powerpc/process: Add the function flush_tmregs_to_thread

This patch creates a function flush_tmregs_to_thread which
will then be used by subsequent patches in this series. The
function checks for self tracing ptrace interface attempts
while in the TM context and logs appropriate warning message.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 20 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 9ee2623e0f67..58ccf86415b4 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1074,6 +1074,26 @@ static inline void restore_sprs(struct thread_struct *old_thread,
 #endif
 }
 
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+void flush_tmregs_to_thread(struct task_struct *tsk)
+{
+        /*
+         * Process self tracing is not yet supported through
+         * ptrace interface. Ptrace generic code should have
+         * prevented this from happening in the first place.
+         * Warn once here with the message, if some how it
+         * is attempted.
+         */
+        WARN_ONCE(tsk == current,
+                "Not expecting ptrace on self: TM regs may be incorrect\n");
+
+        /*
+         * If task is not current, it should have been flushed
+         * already to it's thread_struct during __switch_to().
+         */
+}
+#endif
+
 struct task_struct *__switch_to(struct task_struct *prev,
         struct task_struct *new)
 {