From: Arnd Bergmann <arnd@arndb.de>
Now that gcc-8 and binutils-2.30 are the minimum versions, a lot of
the individual feature checks can go away for simplification.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
arch/arm64/Kconfig | 37 ++-------------------------------
arch/arm64/Makefile | 21 ++-----------------
arch/arm64/include/asm/rwonce.h | 4 ----
arch/arm64/kvm/Kconfig | 1 -
arch/arm64/lib/xor-neon.c | 2 +-
5 files changed, 5 insertions(+), 60 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a182295e6f08..d33e3955566d 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -642,9 +642,6 @@ config ARM64_ERRATUM_843419
If unsure, say Y.
-config ARM64_LD_HAS_FIX_ERRATUM_843419
- def_bool $(ld-option,--fix-cortex-a53-843419)
-
config ARM64_ERRATUM_1024718
bool "Cortex-A55: 1024718: Update of DBM/AP bits without break before make might result in incorrect update"
default y
@@ -1890,13 +1887,9 @@ config ARM64_PAN
The feature is detected at runtime, and will remain as a 'nop'
instruction if the cpu does not implement the feature.
-config AS_HAS_LSE_ATOMICS
- def_bool $(as-instr,.arch_extension lse)
-
config ARM64_LSE_ATOMICS
bool
default ARM64_USE_LSE_ATOMICS
- depends on AS_HAS_LSE_ATOMICS
config ARM64_USE_LSE_ATOMICS
bool "Atomic instructions"
@@ -1908,20 +1901,12 @@ config ARM64_USE_LSE_ATOMICS
Say Y here to make use of these instructions for the in-kernel
atomic routines. This incurs a small overhead on CPUs that do
- not support these instructions and requires the kernel to be
- built with binutils >= 2.25 in order for the new instructions
- to be used.
+ not support these instructions.
endmenu # "ARMv8.1 architectural features"
menu "ARMv8.2 architectural features"
-config AS_HAS_ARMV8_2
- def_bool $(cc-option,-Wa$(comma)-march=armv8.2-a)
-
-config AS_HAS_SHA3
- def_bool $(as-instr,.arch armv8.2-a+sha3)
-
config ARM64_PMEM
bool "Enable support for persistent memory"
select ARCH_HAS_PMEM_API
@@ -1995,7 +1980,6 @@ config ARM64_PTR_AUTH_KERNEL
bool "Use pointer authentication for kernel"
default y
depends on ARM64_PTR_AUTH
- depends on (CC_HAS_SIGN_RETURN_ADDRESS || CC_HAS_BRANCH_PROT_PAC_RET) && AS_HAS_ARMV8_3
# Modern compilers insert a .note.gnu.property section note for PAC
# which is only understood by binutils starting with version 2.33.1.
depends on LD_IS_LLD || LD_VERSION >= 23301 || (CC_IS_GCC && GCC_VERSION < 90100)
@@ -2016,19 +2000,10 @@ config CC_HAS_BRANCH_PROT_PAC_RET
# GCC 9 or later, clang 8 or later
def_bool $(cc-option,-mbranch-protection=pac-ret+leaf)
-config CC_HAS_SIGN_RETURN_ADDRESS
- # GCC 7, 8
- def_bool $(cc-option,-msign-return-address=all)
-
-config AS_HAS_ARMV8_3
- def_bool $(cc-option,-Wa$(comma)-march=armv8.3-a)
-
config AS_HAS_CFI_NEGATE_RA_STATE
+ # binutils 2.34+
def_bool $(as-instr,.cfi_startproc\n.cfi_negate_ra_state\n.cfi_endproc\n)
-config AS_HAS_LDAPR
- def_bool $(as-instr,.arch_extension rcpc)
-
endmenu # "ARMv8.3 architectural features"
menu "ARMv8.4 architectural features"
@@ -2056,20 +2031,13 @@ config ARM64_AMU_EXTN
correctly reflect reality. Most commonly, the value read will be 0,
indicating that the counter is not enabled.
