diff options
| -rw-r--r-- | sys/amd64/amd64/cpu_switch.S | 81 | ||||
| -rw-r--r-- | sys/amd64/amd64/swtch.s | 81 | ||||
| -rw-r--r-- | sys/i386/i386/swtch.s | 81 |
3 files changed, 138 insertions, 105 deletions
diff --git a/sys/amd64/amd64/cpu_switch.S b/sys/amd64/amd64/cpu_switch.S index 356c937..4fa6798 100644 --- a/sys/amd64/amd64/cpu_switch.S +++ b/sys/amd64/amd64/cpu_switch.S @@ -43,7 +43,7 @@ #ifdef SMP #include <machine/apic.h> #include <machine/smptests.h> /* CHEAP_TPR, GRAB_LOPRIO */ -#endif /* SMP */ +#endif #include "assym.s" @@ -73,11 +73,11 @@ ENTRY(cpu_throw) * cpu_switch() */ ENTRY(cpu_switch) - - /* Switch to new process. First, save context as needed. */ + + /* Switch to new thread. First, save context as needed. */ movl PCPU(CURTHREAD),%ecx - /* If no process to save, don't save it (XXX shouldn't happen). */ + /* If no thread to save, don't save it (XXX shouldn't happen). */ testl %ecx,%ecx jz sw1 @@ -116,10 +116,10 @@ ENTRY(cpu_switch) movl %dr0,%eax movl %eax,PCB_DR0(%edx) 1: - + #ifdef SMP /* XXX FIXME: we should be saving the local APIC TPR */ -#endif /* SMP */ +#endif #ifdef DEV_NPX /* have we used fp, and need a save? */ @@ -130,19 +130,21 @@ ENTRY(cpu_switch) call npxsave /* do it in a big C function */ popl %eax 1: -#endif /* DEV_NPX */ +#endif /* Save is done. Now choose a new thread. */ /* XXX still trashing space above the old "Top Of Stack". */ sw1: #ifdef SMP - /* Stop scheduling if smp_active goes to zero and we are not the BSP. */ + /* + * Stop scheduling if smp_active has become zero (for rebooting) and + * we are not the BSP. + */ cmpl $0,smp_active jne 1f cmpl $0,PCPU(CPUID) je 1f - /* Idle thread can run on any kernel context. */ movl PCPU(IDLETHREAD), %eax jmp sw1b 1: @@ -152,8 +154,7 @@ sw1: * Choose a new thread to schedule. choosethread() returns idlethread * if it cannot find another thread to run. */ -sw1a: - call choosethread /* trash ecx, edx, ret eax */ + call choosethread /* Trash ecx, edx; ret eax. */ #ifdef INVARIANTS testl %eax,%eax /* no thread? */ @@ -184,7 +185,7 @@ sw1b: incl tlb_flush_count #endif movl PCB_CR3(%edx),%ebx - movl %ebx,%cr3 /* Load new page tables. */ + movl %ebx,%cr3 4: movl PCPU(CPUID), %esi @@ -194,7 +195,8 @@ sw1b: movl PCB_EXT(%edx), %edi /* new tss descriptor */ jmp 2f 1: - /* update common_tss.tss_esp0 pointer */ + + /* Update common_tss.tss_esp0 pointer. */ leal -16(%edx), %ebx /* leave space for vm86 */ movl %ebx, PCPU(COMMON_TSS) + TSS_ESP0 /* stack is below pcb */ @@ -211,13 +213,13 @@ sw1b: movl $GPROC0_SEL*8, %esi /* GSEL(entry, SEL_KPL) */ ltr %si 3: - /* Note in a vmspace that this cpu is using it. */ + /* Note in vmspace that this cpu is using it. */ movl TD_PROC(%ecx),%eax /* XXXKSE proc from thread */ movl P_VMSPACE(%eax), %ebx movl PCPU(CPUID), %eax btsl %eax, VM_PMAP+PM_ACTIVE(%ebx) - /* restore context */ + /* Restore context. */ movl PCB_EBX(%edx),%ebx movl