This is a note to let you know that I've just added the patch titled
riscv: Handle zicsr/zifencei issue between gcc and binutils
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
riscv-handle-zicsr-zifencei-issue-between-gcc-and-binutils.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ca09f772cccaeec4cd05a21528c37a260aa2dd2c Mon Sep 17 00:00:00 2001
From: Mingzheng Xing <xingmingzheng@xxxxxxxxxxx>
Date: Thu, 10 Aug 2023 00:56:48 +0800
Subject: riscv: Handle zicsr/zifencei issue between gcc and binutils
From: Mingzheng Xing <xingmingzheng@xxxxxxxxxxx>
commit ca09f772cccaeec4cd05a21528c37a260aa2dd2c upstream.
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 6df2a016c0c8 ("riscv: fix build with binutils 2.38")
commit e89c2e815e76 ("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@xxxxxxxxxx
Link: https://lore.kernel.org/all/20230223220546.52879-1-conor@xxxxxxxxxx
Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Acked-by: Guo Ren <guoren@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Mingzheng Xing <xingmingzheng@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230809165648.21071-1-xingmingzheng@xxxxxxxxxxx
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/riscv/Kconfig | 28 +++++++++++++++++-----------
arch/riscv/kernel/compat_vdso/Makefile | 8 +++++++-
2 files changed, 24 insertions(+), 12 deletions(-)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -447,24 +447,30 @@ 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"
--- a/arch/riscv/kernel/compat_vdso/Makefile
+++ b/arch/riscv/kernel/compat_vdso/Makefile
@@ -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.
Patches currently in stable-queue which might be from xingmingzheng@xxxxxxxxxxx are
queue-6.1/riscv-handle-zicsr-zifencei-issue-between-gcc-and-binutils.patch
