KVM: PPC: Introduce branch patching helper

We will need to patch several instruction streams over to a different
code path, so we need a way to patch a single instruction with a branch
somewhere else.

This patch adds a helper to facilitate this patching.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
index 926f93fd722d8bdfb1bca7bec7b4c18269b19cd4..239a70d750a21b97159a282c6ad6eb4a33015f66 100644 (file)
--- a/arch/powerpc/kernel/kvm.c
+++ b/arch/powerpc/kernel/kvm.c
@@ -107,6 +107,20 @@ static void kvm_patch_ins_nop(u32 *inst)
        kvm_patch_ins(inst, KVM_INST_NOP);
 }
 
+static void kvm_patch_ins_b(u32 *inst, int addr)
+{
+#ifdef CONFIG_RELOCATABLE
+       /* On relocatable kernels interrupts handlers and our code
+          can be in different regions, so we don't patch them */
+
+       extern u32 __end_interrupts;
+       if ((ulong)inst < (ulong)&__end_interrupts)
+               return;
+#endif
+
+       kvm_patch_ins(inst, KVM_INST_B | (addr & KVM_INST_B_MASK));
+}
+
 static u32 *kvm_alloc(int len)
 {
        u32 *p;