1 files changed, 64 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 7a0c0199ea28..11f3cd9c832f 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -32,6 +32,8 @@
 #ifdef CONFIG_PPC32
 #include <linux/module.h>
 #endif
+#include <linux/hw_breakpoint.h>
+#include <linux/perf_event.h>
 
 #include <asm/uaccess.h>
 #include <asm/page.h>
@@ -866,9 +868,34 @@ void user_disable_single_step(struct task_struct *task)
         clear_tsk_thread_flag(task, TIF_SINGLESTEP);
 }
 
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+void ptrace_triggered(struct perf_event *bp, int nmi,
+                      struct perf_sample_data *data, struct pt_regs *regs)
+{
+        struct perf_event_attr attr;
+
+        /*
+         * Disable the breakpoint request here since ptrace has defined a
+         * one-shot behaviour for breakpoint exceptions in PPC64.
+         * The SIGTRAP signal is generated automatically for us in do_dabr().
+         * We don't have to do anything about that here
+         */
+        attr = bp->attr;
+        attr.disabled = true;
+        modify_user_hw_breakpoint(bp, &attr);
+}
+#endif /* CONFIG_HAVE_HW_BREAKPOINT */
+
 int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
                                unsigned long data)
 {
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+        int ret;
+        struct thread_struct *thread = &(task->thread);
+        struct perf_event *bp;
+        struct perf_event_attr attr;
+#endif /* CONFIG_HAVE_HW_BREAKPOINT */
+
         /* For ppc64 we support one DABR and no IABR's at the moment (ppc64).
          *  For embedded processors we support one DAC and no IAC's at the
          *  moment.
@@ -896,6 +923,43 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
         /* Ensure breakpoint translation bit is set */
         if (data && !(data & DABR_TRANSLATION))
                 return -EIO;
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+        bp = thread->ptrace_bps[0];
+        if ((!data) || !(data & (DABR_DATA_WRITE | DABR_DATA_READ))) {
+                if (bp) {
+                        unregister_hw_breakpoint(bp);
+                        thread->ptrace_bps[0] = NULL;
+                }
+                return 0;
+        }
+        if (bp) {
+                attr = bp->attr;
+                attr.bp_addr = data & ~HW_BREAKPOINT_ALIGN;
+                arch_bp_generic_fields(data &
+                                        (DABR_DATA_WRITE | DABR_DATA_READ),
+                                                        &attr.bp_type);
+                ret =  modify_user_hw_breakpoint(bp, &attr);
+                if (ret)
+                        return ret;
+                thread->ptrace_bps[0] = bp;
+                thread->dabr = data;
+                return 0;
+        }
+
+        /* Create a new breakpoint request if one doesn't exist already */
+        hw_breakpoint_init(&attr);
+        attr.bp_addr = data & ~HW_BREAKPOINT_ALIGN;
+        arch_bp_generic_fields(data & (DABR_DATA_WRITE | DABR_DATA_READ),
+                                                                &attr.bp_type);
+
+        thread->ptrace_bps[0] = bp = register_user_hw_breakpoint(&attr,
+                                                        ptrace_triggered, task);
+        if (IS_ERR(bp)) {
+                thread->ptrace_bps[0] = NULL;
+                return PTR_ERR(bp);
+        }
+
+#endif /* CONFIG_HAVE_HW_BREAKPOINT */
 
         /* Move contents to the DABR register */
         task->thread.dabr = data;