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Subject[PATCH 04/13] Kbuild: Rust support
Date
From: Miguel Ojeda <ojeda@kernel.org>

This commit includes also the `Kconfig` entries related to Rust,
the Rust configuration printer, the target definition files,
the version detection script and a few other bits.

In the future, we will likely want to generate the target files
on the fly via a script.

With this in place, we will be adding the rest of the bits piece
by piece and enabling their builds.

Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com>
Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com>
Co-developed-by: Geoffrey Thomas <geofft@ldpreload.com>
Signed-off-by: Geoffrey Thomas <geofft@ldpreload.com>
Co-developed-by: Finn Behrens <me@kloenk.de>
Signed-off-by: Finn Behrens <me@kloenk.de>
Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com>
Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com>
Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com>
Co-developed-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
.gitignore | 2 +
.rustfmt.toml | 12 +++
Documentation/kbuild/kbuild.rst | 4 +
Documentation/process/changes.rst | 9 ++
Makefile | 120 +++++++++++++++++++++++--
arch/arm64/rust/target.json | 40 +++++++++
arch/powerpc/rust/target.json | 30 +++++++
arch/x86/rust/target.json | 42 +++++++++
init/Kconfig | 27 ++++++
lib/Kconfig.debug | 100 +++++++++++++++++++++
rust/.gitignore | 5 ++
rust/Makefile | 141 ++++++++++++++++++++++++++++++
scripts/Makefile.build | 19 ++++
scripts/Makefile.lib | 12 +++
scripts/kconfig/confdata.c | 67 +++++++++++++-
scripts/rust-version.sh | 31 +++++++
16 files changed, 654 insertions(+), 7 deletions(-)
create mode 100644 .rustfmt.toml
create mode 100644 arch/arm64/rust/target.json
create mode 100644 arch/powerpc/rust/target.json
create mode 100644 arch/x86/rust/target.json
create mode 100644 rust/.gitignore
create mode 100644 rust/Makefile
create mode 100755 scripts/rust-version.sh

diff --git a/.gitignore b/.gitignore
index 3af66272d6f1..6ba4f516f46c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -37,6 +37,7 @@
*.o
*.o.*
*.patch
+*.rmeta
*.s
*.so
*.so.dbg
@@ -96,6 +97,7 @@ modules.order
!.gitattributes
!.gitignore
!.mailmap
+!.rustfmt.toml

#
# Generated include files
diff --git a/.rustfmt.toml b/.rustfmt.toml
new file mode 100644
index 000000000000..5893c0e3cbde
--- /dev/null
+++ b/.rustfmt.toml
@@ -0,0 +1,12 @@
+edition = "2018"
+format_code_in_doc_comments = true
+newline_style = "Unix"
+
+# Unstable options that help catching some mistakes in formatting and that we may want to enable
+# when they become stable.
+#
+# They are kept here since they are useful to run from time to time.
+#reorder_impl_items = true
+#comment_width = 100
+#wrap_comments = true
+#normalize_comments = true
diff --git a/Documentation/kbuild/kbuild.rst b/Documentation/kbuild/kbuild.rst
index 2d1fc03d346e..1109d18d9377 100644
--- a/Documentation/kbuild/kbuild.rst
+++ b/Documentation/kbuild/kbuild.rst
@@ -57,6 +57,10 @@ CFLAGS_MODULE
-------------
Additional module specific options to use for $(CC).

+KRUSTCFLAGS
+-----------
+Additional options to the Rust compiler (for built-in and modules).
+
LDFLAGS_MODULE
--------------
Additional options used for $(LD) when linking modules.
diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
index dac17711dc11..4b6ba5458706 100644
--- a/Documentation/process/changes.rst
+++ b/Documentation/process/changes.rst
@@ -31,6 +31,8 @@ you probably needn't concern yourself with pcmciautils.
====================== =============== ========================================
GNU C 4.9 gcc --version
Clang/LLVM (optional) 10.0.1 clang --version
+rustc (optional) nightly rustc --version
+bindgen (optional) 0.56.0 bindgen --version
GNU make 3.81 make --version
binutils 2.23 ld -v
flex 2.5.35 flex --version
@@ -56,6 +58,7 @@ iptables 1.4.2 iptables -V
openssl & libcrypto 1.0.0 openssl version
bc 1.06.95 bc --version
Sphinx\ [#f1]_ 1.3 sphinx-build --version
+rustdoc (optional) nightly rustdoc --version
====================== =============== ========================================

.. [#f1] Sphinx is needed only to build the Kernel documentation
@@ -330,6 +333,12 @@ Sphinx
Please see :ref:`sphinx_install` in :ref:`Documentation/doc-guide/sphinx.rst <sphinxdoc>`
for details about Sphinx requirements.