-config AS_HAS_ARMV8_4
- def_bool $(cc-option,-Wa$(comma)-march=armv8.4-a)
-
config ARM64_TLB_RANGE
bool "Enable support for tlbi range feature"
default y
- depends on AS_HAS_ARMV8_4
help
ARMv8.4-TLBI provides TLBI invalidation instruction that apply to a
range of input addresses.
- The feature introduces new assembly instructions, and they were
- support when binutils >= 2.30.
-
endmenu # "ARMv8.4 architectural features"
menu "ARMv8.5 architectural features"
@@ -2145,7 +2113,6 @@ config ARM64_MTE
default y
depends on ARM64_AS_HAS_MTE && ARM64_TAGGED_ADDR_ABI
depends on AS_HAS_ARMV8_5
- depends on AS_HAS_LSE_ATOMICS
# Required for tag checking in the uaccess routines
select ARM64_PAN
select ARCH_HAS_SUBPAGE_FAULTS
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 1d5dfcd1c13e..73a10f65ce8b 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -16,14 +16,11 @@ ifeq ($(CONFIG_RELOCATABLE), y)
# Pass --no-apply-dynamic-relocs to restore pre-binutils-2.27 behaviour
# for relative relocs, since this leads to better Image compression
# with the relocation offsets always being zero.
-LDFLAGS_vmlinux += -shared -Bsymbolic -z notext \
- $(call ld-option, --no-apply-dynamic-relocs)
+LDFLAGS_vmlinux += -shared -Bsymbolic -z notext --no-apply-dynamic-relocs
endif
ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
- ifeq ($(CONFIG_ARM64_LD_HAS_FIX_ERRATUM_843419),y)
LDFLAGS_vmlinux += --fix-cortex-a53-843419
- endif
endif
cc_has_k_constraint := $(call try-run,echo \
@@ -105,12 +102,8 @@ endif
# hardware.
ifeq ($(CONFIG_AS_HAS_ARMV8_5), y)
asm-arch := armv8.5-a
-else ifeq ($(CONFIG_AS_HAS_ARMV8_4), y)
+else
asm-arch := armv8.4-a
-else ifeq ($(CONFIG_AS_HAS_ARMV8_3), y)
- asm-arch := armv8.3-a
-else ifeq ($(CONFIG_AS_HAS_ARMV8_2), y)
- asm-arch := armv8.2-a
endif
ifdef asm-arch
@@ -201,16 +194,6 @@ install zinstall:
archprepare:
$(Q)$(MAKE) $(build)=arch/arm64/tools kapi
-ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
- ifneq ($(CONFIG_ARM64_LD_HAS_FIX_ERRATUM_843419),y)
- @echo "warning: ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum" >&2
- endif
-endif
-ifeq ($(CONFIG_ARM64_USE_LSE_ATOMICS),y)
- ifneq ($(CONFIG_ARM64_LSE_ATOMICS),y)
- @echo "warning: LSE atomics not supported by binutils" >&2
- endif
-endif
ifeq ($(KBUILD_EXTMOD),)
