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Correctly maintain the per-cpu field "curpmap" on amd64 just like we

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do on i386.  The consequences of not doing so on amd64 became apparent
with the introduction of the COUNT_IPIS and COUNT_XINVLTLB_HITS
options.  Specifically, single-threaded applications were generating
unnecessary IPIs to shoot-down the TLB on other processors.  However,
this is clearly nonsensical because a single-threaded application is
only running on the current processor.  The reason that this happens
is that pmap_activate() is unable to properly update the old pmap's
field "pm_active" without the correct "curpmap".  So, in effect, stale
bits in "pm_active" were leading pmap_protect(), pmap_remove(),
pmap_remove_pages(), etc. to flush the TLB contents on some arbitrary
processor that wasn't even running the same application.

Reviewed by:	kib
MFC after:	3 weeks
This commit is contained in:
Alan Cox 2010-07-08 03:35:00 +00:00
parent 2d7cef1612
commit 77cb6e6f8d
2 changed files with 12 additions and 12 deletions
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22
sys/amd64/amd64/cpu_switch.S
View File

@ -69,16 +69,13 @@
* %rsi = newtd
*/
ENTRY(cpu_throw)
movl PCPU(CPUID),%eax
testq %rdi,%rdi
jnz 1f
movq PCPU(IDLETHREAD),%rdi
1:
movq TD_PCB(%rdi),%r8 /* Old pcb */
movl PCPU(CPUID), %eax
jz 1f
/* release bit from old pm_active */
movq TD_PROC(%rdi), %rdx /* oldtd->td_proc */
movq P_VMSPACE(%rdx), %rdx /* proc->p_vmspace */
LK btrl %eax, VM_PMAP+PM_ACTIVE(%rdx) /* clear old */
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 */
@ -140,15 +137,16 @@ swinact:
movq %rcx,%cr3 /* new address space */
movl PCPU(CPUID), %eax
/* Release bit from old pmap->pm_active */
movq TD_PROC(%rdi), %rcx /* oldproc */
movq P_VMSPACE(%rcx), %rcx
LK btrl %eax, VM_PMAP+PM_ACTIVE(%rcx) /* clear old */
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
LK btsl %eax, VM_PMAP+PM_ACTIVE(%rdx) /* set new */
addq $VM_PMAP,%rdx
LK btsl %eax,PM_ACTIVE(%rdx) /* set new */
movq %rdx,PCPU(CURPMAP)
sw1:
#if defined(SCHED_ULE) && defined(SMP)

2
sys/amd64/amd64/pmap.c
View File

@ -1574,6 +1574,7 @@ pmap_pinit0(pmap_t pmap)
pmap->pm_pml4 = (pml4_entry_t *)PHYS_TO_DMAP(KPML4phys);
pmap->pm_root = NULL;
pmap->pm_active = 0;
PCPU_SET(curpmap, pmap);
TAILQ_INIT(&pmap->pm_pvchunk);
bzero(&pmap->pm_stats, sizeof pmap->pm_stats);
}
@ -5008,6 +5009,7 @@ if (oldpmap) /* XXX FIXME */
cr3 = DMAP_TO_PHYS((vm_offset_t)pmap->pm_pml4);
td->td_pcb->pcb_cr3 = cr3;
load_cr3(cr3);
PCPU_SET(curpmap, pmap);
critical_exit();
}