, must set FC
movw %d0,%a1@(10) | for hardware too
LbeX1:
btst #8,%d0 | data fault?
jeq Lbe0 | no, check for hard cases
movl %a1@(16),%d1 | fault address is as given in frame
jra Lbe10 | thats it
Lbe0:
btst #4,%a1@(6) | long (type B) stack frame?
jne Lbe4 | yes, go handle
movl %a1@(2),%d1 | no, can use save PC
btst #14,%d0 | FB set?
jeq Lbe3 | no, try FC
addql #4,%d1 | yes, adjust address
jra Lbe10 | done
Lbe3:
btst #15,%d0 | FC set?
jeq Lbe10 | no, done
addql #2,%d1 | yes, adjust address
jra Lbe10 | done
Lbe4:
movl %a1@(36),%d1 | long format, use stage B address
btst #15,%d0 | FC set?
jeq Lbe10 | no, all done
subql #2,%d1 | yes, adjust address
Lbe10:
movl %d1,%sp@- | push fault VA
movl %d0,%sp@- | and padded SSW
movw %a1@(6),%d0 | get frame format/vector offset
andw #0x0FFF,%d0 | clear out frame format
cmpw #12,%d0 | address error vector?
jeq Lisaerr | yes, go to it
/* MMU-specific code to determine reason for bus error. */
movl %d1,%a0 | fault address
movl %sp@,%d0 | function code from ssw
btst #8,%d0 | data fault?
jne Lbe10a
movql #1,%d0 | user program access FC
| (we dont separate data/program)
btst #5,%a1@ | supervisor mode?
jeq Lbe10a | if no, done
movql #5,%d0 | else supervisor program access
Lbe10a:
ptestr %d0,%a0@,#7 | do a table search
pmove %psr,%sp@ | save result
movb %sp@,%d1
btst #2,%d1 | invalid? (incl. limit viol and berr)
jeq Lmightnotbemerr | no -> wp check
btst #7,%d1 | is it MMU table berr?
jeq Lismerr | no, must be fast
jra Lisberr1 | real bus err needs not be fast
Lmightnotbemerr:
btst #3,%d1 | write protect bit set?
jeq Lisberr1 | no, must be bus error
movl %sp@,%d0 | ssw into low word of d0
andw #0xc0,%d0 | write protect is set on page:
cmpw #0x40,%d0 | was it read cycle?
jeq Lisberr1 | yes, was not WPE, must be bus err
/* End of MMU-specific bus error code. */
Lismerr:
movl #T_MMUFLT,%sp@- | show that we are an MMU fault
jra _ASM_LABEL(faultstkadj) | and deal with it
Lisaerr:
movl #T_ADDRERR,%sp@- | mark address error
jra _ASM_LABEL(faultstkadj) | and deal with it
Lisberr1:
clrw %sp@ | re-clear pad word
Lisberr:
movl #T_BUSERR,%sp@- | mark bus error
jra _ASM_LABEL(faultstkadj) | and deal with it
/*
* FP exceptions.
*/
GLOBAL(fpfline)
clrl %sp@- | stack adjust count
moveml #0xFFFF,%sp@- | save registers
moveq #T_FPEMULI,%d0 | denote as FP emulation trap
jra _ASM_LABEL(fault) | do it
GLOBAL(fpunsupp)
clrl %sp@- | stack adjust count
moveml #0xFFFF,%sp@- | save registers
moveq #T_FPEMULD,%d0 | denote as FP emulation trap
jra _ASM_LABEL(fault) | do it
/*
* Handles all other FP coprocessor exceptions.
* Note that since some FP exceptions generate mid-instruction frames
* and may cause signal delivery, we need to test for stack adjustment
* after the trap call.
*/
GLOBAL(fpfault)
clrl %sp@- | stack adjust count
moveml #0xFFFF,%sp@- | save user registers
movl %usp,%a0 | and save
movl %a0,%sp@(FR_SP) | the user stack pointer
clrl %sp@- | no VA arg
movl _C_LABEL(curpcb),%a0 | current pcb
lea %a0@(PCB_FPCTX),%a0 | address of FP savearea
fsave %a0@ | save state
tstb %a0@ | null state frame?
jeq Lfptnull | yes, safe
clrw %d0 | no, need to tweak BIU
movb %a0@(1),%d0 | get frame size
bset #3,%a0@(0,%d0:w) | set exc_pend bit of BIU
Lfptnull:
fmovem %fpsr,%sp@- | push fpsr as code argument
frestore %a0@ | restore state
movl #T_FPERR,%sp@- | push type arg
jra _ASM_LABEL(faultstkadj) | call trap and deal with stack cleanup
/*
* Other exceptions only cause four and six word stack frame and require
* no post-trap stack adjustment.
