gcov: add support for checksum field

In GCC version 12.1 a checksum field was added.

This patch fixes a kernel crash occurring during boot when using
gcov-kernel with GCC version 12.2.  The crash occurred on a system running
on i.MX6SX.

Link: https://lkml.kernel.org/r/20221220102318.3418501-1-rickaran@axis.com
Fixes: 977ef30 ("gcov: support GCC 12.1 and newer compilers")
Signed-off-by: Rickard x Andersson <rickaran@axis.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Tested-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Reviewed-by: Martin Liska <mliska@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Rickard x Andersson

kernel/gcov/gcc_4_7.c

@@ -82,6 +82,7 @@ struct gcov_fn_info {
  * @version: gcov version magic indicating the gcc version used for compilation
  * @next: list head for a singly-linked list
  * @stamp: uniquifying time stamp
+ * @checksum: unique object checksum
  * @filename: name of the associated gcov data file
  * @merge: merge functions (null for unused counter type)
  * @n_functions: number of instrumented functions
@@ -94,6 +95,10 @@ struct gcov_info {
 	unsigned int version;
 	struct gcov_info *next;
 	unsigned int stamp;
+ /* Since GCC 12.1 a checksum field is added. */
+#if (__GNUC__ >= 12)
+	unsigned int checksum;
+#endif
 	const char *filename;
 	void (*merge[GCOV_COUNTERS])(gcov_type *, unsigned int);
 	unsigned int n_functions;