ftrace: objcopy version test for local symbols

The --globalize-symbols option came out in objcopy version 2.17. If the kernel is being compiled on a system with a lower version of objcopy, then we can not use the globalize / localize trick to link to symbols pointing to local functions. This patch tests the version of objcopy and will only use the trick if the version is greater than or equal to 2.17. Otherwise, if an object has only local functions within a section, it will give a nice warning and recommend the user to upgrade their objcopy. Leaving the symbols unrecorded is not that big of a deal, since the mcount record method changes the actual mcount code to be a simple "ret" without recording registers or anything. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>

ftrace: objcopy version test for local symbols
The --globalize-symbols option came out in objcopy version 2.17. If the kernel is being compiled on a system with a lower version of objcopy, then we can not use the globalize / localize trick to link to symbols pointing to local functions. This patch tests the version of objcopy and will only use the trick if the version is greater than or equal to 2.17. Otherwise, if an object has only local functions within a section, it will give a nice warning and recommend the user to upgrade their objcopy. Leaving the symbols unrecorded is not that big of a deal, since the mcount record method changes the actual mcount code to be a simple "ret" without recording registers or anything. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Steven Rostedt · Ingo Molnar
1 parent ac8825ec6d
Showing 1 changed file with 41 additions and 0 deletions Side-by-side Diff
scripts/recordmcount.pl
@@ -187,6 +187,36 @@
 my $mcount_o = $dirname . "/.tmp_mc_" . $prefix . ".o";
  
 #
+# --globalize-symbols came out in 2.17, we must test the version
+# of objcopy, and if it is less than 2.17, then we can not
+# record local functions.
+my $use_locals = 01;
+my $local_warn_once = 0;
+my $found_version = 0;
+
+open (IN, "$objcopy --version |") || die "error running $objcopy";
+while (<IN>) {
+    if (/objcopy.*\s(\d+)\.(\d+)/) {
+	my $major = $1;
+	my $minor = $2;
+
+	$found_version = 1;
+	if ($major < 2 ||
+	    ($major == 2 && $minor < 17)) {
+	    $use_locals = 0;
+	}
+	last;
+    }
+}
+close (IN);
+
+if (!$found_version) {
+    print STDERR "WARNING: could not find objcopy version.\n" .
+	"\tDisabling local function references.\n";
+}
+
+
+#
 # Step 1: find all the local (static functions) and weak symbols.
 #        't' is local, 'w/W' is weak (we never use a weak function)
 #
@@ -229,6 +259,17 @@
  
     # is this function static? If so, note this fact.
     if (defined $locals{$ref_func}) {
+
+	# only use locals if objcopy supports globalize-symbols
+	if (!$use_locals) {
+	    print STDERR
+		"$inputfile: WARNING: referencing local function " .
+		"$ref_func for mcount\n" .
+		"\tConsider upgrading objcopy to support the globalize-" .
+		"symbols option.\n"
+		if (!$local_warn_once++);
+	    return;
+	}
 	$convert{$ref_func} = 1;
     }
...	...	@@ -187,6 +187,36 @@
187	187	my $mcount_o = $dirname . "/.tmp_mc_" . $prefix . ".o";
188	188
189	189	#
	190	+# --globalize-symbols came out in 2.17, we must test the version
	191	+# of objcopy, and if it is less than 2.17, then we can not
	192	+# record local functions.
	193	+my $use_locals = 01;
	194	+my $local_warn_once = 0;
	195	+my $found_version = 0;
	196	+
	197	+open (IN, "$objcopy --version \|") \|\| die "error running $objcopy";
	198	+while (<IN>) {
	199	+ if (/objcopy.*\s(\d+)\.(\d+)/) {
	200	+ my $major = $1;
	201	+ my $minor = $2;
	202	+
	203	+ $found_version = 1;
	204	+ if ($major < 2 \|\|
	205	+ ($major == 2 && $minor < 17)) {
	206	+ $use_locals = 0;
	207	+ }
	208	+ last;
	209	+ }
	210	+}
	211	+close (IN);
	212	+
	213	+if (!$found_version) {
	214	+ print STDERR "WARNING: could not find objcopy version.\n" .
	215	+ "\tDisabling local function references.\n";
	216	+}
	217	+
	218	+
	219	+#
190	220	# Step 1: find all the local (static functions) and weak symbols.
191	221	# 't' is local, 'w/W' is weak (we never use a weak function)
192	222	#
...	...	@@ -229,6 +259,17 @@
229	259
230	260	# is this function static? If so, note this fact.
231	261	if (defined $locals{$ref_func}) {
	262	+
	263	+ # only use locals if objcopy supports globalize-symbols
	264	+ if (!$use_locals) {
	265	+ print STDERR
	266	+ "$inputfile: WARNING: referencing local function " .
	267	+ "$ref_func for mcount\n" .
	268	+ "\tConsider upgrading objcopy to support the globalize-" .
	269	+ "symbols option.\n"
	270	+ if (!$local_warn_once++);
	271	+ return;
	272	+ }
232	273	$convert{$ref_func} = 1;
233	274	}
234	275