[RFC PATCH 7/7] events: Use early task context tracking if available

[Daniel Bristot de Oliveira]

Use the early task context tracking to detect the current context,
if the arch supports it.

Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Tommaso Cucinotta <tommaso.cucinotta@xxxxxxxxxxxxxxx>
Cc: Romulo Silva de Oliveira <romulo.deoliveira@xxxxxxx>
Cc: Clark Williams <williams@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: x86@xxxxxxxxxx
---
 kernel/events/internal.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/kernel/events/internal.h b/kernel/events/internal.h
index 241a2318bfdc..8e4215f8cb93 100644
--- a/kernel/events/internal.h
+++ b/kernel/events/internal.h
@@ -219,6 +219,18 @@ enum {
 	TRACE_CTX_MAX
 };
 
+#ifdef ARCH_HAS_TASK_CONTEXT
+static __always_inline int trace_get_context_bit(void)
+{
+	unsigned long tc = this_cpu_read(task_context);
+
+	if (tc)
+		return tc & TASK_CTX_NMI ? TRACE_CTX_NMI :
+			tc & TASK_CTX_IRQ ? TRACE_CTX_IRQ : TRACE_CTX_SOFTIRQ;
+	else
+		return TRACE_CTX_NORMAL;
+}
+#else /* ARCH_HAS_TASK_CONTEXT */
 static __always_inline int trace_get_context_bit(void)
 {
 	unsigned long pc = preempt_count();
@@ -229,6 +241,7 @@ static __always_inline int trace_get_context_bit(void)
 	else
 		return TRACE_CTX_NORMAL;
 }
+#endif /* ARCH_HAS_TASK_CONTEXT */
 
 static inline int get_recursion_context(int *recursion)
 {
-- 
2.20.1