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/*-
* Copyright (c) 2003 Peter Wemm.
* 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.
*
* $FreeBSD$
*/
#include <machine/asmacros.h>
#include <machine/specialreg.h>
#include "assym.s"
#include "opt_sched.h"
/*****************************************************************************/
/* Scheduling */
/*****************************************************************************/
.text
#ifdef SMP
#define LK lock ;
#else
#define LK
#endif
#if defined(SCHED_ULE) && defined(SMP)
#define SETLK xchgq
#else
#define SETLK movq
#endif
/*
* 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.
* %rdi = oldtd
* %rsi = newtd
*/
ENTRY(cpu_throw)
movl PCPU(CPUID),%eax
testq %rdi,%rdi
jz 1f
/* release bit from old pm_active */
movq PCPU(CURPMAP),%rdx
LK btrl %eax,PM_ACTIVE(%rdx) /* clear old */
1:
movq TD_PCB(%rsi),%r8 /* newtd->td_proc */
movq PCB_CR3(%r8),%rdx
movq %rdx,%cr3 /* new address space */
jmp swact
END(cpu_throw)
/*
* cpu_switch(old, new, mtx)
*
* Save the current thread state, then select the next thread to run
* and load its state.
* %rdi = oldtd
* %rsi = newtd
* %rdx = mtx
*/
ENTRY(cpu_switch)
/* Switch to new thread. First, save context. */
movq TD_PCB(%rdi),%r8
movb $1,PCB_FULL_IRET(%r8)
movq (%rsp),%rax /* Hardware registers */
movq %r15,PCB_R15(%r8)
movq %r14,PCB_R14(%r8)
movq %r13,PCB_R13(%r8)
movq %r12,PCB_R12(%r8)
movq %rbp,PCB_RBP(%r8)
movq %rsp,PCB_RSP(%r8)
movq %rbx,PCB_RBX(%r8)
movq %rax,PCB_RIP(%r8)
testl $PCB_DBREGS,PCB_FLAGS(%r8)
jnz store_dr /* static predict not taken */
done_store_dr:
/* have we used fp, and need a save? */
cmpq %rdi,PCPU(FPCURTHREAD)
jne 1f
movq PCB_SAVEFPU(%r8),%r8
clts
fxsave (%r8)
smsw %ax
orb $CR0_TS,%al
lmsw %ax
xorl %eax,%eax
movq %rax,PCPU(FPCURTHREAD)
1:
/* Save is done. Now fire up new thread. Leave old vmspace. */
movq TD_PCB(%rsi),%r8
/* switch address space */
movq PCB_CR3(%r8),%rcx
movq %cr3,%rax
cmpq %rcx,%rax /* Same address space? */
jne swinact
SETLK %rdx, TD_LOCK(%rdi) /* Release the old thread */
jmp sw1
swinact:
movq %rcx,%cr3 /* new address space */
movl PCPU(CPUID), %eax
/* Release bit from old pmap->pm_active */
movq PCPU(CURPMAP),%rcx
LK btrl %eax,PM_ACTIVE(%rcx) /* clear old */
SETLK %rdx, TD_LOCK(%rdi) /* Release the old thread */
swact:
/* Set bit in new pmap->pm_active */
movq TD_PROC(%rsi),%rdx /* newproc */
movq P_VMSPACE(%rdx), %rdx
addq $VM_PMAP,%rdx
LK btsl %eax,PM_ACTIVE(%rdx) /* set new */
movq %rdx,PCPU(CURPMAP)
sw1:
#if defined(SCHED_ULE) && defined(SMP)
/* Wait for the new thread to become unblocked */
movq $blocked_lock, %rdx
1:
movq TD_LOCK(%rsi),%rcx
cmpq %rcx, %rdx
pause
je 1b
#endif
/*
* At this point, we've switched address spaces and are ready
* to load up the rest of the next context.
*/
/* Skip loading user fsbase/gsbase for kthreads */
testl $TDP_KTHREAD,TD_PFLAGS(%rsi)
jnz do_kthread
/*
* Load ldt register
*/
movq TD_PROC(%rsi),%rcx
cmpq $0, P_MD+MD_LDT(%rcx)
jne do_ldt
xorl %eax,%eax
ld_ldt: lldt %ax
/* Restore fs base in GDT */
movl PCB_FSBASE(%r8),%eax
movq PCPU(FS32P),%rdx
movw %ax,2(%rdx)
shrl $16,%eax
movb %al,4(%rdx)
shrl $8,%eax
movb %al,7(%rdx)
/* Restore gs base in GDT */
movl PCB_GSBASE(%r8),%eax
movq PCPU(GS32P),%rdx
movw %ax,2(%rdx)
shrl $16,%eax
movb %al,4(%rdx)
shrl $8,%eax
movb %al,7(%rdx)
do_kthread:
/* Do we need to reload tss ? */
movq PCPU(TSSP),%rax
movq PCB_TSSP(%r8),%rdx
testq %rdx,%rdx
cmovzq PCPU(COMMONTSSP),%rdx
cmpq %rax,%rdx
jne do_tss
done_tss:
movq %r8,PCPU(RSP0)
movq %r8,PCPU(CURPCB)
/* Update the TSS_RSP0 pointer for the next interrupt */
movq %r8,COMMON_TSS_RSP0(%rdx)
movq %rsi,PCPU(CURTHREAD) /* into next thread */
/* Test if debug registers should be restored. */
testl $PCB_DBREGS,PCB_FLAGS(%r8)
jnz load_dr /* static predict not taken */
done_load_dr:
/* Restore context. */
movq PCB_R15(%r8),%r15
movq PCB_R14(%r8),%r14
movq PCB_R13(%r8),%r13
movq PCB_R12(%r8),%r12
movq PCB_RBP(%r8),%rbp
movq PCB_RSP(%r8),%rsp
movq PCB_RBX(%r8),%rbx
movq PCB_RIP(%r8),%rax
movq %rax,(%rsp)
ret
/*
* We order these strangely for several reasons.
