perf jit: Check JITHEADER_VERSION

Check the version number when opening a jitdump file.  Accept older
versions, but not newer ones.
Signed-off-by: Stefano Sanfilippo <ssanfilippo@chromium.org>
Signed-off-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Stephane Eranian <eranian@google.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1476356383-30100-9-git-send-email-eranian@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/jitdump.c

@@ -180,6 +180,12 @@ jit_open(struct jit_buf_desc *jd, const char *name)
 			header.elf_mach,
 			jd->use_arch_timestamp);
 
+	if (header.version > JITHEADER_VERSION) {
+		pr_err("wrong jitdump version %u, expected " STR(JITHEADER_VERSION),
+			header.version);
+		goto error;
+	}
+
 	if (header.flags & JITDUMP_FLAGS_RESERVED) {
 		pr_err("jitdump file contains invalid or unsupported flags 0x%llx\n",
 		       (unsigned long long)header.flags & JITDUMP_FLAGS_RESERVED);