1 files changed, 22 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1e78453645be..551f6713ff42 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -477,6 +477,28 @@ struct task_struct *__switch_to(struct task_struct *prev,
         new_thread = &new->thread;
         old_thread = &current->thread;
 
+#if defined(CONFIG_PPC_BOOK3E_64)
+        /* XXX Current Book3E code doesn't deal with kernel side DBCR0,
+         * we always hold the user values, so we set it now.
+         *
+         * However, we ensure the kernel MSR:DE is appropriately cleared too
+         * to avoid spurrious single step exceptions in the kernel.
+         *
+         * This will have to change to merge with the ppc32 code at some point,
+         * but I don't like much what ppc32 is doing today so there's some
+         * thinking needed there
+         */
+        if ((new_thread->dbcr0 | old_thread->dbcr0) & DBCR0_IDM) {
+                u32 dbcr0;
+
+                mtmsr(mfmsr() & ~MSR_DE);
+                isync();
+                dbcr0 = mfspr(SPRN_DBCR0);
+                dbcr0 = (dbcr0 & DBCR0_EDM) | new_thread->dbcr0;
+                mtspr(SPRN_DBCR0, dbcr0);
+        }
+#endif /* CONFIG_PPC64_BOOK3E */
+
 #ifdef CONFIG_PPC64
         /*
          * Collect processor utilization data per process