+rustdoc
+-------
+
+``rustdoc`` is used to generate Rust documentation. Please see
+:ref:`Documentation/rust/docs.rst <rust_docs>` for more information.
+
Getting updated software
========================

diff --git a/Makefile b/Makefile
index 9c75354324ed..62b3bba38635 100644
--- a/Makefile
+++ b/Makefile
@@ -120,6 +120,13 @@ endif

export KBUILD_CHECKSRC

+# Enable "clippy" (a linter) as part of the Rust compilation.
+#
+# Use 'make CLIPPY=1' to enable it.
+ifeq ("$(origin CLIPPY)", "command line")
+ KBUILD_CLIPPY := $(CLIPPY)
+endif
+
# Use make M=dir or set the environment variable KBUILD_EXTMOD to specify the
# directory of external module to build. Setting M= takes precedence.
ifeq ("$(origin M)", "command line")
@@ -263,7 +270,7 @@ no-dot-config-targets := $(clean-targets) \
cscope gtags TAGS tags help% %docs check% coccicheck \
$(version_h) headers headers_% archheaders archscripts \
%asm-generic kernelversion %src-pkg dt_binding_check \
- outputmakefile
+ outputmakefile rustfmt rustfmtcheck
no-sync-config-targets := $(no-dot-config-targets) %install kernelrelease \
image_name
single-targets := %.a %.i %.ko %.lds %.ll %.lst %.mod %.o %.s %.symtypes %/
@@ -444,6 +451,10 @@ OBJDUMP = $(CROSS_COMPILE)objdump
READELF = $(CROSS_COMPILE)readelf
STRIP = $(CROSS_COMPILE)strip
endif
+RUSTC = rustc
+RUSTFMT = rustfmt
+CLIPPY_DRIVER = clippy-driver
+BINDGEN = bindgen
PAHOLE = pahole
RESOLVE_BTFIDS = $(objtree)/tools/bpf/resolve_btfids/resolve_btfids
LEX = flex
@@ -467,9 +478,11 @@ CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
-Wbitwise -Wno-return-void -Wno-unknown-attribute $(CF)
NOSTDINC_FLAGS :=
CFLAGS_MODULE =
+RUSTCFLAGS_MODULE =
AFLAGS_MODULE =
LDFLAGS_MODULE =
CFLAGS_KERNEL =
+RUSTCFLAGS_KERNEL =
AFLAGS_KERNEL =
LDFLAGS_vmlinux =

@@ -498,15 +511,30 @@ KBUILD_CFLAGS := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \
-Werror=return-type -Wno-format-security \
-std=gnu89
KBUILD_CPPFLAGS := -D__KERNEL__
+KBUILD_RUSTCFLAGS := --emit=dep-info,obj,metadata --edition=2018 \
+ -Cpanic=abort -Cembed-bitcode=n -Clto=n -Crpath=n \
+ -Cforce-unwind-tables=n -Ccodegen-units=1 \
+ -Zbinary_dep_depinfo=y -Zsymbol-mangling-version=v0
KBUILD_AFLAGS_KERNEL :=
KBUILD_CFLAGS_KERNEL :=
+KBUILD_RUSTCFLAGS_KERNEL :=
KBUILD_AFLAGS_MODULE := -DMODULE
KBUILD_CFLAGS_MODULE := -DMODULE
+KBUILD_RUSTCFLAGS_MODULE := --cfg MODULE
KBUILD_LDFLAGS_MODULE :=
KBUILD_LDFLAGS :=
CLANG_FLAGS :=

