hw_breakpoints: Allow arch-specific cleanup before breakpoint unregistration

Certain architectures (such as PowerPC) have a need to clean up data
structures before a breakpoint is unregistered.  This introduces an
arch-specific hook in release_bp_slot() along with a weak definition
in the form of a stub function.

Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 7a56b22e0602..71ed3ce29e12 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -242,6 +242,17 @@ toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type,
 }
 
 /*
+ * Function to perform processor-specific cleanup during unregistration
+ */
+__weak void arch_unregister_hw_breakpoint(struct perf_event *bp)
+{
+        /*
+         * A weak stub function here for those archs that don't define
+         * it inside arch/.../kernel/hw_breakpoint.c
+         */
+}
+
+/*
  * Contraints to check before allowing this new breakpoint counter:
  *
  *  == Non-pinned counter == (Considered as pinned for now)
@@ -339,6 +350,7 @@ void release_bp_slot(struct perf_event *bp)
 {
         mutex_lock(&nr_bp_mutex);
 
+        arch_unregister_hw_breakpoint(bp);
         __release_bp_slot(bp);
 
         mutex_unlock(&nr_bp_mutex);