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freebsd-dev/sys/i386/isa/icu.s
Bruce Evans b39b673d37 i386/exception.s, 
Keep track of interrupt nesting level.  It is normally 0
	for syscalls and traps, but is fudged to 1 for their exit
	processing in case they metamorphose into an interrupt
	handler.

i386/genassym.c;
	Remove support for the obsolete pcb_iml and pcb_cmap2.

	Add support for pcb_inl.

i386/swtch.s:
	Fudge the interrupt nesting level across context switches and in
	the idle loop so that the work for preemptive context switches
	gets counted as interrupt time, the work for voluntary context
	switches gets counted mostly as system time (the part when
	curproc == 0 gets counted as interrupt time), and only truly idle
	time gets counted as idle time.

	Remove obsolete support (commented out and otherwise) for pcb_iml.

	Load curpcb just before curproc instead of just after so that
	curpcb is always valid if curproc is.  A few more changes like
	this may fix tracing through context switches.

	Remove obsolete function swtch_to_inactive().

include/cpu.h:
	Use the new interrupt nesting level variable to implement a
	non-fake CLF_INTR() so that accounting for the interrupt state
	works.

	You can use top, iostat or (best) an up to date systat to see
	interrupt overheads.  I see the expected huge interrupt overheads
	for ISA devices (on a 486DX/33, about 55% for an IDE drive
	transferring 1250K/sec and the same for a WD8013EBT network card
	transferring 1100K/sec).  The huge interrupt overheads for serial
	devices are unfortunately normally invisible.

include/pcb.h:
	Remove the obsolete pcb_iml and pcb_cmap2.  Replace them by
	padding to preserve binary compatibility.

	Use part of the new padding for pcb_inl.

isa/icu.s:
isa/vector.s:
	Keep track of interrupt nesting level.
1994-12-03 10:03:19 +00:00