*/
GLOBAL(badtrap)
clrl %sp@- | stack adjust count
moveml #0xFFFF,%sp@- | save std frame regs
jbsr _C_LABEL(straytrap) | report
moveml %sp@+,#0xFFFF | restore regs
addql #4,%sp | stack adjust count
jra _ASM_LABEL(rei) | all done
/*
* Trap 0 is for system calls
*/
GLOBAL(trap0)
clrl %sp@- | stack adjust count
moveml #0xFFFF,%sp@- | save user registers
movl %usp,%a0 | save the user SP
movl %a0,%sp@(FR_SP) | in the savearea
movl %d0,%sp@- | push syscall number
jbsr _C_LABEL(syscall) | handle it
addql #4,%sp | pop syscall arg
movl %sp@(FR_SP),%a0 | grab and restore
movl %a0,%usp | user SP
moveml %sp@+,#0x7FFF | restore most registers
addql #8,%sp | pop SP and stack adjust
jra _ASM_LABEL(rei) | all done
/*
* Trap 12 is the entry point for the cachectl "syscall"
* cachectl(command, addr, length)
* command in d0, addr in a1, length in d1
*/
GLOBAL(trap12)
movl _C_LABEL(curlwp),%a0
movl %a0@(L_PROC),%sp@- | push curproc pointer
movl %d1,%sp@- | push length
movl %a1,%sp@- | push addr
movl %d0,%sp@- | push command
jbsr _C_LABEL(cachectl1) | do it
lea %sp@(16),%sp | pop args
jra _ASM_LABEL(rei) | all done
/*
* Trace (single-step) trap. Kernel-mode is special.
* User mode traps are simply passed on to trap().
*/
GLOBAL(trace)
clrl %sp@- | stack adjust count
moveml #0xFFFF,%sp@-
moveq #T_TRACE,%d0
| Check PSW and see what happen.
| T=0 S=0 (should not happen)
| T=1 S=0 trace trap from user mode
| T=0 S=1 trace trap on a trap instruction
| T=1 S=1 trace trap from system mode (kernel breakpoint)
movw %sp@(FR_HW),%d1 | get PSW
notw %d1 | XXX no support for T0 on 680[234]0
andw #PSL_TS,%d1 | from system mode (T=1, S=1)?
jeq _ASM_LABEL(kbrkpt) | yes, kernel brkpt
jra _ASM_LABEL(fault) | no, user-mode fault
/*
* Trap 15 is used for:
* - GDB breakpoints (in user programs)
* - KGDB breakpoints (in the kernel)
* - trace traps for SUN binaries (not fully supported yet)
* User mode traps are simply passed to trap().
*/
GLOBAL(trap15)
clrl %sp@- | stack adjust count
moveml #0xFFFF,%sp@-
moveq #T_TRAP15,%d0
btst #5,%sp@(FR_HW) | was supervisor mode?
jne _ASM_LABEL(kbrkpt) | yes, kernel brkpt
jra _ASM_LABEL(fault) | no, user-mode fault
ASLOCAL(kbrkpt)
| Kernel-mode breakpoint or trace trap. (%d0=trap_type)
| Save the system sp rather than the user sp.
movw #PSL_HIGHIPL,%sr | lock out interrupts
lea %sp@(FR_SIZE),%a6 | Save stack pointer
movl %a6,%sp@(FR_SP) | from before trap
| If we are not on tmpstk switch to it.
| (so debugger can change the stack pointer)
movl %a6,%d1
cmpl #_ASM_LABEL(tmpstk),%d1
jls Lbrkpt2 | already on tmpstk
| Copy frame to the temporary stack
movl %sp,%a0 | %a0=src
lea _ASM_LABEL(tmpstk)-96,%a1 | %a1=dst
movl %a1,%sp | sp=new frame
moveq #FR_SIZE,%d1
Lbrkpt1:
movl %a0@+,%a1@+
subql #4,%d1
bgt Lbrkpt1
Lbrkpt2:
| Call the trap handler for the kernel debugger.
| Do not call trap() to handle it, so that we can
| set breakpoints in trap() if we want. We know
| the trap type is either T_TRACE or T_BREAKPOINT.
movl %d0,%sp@- | push trap type
jbsr _C_LABEL(trap_kdebug)
addql #4,%sp | pop args
| The stack pointer may have been modified, or
| data below it modified (by kgdb push call),
| so push the hardware frame at the current sp
| before restoring registers and returning.
movl %sp@(FR_SP),%a0 | modified sp
lea %sp@(FR_SIZE),%a1 | end of our frame
movl %a1@-,%a0@- | copy 2 longs with
movl %a1@-,%a0@- | ... predecrement
movl %a0,%sp@(FR_SP) | sp = h/w frame
moveml %sp@+,#0x7FFF | restore all but sp
movl %sp@,%sp | ... and sp
rte | all done
/* Use common m68k sigreturn */
#include <m68k/m68k/sigreturn.s>
/*
* Interrupt handlers. Most are auto-vectored,
* and hard-wired the same way on all sun3 models.