# We need to generate vdso-offsets.h before compiling certain files in kernel/.
diff --git a/arch/arm64/include/asm/rwonce.h b/arch/arm64/include/asm/rwonce.h
index 56f7b1d4d54b..97d9256d33c9 100644
--- a/arch/arm64/include/asm/rwonce.h
+++ b/arch/arm64/include/asm/rwonce.h
@@ -12,16 +12,12 @@
#ifndef BUILD_VDSO
-#ifdef CONFIG_AS_HAS_LDAPR
#define __LOAD_RCPC(sfx, regs...) \
ALTERNATIVE( \
"ldar" #sfx "\t" #regs, \
".arch_extension rcpc\n" \
"ldapr" #sfx "\t" #regs, \
ARM64_HAS_LDAPR)
-#else
-#define __LOAD_RCPC(sfx, regs...) "ldar" #sfx "\t" #regs
-#endif /* CONFIG_AS_HAS_LDAPR */
/*
* When building with LTO, there is an increased risk of the compiler
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 096e45acadb2..713248f240e0 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -19,7 +19,6 @@ if VIRTUALIZATION
menuconfig KVM
bool "Kernel-based Virtual Machine (KVM) support"
- depends on AS_HAS_ARMV8_4
select KVM_COMMON
select KVM_GENERIC_HARDWARE_ENABLING
select KVM_GENERIC_MMU_NOTIFIER
diff --git a/arch/arm64/lib/xor-neon.c b/arch/arm64/lib/xor-neon.c
index f9a53b7f9842..8fffebfa17b2 100644
--- a/arch/arm64/lib/xor-neon.c
+++ b/arch/arm64/lib/xor-neon.c
@@ -319,7 +319,7 @@ static void xor_arm64_eor3_5(unsigned long bytes,
static int __init xor_neon_init(void)
{
- if (IS_ENABLED(CONFIG_AS_HAS_SHA3) && cpu_have_named_feature(SHA3)) {
+ if (cpu_have_named_feature(SHA3)) {
xor_block_inner_neon.do_3 = xor_arm64_eor3_3;
xor_block_inner_neon.do_4 = xor_arm64_eor3_4;
xor_block_inner_neon.do_5 = xor_arm64_eor3_5;
--
2.39.5Hi Arnd,
On Mon, Apr 07, 2025 at 11:41:16AM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> Now that gcc-8 and binutils-2.30 are the minimum versions, a lot of
> the individual feature checks can go away for simplification.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
To address Will's concern, I grabbed the LLVM 13.0.1 (since that's the
minimum supported version) from https://www.kernel.org/pub//tools/llvm/,
and using v6.15-rc1 I checked the Kconfig resulting from:
# magic script that puts the toolchain in my $PATH
usekorg-llvm 13.0.1 make ARCH=arm64 LLVM=1 defconfig
usekorg-llvm 13.0.1 make ARCH=arm64 LLVM=1 menuconfig
I then applied this series, and built a defconfig kernel with the same
toolchain, which built cleanly and boots fine.
The gist is that everything looks good, so:
Acked-by: Mark Rutland <mark.rutland@arm.com>
More specifically, with that I see:
CC_IS_CLANG [=y]
AS_IS_LLVM [=y]
LD_IS_LLD [=y]
... and I've noted each of the Kconfig options below.
[...]
> -config ARM64_LD_HAS_FIX_ERRATUM_843419
> - def_bool $(ld-option,--fix-cortex-a53-843419)
ARM64_LD_HAS_FIX_ERRATUM_843419 [=y]
> -config AS_HAS_LSE_ATOMICS
> - def_bool $(as-instr,.arch_extension lse)
AS_HAS_LSE_ATOMICS [=y]
> -config AS_HAS_ARMV8_2
> - def_bool $(cc-option,-Wa$(comma)-march=armv8.2-a)
AS_HAS_ARMV8_2 [=y]
> -config AS_HAS_SHA3
> - def_bool $(as-instr,.arch armv8.2-a+sha3)
AS_HAS_SHA3 [=y]
> -config CC_HAS_SIGN_RETURN_ADDRESS
> - # GCC 7, 8
> - def_bool $(cc-option,-msign-return-address=all)
CC_HAS_SIGN_RETURN_ADDRESS [=y]
> -config AS_HAS_ARMV8_3
> - def_bool $(cc-option,-Wa$(comma)-march=armv8.3-a)
AS_HAS_ARMV8_3 [=y]
> config AS_HAS_CFI_NEGATE_RA_STATE
> + # binutils 2.34+
> def_bool $(as-instr,.cfi_startproc\n.cfi_negate_ra_state\n.cfi_endproc\n)
AS_HAS_CFI_NEGATE_RA_STATE [=y]
> -config AS_HAS_LDAPR
> - def_bool $(as-instr,.arch_extension rcpc)
AS_HAS_LDAPR [=y]
> -config AS_HAS_ARMV8_4
> - def_bool $(cc-option,-Wa$(comma)-march=armv8.4-a)
AS_HAS_ARMV8_4 [=y]
> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> index 1d5dfcd1c13e..73a10f65ce8b 100644
> --- a/arch/arm64/Makefile
> +++ b/arch/arm64/Makefile
> @@ -16,14 +16,11 @@ ifeq ($(CONFIG_RELOCATABLE), y)
> # Pass --no-apply-dynamic-relocs to restore pre-binutils-2.27 behaviour
> # for relative relocs, since this leads to better Image compression
> # with the relocation offsets always being zero.
