| Message ID | 20230606145606.1153715-2-Jamie.Cunliffe@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Rust enablement for AArch64 | expand |
On Tue, Jun 06, 2023 at 03:56:04PM +0100, Jamie Cunliffe wrote: > This commit provides the build flags for Rust for AArch64. The core Rust > support already in the kernel does the rest. > > When disabling the neon and fp target features to avoid fp & simd > registers. The use of fp-armv8 will cause a warning from rustc about > an unknown feature that is specified. The target feature is still > passed through to LLVM, this behaviour is documented as part of the > warning. This will be fixed in a future version of the rustc > toolchain. > > The Rust samples have been tested with this commit. > > Signed-off-by: Jamie Cunliffe <Jamie.Cunliffe@arm.com> > --- > Documentation/rust/arch-support.rst | 1 + > Makefile | 1 - > arch/arm64/Kconfig | 1 + > arch/arm64/Makefile | 2 ++ > arch/x86/Makefile | 1 + > rust/Makefile | 6 +++++- > scripts/Makefile | 5 +++-- > scripts/generate_rust_target.rs | 4 +++- > 8 files changed, 16 insertions(+), 5 deletions(-) > > diff --git a/Documentation/rust/arch-support.rst b/Documentation/rust/arch-support.rst > index b91e9ef4d0c2..9b022af2f649 100644 > --- a/Documentation/rust/arch-support.rst > +++ b/Documentation/rust/arch-support.rst > @@ -15,6 +15,7 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file. > ============ ================ ============================================== > Architecture Level of support Constraints > ============ ================ ============================================== > +``arm64`` Maintained None. > ``um`` Maintained ``x86_64`` only. > ``x86`` Maintained ``x86_64`` only. > ============ ================ ============================================== > diff --git a/Makefile b/Makefile > index 9d765ebcccf1..16b1e4de70e3 100644 > --- a/Makefile > +++ b/Makefile > @@ -561,7 +561,6 @@ KBUILD_CFLAGS := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \ > -std=gnu11 > KBUILD_CPPFLAGS := -D__KERNEL__ > KBUILD_RUSTFLAGS := $(rust_common_flags) \ > - --target=$(objtree)/scripts/target.json \ > -Cpanic=abort -Cembed-bitcode=n -Clto=n \ > -Cforce-unwind-tables=n -Ccodegen-units=1 \ > -Csymbol-mangling-version=v0 \ > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index b1201d25a8a4..10e9399e8e2f 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -217,6 +217,7 @@ config ARM64 > select HAVE_FUNCTION_ARG_ACCESS_API > select MMU_GATHER_RCU_TABLE_FREE > select HAVE_RSEQ > + select HAVE_RUST > select HAVE_STACKPROTECTOR > select HAVE_SYSCALL_TRACEPOINTS > select HAVE_KPROBES > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > index 2d49aea0ff67..2ce1555e9fc5 100644 > --- a/arch/arm64/Makefile > +++ b/arch/arm64/Makefile > @@ -41,6 +41,8 @@ KBUILD_CFLAGS += -mgeneral-regs-only \ > KBUILD_CFLAGS += $(call cc-disable-warning, psabi) > KBUILD_AFLAGS += $(compat_vdso) > > +KBUILD_RUSTFLAGS += --target aarch64-unknown-none -C target-feature="-neon,-fp-armv8" I don't think you need "-fp-armv8" here, because "aarch64-unknown-none" target doesn't have the target-feature "fp-arm64": rustc +1.68.2 --print cfg --target aarch64-unknown-none | grep target_feature target_feature="neon" , and having the "-fp-armv8" gave me a warning at compile time: RUSTC L rust/core.o warning: unknown feature specified for `-Ctarget-feature`: `fp-armv8` | = note: it is still passed through to the codegen backend = help: consider filing a feature request Regards, Boqun > + > KBUILD_CFLAGS += $(call cc-option,-mabi=lp64) > KBUILD_AFLAGS += $(call cc-option,-mabi=lp64) > > diff --git a/arch/x86/Makefile b/arch/x86/Makefile > index b39975977c03..79cffe92c916 100644 > --- a/arch/x86/Makefile > +++ b/arch/x86/Makefile > @@ -68,6 +68,7 @@ export BITS > # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383 > # > KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx > +KBUILD_RUSTFLAGS += --target=$(objtree)/scripts/target.json > KBUILD_RUSTFLAGS += -Ctarget-feature=-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2 > > ifeq ($(CONFIG_X86_KERNEL_IBT),y) > diff --git a/rust/Makefile b/rust/Makefile > index 7c9d9f11aec5..18d6fdb73fa9 100644 > --- a/rust/Makefile > +++ b/rust/Makefile > @@ -262,6 +262,7 @@ bindgen_skip_c_flags := -mno-fp-ret-in-387 -mpreferred-stack-boundary=% \ > > # Derived from `scripts/Makefile.clang`. > BINDGEN_TARGET_x86 := x86_64-linux-gnu > +BINDGEN_TARGET_arm64 := aarch64-linux-gnu > BINDGEN_TARGET := $(BINDGEN_TARGET_$(SRCARCH)) > > # All warnings are inhibited since GCC builds are very experimental, > @@ -393,8 +394,11 @@ $(obj)/core.o: private skip_clippy = 1 > $(obj)/core.o: private skip_flags = -Dunreachable_pub > $(obj)/core.o: private rustc_objcopy = $(foreach sym,$(redirect-intrinsics),--redefine-sym $(sym)=__rust$(sym)) > $(obj)/core.o: private rustc_target_flags = $(core-cfgs) > -$(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs scripts/target.json FORCE > +$(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs FORCE > $(call if_changed_dep,rustc_library) > +ifeq ($(ARCH),x86_64) > +$(obj)/core.o: scripts/target.json > +endif > > $(obj)/compiler_builtins.o: private rustc_objcopy = -w -W '__*' > $(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE > diff --git a/scripts/Makefile b/scripts/Makefile > index 32b6ba722728..633479d02e33 100644 > --- a/scripts/Makefile > +++ b/scripts/Makefile > @@ -9,12 +9,13 @@ hostprogs-always-$(CONFIG_BUILDTIME_TABLE_SORT) += sorttable > hostprogs-always-$(CONFIG_ASN1) += asn1_compiler > hostprogs-always-$(CONFIG_MODULE_SIG_FORMAT) += sign-file > hostprogs-always-$(CONFIG_SYSTEM_EXTRA_CERTIFICATE) += insert-sys-cert > -always-$(CONFIG_RUST) += target.json > > +ifeq ($(ARCH),x86_64) > +always-$(CONFIG_RUST) += target.json > filechk_rust_target = $< < include/config/auto.conf > - > $(obj)/target.json: scripts/generate_rust_target include/config/auto.conf FORCE > $(call filechk,rust_target) > +endif > > hostprogs += generate_rust_target > generate_rust_target-rust := y > diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs > index 3c6cbe2b278d..ec5ef35dbe52 100644 > --- a/scripts/generate_rust_target.rs > +++ b/scripts/generate_rust_target.rs > @@ -148,7 +148,9 @@ fn main() { > let mut ts = TargetSpec::new(); > > // `llvm-target`s are taken from `scripts/Makefile.clang`. > - if cfg.has("X86_64") { > + if cfg.has("ARM64") { > + panic!("arm64 uses the builtin rustc aarch64-unknown-none target"); > + } else if cfg.has("X86_64") { > ts.push("arch", "x86_64"); > ts.push( > "data-layout", > > -- > 2.30.2 >
> I don't think you need "-fp-armv8" here, because "aarch64-unknown-none" > target doesn't have the target-feature "fp-arm64": > > rustc +1.68.2 --print cfg --target aarch64-unknown-none | grep target_feature > > target_feature="neon" > > , and having the "-fp-armv8" gave me a warning at compile time: > > RUSTC L rust/core.o warning: unknown feature specified for `-Ctarget-feature`: `fp-armv8` > | > = note: it is still passed through to the codegen backend > = help: consider filing a feature request Rust removed the fp feature for arm64 and tied it with Neon. However this initially had a bug that meant it couldn't be disabled. This has now been fixed in https://github.com/rust-lang/rust/pull/107294 so once we can update rustc we can fix that warning by removing the `-fp-armv8`. Until we do that we still need the `-fp-armv8` otherwise we will get some floating point usage. This can be seen by doing an objdump of core.o if you build after removing the `-fp-armv8`. You can also see that fp-armv8 is enabled in the aarch64-unknown-none target here: https://raw.githubusercontent.com/rust-lang/rust/master/compiler/rustc_target/src/spec/aarch64_unknown_none.rs Thanks, Jamie.
