[oe] [meta-initramfs][PATCH] klibc: fix build on i386 with GCC and security flags enabled

[Andrea Adami]

please hold on, v2 is coming.

I think -z relro and -z now (data relocation) should be only added if
the distro is using security flags.
BTW I do this check looking at GCCPIE variable, normally evaluated if
security flags are switched on.

Note: all this because the standard SECURITY_LDFLAGS cannot be used:
these start with -Wl but we are talking with the linker directly.

Cheers
Andrea
On Fri, Sep 14, 2018 at 6:46 PM Andrea Adami <andrea.adami at gmail.com> wrote:
>
> Disable pie for powerpc as in security_flags.inc.
> Fix on i386: ld: discarded output section: `.got.plt'
>
> Signed-off-by: Andrea Adami <andrea.adami at gmail.com>
> ---
>  meta-initramfs/recipes-devtools/klibc/klibc.inc | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/meta-initramfs/recipes-devtools/klibc/klibc.inc b/meta-initramfs/recipes-devtools/klibc/klibc.inc
> index 3d25e96..b3d1568 100644
> --- a/meta-initramfs/recipes-devtools/klibc/klibc.inc
> +++ b/meta-initramfs/recipes-devtools/klibc/klibc.inc
> @@ -47,7 +47,8 @@ EXTRA_OEMAKE = "'KLIBCARCH=${KLIBC_ARCH}' \
>                  'KLIBCOPTFLAGS=${TUNE_CCARGS}' \
>                   V=1 \
>                  "
> -EXTRA_OEMAKE += 'EXTRA_KLIBCAFLAGS="-Wa,--noexecstack" EXTRA_KLIBCLDFLAGS="-z noexecstack"'
> +EXTRA_OEMAKE += "'EXTRA_KLIBCAFLAGS=${SECURITY_CFLAGS} -Wa,--noexecstack' \
> +                 'EXTRA_KLIBCLDFLAGS=${SECURITY_LDFLAGS}'"
>
>  export FIX_ARMV4_EABI_BX = "${FIX_V4BX}"
>  KLIBCTHUMB = "${@['CONFIG_KLIBC_THUMB=n', 'CONFIG_KLIBC_THUMB=y'][(d.getVar('ARM_INSTRUCTION_SET') == 'thumb')]}"
> @@ -74,5 +75,8 @@ KLIBC_ARCH_powerpc = "ppc"
>  KLIBC_ARCH_powerpc64 = "ppc64"
>  THIS_LIBKLIBC = "libklibc (= ${PV}-${PR})"
>
> -SECURITY_CFLAGS = "-fno-PIE -no-pie"
> -SECURITY_LDFLAGS = "-no-pie"
> +SECURITY_LDFLAGS = "${@ '-z relro -z now -z noexecstack -pie' if '${GCCPIE}' \
> +                       else '-z relro -z now -z noexecstack' }"
> +
> +# SECURITY_CFLAGS for powerpc are disabled in security_flags.inc
> +SECURITY_LDFLAGS_powerpc = "-z relro -z now -z noexecstack"
> --
> 2.7.4
>