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Date:      Thu, 8 Jul 2010 03:35:00 +0000 (UTC)
From:      Alan Cox <alc@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r209789 - head/sys/amd64/amd64
Message-ID:  <201007080335.o683Z0wx090934@svn.freebsd.org>
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Author: alc
Date: Thu Jul  8 03:35:00 2010
New Revision: 209789
URL: http://svn.freebsd.org/changeset/base/209789

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

Modified:
  head/sys/amd64/amd64/cpu_switch.S
  head/sys/amd64/amd64/pmap.c

Modified: head/sys/amd64/amd64/cpu_switch.S
==============================================================================
--- head/sys/amd64/amd64/cpu_switch.S	Thu Jul  8 03:28:25 2010	(r209788)
+++ head/sys/amd64/amd64/cpu_switch.S	Thu Jul  8 03:35:00 2010	(r209789)
@@ -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)

Modified: head/sys/amd64/amd64/pmap.c
==============================================================================
--- head/sys/amd64/amd64/pmap.c	Thu Jul  8 03:28:25 2010	(r209788)
+++ head/sys/amd64/amd64/pmap.c	Thu Jul  8 03:35:00 2010	(r209789)
@@ -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();
 }

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