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/*-
* Copyright (c) 1989, 1990 William F. Jolitz.
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*
* @(#)icu.s 7.2 (Berkeley) 5/21/91
*
* $Id: icu.s,v 1.15 1994/09/20 21:35:47 bde Exp $
*/
/*
* AT/386
* Vector interrupt control section
*/
/*
* XXX this file should be named ipl.s. All spls are now soft and the
* only thing related to the hardware icu is that the h/w interrupt
* numbers are used without translation in the masks.
*/
#include <net/netisr.h>
.data
.globl _cpl
_cpl: .long HWI_MASK | SWI_MASK /* current priority (all off) */
.globl _imen
_imen: .long HWI_MASK /* interrupt mask enable (all h/w off) */
.globl _stat_imask
_stat_imask: .long (1 << 8)
.globl _tty_imask
_tty_imask: .long 0
.globl _bio_imask
_bio_imask: .long 0
.globl _net_imask
_net_imask: .long 0
.globl _ipending
_ipending: .long 0
.globl _astpending
_astpending: .long 0 /* tells us an AST needs to be taken */
.globl _netisr
_netisr: .long 0 /* set with bits for which queue to service */
vec:
.long vec0, vec1, vec2, vec3, vec4, vec5, vec6, vec7
.long vec8, vec9, vec10, vec11, vec12, vec13, vec14, vec15
.text
/*
* Handle return from interrupts, traps and syscalls.
*/
SUPERALIGN_TEXT
_doreti:
FAKE_MCOUNT(_bintr) /* init "from" _bintr -> _doreti */
addl $4,%esp /* discard unit number */
popl %eax /* cpl to restore */
doreti_next:
/*
* Check for pending HWIs and SWIs atomically with restoring cpl
* and exiting. The check has to be atomic with exiting to stop
* (ipending & ~cpl) changing from zero to nonzero while we're
* looking at it (this wouldn't be fatal but it would increase
* interrupt latency). Restoring cpl has to be atomic with exiting
* so that the stack cannot pile up (the nesting level of interrupt
* handlers is limited by the number of bits in cpl).
*/
movl %eax,%ecx
notl %ecx
cli
andl _ipending,%ecx
jne doreti_unpend
doreti_exit:
movl %eax,_cpl
decb _intr_nesting_level
MEXITCOUNT
popl %es
popl %ds
popal
addl $8,%esp
iret
ALIGN_TEXT
doreti_unpend:
/*
* Enabling interrupts is safe because we haven't restored cpl yet.
* The locking from the "btrl" test is probably no longer necessary.
* We won't miss any new pending interrupts because we will check
* for them again.
*/
sti
bsfl %ecx,%ecx /* slow, but not worth optimizing */
btrl %ecx,_ipending
jnc doreti_next /* some intr cleared memory copy */
movl ihandlers(,%ecx,4),%edx
testl %edx,%edx
je doreti_next /* "can't happen" */
cmpl $NHWI,%ecx
jae doreti_swi
cli
movl %eax,_cpl
MEXITCOUNT
jmp %edx
ALIGN_TEXT
doreti_swi:
pushl %eax
/*
* The SWI_AST handler has to run at cpl = SWI_AST_MASK and the
* SWI_CLOCK handler at cpl = SWI_CLOCK_MASK, so we have to restore
* all the h/w bits in cpl now and have to worry about stack growth.
* The worst case is currently (30 Jan 1994) 2 SWI handlers nested
* in dying interrupt frames and about 12 HWIs nested in active
* interrupt frames. There are only 4 different SWIs and the HWI
* and SWI masks limit the nesting further.
*/
orl imasks(,%ecx,4),%eax
movl %eax,_cpl
call %edx
popl %eax
jmp doreti_next
ALIGN_TEXT
swi_ast:
addl $8,%esp /* discard raddr & cpl to get trap frame */
testb $SEL_RPL_MASK,TRAPF_CS_OFF(%esp)
je swi_ast_phantom
movl $T_ASTFLT,(2+8+0)*4(%esp)
call _trap
subl %eax,%eax /* recover cpl */
jmp doreti_next
ALIGN_TEXT
swi_ast_phantom:
/*
* These happen when there is an interrupt in a trap handler before
* ASTs can be masked or in an lcall handler before they can be
* masked or after they are unmasked. They could be avoided for
* trap entries by using interrupt gates, and for lcall exits by
* using by using cli, but they are unavoidable for lcall entries.
*/
cli
orl $SWI_AST_PENDING,_ipending
jmp doreti_exit /* SWI_AST is highest so we must be done */
/*
* Interrupt priority mechanism
