Add hooks that the hypervisor can use to establish writable and non-writable
pages for LDT pages. I made these parallel the page flags as defined in
include/linux/page-flags.h, since the flag mechanism is very similar to the
hypercall page flagging, and extended easily later to include PT, PD, PDP,
GDT, etc.
Patch-against: 2.6.13-rc5-mm1
Patch-keys: i386 ldt paravirt xen
Signed-off-by: Zachary Amsden <zach@vmware.com>
Index: linux-2.6.13/arch/i386/kernel/ldt.c
==================================================================---
linux-2.6.13.orig/arch/i386/kernel/ldt.c 2005-08-10 17:06:52.000000000 -0700
+++ linux-2.6.13/arch/i386/kernel/ldt.c 2005-08-10 17:11:38.000000000 -0700
@@ -18,6 +18,7 @@
#include <asm/system.h>
#include <asm/ldt.h>
#include <asm/desc.h>
+#include <mach_pgalloc.h>
#ifdef CONFIG_SMP /* avoids "defined but not used" warning */
static void flush_ldt(void *null)
@@ -59,16 +60,19 @@
#ifdef CONFIG_SMP
cpumask_t mask;
preempt_disable();
+ SetPagesLDT(pc->ldt, (pc->size * LDT_ENTRY_SIZE) / PAGE_SIZE);
load_LDT(pc);
mask = cpumask_of_cpu(smp_processor_id());
if (!cpus_equal(current->mm->cpu_vm_mask, mask))
smp_call_function(flush_ldt, NULL, 1, 1);
preempt_enable();
#else
+ SetPagesLDT(pc->ldt, (pc->size * LDT_ENTRY_SIZE) / PAGE_SIZE);
load_LDT(pc);
#endif
}
if (oldsize) {
+ ClearPagesLDT(oldldt, (oldsize * LDT_ENTRY_SIZE) / PAGE_SIZE);
if (oldsize*LDT_ENTRY_SIZE > PAGE_SIZE)
vfree(oldldt);
else
@@ -83,8 +87,10 @@
down(&old->sem);
err = alloc_ldt(new, 0, old->size, 0);
- if (!err)
+ if (!err) {
memcpy(new->ldt, old->ldt, old->size*LDT_ENTRY_SIZE);
+ SetPagesLDT(new->ldt, (new->size * LDT_ENTRY_SIZE) / PAGE_SIZE);
+ }
up(&old->sem);
return err;
}
@@ -93,6 +99,7 @@
{
if (mm == current->active_mm)
clear_LDT();
+ ClearPagesLDT(mm->context.ldt, (mm->context.size * LDT_ENTRY_SIZE) /
PAGE_SIZE);
if (mm->context.size*LDT_ENTRY_SIZE > PAGE_SIZE)
vfree(mm->context.ldt);
else
Index: linux-2.6.13/include/asm-i386/mach-default/mach_pgalloc.h
==================================================================---
linux-2.6.13.orig/include/asm-i386/mach-default/mach_pgalloc.h 2005-08-10
17:11:38.000000000 -0700
+++ linux-2.6.13/include/asm-i386/mach-default/mach_pgalloc.h 2005-08-10
17:11:38.000000000 -0700
@@ -0,0 +1,7 @@
+#ifndef __ASM_MACH_PGALLOC_H
+#define __ASM_MACH_PGALLOC_H
+
+#define SetPagesLDT(_va, _pages)
+#define ClearPagesLDT(_va, _pages)
+
+#endif
