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Commit 7d5222a6 authored by Matt Fleming's avatar Matt Fleming Committed by Ingo Molnar
Browse files

ftrace: align __mcount_loc sections 



Impact: add alignment option for recordmcount.pl script

Align the __mcount_loc sections so that architectures with strict
alignment requirements need not worry about performing unaligned
accesses.

This fixes an issue where I was seeing unaligned accesses, which are not
supported on our architecture (the results of an unaligned access are
undefined).

Signed-off-by: default avatarMatt Fleming <matthew.fleming@imgtec.com>
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent c76f0694

scripts/recordmcount.pl

+4 −0
Original line number Diff line number Diff line
@@ -134,6 +134,7 @@ my $section_regex; # Find the start of a section 
my $function_regex;	# Find the name of a function

			#    (return offset and func name)

my $mcount_regex;	# Find the call site to mcount (return offset)

my $alignment;         # The .align value to use for $mcount_section



if ($arch eq "x86") {

    if ($bits == 64) {
@@ -148,6 +149,7 @@ if ($arch eq "x86_64") { 
    $function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:";

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

    $type = ".quad";

    $alignment = 8;



    # force flags for this arch

    $ld .= " -m elf_x86_64";
@@ -160,6 +162,7 @@ if ($arch eq "x86_64") { 
    $function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:";

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

    $type = ".long";

    $alignment = 4;



    # force flags for this arch

    $ld .= " -m elf_i386";
@@ -288,6 +291,7 @@ sub update_funcs 
	    open(FILE, ">$mcount_s") || die "can't create $mcount_s\n";

	    $opened = 1;

	    print FILE "\t.section $mcount_section,\"a\",\@progbits\n";

	    print FILE "\t.align $alignment\n";

	}

	printf FILE "\t%s %s + %d\n", $type, $ref_func, $offsets[$i] - $offset;

    }