PERFORCE change 31200 for review

[Peter Wemm]

http://perforce.freebsd.org/chv.cgi?CH=31200

Change 31200 by peter at peter_hammer on 2003/05/14 15:13:01

	Dig out of a hole.  Dont context switch the kernel gsbase.
	Just preserve it across %gs loads, thats all we need.

Affected files ...

.. //depot/projects/hammer/sys/amd64/amd64/cpu_switch.S#6 edit
.. //depot/projects/hammer/sys/amd64/amd64/genassym.c#16 edit
.. //depot/projects/hammer/sys/amd64/amd64/machdep.c#36 edit
.. //depot/projects/hammer/sys/amd64/ia32/ia32_sysvec.c#7 edit
.. //depot/projects/hammer/sys/amd64/include/pcb.h#10 edit

Differences ...

==== //depot/projects/hammer/sys/amd64/amd64/cpu_switch.S#6 (text+ko) ====

@@ -106,12 +106,6 @@
 	pushfq					/* PSL */
 	popq	PCB_RFLAGS(%r8)
 
-	/* Save kernel %gs.base */
-	movl	$MSR_GSBASE,%ecx
-	rdmsr
-	movl	%eax,PCB_KGSBASE(%r8)
-	movl	%edx,PCB_KGSBASE+4(%r8)
-
 	/* Save userland %fs */
 	movl	$MSR_FSBASE,%ecx
 	rdmsr
@@ -176,12 +170,11 @@
 	movl	PCB_DS(%r8),%ds
 	movl	PCB_ES(%r8),%es
 	movl	PCB_FS(%r8),%fs
-	movl	PCB_GS(%r8),%gs
 
-	/* Restore kernel %gs.base */
+	/* Restore userland %gs while preserving kernel gsbase */
 	movl	$MSR_GSBASE,%ecx
-	movl	PCB_KGSBASE(%r8),%eax
-	movl	PCB_KGSBASE+4(%r8),%edx
+	rdmsr
+	movl	PCB_GS(%r8),%gs
 	wrmsr
 
 	/* Restore userland %fs */

==== //depot/projects/hammer/sys/amd64/amd64/genassym.c#16 (text+ko) ====

@@ -125,7 +125,6 @@
 ASSYM(PCB_RFLAGS, offsetof(struct pcb, pcb_rflags));
 ASSYM(PCB_FSBASE, offsetof(struct pcb, pcb_fsbase));
 ASSYM(PCB_GSBASE, offsetof(struct pcb, pcb_gsbase));
-ASSYM(PCB_KGSBASE, offsetof(struct pcb, pcb_kgsbase));
 ASSYM(PCB_DS, offsetof(struct pcb, pcb_ds));
 ASSYM(PCB_ES, offsetof(struct pcb, pcb_es));
 ASSYM(PCB_FS, offsetof(struct pcb, pcb_fs));

==== //depot/projects/hammer/sys/amd64/amd64/machdep.c#36 (text+ko) ====

@@ -481,7 +481,6 @@
 	wrmsr(MSR_KGSBASE, 0);	/* User value while we're in the kernel */
 	pcb->pcb_fsbase = 0;
 	pcb->pcb_gsbase = 0;
-	pcb->pcb_kgsbase = rdmsr(MSR_GSBASE);
 	load_ds(_udatasel);
 	load_es(_udatasel);
 	load_fs(_udatasel);
@@ -1312,7 +1311,6 @@
 	/* setup proc 0's pcb */
 	thread0.td_pcb->pcb_flags = 0; /* XXXKSE */
 	thread0.td_pcb->pcb_cr3 = IdlePML4;
-	thread0.td_pcb->pcb_kgsbase = (u_int64_t)pc;
 	thread0.td_frame = &proc0_tf;
 }
 

==== //depot/projects/hammer/sys/amd64/ia32/ia32_sysvec.c#7 (text+ko) ====

@@ -246,7 +246,6 @@
 	wrmsr(MSR_KGSBASE, 0);	/* User value while we're in the kernel */
 	pcb->pcb_fsbase = 0;
 	pcb->pcb_gsbase = 0;
-	pcb->pcb_kgsbase = rdmsr(MSR_GSBASE);
 	load_ds(_udatasel);
 	load_es(_udatasel);
 	load_fs(_udatasel);

==== //depot/projects/hammer/sys/amd64/include/pcb.h#10 (text+ko) ====

@@ -59,7 +59,6 @@
 	register_t	pcb_rflags;
 	register_t	pcb_fsbase;
 	register_t	pcb_gsbase;
-	register_t	pcb_kgsbase;
 	u_int32_t	pcb_ds;
 	u_int32_t	pcb_es;
 	u_int32_t	pcb_fs;