FreeBSD-5.3/sys/i386/i386/swtch.s
/*-
* 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.
* 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.
*
* $FreeBSD: src/sys/i386/i386/swtch.s,v 1.147 2004/07/15 16:37:48 jhb Exp $
*/
#include "opt_npx.h"
#include <machine/asmacros.h>
#include "assym.s"
/*****************************************************************************/
/* Scheduling */
/*****************************************************************************/
.text
/*
* cpu_throw()
*
* This is the second half of cpu_switch(). It is used when the current
* thread is either a dummy or slated to die, and we no longer care
* about its state. This is only a slight optimization and is probably
* not worth it anymore. Note that we need to clear the pm_active bits so
* we do need the old proc if it still exists.
* 0(%esp) = ret
* 4(%esp) = oldtd
* 8(%esp) = newtd
*/
ENTRY(cpu_throw)
movl PCPU(CPUID), %esi
movl 4(%esp),%ecx /* Old thread */
testl %ecx,%ecx /* no thread? */
jz 1f
/* release bit from old pm_active */
movl PCPU(CURPMAP), %ebx
#ifdef SMP
lock
#endif
btrl %esi, PM_ACTIVE(%ebx) /* clear old */
1:
movl 8(%esp),%ecx /* New thread */
movl TD_PCB(%ecx),%edx
movl PCB_CR3(%edx),%eax
movl %eax,%cr3 /* new address space */
/* set bit in new pm_active */
movl TD_PROC(%ecx),%eax
movl P_VMSPACE(%eax), %ebx
addl $VM_PMAP, %ebx
movl %ebx, PCPU(CURPMAP)
#ifdef SMP
lock
#endif
btsl %esi, PM_ACTIVE(%ebx) /* set new */
jmp sw1
/*
* cpu_switch(old, new)
*
* Save the current thread state, then select the next thread to run
* and load its state.
* 0(%esp) = ret
* 4(%esp) = oldtd
* 8(%esp) = newtd
*/
ENTRY(cpu_switch)
/* Switch to new thread. First, save context. */
movl 4(%esp),%ecx
#ifdef INVARIANTS
testl %ecx,%ecx /* no thread? */
jz badsw2 /* no, panic */
#endif
movl TD_PCB(%ecx),%edx
movl (%esp),%eax /* Hardware registers */
movl %eax,PCB_EIP(%edx)
movl %ebx,PCB_EBX(%edx)
movl %esp,PCB_ESP(%edx)
movl %ebp,PCB_EBP(%edx)
movl %esi,PCB_ESI(%edx)
movl %edi,PCB_EDI(%edx)
movl %gs,PCB_GS(%edx)
pushfl /* PSL */
popl PCB_PSL(%edx)
/* Check to see if we need to call a switchout function. */
movl PCB_SWITCHOUT(%edx),%eax
cmpl $0, %eax
je 1f
call *%eax
1:
/* Test if debug registers should be saved. */
testl $PCB_DBREGS,PCB_FLAGS(%edx)
jz 1f /* no, skip over */
movl %dr7,%eax /* yes, do the save */
movl %eax,PCB_DR7(%edx)
andl $0x0000fc00, %eax /* disable all watchpoints */
movl %eax,%dr7
movl %dr6,%eax
movl %eax,PCB_DR6(%edx)
movl %dr3,%eax
movl %eax,PCB_DR3(%edx)
movl %dr2,%eax
movl %eax,PCB_DR2(%edx)
movl %dr1,%eax
movl %eax,PCB_DR1(%edx)
movl %dr0,%eax
movl %eax,PCB_DR0(%edx)
1:
#ifdef DEV_NPX
/* have we used fp, and need a save? */
cmpl %ecx,PCPU(FPCURTHREAD)
jne 1f
addl $PCB_SAVEFPU,%edx /* h/w bugs make saving complicated */
pushl %edx
call npxsave /* do it in a big C function */
popl %eax
1:
#endif
/* Save is done. Now fire up new thread. Leave old vmspace. */
movl %ecx,%edi
movl 8(%esp),%ecx /* New thread */
#ifdef INVARIANTS
testl %ecx,%ecx /* no thread? */
jz badsw3 /* no, panic */
#endif
movl TD_PCB(%ecx),%edx
movl PCPU(CPUID), %esi
/* switch address space */
movl PCB_CR3(%edx),%eax
#ifdef PAE
cmpl %eax,IdlePDPT /* Kernel address space? */
#else
cmpl %eax,IdlePTD /* Kernel address space? */
#endif
je sw1
movl %cr3,%ebx /* The same address space? */
cmpl %ebx,%eax
je sw1
movl %eax,%cr3 /* new address space */
/* Release bit from old pmap->pm_active */
movl PCPU(CURPMAP), %ebx
#ifdef SMP
lock
#endif
btrl %esi, PM_ACTIVE(%ebx) /* clear old */
/* Set bit in new pmap->pm_active */
movl TD_PROC(%ecx),%eax /* newproc */
movl P_VMSPACE(%eax), %ebx
addl $VM_PMAP, %ebx
movl %ebx, PCPU(CURPMAP)
#ifdef SMP
lock
#endif
btsl %esi, PM_ACTIVE(%ebx) /* set new */
sw1:
/*
* At this point, we've switched address spaces and are ready
* to load up the rest of the next context.
*/
cmpl $0, PCB_EXT(%edx) /* has pcb extension? */
je 1f /* If not, use the default */
btsl %esi, private_tss /* mark use of private tss */
movl PCB_EXT(%edx), %edi /* new tss descriptor */
jmp 2f /* Load it up */
1: /*
* Use the common default TSS instead of our own.
