[PATCH, resend] x86-64: fix HYPERVISOR_update_descriptor()

[Jan Beulich]

Impact: fix potential oops during app-initiated LDT manipulation

The underlying hypercall has differing argument requirements on 32-
and 64-bit.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>

---
 arch/x86/include/asm/xen/hypercall.h |    2 ++
 1 file changed, 2 insertions(+)

--- linux-2.6.29-rc7/arch/x86/include/asm/xen/hypercall.h	2009-03-11 17:52:10.000000000 +0100
+++ 2.6.29-rc7-x86_64-xen-update-descr/arch/x86/include/asm/xen/hypercall.h	2009-02-13 11:41:39.000000000 +0100
@@ -296,6 +296,8 @@ HYPERVISOR_get_debugreg(int reg)
 static inline int
 HYPERVISOR_update_descriptor(u64 ma, u64 desc)
 {
+	if (sizeof(u64) == sizeof(long))
+		return _hypercall2(int, update_descriptor, ma, desc);
 	return _hypercall4(int, update_descriptor, ma, ma>>32, desc, desc>>32);
 }
 



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