PCB_ESP(%edx),%esp movl PCB_EBP(%edx),%ebp @@ -226,36 +228,40 @@ sw1b: movl PCB_EIP(%edx),%eax movl %eax,(%esp) -#ifdef SMP -#ifdef GRAB_LOPRIO /* hold LOPRIO for INTs */ +#if defined(SMP) && defined(GRAP_LOPRIO) + /* Hold LOPRIO for interrupts. */ #ifdef CHEAP_TPR movl $0, lapic+LA_TPR #else andl $~APIC_TPR_PRIO, lapic+LA_TPR -#endif /** CHEAP_TPR */ -#endif /** GRAB_LOPRIO */ -#endif /* SMP */ +#endif +#endif movl %edx, PCPU(CURPCB) movl %ecx, PCPU(CURTHREAD) /* into next thread */ #ifdef SMP /* XXX FIXME: we should be restoring the local APIC TPR */ -#endif /* SMP */ +#endif + /* + * 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) /* Have an LDT? */ - jnz 1f /* Yes, use it. */ - movl _default_ldt,%eax /* Otherwise, use default. */ + 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: pushl %edx /* Preserve pointer to pcb. */ +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 /* Check and load the ldt. */ + call set_user_ldt addl $4,%esp popl %edx 2: @@ -265,11 +271,16 @@ sw1b: cpu_switch_load_gs: movl PCB_GS(%edx),%gs - /* test if debug regisers should be restored */ + /* Test if debug regisers should be restored. */ movb PCB_FLAGS(%edx),%al andb $PCB_DBREGS,%al - jz 1f /* no, skip over */ - movl PCB_DR6(%edx),%eax /* yes, do the restore */ + 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 @@ -279,10 +290,10 @@ cpu_switch_load_gs: movl %eax,%dr1 movl PCB_DR0(%edx),%eax movl %eax,%dr0 - movl %dr7,%eax /* load dr7 so as not to */ - andl $0x0000fc00,%eax /* disturb reserved bits */ + movl %dr7,%eax + andl $0x0000fc00,%eax movl PCB_DR7(%edx),%ecx - andl $~0x0000fc00,%ecx /* re-enable the restored watchpoints */ + andl $~0x0000fc00,%ecx orl %ecx,%eax movl %eax,%dr7 1: @@ -307,10 +318,10 @@ sw0_3: .asciz "cpu_switch: choosethread returned NULL" * Update pcb, saving current processor state. */ ENTRY(savectx) - /* fetch PCB */ + /* Fetch PCB. */ movl 4(%esp),%ecx - /* caller's return address - child won't execute this routine */ + /* Save caller's return address. Child won't execute this routine. */ movl (%esp),%eax movl %eax,PCB_EIP(%ecx) diff --git a/sys/amd64/amd64/swtch.s b/sys/amd64/amd64/swtch.s index 356c937..4fa6798 100644 --- a/sys/amd64/amd64/swtch.s +++ b/sys/amd64/amd64/swtch.s @@ -43,7 +43,7 @@ #ifdef SMP #include <machine/apic.h> #include <machine/smptests.h> /* CHEAP_TPR, GRAB_LOPRIO */ -#endif /* SMP */ +#endif #include "assym.s" @@ -73,11 +73,11 @@ ENTRY(cpu_throw) * cpu_switch() */ ENTRY(cpu_switch) - - /* Switch to new process. First, save context as needed. */ + + /* Switch to new thread. First, save context as needed. */ movl PCPU(CURTHREAD),%ecx - /* If no process to save, don't save it (XXX shouldn't happen). */ + /* If no thread to save, don't save it (XXX shouldn't happen). */ testl %ecx,%ecx jz sw1 @@ -116,10 +116,10 @@ ENTRY(cpu_switch) movl %dr0,%eax movl %eax,PCB_DR0(%edx) 1: - + #ifdef SMP /* XXX FIXME: we