x86/oprofile: add IBS support for AMD CPUs, IBS buffer handling routines

This patchset supports the new profiling hardware available in the
latest AMD CPUs in the oProfile driver.

Signed-off-by: Barry Kasindorf <barry.kasindorf@amd.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>
Cc: oprofile-list <oprofile-list@lists.sourceforge.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 67 insertions, 1 deletions

diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c
index 2450b3a393f..c9ac4e15691 100644
--- a/drivers/oprofile/cpu_buffer.c
+++ b/drivers/oprofile/cpu_buffer.c
@@ -5,6 +5,7 @@
  * @remark Read the file COPYING
  *
  * @author John Levon <levon@movementarian.org>
+ * @author Barry Kasindorf <barry.kasindorf@amd.com>
  *
  * Each CPU has a local buffer that stores PC value/event
  * pairs. We also log context switches when we notice them.
@@ -207,7 +208,7 @@ static int log_sample(struct oprofile_cpu_buffer * cpu_buf, unsigned long pc,
 	return 1;
 }
 
-static int oprofile_begin_trace(struct oprofile_cpu_buffer * cpu_buf)
+static int oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf)
 {
 	if (nr_available_slots(cpu_buf) < 4) {
 		cpu_buf->sample_lost_overflow++;
@@ -252,6 +253,71 @@ void oprofile_add_sample(struct pt_regs * const regs, unsigned long event)
 	oprofile_add_ext_sample(pc, regs, event, is_kernel);
 }
 
+#define MAX_IBS_SAMPLE_SIZE	14
+static int log_ibs_sample(struct oprofile_cpu_buffer *cpu_buf,
+	unsigned long pc, int is_kernel, unsigned  int *ibs, int ibs_code)
+{
+	struct task_struct *task;
+
+	cpu_buf->sample_received++;
+
+	if (nr_available_slots(cpu_buf) < MAX_IBS_SAMPLE_SIZE) {
+		cpu_buf->sample_lost_overflow++;
+		return 0;
+	}
+
+	is_kernel = !!is_kernel;
+
+	/* notice a switch from user->kernel or vice versa */
+	if (cpu_buf->last_is_kernel != is_kernel) {
+		cpu_buf->last_is_kernel = is_kernel;
+		add_code(cpu_buf, is_kernel);
+	}
+
+	/* notice a task switch */
+	if (!is_kernel) {
+		task = current;
+
+		if (cpu_buf->last_task != task) {
+			cpu_buf->last_task = task;
+			add_code(cpu_buf, (unsigned long)task);
+		}
+	}
+
+	add_code(cpu_buf, ibs_code);
+	add_sample(cpu_buf, ibs[0], ibs[1]);
+	add_sample(cpu_buf, ibs[2], ibs[3]);
+	add_sample(cpu_buf, ibs[4], ibs[5]);
+
+	if (ibs_code == IBS_OP_BEGIN) {
+	add_sample(cpu_buf, ibs[6], ibs[7]);
+	add_sample(cpu_buf, ibs[8], ibs[9]);
+	add_sample(cpu_buf, ibs[10], ibs[11]);
+	}
+
+	return 1;
+}
+
+void oprofile_add_ibs_sample(struct pt_regs *const regs,
+				unsigned int * const ibs_sample, u8 code)
+{
+	int is_kernel = !user_mode(regs);
+	unsigned long pc = profile_pc(regs);
+
+	struct oprofile_cpu_buffer *cpu_buf =
+			 &per_cpu(cpu_buffer, smp_processor_id());
+
+	if (!backtrace_depth) {
+		log_ibs_sample(cpu_buf, pc, is_kernel, ibs_sample, code);
+		return;
+	}
+
+	/* if log_sample() fails we can't backtrace since we lost the source
+	* of this event */
+	if (log_ibs_sample(cpu_buf, pc, is_kernel, ibs_sample, code))
+		oprofile_ops.backtrace(regs, backtrace_depth);
+}
+
 void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event)
 {
 	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);