The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

FreeBSD/Linux Kernel Cross Reference
sys/amd64/amd64/cpu_switch.S

Version: -  FREEBSD  -  FREEBSD-13-STABLE  -  FREEBSD-13-0  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  l41  -  OPENBSD  -  linux-2.6  -  MK84  -  PLAN9  -  xnu-8792 
SearchContext: -  none  -  3  -  10 

    1 /*-
    2  * Copyright (c) 2003 Peter Wemm.
    3  * Copyright (c) 1990 The Regents of the University of California.
    4  * All rights reserved.
    5  *
    6  * This code is derived from software contributed to Berkeley by
    7  * William Jolitz.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 4. Neither the name of the University nor the names of its contributors
   18  *    may be used to endorse or promote products derived from this software
   19  *    without specific prior written permission.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  *
   33  * $FreeBSD$
   34  */
   35 
   36 #include <machine/asmacros.h>
   37 #include <machine/specialreg.h>
   38 
   39 #include "assym.s"
   40 #include "opt_sched.h"
   41 
   42 /*****************************************************************************/
   43 /* Scheduling                                                                */
   44 /*****************************************************************************/
   45 
   46         .text
   47 
   48 #ifdef SMP
   49 #define LK      lock ;
   50 #else
   51 #define LK
   52 #endif
   53 
   54 #if defined(SCHED_ULE) && defined(SMP)
   55 #define SETLK   xchgq
   56 #else
   57 #define SETLK   movq
   58 #endif
   59 
   60 /*
   61  * cpu_throw()
   62  *
   63  * This is the second half of cpu_switch(). It is used when the current
   64  * thread is either a dummy or slated to die, and we no longer care
   65  * about its state.  This is only a slight optimization and is probably
   66  * not worth it anymore.  Note that we need to clear the pm_active bits so
   67  * we do need the old proc if it still exists.
   68  * %rdi = oldtd
   69  * %rsi = newtd
   70  */
   71 ENTRY(cpu_throw)
   72         movl    PCPU(CPUID), %eax
   73         testq   %rdi,%rdi                       /* no thread? */
   74         jz      1f
   75         /* release bit from old pm_active */
   76         movq    TD_PROC(%rdi), %rdx             /* oldtd->td_proc */
   77         movq    P_VMSPACE(%rdx), %rdx           /* proc->p_vmspace */
   78         LK btrl %eax, VM_PMAP+PM_ACTIVE(%rdx)   /* clear old */
   79 1:
   80         movq    TD_PCB(%rsi),%rdx               /* newtd->td_proc */
   81         movq    PCB_CR3(%rdx),%rdx
   82         movq    %rdx,%cr3                       /* new address space */
   83         jmp     swact
   84 END(cpu_throw)
   85 
   86 /*
   87  * cpu_switch(old, new, mtx)
   88  *
   89  * Save the current thread state, then select the next thread to run
   90  * and load its state.
   91  * %rdi = oldtd
   92  * %rsi = newtd
   93  * %rdx = mtx
   94  */
   95 ENTRY(cpu_switch)
   96         /* Switch to new thread.  First, save context. */
   97         movq    TD_PCB(%rdi),%r8
   98 
   99         movq    (%rsp),%rax                     /* Hardware registers */
  100         movq    %rax,PCB_RIP(%r8)
  101         movq    %rbx,PCB_RBX(%r8)
  102         movq    %rsp,PCB_RSP(%r8)
  103         movq    %rbp,PCB_RBP(%r8)
  104         movq    %r12,PCB_R12(%r8)
  105         movq    %r13,PCB_R13(%r8)
  106         movq    %r14,PCB_R14(%r8)
  107         movq    %r15,PCB_R15(%r8)
  108 
  109         testl   $PCB_32BIT,PCB_FLAGS(%r8)
  110         jz      1f                              /* no, skip over */
  111 
  112         /* Save userland %gs */
  113         movl    %gs,PCB_GS(%r8)
  114         movq    PCB_GS32P(%r8),%rax
  115         movq    (%rax),%rax