On Mon, Jun 12, 2023 at 04:26:39PM +0100, Jamie Cunliffe wrote: > > I don't think you need "-fp-armv8" here, because "aarch64-unknown-none" > > target doesn't have the target-feature "fp-arm64": > > > > rustc +1.68.2 --print cfg --target aarch64-unknown-none | grep target_feature > > > > target_feature="neon" > > > > , and having the "-fp-armv8" gave me a warning at compile time: > > > > RUSTC L rust/core.o warning: unknown feature specified for `-Ctarget-feature`: `fp-armv8` > > | > > = note: it is still passed through to the codegen backend > > = help: consider filing a feature request > > Rust removed the fp feature for arm64 and tied it with Neon. However > this initially had a bug that meant it couldn't be disabled. This has > now been fixed in https://github.com/rust-lang/rust/pull/107294 so > once we can update rustc we can fix that warning by removing the > `-fp-armv8`. Until we do that we still need the `-fp-armv8` otherwise > we will get some floating point usage. This can be seen by doing an > objdump of core.o if you build after removing the `-fp-armv8`. > Thanks for the information (and the fix)! That's good to know. Looks like the fix will be in 1.71, then agree, we should keep `-fp-armv8` until we update to 1.71 or later. Regards, Boqun > > You can also see that fp-armv8 is enabled in the aarch64-unknown-none target > here: https://raw.githubusercontent.com/rust-lang/rust/master/compiler/rustc_target/src/spec/aarch64_unknown_none.rs > > > Thanks, > Jamie.
On Thu, Jun 29, 2023 at 12:46:13PM -0700, Boqun Feng wrote: > On Mon, Jun 12, 2023 at 04:26:39PM +0100, Jamie Cunliffe wrote: > > > I don't think you need "-fp-armv8" here, because "aarch64-unknown-none" > > > target doesn't have the target-feature "fp-arm64": > > > > > > rustc +1.68.2 --print cfg --target aarch64-unknown-none | grep target_feature > > > > > > target_feature="neon" > > > > > > , and having the "-fp-armv8" gave me a warning at compile time: > > > > > > RUSTC L rust/core.o warning: unknown feature specified for `-Ctarget-feature`: `fp-armv8` > > > | > > > = note: it is still passed through to the codegen backend > > > = help: consider filing a feature request > > > > Rust removed the fp feature for arm64 and tied it with Neon. However > > this initially had a bug that meant it couldn't be disabled. This has > > now been fixed in https://github.com/rust-lang/rust/pull/107294 so > > once we can update rustc we can fix that warning by removing the > > `-fp-armv8`. Until we do that we still need the `-fp-armv8` otherwise > > we will get some floating point usage. This can be seen by doing an > > objdump of core.o if you build after removing the `-fp-armv8`. > > > > Thanks for the information (and the fix)! That's good to know. Looks > like the fix will be in 1.71, then agree, we should keep `-fp-armv8` > until we update to 1.71 or later. > Just FYI, rustc has been bumped to 1.71: https://lore.kernel.org/rust-for-linux/CANiq72mrzALO3J2VvDntscXwt7Z9KzT4+S8sc_HGc8u8izjyLw@mail.gmail.com/ BTW, recently I learned that ARCH is set as "x86" by default even on x86_64 host, so things like: +ifeq ($(ARCH),x86_64) +$(obj)/core.o: scripts/target.json +endif "ifeq .." will return false if compiled with "make LLVM=1" even on a x86_64 host. Maybe use ifdef CONFIG_X86_64 ? Regards, Boqun > Regards, > Boqun > > > > > You can also see that fp-armv8 is enabled in the aarch64-unknown-none target > > here: https://raw.githubusercontent.com/rust-lang/rust/master/compiler/rustc_target/src/spec/aarch64_unknown_none.rs > > > > > > Thanks, > > Jamie.
diff --git a/Documentation/rust/arch-support.rst b/Documentation/rust/arch-support.rst index b91e9ef4d0c2..9b022af2f649 100644 --- a/Documentation/rust/arch-support.rst +++ b/Documentation/rust/arch-support.rst @@ -15,6 +15,7 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file. ============ ================ ============================================== Architecture Level of support Constraints ============ ================ ============================================== +``arm64`` Maintained None. ``um`` Maintained ``x86_64`` only. ``x86`` Maintained ``x86_64`` only. ============ ================ ============================================== diff --git a/Makefile b/Makefile index 9d765ebcccf1..16b1e4de70e3 100644 --- a/Makefile +++ b/Makefile @@ -561,7 +561,6 @@ KBUILD_CFLAGS := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \ -std=gnu11 KBUILD_CPPFLAGS := -D__KERNEL__ KBUILD_RUSTFLAGS := $(rust_common_flags) \ - --target=$(objtree)/scripts/target.json \ -Cpanic=abort -Cembed-bitcode=n -Clto=n \ -Cforce-unwind-tables=n -Ccodegen-units=1 \ -Csymbol-mangling-version=v0 \ diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index b1201d25a8a4..10e9399e8e2f 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -217,6 +217,7 @@ config ARM64 select HAVE_FUNCTION_ARG_ACCESS_API select MMU_GATHER_RCU_TABLE_FREE select HAVE_RSEQ + select HAVE_RUST select HAVE_STACKPROTECTOR select HAVE_SYSCALL_TRACEPOINTS select HAVE_KPROBES diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 2d49aea0ff67..2ce1555e9fc5 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -41,6 +41,8 @@ KBUILD_CFLAGS += -mgeneral-regs-only \ KBUILD_CFLAGS += $(call cc-disable-warning, psabi) KBUILD_AFLAGS += $(compat_vdso) +KBUILD_RUSTFLAGS += --target aarch64-unknown-none -C target-feature="-neon,-fp-armv8" + KBUILD_CFLAGS += $(call cc-option,-mabi=lp64) KBUILD_AFLAGS += $(call cc-option,-mabi=lp64) diff --git a/arch/x86/Makefile b/arch/x86/Makefile index b39975977c03..79cffe92c916 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -68,6 +68,7 @@ export BITS # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383 # KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx +KBUILD_RUSTFLAGS += --target=$(objtree)/scripts/target.json KBUILD_RUSTFLAGS += -Ctarget-feature=-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2 ifeq ($(CONFIG_X86_KERNEL_IBT),y) diff --git a/rust/Makefile b/rust/Makefile index 7c9d9f11aec5..18d6fdb73fa9 100644 --- a/rust/Makefile +++ b/rust/Makefile @@ -262,6 +262,7 @@ bindgen_skip_c_flags := -mno-fp-ret-in-387 -mpreferred-stack-boundary=% \ # Derived from `scripts/Makefile.clang`. BINDGEN_TARGET_x86 := x86_64-linux-gnu +BINDGEN_TARGET_arm64 := aarch64-linux-gnu BINDGEN_TARGET := $(BINDGEN_TARGET_$(SRCARCH)) # All warnings are inhibited since GCC builds are very experimental, @@ -393,8 +394,11 @@ $(obj)/core.o: private skip_clippy = 1 $(obj)/core.o: private skip_flags = -Dunreachable_pub $(obj)/core.o: private rustc_objcopy = $(foreach sym,$(redirect-intrinsics),--redefine-sym $(sym)=__rust$(sym)) $(obj)/core.o: private rustc_target_flags = $(core-cfgs) -$(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs scripts/target.json FORCE +$(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs FORCE $(call if_changed_dep,rustc_library) +ifeq ($(ARCH),x86_64) +$(obj)/core.o: scripts/target.json +endif $(obj)/compiler_builtins.o: private rustc_objcopy = -w -W '__*' $(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE diff --git a/scripts/Makefile b/scripts/Makefile index 32b6ba722728..633479d02e33 100644 --- a/scripts/Makefile +++ b/scripts/Makefile @@ -9,12 +9,13 @@ hostprogs-always-$(CONFIG_BUILDTIME_TABLE_SORT) += sorttable hostprogs-always-$(CONFIG_ASN1) += asn1_compiler hostprogs-always-$(CONFIG_MODULE_SIG_FORMAT) += sign-file hostprogs-always-$(CONFIG_SYSTEM_EXTRA_CERTIFICATE) += insert-sys-cert -always-$(CONFIG_RUST) += target.json +ifeq ($(ARCH),x86_64) +always-$(CONFIG_RUST) += target.json filechk_rust_target = $< < include/config/auto.conf - $(obj)/target.json: scripts/generate_rust_target include/config/auto.conf FORCE $(call filechk,rust_target) +endif hostprogs += generate_rust_target generate_rust_target-rust := y diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs index 3c6cbe2b278d..ec5ef35dbe52 100644 --- a/scripts/generate_rust_target.rs +++ b/scripts/generate_rust_target.rs @@ -148,7 +148,9 @@ fn main() { let mut ts = TargetSpec::new(); // `llvm-target`s are taken from `scripts/Makefile.clang`. - if cfg.has("X86_64") { + if cfg.has("ARM64") { + panic!("arm64 uses the builtin rustc aarch64-unknown-none target"); + } else if cfg.has("X86_64") { ts.push("arch", "x86_64"); ts.push( "data-layout",
This commit provides the build flags for Rust for AArch64. The core Rust support already in the kernel does the rest. When disabling the neon and fp target features to avoid fp & simd registers. The use of fp-armv8 will cause a warning from rustc about an unknown feature that is specified. The target feature is still passed through to LLVM, this behaviour is documented as part of the warning. This will be fixed in a future version of the rustc toolchain. The Rust samples have been tested with this commit. Signed-off-by: Jamie Cunliffe <Jamie.Cunliffe@arm.com> --- Documentation/rust/arch-support.rst | 1 + Makefile | 1 - arch/arm64/Kconfig | 1 + arch/arm64/Makefile | 2 ++ arch/x86/Makefile | 1 + rust/Makefile | 6 +++++- scripts/Makefile | 5 +++-- scripts/generate_rust_target.rs | 4 +++- 8 files changed, 16 insertions(+), 5 deletions(-)