boot/arm-trusted-firmware: add -no-pie to LDFLAGS

Arm Trusted Firmware (TF-A) v2.11 fails to build in some situations
with the error message:

    ld: build/qemu/release/bl1/bl1.elf: error: PHDR segment not covered by LOAD segment

This error can be reproduced with the commands:

    make qemu_aarch64_ebbr_defconfig
    utils/config --set-str BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_VERSION_VALUE v2.11
    make olddefconfig
    make

This issue was reported in [1].

This error is coming from a check that was made more strict since
binutils ld 2.34. This error message is normally related to dynamic
linker, so it should normally not apply to a package like TF-A.

When BR2_SHARED_LIBS=y (shared libraries only) and BR2_PIC_PIE=y
(Build code with PIC/PIE), the Buildroot toolchain-wrapper will try
to enable position-independent code/executables. See [2]. This
configuration is a common default.

Arm Trusted Firmware (TF-A) build system, on its side, tries to detect
if the toolchain enables PIE automatically. It does so by checking if
--enable-default-pie is in the output of "$(CC) -v". If found, the TF-A
build system tries to disable PIE globally (it can be explicitly
enabled again with the ENABLE_PIE=1 build variable, in some specific
configurations). This detection mechanism is not working with the
Buildroot toolchain wrapper which is enabling PIE silently. See [3].

Commit 1061ed6c "boot/arm-trusted-firmware: add -fno-PIE to CFLAGS"
added the option -fno-PIE in CFLAGS for that reason. See [4].
TF-A >= v2.11 now needs the same treatment for LDFLAGS. This is
because TF-A switched the default linker from "ld" to "gcc", in
upstream commit [5]. This change makes the Buildroot toolchain wrapper
to enable PIE at link, without passing the "--no-dynamic-linker" option
that would normally avoids this ld error.

Also, even if there is no defconfigs using the
BR2_TARGET_ARM_TRUSTED_FIRMWARE_LATEST_VERSION config directive, it is
worth mentioning that the Buildroot TF-A "latest version" was updated
to v2.11 in commit 9c50759cd "boot/arm-trusted-firmware: bump to
v2.11". See [6]. This latest version is the default choice. So
Buildroot is subject to generate this build failure. This can be
reproduced with the commands:

    cat <<EOF >.config
    BR2_aarch64=y
    BR2_TARGET_ARM_TRUSTED_FIRMWARE=y
    BR2_TARGET_ARM_TRUSTED_FIRMWARE_PLATFORM="qemu"
    BR2_TOOLCHAIN_EXTERNAL=y
    EOF
    make olddefconfig
    make arm-trusted-firmware

This commit fixes the issue by adding the option "-no-pie" in LDFLAGS.
This will prevent the Buildroot toolchain wrapper to enable PIE, for
versions using "gcc" as a linker. This change should also remain
compatible with older TF-A < 2.11 using "ld" as a linker, since
"-no-pie" is also a valid ld option.

Fixes:

    ld: build/qemu/release/bl1/bl1.elf: error: PHDR segment not covered by LOAD segment

[1] https://github.com/TrustedFirmware-A/trusted-firmware-a/issues/26
[2] https://gitlab.com/buildroot.org/buildroot/-/blob/2024.08-rc3/toolchain/toolchain-wrapper.c?ref_type=tags#L403
[3] https://git.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a.git/+/refs/tags/v2.11.0/Makefile#711
[4] https://gitlab.com/buildroot.org/buildroot/-/commit/1061ed6c6273e90618b05ddc0cb66be17364da33
[5] https://git.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a.git/+/2f1c5e7eb1775b252fa4998e10093b8ac34ca699%5E%21/
[6] https://gitlab.com/buildroot.org/buildroot/-/commit/9c50759cd1677e1739078239a1e86fb1d62e33e8

Reported-by: Vincent Stehlé <vincent.stehle@arm.com>
Tested-by: Vincent Stehlé <vincent.stehle@arm.com>
Signed-off-by: Julien Olivain <ju.o@free.fr>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
1 file changed