freebsd-dev/sys/i386/isa/ipl.s
John Baldwin 0f345c4054 Add an optimization where we check hte PS_ASTPENDING and PS_NEEDRESCHED
flags with interrupts disabled to see if we should call ast() during
doreti.  This was mostly submitted by Bruce, but his original patch did
the looping in ast() in assembly rather than in the ast() function itself.
Once we've actually called into the ast() function, it's cheaper to just
loop inside the function rather than returning from the function,
performing the check, and then calling the function again.  However, we
can optimize the first check to avoid calling the function at all.
Other architectures may choose to implement this optimization if they
wish but it is not required for correct operation.

Submitted by:	bde
2001-08-10 23:00:07 +00:00

138 lines
4.1 KiB
ArmAsm

/*-
* 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.
*
* @(#)ipl.s
*
* $FreeBSD$
*/
/*
* AT/386
* Vector interrupt control section
*/
.text
/*
* void doreti(struct trapframe)
*
* Handle return from interrupts, traps and syscalls.
*/
SUPERALIGN_TEXT
.type doreti,@function
doreti:
FAKE_MCOUNT(bintr) /* init "from" bintr -> doreti */
doreti_next:
/* Check if ASTs can be handled now. */
testb $SEL_RPL_MASK,TF_CS(%esp) /* are we in user mode? */
jne doreti_ast /* yes, do it now. */
testl $PSL_VM,TF_EFLAGS(%esp) /* kernel mode */
je doreti_exit /* and not VM86 mode, defer */
cmpl $1,in_vm86call /* are we in a VM86 call? */
je doreti_exit /* no, defer */
doreti_ast:
/*
* Check for ASTs atomically with returning. Disabling CPU
* interrupts provides sufficient locking evein the SMP case,
* since we will be informed of any new ASTs by an IPI.
*/
cli
movl PCPU(CURPROC),%eax
testl $PS_ASTPENDING | PS_NEEDRESCHED,P_SFLAG(%eax)
je doreti_exit
sti
pushl %esp /* pass a pointer to the trapframe */
call ast
add $4,%esp
/*
* doreti_exit: pop registers, iret.
*
* The segment register pop is a special case, since it may
* fault if (for example) a sigreturn specifies bad segment
* registers. The fault is handled in trap.c.
*/
doreti_exit:
MEXITCOUNT
.globl doreti_popl_fs
doreti_popl_fs:
popl %fs
.globl doreti_popl_es
doreti_popl_es:
popl %es
.globl doreti_popl_ds
doreti_popl_ds:
popl %ds
popal
addl $8,%esp
.globl doreti_iret
doreti_iret:
iret
/*
* doreti_iret_fault and friends. Alternative return code for
* the case where we get a fault in the doreti_exit code
* above. trap() (i386/i386/trap.c) catches this specific
* case, sends the process a signal and continues in the
* corresponding place in the code below.
*/
ALIGN_TEXT
.globl doreti_iret_fault
doreti_iret_fault:
subl $8,%esp
pushal
pushl %ds
.globl doreti_popl_ds_fault
doreti_popl_ds_fault:
pushl %es
.globl doreti_popl_es_fault
doreti_popl_es_fault:
pushl %fs
.globl doreti_popl_fs_fault
doreti_popl_fs_fault:
movl $0,TF_ERR(%esp) /* XXX should be the error code */
movl $T_PROTFLT,TF_TRAPNO(%esp)
jmp alltraps_with_regs_pushed
#ifdef APIC_IO
#include "i386/isa/apic_ipl.s"
#else
#include "i386/isa/icu_ipl.s"
#endif /* APIC_IO */