xen: add variable hypercall caller

Allow non-constant hypercall to be called, for privcmd.

[ Impact: make arbitrary hypercalls; needed for privcmd ]

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/arch/x86/include/asm/xen/hypercall.h b/arch/x86/include/asm/xen/hypercall.h
index 7fda040a76cd..a3c28ae4025b 100644
--- a/arch/x86/include/asm/xen/hypercall.h
+++ b/arch/x86/include/asm/xen/hypercall.h
@@ -200,6 +200,23 @@ extern struct { char _entry[32]; } hypercall_page[];
         (type)__res;                                                    \
 })
 
+static inline long
+privcmd_call(unsigned call,
+             unsigned long a1, unsigned long a2,
+             unsigned long a3, unsigned long a4,
+             unsigned long a5)
+{
+        __HYPERCALL_DECLS;
+        __HYPERCALL_5ARG(a1, a2, a3, a4, a5);
+
+        asm volatile("call *%[call]"
+                     : __HYPERCALL_5PARAM
+                     : [call] "a" (&hypercall_page[call])
+                     : __HYPERCALL_CLOBBER5);
+
+        return (long)__res;
+}
+
 static inline int
 HYPERVISOR_set_trap_table(struct trap_info *table)
 {