Commit d6aa3d86 authored Nov 20, 2018 by Joe Lawrence Committed by Greg Kroah-Hartman Mar 17, 2021

scripts/recordmcount.{c,pl}: support -ffunction-sections .text.* section names

commit 9c8e2f6d3d361439cc6744a094f1c15681b55269 upstream.

When building with -ffunction-sections, the compiler will place each
function into its own ELF section, prefixed with ".text".  For example,
a simple test module with functions test_module_do_work() and
test_module_wq_func():

  % objdump --section-headers test_module.o | awk '/\.text/{print $2}'
  .text
  .text.test_module_do_work
  .text.test_module_wq_func
  .init.text
  .exit.text

Adjust the recordmcount scripts to look for ".text" as a section name
prefix.  This will ensure that those functions will be included in the
__mcount_loc relocations:

  % objdump --reloc --section __mcount_loc test_module.o
  OFFSET           TYPE              VALUE
  0000000000000000 R_X86_64_64       .text.test_module_do_work
  0000000000000008 R_X86_64_64       .text.test_module_wq_func
  0000000000000010 R_X86_64_64       .init.text

Link: http://lkml.kernel.org/r/1542745158-25392-2-git-send-email-joe.lawrence@redhat.com



Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
[Manoj: Resolve conflict on 4.4.y/4.9.y because of missing 42c269c88dc1]
Signed-off-by: Manoj Gupta <manojgupta@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent bf56e12f

scripts/recordmcount.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -362,7 +362,7 @@ static uint32_t (*w2)(uint16_t);
		static int
		is_mcounted_section_name(char const *const txtname)
		{
		return strcmp(".text", txtname) == 0 \|\|
		return strncmp(".text", txtname, 5) == 0 \|\|
		strcmp(".ref.text", txtname) == 0 \|\|
		strcmp(".sched.text", txtname) == 0 \|\|
		strcmp(".spinlock.text", txtname) == 0 \|\|

scripts/recordmcount.pl

+13 −0

Original line number	Diff line number	Diff line
		@@ -140,6 +140,11 @@ my %text_sections = (
		".text.unlikely" => 1,
		);

		# Acceptable section-prefixes to record.
		my %text_section_prefixes = (
		".text." => 1,
		);

		# Note: we are nice to C-programmers here, thus we skip the '\|\|='-idiom.
		$objdump = 'objdump' if (!$objdump);
		$objcopy = 'objcopy' if (!$objcopy);
		@@ -505,6 +510,14 @@ while (<IN>) {

		# Only record text sections that we know are safe
		$read_function = defined($text_sections{$1});
		if (!$read_function) {
		foreach my $prefix (keys %text_section_prefixes) {
		if (substr($1, 0, length $prefix) eq $prefix) {
		$read_function = 1;
		last;
		}
		}
		}
		# print out any recorded offsets
		update_funcs();