[PATCH v9 25/27] x86: enable initial Rust support

Miguel Ojeda
2022-08-05T15:47:59Z

Note that only x86_64 is covered and not all features nor mitigations
are handled, but it is enough as a starting point and showcases
the basics needed to add Rust support for a new architecture.

Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com>
Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com>
Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com>
Co-developed-by: David Gow <davidgow@google.com>
Signed-off-by: David Gow <davidgow@google.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
Documentation/rust/arch-support.rst | 1 +
arch/x86/Kconfig | 1 +
arch/x86/Makefile | 10 ++++++++++
scripts/generate_rust_target.rs | 15 +++++++++++++--
4 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/Documentation/rust/arch-support.rst b/Documentation/rust/arch-support.rst
index 1152e0fbdad0..6982b63775da 100644
--- a/Documentation/rust/arch-support.rst
+++ b/Documentation/rust/arch-support.rst
@@ -15,4 +15,5 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file.
============ ================ ==============================================
Architecture Level of support Constraints
============ ================ ==============================================
+``x86`` Maintained ``x86_64`` only.
============ ================ ==============================================
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 52a7f91527fe..4d5a3f256cbc 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -258,6 +258,7 @@ config X86
select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
select HAVE_PREEMPT_DYNAMIC_CALL
select HAVE_RSEQ
+ select HAVE_RUST if X86_64
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
select HAVE_UNSTABLE_SCHED_CLOCK
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 7854685c5f25..bab595003f07 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 += -Ctarget-feature=-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2

ifeq ($(CONFIG_X86_KERNEL_IBT),y)
#
@@ -155,8 +156,17 @@ else
cflags-$(CONFIG_GENERIC_CPU) += -mtune=generic
KBUILD_CFLAGS += $(cflags-y)

+ rustflags-$(CONFIG_MK8) += -Ctarget-cpu=k8
+ rustflags-$(CONFIG_MPSC) += -Ctarget-cpu=nocona
+ rustflags-$(CONFIG_MCORE2) += -Ctarget-cpu=core2
+ rustflags-$(CONFIG_MATOM) += -Ctarget-cpu=atom
+ rustflags-$(CONFIG_GENERIC_CPU) += -Ztune-cpu=generic
+ KBUILD_RUSTFLAGS += $(rustflags-y)
+
KBUILD_CFLAGS += -mno-red-zone
KBUILD_CFLAGS += -mcmodel=kernel
+ KBUILD_RUSTFLAGS += -Cno-redzone=y
+ KBUILD_RUSTFLAGS += -Ccode-model=kernel
endif

#
diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs
index 7256c9606cf0..3c6cbe2b278d 100644
--- a/scripts/generate_rust_target.rs
+++ b/scripts/generate_rust_target.rs
@@ -148,8 +148,19 @@ fn main() {
let mut ts = TargetSpec::new();

// `llvm-target`s are taken from `scripts/Makefile.clang`.
- if cfg.has("DUMMY_ARCH") {
- ts.push("arch", "dummy_arch");
+ if cfg.has("X86_64") {
+ ts.push("arch", "x86_64");
+ ts.push(
+ "data-layout",
+ "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128",
+ );
+ let mut features = "-3dnow,-3dnowa,-mmx,+soft-float".to_string();
+ if cfg.has("RETPOLINE") {
+ features += ",+retpoline-external-thunk";
+ }
+ ts.push("features", features);
+ ts.push("llvm-target", "x86_64-linux-gnu");
+ ts.push("target-pointer-width", "64");
} else {
panic!("Unsupported architecture");
}
--
2.37.1