Subject: Re: [PATCH v8 4/8] ppc64 ftrace_with_regs configuration variables

From: Balbir Singh <[email-masked]>
Date: Thu, 11 Feb 2016 18:48:17 +1100

On Wed, 2016-02-10 at 17:25 +0100, Torsten Duwe wrote:

snip

> diff --git a/arch/powerpc/gcc-mprofile-kernel-notrace.sh b/arch/powerpc/gcc-mprofile-kernel-notrace.sh
> new file mode 100755
> index 0000000..68d6482
> --- /dev/null
> +++ b/arch/powerpc/gcc-mprofile-kernel-notrace.sh
> @@ -0,0 +1,33 @@
> +#!/bin/sh
> +# Test whether the compile option -mprofile-kernel
> +# generates profiling code ( = a call to mcount), and
> +# whether a function without any global references sets
> +# the TOC pointer properly at the beginning, and
> +# whether the "notrace" function attribute successfully
> +# suppresses the _mcount call.
> +
> +echo "int func() { return 0; }" | \
> +    $* -S -x c -O2 -p -mprofile-kernel - -o - 2> /dev/null | \
> +    grep -q "mcount"
> +
> +trace_result=$?
> +
> +echo "int func() { return 0; }" | \
> +    $* -S -x c -O2 -p -mprofile-kernel - -o - 2> /dev/null | \
> +    sed -n -e '/func:/,/bl _mcount/p' | grep -q TOC
> +
> +leaf_toc_result=$?
> +

leaf_toc_result failed for me with gcc 5. I'll try and grab gcc-6
and give the patches a spin

> +/bin/echo -e "#include \nnotrace int func() { return 0; }" | \
> +    $* -S -x c -O2 -p -mprofile-kernel - -o - 2> /dev/null | \
> +    grep -q "mcount"
> +
> +notrace_result=$?
> +
> +if [ "$trace_result" -eq "0" -a \
> +	"$leaf_toc_result" -eq "0" -a \
> +	"$notrace_result" -eq "1" ]; then
> +	echo y
> +else
> +	echo n
> +fi