From c4cdbe3c18bca496dc6b4af17e2637379528ad02 Mon Sep 17 00:00:00 2001

From: Valentin Schneider <valentin.schneider@arm.com>

Date: Thu, 3 Sep 2020 21:28:46 +0100

Subject: [PATCH 2/3] extensions/trace: Rename trace_buffer to array_buffer

This renaming is present from Linux v5.6 upwards, and was introduced by

commit:

  1c5eb4481e01 ("tracing: Rename trace_buffer to array_buffer")

Rename the internal references from trace_buffer to array_buffer. Backwards

compatibility with older kernels is provided by checking whether struct

trace_array has an array_buffer field - should that not be the case, the

old naming scheme is used instead.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>

---

 trace.c | 53 +++++++++++++++++++++++++++++++++++------------------

 1 file changed, 35 insertions(+), 18 deletions(-)

diff --git a/trace.c b/trace.c

index c26b6c7ec475..2cea5b2d650a 100644

--- a/trace.c

+++ b/trace.c

@@ -31,9 +31,9 @@ static int per_cpu_buffer_sizes;

  */

 static int encapsulated_current_trace;

 /*

- * trace_buffer is supported

+ * array_buffer (trace_buffer pre v5.6) is supported

  */

-static int trace_buffer_available;

+static int array_buffer_available;

 /*

  * max_buffer is supported

  */

@@ -51,9 +51,9 @@ static int buffer_page_real_end_available;

 #define koffset(struct, member) struct##_##member##_offset

 static int koffset(trace_array, current_trace);

-static int koffset(trace_array, trace_buffer);

+static int koffset(trace_array, array_buffer);

 static int koffset(trace_array, max_buffer);

-static int koffset(trace_buffer, buffer);

+static int koffset(array_buffer, buffer);

 static int koffset(trace_array, buffer);

 static int koffset(tracer, name);

@@ -117,7 +117,7 @@ static ulong max_tr_trace;

 struct trace_instance {

 	char name[NAME_MAX + 1];

-	ulong trace_buffer;

+	ulong array_buffer;

 	ulong max_buffer;

 	ulong ring_buffer;

 	unsigned pages;

@@ -174,8 +174,7 @@ static int write_and_check(int fd, void *data, size_t size)

 static int init_offsets(void)

 {

-#define init_offset(struct, member) do {				\

-		koffset(struct, member) = MEMBER_OFFSET(#struct, #member);\

+#define check_offset(struct, member) do { \

 		if (koffset(struct, member) < 0) {			\

 			fprintf(fp, "failed to init the offset, struct:"\

 				#struct ", member:" #member);		\

@@ -184,12 +183,29 @@ static int init_offsets(void)

 		}							\

 	} while (0)

+#define init_offset(struct, member) do {				\

+		koffset(struct, member) = MEMBER_OFFSET(#struct, #member); \

+		check_offset(struct, member);				\

+	} while (0)

+

+#define init_offset_alternative(struct, member, alt_struct, alt_member) do {	\

+		koffset(struct, member) = MEMBER_OFFSET(#alt_struct, #alt_member); \

+		check_offset(struct, member);				\

+	} while (0)

+

 	if (encapsulated_current_trace)

 		init_offset(trace_array, current_trace);

-	if (trace_buffer_available) {

-		init_offset(trace_array, trace_buffer);

-		init_offset(trace_buffer, buffer);

+	if (array_buffer_available) {

+		if (MEMBER_EXISTS("trace_array", "array_buffer")) {

+			init_offset(trace_array, array_buffer);

+			init_offset(array_buffer, buffer);

+		} else {

+			init_offset_alternative(trace_array, array_buffer,

+						trace_array, trace_buffer);

+			init_offset_alternative(array_buffer, buffer,

+						trace_buffer, buffer);

+		}

 		if (max_buffer_available)

 			init_offset(trace_array, max_buffer);

@@ -486,17 +502,17 @@ out_fail:

 static int ftrace_init_trace(struct trace_instance *ti, ulong instance_addr)

 {

-	if (trace_buffer_available) {

-		ti->trace_buffer = instance_addr +

-				koffset(trace_array, trace_buffer);

-		read_value(ti->ring_buffer, ti->trace_buffer,

-				trace_buffer, buffer);

+	if (array_buffer_available) {

+		ti->array_buffer = instance_addr +

+				koffset(trace_array, array_buffer);

+		read_value(ti->ring_buffer, ti->array_buffer,

+			   array_buffer, buffer);

 		if (max_buffer_available) {

 			ti->max_buffer = instance_addr +

 					koffset(trace_array, max_buffer);

 			read_value(ti->max_tr_ring_buffer, ti->max_buffer,

-					trace_buffer, buffer);

+					array_buffer, buffer);

 		}

 	} else {

 		read_value(ti->ring_buffer, instance_addr, trace_array, buffer);

@@ -683,8 +699,9 @@ static int ftrace_init(void)

 		current_trace = sym_current_trace->value;

 	}

-	if (MEMBER_EXISTS("trace_array", "trace_buffer")) {

-		trace_buffer_available = 1;

+	if (MEMBER_EXISTS("trace_array", "array_buffer") ||

+	    MEMBER_EXISTS("trace_array", "trace_buffer")) {

+		array_buffer_available = 1;

 		if (MEMBER_EXISTS("trace_array", "max_buffer"))

 			max_buffer_available = 1;

-- 

2.17.1