These changes are the raw update to linux-4.4.6-rt14. Kernel sources

[kvmfornfv.git] / kernel / arch / arm / xen / hypercall.S

diff --git a/kernel/arch/arm/xen/hypercall.S b/kernel/arch/arm/xen/hypercall.S
index f00e080..10fd99c 100644 (file)
--- a/kernel/arch/arm/xen/hypercall.S
+++ b/kernel/arch/arm/xen/hypercall.S
@@ -98,8 +98,23 @@ ENTRY(privcmd_call)
        mov r1, r2
        mov r2, r3
        ldr r3, [sp, #8]
+       /*
+        * Privcmd calls are issued by the userspace. We need to allow the
+        * kernel to access the userspace memory before issuing the hypercall.
+        */
+       uaccess_enable r4
+
+       /* r4 is loaded now as we use it as scratch register before */
        ldr r4, [sp, #4]
        __HVC(XEN_IMM)
+
+       /*
+        * Disable userspace access from kernel. This is fine to do it
+        * unconditionally as no set_fs(KERNEL_DS)/set_fs(get_ds()) is
+        * called before.
+        */
+       uaccess_disable r4
+
        ldm sp!, {r4}
        ret lr
 ENDPROC(privcmd_call);