On Fri, Mar 12, 2021 at 12:39 PM Manoj Gupta <manojgupta@xxxxxxxxxx> wrote:
>
> From: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
>
> 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@xxxxxxxxxx
>
> Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
>
> [nc: Resolve conflict because of missing 42c269c88dc146982a54a8267f71abc99f12852a]
^ Isn't `nc:` here supposed to be your initials, ie. `mg:`, or do I
have that wrong?
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
doesn't clarify.
> Signed-off-by: Manoj Gupta <manojgupta@xxxxxxxxxx>
> ---
> scripts/recordmcount.c | 2 +-
> scripts/recordmcount.pl | 13 +++++++++++++
> 2 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
> index 7250fb38350c..8cba4c44da4c 100644
> --- a/scripts/recordmcount.c
> +++ b/scripts/recordmcount.c
> @@ -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 ||
> diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
> index ccd6614ea218..5ca4ec297019 100755
> --- a/scripts/recordmcount.pl
> +++ b/scripts/recordmcount.pl
> @@ -138,6 +138,11 @@ 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);
> @@ -503,6 +508,14 @@ 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();
>
> --
> 2.31.0.rc2.261.g7f71774620-goog
>
--
Thanks,
~Nick Desaulniers