> -LDFLAGS_vmlinux += -shared -Bsymbolic -z notext \
> - $(call ld-option, --no-apply-dynamic-relocs)
> +LDFLAGS_vmlinux += -shared -Bsymbolic -z notext --no-apply-dynamic-relocs
> endif
Looks good:
[mark@lakrids:~/src/linux]% usekorg-llvm 13.0.1 ld.lld -shared -Bsymbolic -z notext --made-up-argument
ld.lld: error: unknown argument '--made-up-argument'
[mark@lakrids:~/src/linux]% usekorg-llvm 13.0.1 ld.lld -shared -Bsymbolic -z notext --no-apply-dynamic-relocs
ld.lld: error: no input files
> ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
> - ifeq ($(CONFIG_ARM64_LD_HAS_FIX_ERRATUM_843419),y)
> LDFLAGS_vmlinux += --fix-cortex-a53-843419
> - endif
> endif
Looks good:
[mark@lakrids:~/src/linux]% usekorg-llvm 13.0.1 ld.lld --made-up-argument
ld.lld: error: unknown argument '--made-up-argument'
[mark@lakrids:~/src/linux]% usekorg-llvm 13.0.1 ld.lld --fix-cortex-a53-843419
ld.lld: error: no input files
[...]
> ifeq ($(CONFIG_AS_HAS_ARMV8_5), y)
> asm-arch := armv8.5-a
> -else ifeq ($(CONFIG_AS_HAS_ARMV8_4), y)
> +else
> asm-arch := armv8.4-a
> -else ifeq ($(CONFIG_AS_HAS_ARMV8_3), y)
> - asm-arch := armv8.3-a
> -else ifeq ($(CONFIG_AS_HAS_ARMV8_2), y)
> - asm-arch := armv8.2-a
> endif
Looks good; this was checked in Kconfig.
[...]
> archprepare:
> $(Q)$(MAKE) $(build)=arch/arm64/tools kapi
> -ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
> - ifneq ($(CONFIG_ARM64_LD_HAS_FIX_ERRATUM_843419),y)
> - @echo "warning: ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum" >&2
> - endif
> -endif
> -ifeq ($(CONFIG_ARM64_USE_LSE_ATOMICS),y)
> - ifneq ($(CONFIG_ARM64_LSE_ATOMICS),y)
> - @echo "warning: LSE atomics not supported by binutils" >&2
> - endif
> -endif
Looks good; both were checked in Kconfig.
[...]
> -#ifdef CONFIG_AS_HAS_LDAPR
> #define __LOAD_RCPC(sfx, regs...) \
> ALTERNATIVE( \
> "ldar" #sfx "\t" #regs, \
> ".arch_extension rcpc\n" \
> "ldapr" #sfx "\t" #regs, \
> ARM64_HAS_LDAPR)
> -#else
> -#define __LOAD_RCPC(sfx, regs...) "ldar" #sfx "\t" #regs
> -#endif /* CONFIG_AS_HAS_LDAPR */
Looks good.
>
> /*
> * When building with LTO, there is an increased risk of the compiler
> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
> index 096e45acadb2..713248f240e0 100644
> --- a/arch/arm64/kvm/Kconfig
> +++ b/arch/arm64/kvm/Kconfig
> @@ -19,7 +19,6 @@ if VIRTUALIZATION
>
> menuconfig KVM
> bool "Kernel-based Virtual Machine (KVM) support"
> - depends on AS_HAS_ARMV8_4
> select KVM_COMMON
> select KVM_GENERIC_HARDWARE_ENABLING
> select KVM_GENERIC_MMU_NOTIFIER
Looks good.
