Commit ccb8ce52 authored by Christian Schrrefl's avatar Christian Schrrefl Committed by Russell King (Oracle)
Browse files

ARM: 9441/1: rust: Enable Rust support for ARMv7 



This commit allows building ARMv7 kernels with Rust support.

The rust core library expects some __eabi_... functions
that are not implemented in the kernel.
Those functions are some float operations and __aeabi_uldivmod.
For now those are implemented with define_panicking_intrinsics!.

This is based on the code by Sven Van Asbroeck from the original
rust branch and inspired by the AArch version by Jamie Cunliffe.

I have tested the rust samples and a custom simple MMIO module
on hardware (De1SoC FPGA + Arm A9 CPU).

Tested-by: default avatarRudraksha Gupta <guptarud@gmail.com>
Reviewed-by: default avatarAlice Ryhl <aliceryhl@google.com>
Acked-by: default avatarMiguel Ojeda <ojeda@kernel.org>
Tested-by: default avatarMiguel Ojeda <ojeda@kernel.org>
Acked-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarChristian Schrefl <chrisi.schrefl@gmail.com>
Signed-off-by: default avatarRussell King (Oracle) <rmk+kernel@armlinux.org.uk>
parent f9733aa9

Documentation/rust/arch-support.rst

+1 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file. 
=============  ================  ==============================================

Architecture   Level of support  Constraints

=============  ================  ==============================================

``arm``        Maintained        ARMv7 Little Endian only.

``arm64``      Maintained        Little Endian only.

``loongarch``  Maintained        \-

``riscv``      Maintained        ``riscv64`` and LLVM/Clang only.

arch/arm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -133,6 +133,7 @@ config ARM 
	select MMU_GATHER_RCU_TABLE_FREE if SMP && ARM_LPAE

	select HAVE_REGS_AND_STACK_ACCESS_API

	select HAVE_RSEQ

	select HAVE_RUST if CPU_LITTLE_ENDIAN && CPU_32v7

	select HAVE_STACKPROTECTOR

	select HAVE_SYSCALL_TRACEPOINTS

	select HAVE_UID16

arch/arm/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -150,6 +150,7 @@ endif 
KBUILD_CPPFLAGS	+=$(cpp-y)

KBUILD_CFLAGS	+=$(CFLAGS_ABI) $(CFLAGS_ISA) $(arch-y) $(tune-y) $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -msoft-float -Uarm

KBUILD_AFLAGS	+=$(CFLAGS_ABI) $(AFLAGS_ISA) -Wa,$(arch-y) $(tune-y) -include asm/unified.h -msoft-float

KBUILD_RUSTFLAGS += --target=arm-unknown-linux-gnueabi



CHECKFLAGS	+= -D__arm__

rust/Makefile

+8 −0
Original line number Diff line number Diff line
@@ -245,6 +245,7 @@ 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_arm	:= arm-linux-gnueabi

BINDGEN_TARGET		:= $(BINDGEN_TARGET_$(SRCARCH))



# All warnings are inhibited since GCC builds are very experimental,
@@ -397,6 +398,13 @@ redirect-intrinsics = \ 
	__muloti4 __multi3 \

	__udivmodti4 __udivti3 __umodti3



ifdef CONFIG_ARM

	# Add eabi initrinsics for ARM 32-bit

	redirect-intrinsics += \

		__aeabi_fadd __aeabi_fmul __aeabi_fcmpeq __aeabi_fcmple __aeabi_fcmplt __aeabi_fcmpun \

		__aeabi_dadd __aeabi_dmul __aeabi_dcmple __aeabi_dcmplt __aeabi_dcmpun \

		__aeabi_uldivmod

endif

ifneq ($(or $(CONFIG_ARM64),$(and $(CONFIG_RISCV),$(CONFIG_64BIT))),)

	# These intrinsics are defined for ARM64 and RISCV64

	redirect-intrinsics += \

rust/compiler_builtins.rs

+24 −0
Original line number Diff line number Diff line
@@ -73,5 +73,29 @@ pub extern "C" fn $ident() { 
    __umodti3,

});



#[cfg(target_arch = "arm")]

define_panicking_intrinsics!("`f32` should not be used", {

    __aeabi_fadd,

    __aeabi_fmul,

    __aeabi_fcmpeq,

    __aeabi_fcmple,

    __aeabi_fcmplt,

    __aeabi_fcmpun,

});



#[cfg(target_arch = "arm")]

define_panicking_intrinsics!("`f64` should not be used", {

    __aeabi_dadd,

    __aeabi_dmul,

    __aeabi_dcmple,

    __aeabi_dcmplt,

    __aeabi_dcmpun,

});



#[cfg(target_arch = "arm")]

define_panicking_intrinsics!("`u64` division/modulo should not be used", {

    __aeabi_uldivmod,

});



// NOTE: if you are adding a new intrinsic here, you should also add it to

// `redirect-intrinsics` in `rust/Makefile`.