  116         movq    %rax,PCB_GS32SD(%r8)
  117 
  118 1:
  119         /* Test if debug registers should be saved. */
  120         testl   $PCB_DBREGS,PCB_FLAGS(%r8)
  121         jz      1f                              /* no, skip over */
  122         movq    %dr7,%rax                       /* yes, do the save */
  123         movq    %rax,PCB_DR7(%r8)
  124         andq    $0x0000fc00, %rax               /* disable all watchpoints */
  125         movq    %rax,%dr7
  126         movq    %dr6,%rax
  127         movq    %rax,PCB_DR6(%r8)
  128         movq    %dr3,%rax
  129         movq    %rax,PCB_DR3(%r8)
  130         movq    %dr2,%rax
  131         movq    %rax,PCB_DR2(%r8)
  132         movq    %dr1,%rax
  133         movq    %rax,PCB_DR1(%r8)
  134         movq    %dr0,%rax
  135         movq    %rax,PCB_DR0(%r8)
  136 1:
  137 
  138         /* have we used fp, and need a save? */
  139         cmpq    %rdi,PCPU(FPCURTHREAD)
  140         jne     1f
  141         addq    $PCB_SAVEFPU,%r8
  142         clts
  143         fxsave  (%r8)
  144         smsw    %ax
  145         orb     $CR0_TS,%al
  146         lmsw    %ax
  147         xorl    %eax,%eax
  148         movq    %rax,PCPU(FPCURTHREAD)
  149 1:
  150 
  151         /* Save is done.  Now fire up new thread. Leave old vmspace. */
  152         movq    TD_PCB(%rsi),%r8
  153 
  154         /* switch address space */
  155         movq    PCB_CR3(%r8),%rcx
  156         movq    %cr3,%rax
  157         cmpq    %rcx,%rax                       /* Same address space? */
  158         jne     swinact
  159         SETLK   %rdx, TD_LOCK(%rdi)             /* Release the old thread */
  160         jmp     sw1
  161 swinact:
  162         movq    %rcx,%cr3                       /* new address space */
  163         movl    PCPU(CPUID), %eax
  164         /* Release bit from old pmap->pm_active */
  165         movq    TD_PROC(%rdi), %rcx             /* oldproc */
  166         movq    P_VMSPACE(%rcx), %rcx
  167         LK btrl %eax, VM_PMAP+PM_ACTIVE(%rcx)   /* clear old */
  168         SETLK   %rdx, TD_LOCK(%rdi)             /* Release the old thread */
  169 swact:
  170         /* Set bit in new pmap->pm_active */
  171         movq    TD_PROC(%rsi),%rdx              /* newproc */
  172         movq    P_VMSPACE(%rdx), %rdx
  173         LK btsl %eax, VM_PMAP+PM_ACTIVE(%rdx)   /* set new */
  174 
  175 sw1:
  176 #if defined(SCHED_ULE) && defined(SMP)
  177         /* Wait for the new thread to become unblocked */
  178         movq    $blocked_lock, %rdx
  179 1:
  180         movq    TD_LOCK(%rsi),%rcx
  181         cmpq    %rcx, %rdx
  182         pause
  183         je      1b
  184         lfence
  185 #endif
  186         /*
  187          * At this point, we've switched address spaces and are ready
  188          * to load up the rest of the next context.
  189          */
  190         movq    TD_PCB(%rsi),%r8
  191 
  192         /* Restore userland %fs */
  193         movl    $MSR_FSBASE,%ecx
  194         movl    PCB_FSBASE(%r8),%eax
  195         movl    PCB_FSBASE+4(%r8),%edx
  196         wrmsr
  197 
  198         /* Restore userland %gs */
  199         movl    $MSR_KGSBASE,%ecx
  200         movl    PCB_GSBASE(%r8),%eax
  201         movl    PCB_GSBASE+4(%r8),%edx
  202         wrmsr
  203 
  204         /* Update the TSS_RSP0 pointer for the next interrupt */
  205         movq    PCPU(TSSP), %rax
  206         addq    $COMMON_TSS_RSP0, %rax
  207         leaq    -16(%r8), %rbx
  208         movq    %rbx, (%rax)
  209         movq    %rbx, PCPU(RSP0)
  210 
  211         movq    %r8, PCPU(CURPCB)
  212         movq    %rsi, PCPU(CURTHREAD)           /* into next thread */
  213 
  214         testl   $PCB_32BIT,PCB_FLAGS(%r8)
