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riscv: Handle zicsr/zifencei issue between gcc and binutils

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Binutils-2.38 and GCC-12.1.0 bumped[0][1] the default ISA spec to the newer
20191213 version which moves some instructions from the I extension to the
Zicsr and Zifencei extensions. So if one of the binutils and GCC exceeds
that version, we should explicitly specifying Zicsr and Zifencei via -march
to cope with the new changes. but this only occurs when binutils >= 2.36
and GCC >= 11.1.0. It's a different story when binutils < 2.36.

binutils-2.36 supports the Zifencei extension[2] and splits Zifencei and
Zicsr from I[3]. GCC-11.1.0 is particular[4] because it add support Zicsr
and Zifencei extension for -march. binutils-2.35 does not support the
Zifencei extension, and does not need to specify Zicsr and Zifencei when
working with GCC >= 12.1.0.

To make our lives easier, let's relax the check to binutils >= 2.36 in
CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI. For the other two cases,
where clang < 17 or GCC < 11.1.0, we will deal with them in
CONFIG_TOOLCHAIN_NEEDS_OLD_ISA_SPEC.

For more information, please refer to:
commit 6df2a016c0 ("riscv: fix build with binutils 2.38")
commit e89c2e815e ("riscv: Handle zicsr/zifencei issues between clang and binutils")

Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc [0]
Link: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd [1]
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=5a1b31e1e1cee6e9f1c92abff59cdcfff0dddf30 [2]
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=729a53530e86972d1143553a415db34e6e01d5d2 [3]
Link: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b03be74bad08c382da47e048007a78fa3fb4ef49 [4]
Link: https://lore.kernel.org/all/20230308220842.1231003-1-conor@kernel.org
Link: https://lore.kernel.org/all/20230223220546.52879-1-conor@kernel.org
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Guo Ren <guoren@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Mingzheng Xing <xingmingzheng@iscas.ac.cn>
Link: https://lore.kernel.org/r/20230809165648.21071-1-xingmingzheng@iscas.ac.cn
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Mingzheng Xing 2023-08-10 00:56:48 +08:00 committed by Palmer Dabbelt
parent 4b05b99390
commit ca09f772cc
No known key found for this signature in database
GPG Key ID: 2E1319F35FBB1889
2 changed files with 24 additions and 12 deletions
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28
arch/riscv/Kconfig
View File

@ -570,24 +570,30 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE
config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
def_bool y
# https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
depends on AS_IS_GNU && AS_VERSION >= 23800
# https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
depends on AS_IS_GNU && AS_VERSION >= 23600
help
Newer binutils versions default to ISA spec version 20191213 which
moves some instructions from the I extension to the Zicsr and Zifencei
extensions.
Binutils-2.38 and GCC-12.1.0 bumped the default ISA spec to the newer
20191213 version, which moves some instructions from the I extension to
the Zicsr and Zifencei extensions. This requires explicitly specifying
Zicsr and Zifencei when binutils >= 2.38 or GCC >= 12.1.0. Zicsr
and Zifencei are supported in binutils from version 2.36 onwards.
To make life easier, and avoid forcing toolchains that default to a
newer ISA spec to version 2.2, relax the check to binutils >= 2.36.
For clang < 17 or GCC < 11.1.0, for which this is not possible, this is
dealt with in CONFIG_TOOLCHAIN_NEEDS_OLD_ISA_SPEC.
config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
def_bool y
depends on TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
# https://github.com/llvm/llvm-project/commit/22e199e6afb1263c943c0c0d4498694e15bf8a16
depends on CC_IS_CLANG && CLANG_VERSION < 170000
# https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b03be74bad08c382da47e048007a78fa3fb4ef49
depends on (CC_IS_CLANG && CLANG_VERSION < 170000) || (CC_IS_GCC && GCC_VERSION < 110100)
help
Certain versions of clang do not support zicsr and zifencei via -march
but newer versions of binutils require it for the reasons noted in the
help text of CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI. This
option causes an older ISA spec compatible with these older versions
of clang to be passed to GAS, which has the same result as passing zicsr
and zifencei to -march.
Certain versions of clang and GCC do not support zicsr and zifencei via
-march. This option causes an older ISA spec compatible with these older
versions of clang and GCC to be passed to GAS, which has the same result
as passing zicsr and zifencei to -march.
config FPU
bool "FPU support"

8
arch/riscv/kernel/compat_vdso/Makefile
View File

@ -11,7 +11,13 @@ compat_vdso-syms += flush_icache
COMPAT_CC := $(CC)
COMPAT_LD := $(LD)
COMPAT_CC_FLAGS := -march=rv32g -mabi=ilp32
# binutils 2.35 does not support the zifencei extension, but in the ISA
# spec 20191213, G stands for IMAFD_ZICSR_ZIFENCEI.
ifdef CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
COMPAT_CC_FLAGS := -march=rv32g -mabi=ilp32
else
COMPAT_CC_FLAGS := -march=rv32imafd -mabi=ilp32
endif
COMPAT_LD_FLAGS := -melf32lriscv
# Disable attributes, as they're useless and break the build.