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x86: adjust/fix LDT handling for Xen

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Based on patch from Jan Beulich <jbeulich@novell.com>.

Don't rely on kmalloc(PAGE_SIZE) returning PAGE_SIZE aligned memory
(Xen requires GDT *and* LDT to be page-aligned). Using the page
allocator interface also removes the (albeit small) slab allocator
overhead. The same change being done for 64-bits for consistency.

Further, the Xen hypercall interface expects the LDT address to be
virtual, not machine.

[ Adjusted to unified ldt.c - Jeremy ]

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Acked-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Jan Beulich
2008-01-30 13:33:14 +01:00
committed by Ingo Molnar
parent c0400030b2
commit 4dbf7af644
2 changed files with 4 additions and 12 deletions
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7
arch/x86/kernel/ldt.c
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@@ -12,7 +12,6 @@
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <asm/system.h>
@@ -40,7 +39,7 @@ static int alloc_ldt(mm_context_t *pc, int mincount, int reload)
if (mincount * LDT_ENTRY_SIZE > PAGE_SIZE)
newldt = vmalloc(mincount * LDT_ENTRY_SIZE);
else
newldt = kmalloc(mincount * LDT_ENTRY_SIZE, GFP_KERNEL);
newldt = (void *)__get_free_page(GFP_KERNEL);
if (!newldt)
return -ENOMEM;
@@ -78,7 +77,7 @@ static int alloc_ldt(mm_context_t *pc, int mincount, int reload)
if (oldsize * LDT_ENTRY_SIZE > PAGE_SIZE)
vfree(oldldt);
else
kfree(oldldt);
put_page(virt_to_page(oldldt));
}
return 0;
}
@@ -129,7 +128,7 @@ void destroy_context(struct mm_struct *mm)
if (mm->context.size * LDT_ENTRY_SIZE > PAGE_SIZE)
vfree(mm->context.ldt);
else
kfree(mm->context.ldt);
put_page(virt_to_page(mm->context.ldt));
mm->context.size = 0;
}
}