* Format in the stack is:
* %d0,%d1,%a0,%a1, sr, pc, vo
*/
/*
* This is the common auto-vector interrupt handler,
* for which the CPU provides the vector=0x18+level.
* These are installed in the interrupt vector table.
*/
#ifdef __ELF__
.align 4
#else
.align 2
#endif
GLOBAL(_isr_autovec)
INTERRUPT_SAVEREG
jbsr _C_LABEL(isr_autovec)
INTERRUPT_RESTOREREG
jra _ASM_LABEL(rei)
/* clock: see clock.c */
#ifdef __ELF__
.align 4
#else
.align 2
#endif
GLOBAL(_isr_clock)
INTERRUPT_SAVEREG
jbsr _C_LABEL(clock_intr)
INTERRUPT_RESTOREREG
jra _ASM_LABEL(rei)
| Handler for all vectored interrupts (i.e. VME interrupts)
#ifdef __ELF__
.align 4
#else
.align 2
#endif
GLOBAL(_isr_vectored)
INTERRUPT_SAVEREG
jbsr _C_LABEL(isr_vectored)
INTERRUPT_RESTOREREG
jra _ASM_LABEL(rei)
/* interrupt counters (needed by vmstat) */
GLOBAL(intrnames)
.asciz "spur" | 0
.asciz "lev1" | 1
.asciz "lev2" | 2
.asciz "lev3" | 3
.asciz "lev4" | 4
.asciz "clock" | 5
.asciz "lev6" | 6
.asciz "nmi" | 7
GLOBAL(eintrnames)
.data
.even
GLOBAL(intrcnt)
.long 0,0,0,0,0,0,0,0
GLOBAL(eintrcnt)
.text
/*
* Emulation of VAX REI instruction.
*
* This code is (mostly) un-altered from the hp300 code,
* except that sun machines do not need a simulated SIR
* because they have a real software interrupt register.
*
* This code deals with checking for and servicing ASTs
* (profiling, scheduling) and software interrupts (network, softclock).
* We check for ASTs first, just like the VAX. To avoid excess overhead
* the T_ASTFLT handling code will also check for software interrupts so we
* do not have to do it here. After identifying that we need an AST we
* drop the IPL to allow device interrupts.
*
* This code is complicated by the fact that sendsig may have been called
* necessitating a stack cleanup.
*/
ASGLOBAL(rei)
#ifdef DIAGNOSTIC
tstl _C_LABEL(panicstr) | have we panicked?
jne Ldorte | yes, do not make matters worse
#endif
tstl _C_LABEL(astpending) | AST pending?
jeq Ldorte | no, done
Lrei1:
btst #5,%sp@ | yes, are we returning to user mode?
jne Ldorte | no, done
movw #PSL_LOWIPL,%sr | lower SPL
clrl %sp@- | stack adjust
moveml #0xFFFF,%sp@- | save all registers
movl %usp,%a1 | including
movl %a1,%sp@(FR_SP) | the users SP
clrl %sp@- | VA == none
clrl %sp@- | code == none
movl #T_ASTFLT,%sp@- | type == async system trap
pea %sp@(12) | fp == address of trap frame
jbsr _C_LABEL(trap) | go handle it
lea %sp@(16),%sp | pop value args
movl %sp@(FR_SP),%a0 | restore user SP
movl %a0,%usp | from save area
movw %sp@(FR_ADJ),%d0 | need to adjust stack?
jne Laststkadj | yes, go to it
moveml %sp@+,#0x7FFF | no, restore most user regs
addql #8,%sp | toss SP and stack adjust
rte | and do real RTE
Laststkadj:
lea %sp@(FR_HW),%a1 | pointer to HW frame
addql #8,%a1 | source pointer
movl %a1,%a0 | source
addw %d0,%a0 | + hole size = dest pointer
movl %a1@-,%a0@- | copy
movl %a1@-,%a0@- | 8 bytes
movl %a0,%sp@(FR_SP) | new SSP
moveml %sp@+,#0x7FFF | restore user registers
movl %sp@,%sp | and our SP
Ldorte:
rte | real return
/*
* Initialization is at the beginning of this file, because the
* kernel entry point needs to be at zero for compatibility with
* the Sun boot loader. This works on Sun machines because the
* interrupt vector table for reset is NOT at address zero.
