Re: [PATCH] ARM: linker script: GCOV kernel may refers data in __exit

From: Masami Hiramatsu
Date: Tue Sep 11 2018 - 10:12:59 EST


Hi,

Please drop it, since Peter's patch fixes this problem better way.

https://lkml.org/lkml/2018/9/6/403

Thank you,

On Sat, 1 Sep 2018 21:38:13 +0900
Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:

> GCOV kernel embeds counters in the kernel for each line
> and a part of that embed in __exit text. So we need to
> keep the __exit text if CONFIG_GCOV_KERNEL=y.
>
> Without this patch, if we discards __exit text (e.g.
> disables CONFIG_GENERIC_BUG, CONFIG_JUMP_LABEL and
> CONFIG_SMP_ON_UP) but enables CONFIG_GCOV_PROFILE_FTRACE,
> ld will error like below on ARM.
>
> `.text.exit' referenced in section `.ARM.exidx.text.exit' of
> kernel/trace/trace_clock.o: defined in discarded section `.text.exit'
> of kernel/trace/trace_clock.o
>
> To fix this issue, we keep __exit when CONFIG_GCOV_KERNEL=y.
>
> The reason why not depending CONFIG_GCOV_PROFILE_X, is
> that the Documentation/dev-tools/gcov.rst says that the
> developer can enable gcov profile on a file or a directory
> by customizing Makefile, and that will only depend on
> CONFIG_GCOV_KERNEL.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Reported-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> arch/arm/kernel/vmlinux.lds.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/kernel/vmlinux.lds.h b/arch/arm/kernel/vmlinux.lds.h
> index ae5fdff18406..baaacee9f5ce 100644
> --- a/arch/arm/kernel/vmlinux.lds.h
> +++ b/arch/arm/kernel/vmlinux.lds.h
> @@ -9,7 +9,8 @@
> #endif
>
> #if (defined(CONFIG_SMP_ON_UP) && !defined(CONFIG_DEBUG_SPINLOCK)) || \
> - defined(CONFIG_GENERIC_BUG) || defined(CONFIG_JUMP_LABEL)
> + defined(CONFIG_GENERIC_BUG) || defined(CONFIG_JUMP_LABEL) || \
> + defined(CONFIG_GCOV_KERNEL)
> #define ARM_EXIT_KEEP(x) x
> #define ARM_EXIT_DISCARD(x)
> #else
>


--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>