> diff --git a/arch/arm64/lib/xor-neon.c b/arch/arm64/lib/xor-neon.c
> index f9a53b7f9842..8fffebfa17b2 100644
> --- a/arch/arm64/lib/xor-neon.c
> +++ b/arch/arm64/lib/xor-neon.c
> @@ -319,7 +319,7 @@ static void xor_arm64_eor3_5(unsigned long bytes,
>
> static int __init xor_neon_init(void)
> {
> - if (IS_ENABLED(CONFIG_AS_HAS_SHA3) && cpu_have_named_feature(SHA3)) {
> + if (cpu_have_named_feature(SHA3)) {
Looks good.
Mark.
Hi Arnd, On Mon, Apr 07, 2025 at 11:41:16AM +0200, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > Now that gcc-8 and binutils-2.30 are the minimum versions, a lot of > the individual feature checks can go away for simplification. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > arch/arm64/Kconfig | 37 ++------------------------------- > arch/arm64/Makefile | 21 ++----------------- > arch/arm64/include/asm/rwonce.h | 4 ---- > arch/arm64/kvm/Kconfig | 1 - > arch/arm64/lib/xor-neon.c | 2 +- > 5 files changed, 5 insertions(+), 60 deletions(-) Since some of these checks are dynamic (i.e. they try passing various options to the tools to see if they barf), have you checked that the minimum supported version of clang implements them all? Will
On Tue, Apr 8, 2025, at 10:46, Will Deacon wrote:
> Hi Arnd,
>
> On Mon, Apr 07, 2025 at 11:41:16AM +0200, Arnd Bergmann wrote:
>> From: Arnd Bergmann <arnd@arndb.de>
>>
>> Now that gcc-8 and binutils-2.30 are the minimum versions, a lot of
>> the individual feature checks can go away for simplification.
>>
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> ---
>> arch/arm64/Kconfig | 37 ++-------------------------------
>> arch/arm64/Makefile | 21 ++-----------------
>> arch/arm64/include/asm/rwonce.h | 4 ----
>> arch/arm64/kvm/Kconfig | 1 -
>> arch/arm64/lib/xor-neon.c | 2 +-
>> 5 files changed, 5 insertions(+), 60 deletions(-)
>
> Since some of these checks are dynamic (i.e. they try passing various
> options to the tools to see if they barf), have you checked that the
> minimum supported version of clang implements them all?
I did some randconfig build testing with clang-13/lld-13, since that
is the oldest supported version, and checked that the options are
all supported. I'm pretty sure it's been there for a long time before
that already.
Arnd
On Tue, Apr 08, 2025 at 03:10:57PM +0200, Arnd Bergmann wrote: > On Tue, Apr 8, 2025, at 10:46, Will Deacon wrote: > > Hi Arnd, > > > > On Mon, Apr 07, 2025 at 11:41:16AM +0200, Arnd Bergmann wrote: > >> From: Arnd Bergmann <arnd@arndb.de> > >> > >> Now that gcc-8 and binutils-2.30 are the minimum versions, a lot of > >> the individual feature checks can go away for simplification. > >> > >> Signed-off-by: Arnd Bergmann <arnd@arndb.de> > >> --- > >> arch/arm64/Kconfig | 37 ++------------------------------- > >> arch/arm64/Makefile | 21 ++----------------- > >> arch/arm64/include/asm/rwonce.h | 4 ---- > >> arch/arm64/kvm/Kconfig | 1 - > >> arch/arm64/lib/xor-neon.c | 2 +- > >> 5 files changed, 5 insertions(+), 60 deletions(-) > > > > Since some of these checks are dynamic (i.e. they try passing various > > options to the tools to see if they barf), have you checked that the > > minimum supported version of clang implements them all? > > I did some randconfig build testing with clang-13/lld-13, since that > is the oldest supported version, and checked that the options are > all supported. I'm pretty sure it's been there for a long time before > that already. Thanks (especially to Mark!) for checking. Will
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