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: Matt Fleming <matthew.fleming@imgtec.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 4 insertions, 0 deletions

diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 6b9fe3eb8360..eeac71c87c66 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -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;
     }