should be saving the local APIC TPR */ -#endif /* SMP */ +#endif #ifdef DEV_NPX /* have we used fp, and need a save? */ @@ -130,19 +130,21 @@ ENTRY(cpu_switch) call npxsave /* do it in a big C function */ popl %eax 1: -#endif /* DEV_NPX */ +#endif /* Save is done. Now choose a new thread. */ /* XXX still trashing space above the old "Top Of Stack". */ sw1: #ifdef SMP - /* Stop scheduling if smp_active goes to zero and we are not the BSP. */ + /* + * Stop scheduling if smp_active has become zero (for rebooting) and + * we are not the BSP. + */ cmpl $0,smp_active jne 1f cmpl $0,PCPU(CPUID) je 1f - /* Idle thread can run on any kernel context. */ movl PCPU(IDLETHREAD), %eax jmp sw1b 1: @@ -152,8 +154,7 @@ sw1: * Choose a new thread to schedule. choosethread() returns idlethread * if it cannot find another thread to run. */ -sw1a: - call choosethread /* trash ecx, edx, ret eax */ + call choosethread /* Trash ecx, edx; ret eax. */ #ifdef INVARIANTS testl %eax,%eax /* no thread? */ @@ -184,7 +185,7 @@ sw1b: incl tlb_flush_count #endif movl PCB_CR3(%edx),%ebx - movl %ebx,%cr3 /* Load new page tables. */ + movl %ebx,%cr3 4: movl PCPU(CPUID), %esi @@ -194,7 +195,8 @@ sw1b: movl PCB_EXT(%edx), %edi /* new tss descriptor */ jmp 2f 1: - /* update common_tss.tss_esp0 pointer */ + + /* Update common_tss.tss_esp0 pointer. */ leal -16(%edx), %ebx /* leave space for vm86 */ movl %ebx, PCPU(COMMON_TSS) + TSS_ESP0 /* stack is below pcb */ @@ -211,13 +213,13 @@ sw1b: movl $GPROC0_SEL*8, %esi /* GSEL(entry, SEL_KPL) */ ltr %si 3: - /* Note in a vmspace that this cpu is using it. */ + /* Note in vmspace that this cpu is using it. */ movl TD_PROC(%ecx),%eax /* XXXKSE proc from thread */ movl P_VMSPACE(%eax), %ebx movl PCPU(CPUID), %eax btsl %eax, VM_PMAP+PM_ACTIVE(%ebx) - /* restore context */ + /* Restore context. */ movl PCB_EBX(%edx),%ebx movl PCB_ESP(%edx),%esp movl PCB_EBP(%edx),%ebp @@ -226,36 +228,40 @@ sw1b: movl PCB_EIP(%edx),%eax movl %eax,(%esp) -#ifdef SMP -#ifdef GRAB_LOPRIO /* hold LOPRIO for INTs */ +#if defined(SMP) && defined(GRAP_LOPRIO) + /* Hold LOPRIO for interrupts. */ #ifdef CHEAP_TPR movl $0, lapic+LA_TPR #else andl $~APIC_TPR_PRIO, lapic+LA_TPR -#endif /** CHEAP_TPR */ -#endif /** GRAB_LOPRIO */ -#endif /* SMP */ +#endif +#endif movl %edx, PCPU(CURPCB) movl %ecx, PCPU(CURTHREAD) /* into next thread */ #ifdef SMP /* XXX FIXME: we should be restoring the local APIC TPR */ -#endif /* SMP */ +#endif + /* + * 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) /* Have an LDT? */ - jnz 1f /* Yes, use it. */ - movl _default_ldt,%eax /* Otherwise, use default. */ + 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: pushl %edx /* Preserve pointer to pcb. */ +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 /* Check and load the ldt. */ + call set_user_ldt addl $4,%esp popl %edx 2: @@ -265,11 +271,16 @@ sw1b: cpu_switch_load_gs: movl PCB_GS(%edx),%gs - /* test if debug regisers should be restored */ + /* Test if debug regisers should be restored. */ movb PCB_FLAGS(%edx),%al andb $PCB_DBREGS,%al - jz 1f /* no, skip over */ - movl PCB_DR6(%edx),%eax /* yes, do the restore */ + 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 @@ -279,10 +290,10 @@ cpu_switch_load_gs: movl %eax,%dr1 movl PCB_DR0(%edx),%eax movl %eax,%dr0 - movl %dr7,%eax /* load dr7 so as not to */ - andl $0x0000fc00,%eax /* disturb reserved bits */ + movl %dr7,%eax + andl $0x0000fc00,%eax movl PCB_DR7(%edx),%ecx - andl $~0x0000fc00,%ecx /* re-enable the restored watchpoints */ + andl $~0x0000fc00,%ecx orl %ecx,%eax movl %eax,%dr7 1: @@ -307,10 +318,10 @@ sw0_3: .asciz "cpu_switch: choosethread returned NULL" * Update pcb, saving current processor state. */ ENTRY(savectx) - /* fetch PCB */ + /* Fetch PCB. */ movl 4(%esp),%ecx - /* caller's return address - child won't execute this routine */ + /* Save caller's return address. Child won't execute this routine. */ movl (%esp),%eax movl %eax,PCB_EIP(%ecx) diff --git a/sys/i386/i386/swtch.s b/sys/i386/i386/swtch.s index 356c937..4fa6798 100644 --- a/sys/i386/i386/swtch.s +++ b/sys/i386/i386/swtch.s @@ -43,7 +43,7 @@ #ifdef SMP #include <machine/apic.h> #include <machine/smptests.h> /* CHEAP_TPR, GRAB_LOPRIO */ -#endif /* SMP */ +#endif #include "assym.s" @@ -73,11 +73,11 @@ ENTRY(cpu_throw) * cpu_switch() */ ENTRY(cpu_switch) - - /* Switch to new process. First, save context as needed. */ + + /* Switch to new thread. First, save context as needed. */ movl PCPU(CURTHREAD),%ecx - /* If no process to save, don't save it (XXX shouldn't happen). */ + /* If no thread to save, don't save it (XXX shouldn't happen). */ testl %ecx,%ecx jz sw1 @@ -116,10 +116,10 @@ ENTRY(cpu_switch) movl %dr0,%eax movl %eax,PCB_DR0(%edx) 1: - + #ifdef SMP /* XXX FIXME: we should be saving the local APIC TPR */ -#endif /* SMP */ +#endif #ifdef DEV_NPX /* have we used fp, and need a save? */ @@ -130,19 +130,21 @@ ENTRY(cpu_switch) call npxsave /* do it in a big C function */ popl %eax 1: -#endif /* DEV_NPX */ +#endif /* Save is done. Now choose a new thread. */ /* XXX still trashing space above the old "Top Of Stack". */ sw1: #ifdef SMP - /* Stop scheduling if smp_active goes to zero and we are not the BSP. */ + /* + * Stop scheduling if smp_active has become zero (for rebooting) and + * we are not the BSP. + */ cmpl $0,smp_active jne 1f cmpl $0,PCPU(CPUID) je 1f - /* Idle thread can run on any kernel context. */ movl PCPU(IDLETHREAD), %eax jmp sw1b 1: @@ -152,8 +154,7 @@ sw1: * Choose a new thread to schedule. choosethread() returns idlethread * if it cannot find another thread to run. */ -sw1a: - call choosethread /* trash ecx, edx, ret eax */ + call choosethread /* Trash ecx, edx; ret eax. */ #ifdef INVARIANTS testl %eax,%eax /* no thread? */ @@ -184,7 +185,7 @@ sw1b: incl tlb_flush_count #endif movl