Commit 34698bcb authored by Steven Rostedt's avatar Steven Rostedt Committed by Ingo Molnar
Browse files

ftrace: dynamic ftrace process only text section 



The text section stays in memory without ever leaving. With the exception
of modules, but modules know how to handle that case. With the dynamic
ftrace tracer, we need to make sure that it does not try to modify code
that no longer exists. The only safe section is .text.

This patch changes the recordmcount script to only record the mcount calls
in the .text sections.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent dce9d18a

scripts/recordmcount.pl

+14 −3
Original line number Diff line number Diff line
@@ -109,6 +109,11 @@ if ($#ARGV < 6) { 
my ($arch, $bits, $objdump, $objcopy, $cc,

    $ld, $nm, $rm, $mv, $inputfile) = @ARGV;



# Acceptable sections to record.

my %text_sections = (

     ".text" => 1,

);



$objdump = "objdump" if ((length $objdump) == 0);

$objcopy = "objcopy" if ((length $objcopy) == 0);

$cc = "gcc" if ((length $cc) == 0);
@@ -139,7 +144,7 @@ if ($arch eq "x86") { 
}



if ($arch eq "x86_64") {

    $section_regex = "Disassembly of section";

    $section_regex = "Disassembly of section\\s+(\\S+):";

    $function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:";

    $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\smcount([+-]0x[0-9a-zA-Z]+)?\$";

    $type = ".quad";
@@ -151,7 +156,7 @@ if ($arch eq "x86_64") { 
    $cc .= " -m64";



} elsif ($arch eq "i386") {

    $section_regex = "Disassembly of section";

    $section_regex = "Disassembly of section\\s+(\\S+):";

    $function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:";

    $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\smcount\$";

    $type = ".long";
@@ -298,7 +303,13 @@ my $text; 
while (<IN>) {

    # is it a section?

    if (/$section_regex/) {



	# Only record text sections that we know are safe

	if (defined($text_sections{$1})) {

	    $read_function = 1;

	} else {

	    $read_function = 0;

	}

	# print out any recorded offsets

	update_funcs() if ($text_found);

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