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Commit 4dbf7af6 authored by Jan Beulich's avatar Jan Beulich Committed by Ingo Molnar
Browse files

x86: adjust/fix LDT handling for Xen 



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: default avatarJan Beulich <jbeulich@novell.com>
Acked-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent c0400030

arch/x86/kernel/ldt.c

+3 −4
Original line number Diff line number Diff line
@@ -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;

	}

}

arch/x86/xen/enlighten.c

+1 −8
Original line number Diff line number Diff line
@@ -275,19 +275,12 @@ static unsigned long xen_store_tr(void) 


static void xen_set_ldt(const void *addr, unsigned entries)

{

	unsigned long linear_addr = (unsigned long)addr;

	struct mmuext_op *op;

	struct multicall_space mcs = xen_mc_entry(sizeof(*op));



	op = mcs.args;

	op->cmd = MMUEXT_SET_LDT;

	if (linear_addr) {

		/* ldt my be vmalloced, use arbitrary_virt_to_machine */

		xmaddr_t maddr;

		maddr = arbitrary_virt_to_machine((unsigned long)addr);

		linear_addr = (unsigned long)maddr.maddr;

	}

	op->arg1.linear_addr = linear_addr;

	op->arg1.linear_addr = (unsigned long)addr;

	op->arg2.nr_ents = entries;



	MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);