  215         jz      1f                              /* no, skip over */
  216 
  217         /* Restore userland %gs while preserving kernel gsbase */
  218         movq    PCB_GS32P(%r8),%rax
  219         movq    PCB_GS32SD(%r8),%rbx
  220         movq    %rbx,(%rax)
  221         movl    $MSR_GSBASE,%ecx
  222         rdmsr
  223         movl    PCB_GS(%r8),%gs
  224         wrmsr
  225 
  226 1:
  227         /* Restore context. */
  228         movq    PCB_RBX(%r8),%rbx
  229         movq    PCB_RSP(%r8),%rsp
  230         movq    PCB_RBP(%r8),%rbp
  231         movq    PCB_R12(%r8),%r12
  232         movq    PCB_R13(%r8),%r13
  233         movq    PCB_R14(%r8),%r14
  234         movq    PCB_R15(%r8),%r15
  235         movq    PCB_RIP(%r8),%rax
  236         movq    %rax,(%rsp)
  237 
  238         /* Test if debug registers should be restored. */
  239         testl   $PCB_DBREGS,PCB_FLAGS(%r8)
  240         jz      1f
  241         movq    PCB_DR6(%r8),%rax
  242         movq    %rax,%dr6
  243         movq    PCB_DR3(%r8),%rax
  244         movq    %rax,%dr3
  245         movq    PCB_DR2(%r8),%rax
  246         movq    %rax,%dr2
  247         movq    PCB_DR1(%r8),%rax
  248         movq    %rax,%dr1
  249         movq    PCB_DR0(%r8),%rax
  250         movq    %rax,%dr0
  251         /* But preserve reserved bits in %dr7 */
  252         movq    %dr7,%rax
  253         andq    $0x0000fc00,%rax
  254         movq    PCB_DR7(%r8),%rcx
  255         andq    $~0x0000fc00,%rcx
  256         orq     %rcx,%rax
  257         movq    %rax,%dr7
  258 1:
  259         ret
  260 END(cpu_switch)
  261         
  262 /*
  263  * savectx(pcb)
  264  * Update pcb, saving current processor state.
  265  */
  266 ENTRY(savectx)
  267         /* Fetch PCB. */
  268         movq    %rdi,%rcx
  269 
  270         /* Save caller's return address. */
  271         movq    (%rsp),%rax
  272         movq    %rax,PCB_RIP(%rcx)
  273 
  274         movq    %cr3,%rax
  275         movq    %rax,PCB_CR3(%rcx)
  276 
  277         movq    %rbx,PCB_RBX(%rcx)
  278         movq    %rsp,PCB_RSP(%rcx)
  279         movq    %rbp,PCB_RBP(%rcx)
  280         movq    %r12,PCB_R12(%rcx)
  281         movq    %r13,PCB_R13(%rcx)
  282         movq    %r14,PCB_R14(%rcx)
  283         movq    %r15,PCB_R15(%rcx)
  284 
  285         /*
  286          * If fpcurthread == NULL, then the fpu h/w state is irrelevant and the
  287          * state had better already be in the pcb.  This is true for forks
  288          * but not for dumps (the old book-keeping with FP flags in the pcb
  289          * always lost for dumps because the dump pcb has 0 flags).
  290          *
  291          * If fpcurthread != NULL, then we have to save the fpu h/w state to
  292          * fpcurthread's pcb and copy it to the requested pcb, or save to the
  293          * requested pcb and reload.  Copying is easier because we would
  294          * have to handle h/w bugs for reloading.  We used to lose the
  295          * parent's fpu state for forks by forgetting to reload.
  296          */
  297         pushfq
  298         cli
  299         movq    PCPU(FPCURTHREAD),%rax
  300         testq   %rax,%rax
  301         je      1f
  302 
  303         movq    TD_PCB(%rax),%rdi
  304         leaq    PCB_SAVEFPU(%rdi),%rdi
  305         clts
  306         fxsave  (%rdi)
  307         smsw    %ax
  308         orb     $CR0_TS,%al
  309         lmsw    %ax
  310 
  311         movq    $PCB_SAVEFPU_SIZE,%rdx  /* arg 3 */
  312         leaq    PCB_SAVEFPU(%rcx),%rsi  /* arg 2 */
  313         /* arg 1 (%rdi) already loaded */
  314         call    bcopy
  315 1:
  316         popfq
  317 
  318         ret
  319 END(savectx)

Cache object: f30fec0abf14a41131baaf734c80b928


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.