PCB_CR3(%edx),%ebx - movl %ebx,%cr3 /* Load new page tables. */ + movl %ebx,%cr3 4: movl PCPU(CPUID), %esi @@ -194,7 +195,8 @@ sw1b: movl PCB_EXT(%edx), %edi /* new tss descriptor */ jmp 2f 1: - /* update common_tss.tss_esp0 pointer */ + + /* Update common_tss.tss_esp0 pointer. */ leal -16(%edx), %ebx /* leave space for vm86 */ movl %ebx, PCPU(COMMON_TSS) + TSS_ESP0 /* stack is below pcb */ @@ -211,13 +213,13 @@ sw1b: movl $GPROC0_SEL*8, %esi /* GSEL(entry, SEL_KPL) */ ltr %si 3: - /* Note in a vmspace that this cpu is using it. */ + /* Note in vmspace that this cpu is using it. */ movl TD_PROC(%ecx),%eax /* XXXKSE proc from thread */ movl P_VMSPACE(%eax), %ebx movl PCPU(CPUID), %eax btsl %eax, VM_PMAP+PM_ACTIVE(%ebx) - /* restore context */ + /* Restore context. */ movl PCB_EBX(%edx),%ebx movl PCB_ESP(%edx),%esp movl PCB_EBP(%edx),%ebp @@ -226,36 +228,40 @@ sw1b: movl PCB_EIP(%edx),%eax movl %eax,(%esp) -#ifdef SMP -#ifdef GRAB_LOPRIO /* hold LOPRIO for INTs */ +#if defined(SMP) && defined(GRAP_LOPRIO) + /* Hold LOPRIO for interrupts. */ #ifdef CHEAP_TPR movl $0, lapic+LA_TPR #else andl $~APIC_TPR_PRIO, lapic+LA_TPR -#endif /** CHEAP_TPR */ -#endif /** GRAB_LOPRIO */ -#endif /* SMP */ +#endif +#endif movl %edx, PCPU(CURPCB) movl %ecx, PCPU(CURTHREAD) /* into next thread */ #ifdef SMP /* XXX FIXME: we should be restoring the local APIC TPR */ -#endif /* SMP */ +#endif + /* + * 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) /* Have an LDT? */ - jnz 1f /* Yes, use it. */ - movl _default_ldt,%eax /* Otherwise, use default. */ + 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: pushl %edx /* Preserve pointer to pcb. */ +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 /* Check and load the ldt. */ + call set_user_ldt addl $4,%esp popl %edx 2: @@ -265,11 +271,16 @@ sw1b: cpu_switch_load_gs: movl PCB_GS(%edx),%gs - /* test if debug regisers should be restored */ + /* Test if debug regisers should be restored. */ movb PCB_FLAGS(%edx),%al andb $PCB_DBREGS,%al - jz 1f /* no, skip over */ - movl PCB_DR6(%edx),%eax /* yes, do the restore */ + 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 @@ -279,10 +290,10 @@ cpu_switch_load_gs: movl %eax,%dr1 movl PCB_DR0(%edx),%eax movl %eax,%dr0 - movl %dr7,%eax /* load dr7 so as not to */ - andl $0x0000fc00,%eax /* disturb reserved bits */ + movl %dr7,%eax + andl $0x0000fc00,%eax movl PCB_DR7(%edx),%ecx - andl $~0x0000fc00,%ecx /* re-enable the restored watchpoints */ + andl $~0x0000fc00,%ecx orl %ecx,%eax movl %eax,%dr7 1: @@ -307,10 +318,10 @@ sw0_3: .asciz "cpu_switch: choosethread returned NULL" * Update pcb, saving current processor state. */ ENTRY(savectx) - /* fetch PCB */ + /* Fetch PCB. */ movl 4(%esp),%ecx - /* caller's return address - child won't execute this routine */ + /* Save caller's return address. Child won't execute this routine. */ movl (%esp),%eax movl %eax,PCB_EIP(%ecx) |
