[PATCH v2] RISC-V: Stop emitting attributes

[Palmer Dabbelt]

On Thu, 23 Feb 2023 14:57:08 PST (-0800), Conor Dooley wrote:
> On Thu, Feb 23, 2023 at 02:46:05PM -0800, Palmer Dabbelt wrote:
>> The RISC-V ELF attributes don't contain any useful information.  New
>> toolchains ignore them, but they frequently trip up various older/mixed
>> toolchains.  So just turn them off.
>
> +cc: stable, yeah?

Ya, seems reasonable.  I'm putting it on fixes as well, so it gets 
backported ASAP.

>
>> Signed-off-by: Palmer Dabbelt <palmer at rivosinc.com>
>
> Fixes the build for me w/ my awful config w/ gcc-13 + 2 different
> binutils versions:
> Tested-by: Conor Dooley <conor.dooley at microchip.com>
>
> I still see issues with llvm-17, LLVM=1 & ld-2.35 in both purgatory and
> regular modules:
>   LD      arch/riscv/purgatory/purgatory.ro
> /stuff/toolchains/binutils-2.35/bin/riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_c2p0_zicsr2p0_zifencei2p0: Invalid or unknown z ISA extension: 'zifencei'
> /stuff/toolchains/binutils-2.35/bin/riscv64-linux-gnu-ld: failed to merge target specific data of file arch/riscv/purgatory/sha256.o
> /stuff/toolchains/binutils-2.35/bin/riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_c2p0_zicsr2p0_zifencei2p0: Invalid or unknown z ISA extension: 'zifencei'
> /stuff/toolchains/binutils-2.35/bin/riscv64-linux-gnu-ld: failed to merge target specific data of file arch/riscv/purgatory/string.o
> /stuff/toolchains/binutils-2.35/bin/riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_c2p0_zicsr2p0_zifencei2p0: Invalid or unknown z ISA extension: 'zifencei'
> /stuff/toolchains/binutils-2.35/bin/riscv64-linux-gnu-ld: failed to merge target specific data of file arch/riscv/purgatory/ctype.o
> make[6]: *** [/stuff/linux/arch/riscv/purgatory/Makefile:95: arch/riscv/purgatory/purgatory.ro] Error 1
>
> So probably still need to pick up some variant of my series I posted
> earlier unfortunately:
> https://lore.kernel.org/linux-riscv/20230223220546.52879-1-conor@kernel.org/
>
> Thanks!
>
>> ---
>> Changes since v1 <20230223195112.10489-1-palmer at rivosinc.com/>:
>>
>> * Add the attributes to both KBUILD_CFLAGS and KBUILD_AFLAGS, so
>>   assembly files build without attributes.
>> * Set COMPAT_CFLAGS so the compat VDSO builds without attributes.
>> ---
>>  arch/riscv/Makefile                    | 7 +++++++
>>  arch/riscv/kernel/compat_vdso/Makefile | 4 ++++
>>  2 files changed, 11 insertions(+)
>>
>> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
>> index 76989561566b..7b53f0be56b2 100644
>> --- a/arch/riscv/Makefile
>> +++ b/arch/riscv/Makefile
>> @@ -81,6 +81,13 @@ ifeq ($(CONFIG_PERF_EVENTS),y)
>>          KBUILD_CFLAGS += -fno-omit-frame-pointer
>>  endif
>>
>> +# The RISC-V attributes frequently cause compatibility issues and provide no
>> +# information, so just turn them off.
>> +KBUILD_CFLAGS += $(call cc-option,-mno-riscv-attribute)
>> +KBUILD_AFLAGS += $(call cc-option,-mno-riscv-attribute)
>> +KBUILD_CFLAGS += $(call as-option,-Wa$(comma)-mno-arch-attr)
>> +KBUILD_AFLAGS += $(call as-option,-Wa$(comma)-mno-arch-attr)
>> +
>>  KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-relax)
>>  KBUILD_AFLAGS_MODULE += $(call as-option,-Wa$(comma)-mno-relax)
>>
>> diff --git a/arch/riscv/kernel/compat_vdso/Makefile b/arch/riscv/kernel/compat_vdso/Makefile
>> index 260daf3236d3..7f34f3c7c882 100644
>> --- a/arch/riscv/kernel/compat_vdso/Makefile
>> +++ b/arch/riscv/kernel/compat_vdso/Makefile
>> @@ -14,6 +14,10 @@ COMPAT_LD := $(LD)
>>  COMPAT_CC_FLAGS := -march=rv32g -mabi=ilp32
>>  COMPAT_LD_FLAGS := -melf32lriscv
>>
>> +# Disable attributes, as they're useless and break the build.
>> +COMPAT_CC_FLAGS += $(call cc-option,-mno-riscv-attribute)
>> +COMPAT_CC_FLAGS += $(call as-option,-Wa$(comma)-mno-arch-attr)
>> +
>>  # Files to link into the compat_vdso
>>  obj-compat_vdso = $(patsubst %, %.o, $(compat_vdso-syms)) note.o
>>
>> --
>> 2.39.1
>>
>>
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>
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