3 files changed, 24 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index b111713b593e..6576bad1069c 100644
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h
@@ -65,9 +65,12 @@ static inline void hw_breakpoint_disable(void)
 {
         set_dabr(0);
 }
+extern void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs);
 
 #else   /* CONFIG_HAVE_HW_BREAKPOINT */
 static inline void hw_breakpoint_disable(void) { }
+static inline void thread_change_pc(struct task_struct *tsk,
+                                        struct pt_regs *regs) { }
 #endif  /* CONFIG_HAVE_HW_BREAKPOINT */
 #endif  /* __KERNEL__ */
 #endif  /* _PPC_BOOK3S_64_HW_BREAKPOINT_H */
diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 7a2ad5e84c16..7bd01a56d194 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -175,6 +175,24 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
 }
 
 /*
+ * Restores the breakpoint on the debug registers.
+ * Invoke this function if it is known that the execution context is
+ * about to change to cause loss of MSR_SE settings.
+ */
+void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs)
+{
+        struct arch_hw_breakpoint *info;
+
+        if (likely(!tsk->thread.last_hit_ubp))
+                return;
+
+        info = counter_arch_bp(tsk->thread.last_hit_ubp);
+        regs->msr &= ~MSR_SE;
+        set_dabr(info->address | info->type | DABR_TRANSLATION);
+        tsk->thread.last_hit_ubp = NULL;
+}
+
+/*
  * Handle debug exception notifications.
  */
 int __kprobes hw_breakpoint_handler(struct die_args *args)
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index a0afb555a7c9..7109f5b1baa8 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -11,6 +11,7 @@
 
 #include <linux/tracehook.h>
 #include <linux/signal.h>
+#include <asm/hw_breakpoint.h>
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
 
@@ -149,6 +150,8 @@ static int do_signal_pending(sigset_t *oldset, struct pt_regs *regs)
         if (current->thread.dabr)
                 set_dabr(current->thread.dabr);
 #endif
+        /* Re-enable the breakpoints for the signal stack */
+        thread_change_pc(current, regs);
 
         if (is32) {
                 if (ka.sa.sa_flags & SA_SIGINFO)