[U-Boot] Fwd: build u-boot failed with config CONFIG_ARMV8_PSCI by aarch linux gcc 8.1

[Renlin Li]

CC u-boot mailing list to make people aware of the discussion.

By the way, I also noticed that, the final linking command is using:
'''-pie -Bstatic --no-dynamic-linker'''
And there are self-relocating code in Start.S.

BUT it is not included when u-boot is not configured using
"POSITION_INDEPENDENT"
Which means, PIE feature cannot be used at load time.
I am not sure about the code design and use cases, but '''LDFLAGS_u-boot +=
-pie''' may need to be guarded with '''CONFIG_POSITION_INDEPENDENT''' as
well? Otherwise what is the purpose of pie without processing the dynamic
relocations?

I tried to do that, and with some fixes in other places to change the
checks for relocations, it could generate a binary without any relocations.
Though, I am NOT sure about the CORRECTNESS of the binary.

In the original code, R_AARCH64_ABS32 relocation is used to resolve an
address at static linking time. It seems works fine originally (which
doesn't mean it is not bugous). I assume it is because, no one is trying to
use pie feature really.

If people is using pie feature to load the binary in a different address,
proper relocations are required, as well as the self-relocating code.

The linker won't generate a dynamic RELATIVE relocation for _AARCH64_ABS32.
SO the address in the table won't be updated by the fixup code. However,
bfd linker will generate a dynamic RELATIVE relocation for R_AARCH64_ABS64
relocation, and it could be processed by self-relocating code, taking the
load address into account.


Regards,
Renlin


On Tue, Oct 2, 2018 at 11:45 AM Renlin Li <renlin.dev at gmail.com> wrote:

> Hi Meng,
>
> Thanks for raising the issue!
> I could reproduce the issue with the information you gave.
>
> It seems to me that, the change I made earlier catches an issue here.
> in /arch/arm/cpu/armv8/psci.S
>
> */* PSCI function and ID table definition*/*
> *#define PSCI_TABLE(__id, __fn) \*
> * .word __id; \*
> * .word __fn*
>
> "*.word*" is used to hold the address of a function.
>
> The toolchain you used is aarch64-linux, which by default supports LP64
> ABI.
> This means Long and void * (pointer) data type is 64-bit.
>
> IIUC, a "*.xword*" should be used instead. Otherwise, you should use
> ILP32 ABI. But be aware, the support for ILP32 might not be complete.
>
> Regards,
> Renlin
>
>
>
>>
>> Hi All,
>> Could you please help to have a look whether below issue is valuable?
>> I got u-boot source code from https://github.com/u-boot/u-boot.git,
>> branch =
>> is master.
>> I got toolchain from
>> https://mirrors.edge.kernel.org/pub/tools/crosstool/fi=
>> les/bin/x86_64/8.1.0/
>> I built stratix10(socfpga) platform with below commands:
>> export
>> CROSS_COMPILE=3Dxxx/gcc-8.1.0-nolibc/aarch64-linux/bin/aarch64-linux=
>> -
>> export ARCH=3Darm64
>> make mrproper
>> make socfpga_stratix10_defconfig
>> make menuconfig, and then enable CONFIG_ARMV8_PSCI
>> make
>> there will be below error:
>>   LD      u-boot
>>
>> /home/wrsadmin/Project/Native/SDK/Altera-Arria-10/gcc-8.1.0-nolibc/aarch64-=
>> linux/bin/aarch64-linux-ld.bfd: arch/arm/cpu/armv8/built-in.o: relocation
>> R=
>> _AARCH64_ABS32 against `psci_cpu_suspend' can not be used when making a
>> sha=
>> red object
>
>