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-rw-r--r--arch/powerpc/kernel/process.c22
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