* (The MMU has a "boot" bit that forces access to the PROM)
*/
/*
* Use common m68k sigcode.
*/
#include <m68k/m68k/sigcode.s>
#ifdef COMPAT_SUNOS
#include <m68k/m68k/sunos_sigcode.s>
#endif
.text
/*
* Primitives
*/
/*
* Use common m68k support routines.
*/
#include <m68k/m68k/support.s>
/*
* Use common m68k process/lwp switch and context save subroutines.
*/
#define FPCOPROC /* XXX: Temp. Reqd. */
#include <m68k/m68k/switch_subr.s>
/* suline() */
#ifdef DEBUG
.data
ASGLOBAL(fulltflush)
.long 0
ASGLOBAL(fullcflush)
.long 0
.text
#endif
ENTRY(ecacheon)
rts
ENTRY(ecacheoff)
rts
/*
* Get callers current SP value.
* Note that simply taking the address of a local variable in a C function
* doesn't work because callee saved registers may be outside the stack frame
* defined by A6 (e.g. GCC generated code).
*
* [I don't think the ENTRY() macro will do the right thing with this -- glass]
*/
GLOBAL(getsp)
movl %sp,%d0 | get current SP
addql #4,%d0 | compensate for return address
movl %d0,%a0
rts
ENTRY(getvbr)
movc %vbr,%d0
movl %d0,%a0
rts
ENTRY(setvbr)
movl %sp@(4),%d0
movc %d0,%vbr
rts
/*
* Load a new CPU Root Pointer (CRP) into the MMU.
* void loadcrp(struct mmu_rootptr *);
*/
ENTRY(loadcrp)
movl %sp@(4),%a0 | arg1: &CRP
movl #CACHE_CLR,%d0
movc %d0,%cacr | invalidate cache(s)
pflusha | flush entire TLB
pmove %a0@,%crp | load new user root pointer
rts
ENTRY(getcrp)
movl %sp@(4),%a0 | arg1: &crp
pmove %crp,%a0@ | *crpp = %crp
rts
/*
* Get the physical address of the PTE for a given VA.
*/
ENTRY(ptest_addr)
movl %sp@(4),%a1 | VA
ptestr #5,%a1@,#7,%a0 | %a0 = addr of PTE
movl %a0,%d0 | Result in %d0 (not a pointer return)
rts
/*
* Set processor priority level calls. Most are implemented with
* inline asm expansions. However, we need one instantiation here
* in case some non-optimized code makes external references.
* Most places will use the inlined functions param.h supplies.
*/
ENTRY(_getsr)
clrl %d0
movw %sr,%d0
movl %a1,%d0
rts
ENTRY(_spl)
clrl %d0
movw %sr,%d0
movl %sp@(4),%d1
movw %d1,%sr
rts
ENTRY(_splraise)
clrl %d0
movw %sr,%d0
movl %d0,%d1
andl #PSL_HIGHIPL,%d1 | old &= PSL_HIGHIPL
cmpl %sp@(4),%d1 | (old - new)
bge Lsplr
movl %sp@(4),%d1
movw %d1,%sr
Lsplr:
rts
/*
* _delay(unsigned N)
* Delay for at least (N/256) microseconds.
* This routine depends on the variable: delay_divisor
* which should be set based on the CPU clock rate.
* XXX: Currently this is set based on the CPU model,
* XXX: but this should be determined at run time...
*/
GLOBAL(_delay)
| %d0 = arg = (usecs << 8)
movl %sp@(4),%d0
| %d1 = delay_divisor;
movl _C_LABEL(delay_divisor),%d1
jra L_delay /* Jump into the loop! */
/*
* Align the branch target of the loop to a half-line (8-byte)
* boundary to minimize cache effects. This guarantees both
* that there will be no prefetch stalls due to cache line burst
* operations and that the loop will run from a single cache
* half-line.
*/
#ifdef __ELF__
.align 8
#else
.align 3
#endif
L_delay:
subl %d1,%d0
jgt L_delay
rts
| Define some addresses, mostly so DDB can print useful info.
| Not using _C_LABEL() here because these symbols are never
| referenced by any C code, and if the leading underscore
| ever goes away, these lines turn into syntax errors...
.set _KERNBASE3X,KERNBASE3X
.set _MONSTART,SUN3X_MONSTART
.set _PROM_BASE,SUN3X_PROM_BASE
.set _MONEND,SUN3X_MONEND
|The end!