* 1: I wanted to use static branch prediction hints
* 2: Most athlon64/opteron cpus don't have them. They define
* a forward branch as 'predict not taken'. Intel cores have
* the 'rep' prefix to invert this.
* So, to make it work on both forms of cpu we do the detour.
* We use jumps rather than call in order to avoid the stack.
*/
store_dr:
movq %dr7,%rax /* yes, do the save */
movq %dr0,%r15
movq %dr1,%r14
movq %dr2,%r13
movq %dr3,%r12
movq %dr6,%r11
movq %r15,PCB_DR0(%r8)
movq %r14,PCB_DR1(%r8)
movq %r13,PCB_DR2(%r8)
movq %r12,PCB_DR3(%r8)
movq %r11,PCB_DR6(%r8)
movq %rax,PCB_DR7(%r8)
andq $0x0000fc00, %rax /* disable all watchpoints */
movq %rax,%dr7
jmp done_store_dr
load_dr:
movq %dr7,%rax
movq PCB_DR0(%r8),%r15
movq PCB_DR1(%r8),%r14
movq PCB_DR2(%r8),%r13
movq PCB_DR3(%r8),%r12
movq PCB_DR6(%r8),%r11
movq PCB_DR7(%r8),%rcx
movq %r15,%dr0
movq %r14,%dr1
/* Preserve reserved bits in %dr7 */
andq $0x0000fc00,%rax
andq $~0x0000fc00,%rcx
movq %r13,%dr2
movq %r12,%dr3
orq %rcx,%rax
movq %r11,%dr6
movq %rax,%dr7
jmp done_load_dr
do_tss: movq %rdx,PCPU(TSSP)
movq %rdx,%rcx
movq PCPU(TSS),%rax
movw %rcx,2(%rax)
shrq $16,%rcx
movb %cl,4(%rax)
shrq $8,%rcx
movb %cl,7(%rax)
shrq $8,%rcx
movl %ecx,8(%rax)
movb $0x89,5(%rax) /* unset busy */
movl $TSSSEL,%eax
ltr %ax
jmp done_tss
do_ldt: movq PCPU(LDT),%rax
movq P_MD+MD_LDT_SD(%rcx),%rdx
movq %rdx,(%rax)
movq P_MD+MD_LDT_SD+8(%rcx),%rdx
movq %rdx,8(%rax)
movl $LDTSEL,%eax
jmp ld_ldt
END(cpu_switch)
/*
* savectx(pcb)
* Update pcb, saving current processor state.
*/
ENTRY(savectx)
/* Save caller's return address. */
movq (%rsp),%rax
movq %rax,PCB_RIP(%rdi)
movq %rbx,PCB_RBX(%rdi)
movq %rsp,PCB_RSP(%rdi)
movq %rbp,PCB_RBP(%rdi)
movq %r12,PCB_R12(%rdi)
movq %r13,PCB_R13(%rdi)
movq %r14,PCB_R14(%rdi)
movq %r15,PCB_R15(%rdi)
movq %cr0,%rsi
movq %rsi,PCB_CR0(%rdi)
movq %cr2,%rax
movq %rax,PCB_CR2(%rdi)
movq %cr3,%rax
movq %rax,PCB_CR3(%rdi)
movq %cr4,%rax
movq %rax,PCB_CR4(%rdi)
movq %dr0,%rax
movq %rax,PCB_DR0(%rdi)
movq %dr1,%rax
movq %rax,PCB_DR1(%rdi)
movq %dr2,%rax
movq %rax,PCB_DR2(%rdi)
movq %dr3,%rax
movq %rax,PCB_DR3(%rdi)
movq %dr6,%rax
movq %rax,PCB_DR6(%rdi)
movq %dr7,%rax
movq %rax,PCB_DR7(%rdi)
movl $MSR_FSBASE,%ecx
rdmsr
shlq $32,%rdx
leaq (%rax,%rdx),%rax
movq %rax,PCB_FSBASE(%rdi)
movl $MSR_GSBASE,%ecx
rdmsr
shlq $32,%rdx
leaq (%rax,%rdx),%rax
movq %rax,PCB_GSBASE(%rdi)
movl $MSR_KGSBASE,%ecx
rdmsr
shlq $32,%rdx
leaq (%rax,%rdx),%rax
movq %rax,PCB_KGSBASE(%rdi)
sgdt PCB_GDT(%rdi)
sidt PCB_IDT(%rdi)
sldt PCB_LDT(%rdi)
str PCB_TR(%rdi)
clts
fxsave PCB_USERFPU(%rdi)
movq %rsi,%cr0 /* The previous %cr0 is saved in %rsi. */
movl $1,%eax
ret
END(savectx)
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