* -- soft splXX masks with group mechanism (cpl)
* -- h/w masks for currently active or unused interrupts (imen)
* -- ipending = active interrupts currently masked by cpl
*/
ENTRY(splz)
/*
* The caller has restored cpl and checked that (ipending & ~cpl)
* is nonzero. We have to repeat the check since if there is an
* interrupt while we're looking, _doreti processing for the
* interrupt will handle all the unmasked pending interrupts
* because we restored early. We're repeating the calculation
* of (ipending & ~cpl) anyway so that the caller doesn't have
* to pass it, so this only costs one "jne". "bsfl %ecx,%ecx"
* is undefined when %ecx is 0 so we can't rely on the secondary
* btrl tests.
*/
movl _cpl,%eax
splz_next:
/*
* We don't need any locking here. (ipending & ~cpl) cannot grow
* while we're looking at it - any interrupt will shrink it to 0.
*/
movl %eax,%ecx
notl %ecx
andl _ipending,%ecx
jne splz_unpend
ret
ALIGN_TEXT
splz_unpend:
bsfl %ecx,%ecx
btrl %ecx,_ipending
jnc splz_next
movl ihandlers(,%ecx,4),%edx
testl %edx,%edx
je splz_next /* "can't happen" */
cmpl $NHWI,%ecx
jae splz_swi
/*
* We would prefer to call the intr handler directly here but that
* doesn't work for badly behaved handlers that want the interrupt
* frame. Also, there's a problem determining the unit number.
* We should change the interface so that the unit number is not
* determined at config time.
*/
jmp *vec(,%ecx,4)
ALIGN_TEXT
splz_swi:
cmpl $SWI_AST,%ecx
je splz_next /* "can't happen" */
pushl %eax
orl imasks(,%ecx,4),%eax
movl %eax,_cpl
call %edx
popl %eax
movl %eax,_cpl
jmp splz_next
/*
* Fake clock interrupt(s) so that they appear to come from our caller instead
* of from here, so that system profiling works.
* XXX do this more generally (for all vectors; look up the C entry point).
* XXX frame bogusness stops us from just jumping to the C entry point.
*/
ALIGN_TEXT
vec0:
popl %eax /* return address */
pushfl
#define KCSEL 8
pushl $KCSEL
pushl %eax
cli
MEXITCOUNT
jmp _Xintr0 /* XXX might need _Xfastintr0 */
ALIGN_TEXT
vec8:
popl %eax
pushfl
pushl $KCSEL
pushl %eax
cli
MEXITCOUNT
jmp _Xintr8 /* XXX might need _Xfastintr8 */
#define BUILD_VEC(irq_num) \
ALIGN_TEXT ; \
vec/**/irq_num: ; \
int $ICU_OFFSET + (irq_num) ; \
ret
BUILD_VEC(1)
BUILD_VEC(2)
BUILD_VEC(3)
BUILD_VEC(4)
BUILD_VEC(5)
BUILD_VEC(6)
BUILD_VEC(7)
BUILD_VEC(9)
BUILD_VEC(10)
BUILD_VEC(11)
BUILD_VEC(12)
BUILD_VEC(13)
BUILD_VEC(14)
BUILD_VEC(15)
ALIGN_TEXT
.globl _dummynetisr
_dummynetisr:
MCOUNT
ret
.data
.globl _netisrs
_netisrs:
.long _dummynetisr, _dummynetisr, _dummynetisr, _dummynetisr
.long _dummynetisr, _dummynetisr, _dummynetisr, _dummynetisr
.long _dummynetisr, _dummynetisr, _dummynetisr, _dummynetisr
.long _dummynetisr, _dummynetisr, _dummynetisr, _dummynetisr
.long _dummynetisr, _dummynetisr, _dummynetisr, _dummynetisr
.long _dummynetisr, _dummynetisr, _dummynetisr, _dummynetisr
.long _dummynetisr, _dummynetisr, _dummynetisr, _dummynetisr
.long _dummynetisr, _dummynetisr, _dummynetisr, _dummynetisr
.text
#define DONET(s) ; \
btrl $s,_netisr ; \
jnc 9f ; \
movl $_netisrs+4*s,%eax ; \
call (%eax) ; \
9:
ALIGN_TEXT
swi_net:
MCOUNT
DONET(0) ; DONET(1) ; DONET(2) ; DONET(3) ; DONET(4)
DONET(5) ; DONET(6) ; DONET(7) ; DONET(8) ; DONET(9)
DONET(10) ; DONET(11) ; DONET(12) ; DONET(13) ; DONET(14)
DONET(15) ; DONET(16) ; DONET(17) ; DONET(18) ; DONET(19)
DONET(20) ; DONET(21) ; DONET(22) ; DONET(23) ; DONET(24)
DONET(25) ; DONET(26) ; DONET(27) ; DONET(28) ; DONET(29)
DONET(30) ; DONET(31)
ret
/*
* XXX there should be a registration function to put the handler for the
* attached driver directly in ihandlers. Then this function will go away.
*/
ALIGN_TEXT
swi_tty:
MCOUNT
#include "sio.h"
#if NSIO > 0
jmp _siopoll
#else
ret
#endif
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