Linux Virtualization - Apr 2007 - [PATCH 1/3] Bogus tls from gdt

* Zachary Amsden <zach@vmware.com> wrote:
> The per-CPU initialization code is copying in bogus data into 
> thread->tls_array.  Note that it copies &per_cpu(cpu_gdt_table,
cpu),
> not &per_cpu(cpu_gdt_table, cpu)[GDT_ENTRY_TLS_MIN).  That is totally 
> broken and unnecessary.  Make the initialization explicitly NULL.
> 
> Signed-off-by: Zachary Amsden <zach@vmware.com>
Acked-by: Ingo Molnar <mingo@elte.hu>

	Ingo

The per-CPU initialization code is copying in bogus data into
thread->tls_array.  Note that it copies &per_cpu(cpu_gdt_table, cpu),
not &per_cpu(cpu_gdt_table, cpu)[GDT_ENTRY_TLS_MIN).  That is totally
broken and unnecessary.  Make the initialization explicitly NULL.

Signed-off-by: Zachary Amsden <zach@vmware.com>

Index: linux-2.6.14-rc1/arch/i386/kernel/cpu/common.c
==================================================================---
linux-2.6.14-rc1.orig/arch/i386/kernel/cpu/common.c	2005-09-20
14:49:10.000000000 -0700
+++ linux-2.6.14-rc1/arch/i386/kernel/cpu/common.c	2005-09-20 14:49:41.000000000
-0700
@@ -607,12 +607,6 @@ void __devinit cpu_init(void)
 	cpu_gdt_descr[cpu].address  	    (unsigned long)&per_cpu(cpu_gdt_table,
cpu);
 
-	/*
-	 * Set up the per-thread TLS descriptor cache:
-	 */
-	memcpy(thread->tls_array, &per_cpu(cpu_gdt_table, cpu),
-		GDT_ENTRY_TLS_ENTRIES * 8);
-
 	load_gdt(&cpu_gdt_descr[cpu]);
 	load_idt(&idt_descr);