x86: insn decoder test checks objdump version

Check objdump version before using it for insn decoder build test,
because some older objdump can't decode AVX code correctly.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Jim Keniston <jkenisto@us.ibm.com>
LKML-Reference: <20091120171314.6715.30390.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/tools/Makefile

@@ -12,8 +12,11 @@ else
   posttest_64bit = -n
 endif
 
+distill_awk = $(srctree)/arch/x86/tools/distill.awk
+chkobjdump = $(srctree)/arch/x86/tools/chkobjdump.awk
+
 quiet_cmd_posttest = TEST    $@
-      cmd_posttest = $(OBJDUMP) -d -j .text $(objtree)/vmlinux | $(AWK) -f $(srctree)/arch/x86/tools/distill.awk | $(obj)/test_get_len $(posttest_64bit) $(posttest_verbose)
+      cmd_posttest = ($(OBJDUMP) -v | $(AWK) -f $(chkobjdump)) || $(OBJDUMP) -d -j .text $(objtree)/vmlinux | $(AWK) -f $(distill_awk) | $(obj)/test_get_len $(posttest_64bit) $(posttest_verbose)
 
 posttest: $(obj)/test_get_len vmlinux
 	$(call cmd,posttest)

arch/x86/tools/chkobjdump.awk

@@ -0,0 +1,23 @@
+# GNU objdump version checker
+#
+# Usage:
+# objdump -v | awk -f chkobjdump.awk
+BEGIN {
+	# objdump version 2.19 or later is OK for the test.
+	od_ver = 2;
+	od_sver = 19;
+}
+
+/^GNU/ {
+	split($4, ver, ".");
+	if (ver[1] > od_ver ||
+	    (ver[1] == od_ver && ver[2] >= od_sver)) {
+		exit 1;
+	} else {
+		printf("Warning: objdump version %s is older than %d.%d\n",
+		       $4, od_ver, od_sver);
+		print("Warning: Skipping posttest.");
+		# Logic is inverted, because we just skip test without error.
+		exit 0;
+	}
+}