* Set our stack pointer into the TSS, it's set to just
* below the PCB. In C, common_tss.tss_esp0 = &pcb - 16;
*/
leal -16(%edx), %ebx /* leave space for vm86 */
movl %ebx, PCPU(COMMON_TSS) + TSS_ESP0
/*
* Test this CPU's bit in the bitmap to see if this
* CPU was using a private TSS.
*/
btrl %esi, private_tss /* Already using the common? */
jae 3f /* if so, skip reloading */
PCPU_ADDR(COMMON_TSSD, %edi)
2:
/* Move correct tss descriptor into GDT slot, then reload tr. */
movl PCPU(TSS_GDT), %ebx /* entry in GDT */
movl 0(%edi), %eax
movl %eax, 0(%ebx)
movl 4(%edi), %eax
movl %eax, 4(%ebx)
movl $GPROC0_SEL*8, %esi /* GSEL(entry, SEL_KPL) */
ltr %si
3:
/* Restore context. */
movl PCB_EBX(%edx),%ebx
movl PCB_ESP(%edx),%esp
movl PCB_EBP(%edx),%ebp
movl PCB_ESI(%edx),%esi
movl PCB_EDI(%edx),%edi
movl PCB_EIP(%edx),%eax
movl %eax,(%esp)
pushl PCB_PSL(%edx)
popfl
movl %edx, PCPU(CURPCB)
movl %ecx, PCPU(CURTHREAD) /* into next thread */
/*
* Determine the LDT to use and load it if is the default one and
* that is not the current one.
*/
movl TD_PROC(%ecx),%eax
cmpl $0,P_MD+MD_LDT(%eax)
jnz 1f
movl _default_ldt,%eax
cmpl PCPU(CURRENTLDT),%eax
je 2f
lldt _default_ldt
movl %eax,PCPU(CURRENTLDT)
jmp 2f
1:
/* Load the LDT when it is not the default one. */
pushl %edx /* Preserve pointer to pcb. */
addl $P_MD,%eax /* Pointer to mdproc is arg. */
pushl %eax
call set_user_ldt
addl $4,%esp
popl %edx
2:
/* This must be done after loading the user LDT. */
.globl cpu_switch_load_gs
cpu_switch_load_gs:
movl PCB_GS(%edx),%gs
/* Test if debug registers should be restored. */
testl $PCB_DBREGS,PCB_FLAGS(%edx)
jz 1f
/*
* Restore debug registers. The special code for dr7 is to
* preserve the current values of its reserved bits.
*/
movl PCB_DR6(%edx),%eax
movl %eax,%dr6
movl PCB_DR3(%edx),%eax
movl %eax,%dr3
movl PCB_DR2(%edx),%eax
movl %eax,%dr2
movl PCB_DR1(%edx),%eax
movl %eax,%dr1
movl PCB_DR0(%edx),%eax
movl %eax,%dr0
movl %dr7,%eax
andl $0x0000fc00,%eax
movl PCB_DR7(%edx),%ecx
andl $~0x0000fc00,%ecx
orl %ecx,%eax
movl %eax,%dr7
1:
ret
#ifdef INVARIANTS
badsw1:
pushal
pushl $sw0_1
call panic
sw0_1: .asciz "cpu_throw: no newthread supplied"
badsw2:
pushal
pushl $sw0_2
call panic
sw0_2: .asciz "cpu_switch: no curthread supplied"
badsw3:
pushal
pushl $sw0_3
call panic
sw0_3: .asciz "cpu_switch: no newthread supplied"
#endif
/*
* savectx(pcb)
* Update pcb, saving current processor state.
*/
ENTRY(savectx)
/* Fetch PCB. */
movl 4(%esp),%ecx
/* Save caller's return address. Child won't execute this routine. */
movl (%esp),%eax
movl %eax,PCB_EIP(%ecx)
movl %cr3,%eax
movl %eax,PCB_CR3(%ecx)
movl %ebx,PCB_EBX(%ecx)
movl %esp,PCB_ESP(%ecx)
movl %ebp,PCB_EBP(%ecx)
movl %esi,PCB_ESI(%ecx)
movl %edi,PCB_EDI(%ecx)
movl %gs,PCB_GS(%ecx)
pushfl
popl PCB_PSL(%ecx)
#ifdef DEV_NPX
/*
* If fpcurthread == NULL, then the npx h/w state is irrelevant and the
* state had better already be in the pcb. This is true for forks
* but not for dumps (the old book-keeping with FP flags in the pcb
* always lost for dumps because the dump pcb has 0 flags).
*
* If fpcurthread != NULL, then we have to save the npx h/w state to
* fpcurthread's pcb and copy it to the requested pcb, or save to the
* requested pcb and reload. Copying is easier because we would
* have to handle h/w bugs for reloading. We used to lose the
* parent's npx state for forks by forgetting to reload.
*/
pushfl
cli
movl PCPU(FPCURTHREAD),%eax
testl %eax,%eax
je 1f
pushl %ecx
movl TD_PCB(%eax),%eax
leal PCB_SAVEFPU(%eax),%eax
pushl %eax
pushl %eax
call npxsave
addl $4,%esp
popl %eax
popl %ecx
pushl $PCB_SAVEFPU_SIZE
leal PCB_SAVEFPU(%ecx),%ecx
pushl %ecx
pushl %eax
call bcopy
addl $12,%esp
1:
popfl
#endif /* DEV_NPX */
ret