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/*- * 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: release/9.1.0/sys/i386/i386/swtch.s 235796 2012-05-22 17:44:01Z iwasaki $ */ #include "opt_npx.h" #include "opt_sched.h" #include <machine/asmacros.h> #include "assym.s" #if defined(SMP) && defined(SCHED_ULE) #define SETOP xchgl #define BLOCK_SPIN(reg) \ movl $blocked_lock,%eax ; \ 100: ; \ lock ; \ cmpxchgl %eax,TD_LOCK(reg) ; \ jne 101f ; \ pause ; \ jmp 100b ; \ 101: #else #define SETOP movl #define BLOCK_SPIN(reg) #endif /*****************************************************************************/ /* 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 LOAD_CR3(%eax) /* 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 END(cpu_throw) /* * 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 * 12(%esp) = newlock */ 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) mov %gs,PCB_GS(%edx) pushfl /* PSL */ popl PCB_PSL(%edx) /* 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 pushl PCB_SAVEFPU(%edx) /* h/w bugs make saving complicated */ 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 4(%esp),%edi movl 8(%esp),%ecx /* New thread */ movl 12(%esp),%esi /* New lock */ #ifdef INVARIANTS testl %ecx,%ecx /* no thread? */ jz badsw3 /* no, panic */ #endif movl TD_PCB(%ecx),%edx /* 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 sw0 READ_CR3(%ebx) /* The same address space? */ cmpl %ebx,%eax je sw0 LOAD_CR3(%eax) /* new address space */ movl %esi,%eax movl PCPU(CPUID),%esi SETOP %eax,TD_LOCK(%edi) /* Switchout td_lock */ /* 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 */ jmp sw1 sw0: SETOP %esi,TD_LOCK(%edi) /* Switchout td_lock */ sw1: BLOCK_SPIN(%ecx) #ifdef XEN pushl %eax pushl %ecx pushl %edx call xen_handle_thread_switch popl %edx popl %ecx popl %eax /* * XXX set IOPL */ #else /* * 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 */ movl $1, PCPU(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. */ cmpl $0, PCPU(PRIVATE_TSS) /* Already using the common? */ je 3f /* if so, skip reloading */ movl $0, PCPU(PRIVATE_TSS) 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 4(%edi), %esi movl %eax, 0(%ebx) movl %esi, 4(%ebx) movl $GPROC0_SEL*8, %esi /* GSEL(GPROC0_SEL, SEL_KPL) */ ltr %si 3: /* Copy the %fs and %gs selectors into this pcpu gdt */ leal PCB_FSD(%edx), %esi movl PCPU(FSGS_GDT), %edi movl 0(%esi), %eax /* %fs selector */ movl 4(%esi), %ebx movl %eax, 0(%edi) movl %ebx, 4(%edi) movl 8(%esi), %eax /* %gs selector, comes straight after */ movl 12(%esi), %ebx movl %eax, 8(%edi) movl %ebx, 12(%edi) #endif /* 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 TD_TID(%ecx),%eax 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: mov 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 END(cpu_switch) /* * 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) mov %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 movl PCB_SAVEFPU(%eax),%eax pushl %eax pushl %eax call npxsave addl $4,%esp popl %eax popl %ecx pushl $PCB_SAVEFPU_SIZE leal PCB_USERFPU(%ecx),%ecx pushl %ecx pushl %eax call bcopy addl $12,%esp 1: popfl #endif /* DEV_NPX */ ret END(savectx) /* * suspendctx(pcb) * Update pcb, suspending current processor state. */ ENTRY(suspendctx) /* Fetch PCB. */ movl 4(%esp),%ecx /* Save context by calling savectx(). */ pushl %ecx call savectx addl $4,%esp /* Fetch PCB again. */ movl 4(%esp),%ecx /* Update caller's return address and stack pointer. */ movl (%esp),%eax movl %eax,PCB_EIP(%ecx) movl %esp,PCB_ESP(%ecx) /* Save other registers and descriptor tables. */ movl %cr0,%eax movl %eax,PCB_CR0(%ecx) movl %cr2,%eax movl %eax,PCB_CR2(%ecx) movl %cr4,%eax movl %eax,PCB_CR4(%ecx) movl %dr0,%eax movl %eax,PCB_DR0(%ecx) movl %dr1,%eax movl %eax,PCB_DR1(%ecx) movl %dr2,%eax movl %eax,PCB_DR2(%ecx) movl %dr3,%eax movl %eax,PCB_DR3(%ecx) movl %dr6,%eax movl %eax,PCB_DR6(%ecx) movl %dr7,%eax movl %eax,PCB_DR7(%ecx) mov %ds,PCB_DS(%ecx) mov %es,PCB_ES(%ecx) mov %fs,PCB_FS(%ecx) mov %ss,PCB_SS(%ecx) sgdt PCB_GDT(%ecx) sidt PCB_IDT(%ecx) sldt PCB_LDT(%ecx) str PCB_TR(%ecx) movl $1,%eax ret END(suspendctx) /* * resumectx(pcb in %esi) * Resuming processor state from pcb. */ ENTRY(resumectx) /* Fetch PCB. */ movl %esi,%ecx /* Restore GDT. */ lgdt PCB_GDT(%ecx) /* Restore segment registers */ movzwl PCB_DS(%ecx),%eax mov %ax,%ds movzwl PCB_ES(%ecx),%eax mov %ax,%es movzwl PCB_FS(%ecx),%eax mov %ax,%fs movzwl PCB_GS(%ecx),%eax movw %ax,%gs movzwl PCB_SS(%ecx),%eax mov %ax,%ss /* Restore CR2, CR4, CR3 and CR0 */ movl PCB_CR2(%ecx),%eax movl %eax,%cr2 movl PCB_CR4(%ecx),%eax movl %eax,%cr4 movl PCB_CR3(%ecx),%eax movl %eax,%cr3 movl PCB_CR0(%ecx),%eax movl %eax,%cr0 jmp 1f 1: /* Restore descriptor tables */ lidt PCB_IDT(%ecx) lldt PCB_LDT(%ecx) #define SDT_SYS386TSS 9 #define SDT_SYS386BSY 11 /* Clear "task busy" bit and reload TR */ movl PCPU(TSS_GDT),%eax andb $(~SDT_SYS386BSY | SDT_SYS386TSS),5(%eax) movzwl PCB_TR(%ecx),%eax ltr %ax #undef SDT_SYS386TSS #undef SDT_SYS386BSY /* Restore debug registers */ movl PCB_DR0(%ecx),%eax movl %eax,%dr0 movl PCB_DR1(%ecx),%eax movl %eax,%dr1 movl PCB_DR2(%ecx),%eax movl %eax,%dr2 movl PCB_DR3(%ecx),%eax movl %eax,%dr3 movl PCB_DR6(%ecx),%eax movl %eax,%dr6 movl PCB_DR7(%ecx),%eax movl %eax,%dr7 #ifdef DEV_NPX /* XXX FIX ME */ #endif /* Restore other registers */ movl PCB_EDI(%ecx),%edi movl PCB_ESI(%ecx),%esi movl PCB_EBP(%ecx),%ebp movl PCB_ESP(%ecx),%esp movl PCB_EBX(%ecx),%ebx /* reload code selector by turning return into intersegmental return */ pushl PCB_EIP(%ecx) movl $KCSEL,4(%esp) xorl %eax,%eax lret END(resumectx)