[PATCH 3/6] x86, ptrace: Ifdef HW_BREAKPOINTS code in ptrace

[Andi Kleen]

From: Andi Kleen <ak@xxxxxxxxxxxxxxx>

Add ifdefs on CONFIG_HW_BREAKPOINTS to the hardware
break point code in x86 ptrace.c. This prepares
this file for being able to disable HW_BREAKPOINTS.

The only debug register that needs to be handled
without break points is DR6, so do that in a simple
separate function without breakpoints.

Cc: fweisbec@xxxxxxxxx
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
 arch/x86/kernel/ptrace.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 7461f50..dda433f 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -561,6 +561,8 @@ static int genregs_set(struct task_struct *target,
 	return ret;
 }
 
+#ifdef CONFIG_HW_BREAKPOINTS
+
 static void ptrace_triggered(struct perf_event *bp,
 			     struct perf_sample_data *data,
 			     struct pt_regs *regs)
@@ -778,6 +780,34 @@ static int ptrace_set_debugreg(struct task_struct *tsk, int n,
 	return rc;
 }
 
+#else
+
+/* Without breakpoints only handle DR6 */
+static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n)
+{
+	struct thread_struct *thread = &tsk->thread;
+
+	if (n == 6)
+		return thread->debugreg6;
+	return 0;
+}
+
+/* Without breakpoints only handle DR6 */
+static int ptrace_set_debugreg(struct task_struct *tsk, int n,
+			       unsigned long val)
+{
+	struct thread_struct *thread = &tsk->thread;
+	int rc = -EIO;
+
+	if (n == 6) {
+		thread->debugreg6 = val;
+		rc = 0;
+	}
+	return rc;
+}
+
+#endif
+
 /*
  * These access the current or another (stopped) task's io permission
  * bitmap for debugging or core dump.
-- 
1.8.3.1

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