linux-kernel - [PATCH] ftrace: objcopy version test for local symbols

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 25 Aug 2008 14:52:11 -0400 (EDT)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Ingo Molnar <mingo@...e.hu>
cc:	Stephen Rothwell <sfr@...b.auug.org.au>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, linux-next@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] ftrace: objcopy version test for local symbols

From: Steven Rostedt <srostedt@...hat.com>
Subject: 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.

Signed-off-by: Steven Rostedt <srostedt@...hat.com>
---
 scripts/recordmcount.pl |   41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

Index: linux-tip.git/scripts/recordmcount.pl
===================================================================
--- linux-tip.git.orig/scripts/recordmcount.pl	2008-08-25 14:02:03.000000000 -0400
+++ linux-tip.git/scripts/recordmcount.pl	2008-08-25 14:38:36.000000000 -0400
@@ -187,6 +187,36 @@ my $mcount_s = $dirname . "/.tmp_mc_" . 
 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 @@ sub update_funcs
 
     # 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;
     }
 
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/