-export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC
+ifeq ($(KBUILD_CLIPPY),1)
+ RUSTC_OR_CLIPPY_QUIET := CLIPPY
+ RUSTC_OR_CLIPPY = $(CLIPPY_DRIVER)
+else
+ RUSTC_OR_CLIPPY_QUIET := RUSTC
+ RUSTC_OR_CLIPPY = $(RUSTC)
+endif
+export RUSTC_OR_CLIPPY_QUIET RUSTC_OR_CLIPPY
+
+export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC RUSTC BINDGEN
export CPP AR NM STRIP OBJCOPY OBJDUMP READELF PAHOLE RESOLVE_BTFIDS LEX YACC AWK INSTALLKERNEL
export PERL PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX
export KGZIP KBZIP2 KLZOP LZMA LZ4 XZ ZSTD
@@ -514,9 +542,10 @@ export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS LDFLAGS_MODULE

export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS KBUILD_LDFLAGS
export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
+export KBUILD_RUSTCFLAGS RUSTCFLAGS_KERNEL RUSTCFLAGS_MODULE
export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
-export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
-export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
+export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_RUSTCFLAGS_MODULE KBUILD_LDFLAGS_MODULE
+export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL KBUILD_RUSTCFLAGS_KERNEL

# Files to ignore in find ... statements

@@ -712,7 +741,7 @@ $(KCONFIG_CONFIG):
quiet_cmd_syncconfig = SYNC $@
cmd_syncconfig = $(MAKE) -f $(srctree)/Makefile syncconfig

-%/config/auto.conf %/config/auto.conf.cmd %/generated/autoconf.h: $(KCONFIG_CONFIG)
+%/config/auto.conf %/config/auto.conf.cmd %/generated/autoconf.h %/generated/rustc_cfg: $(KCONFIG_CONFIG)
+$(call cmd,syncconfig)
else # !may-sync-config
# External modules and some install targets need include/generated/autoconf.h
@@ -738,12 +767,43 @@ KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow)
KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)

+ifdef CONFIG_RUST_DEBUG_ASSERTIONS
+KBUILD_RUSTCFLAGS += -Cdebug-assertions=y
+else
+KBUILD_RUSTCFLAGS += -Cdebug-assertions=n
+endif
+
+ifdef CONFIG_RUST_OVERFLOW_CHECKS
+KBUILD_RUSTCFLAGS += -Coverflow-checks=y
+else
+KBUILD_RUSTCFLAGS += -Coverflow-checks=n
+endif
+
ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
KBUILD_CFLAGS += -O2
+KBUILD_RUSTCFLAGS_OPT_LEVEL_MAP := 2
else ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3
KBUILD_CFLAGS += -O3
+KBUILD_RUSTCFLAGS_OPT_LEVEL_MAP := 3
else ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
KBUILD_CFLAGS += -Os
+KBUILD_RUSTCFLAGS_OPT_LEVEL_MAP := z
+endif
+
+ifdef CONFIG_RUST_OPT_LEVEL_SIMILAR_AS_CHOSEN_FOR_C
+KBUILD_RUSTCFLAGS += -Copt-level=$(KBUILD_RUSTCFLAGS_OPT_LEVEL_MAP)
+else ifdef CONFIG_RUST_OPT_LEVEL_0
+KBUILD_RUSTCFLAGS += -Copt-level=0
+else ifdef CONFIG_RUST_OPT_LEVEL_1
+KBUILD_RUSTCFLAGS += -Copt-level=1
+else ifdef CONFIG_RUST_OPT_LEVEL_2
+KBUILD_RUSTCFLAGS += -Copt-level=2
+else ifdef CONFIG_RUST_OPT_LEVEL_3
+KBUILD_RUSTCFLAGS += -Copt-level=3
+else ifdef CONFIG_RUST_OPT_LEVEL_S
+KBUILD_RUSTCFLAGS += -Copt-level=s
+else ifdef CONFIG_RUST_OPT_LEVEL_Z
+KBUILD_RUSTCFLAGS += -Copt-level=z
endif

# Tell gcc to never replace conditional load with a non-conditional one
@@ -793,6 +853,7 @@ endif
KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
ifdef CONFIG_FRAME_POINTER
KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls
+KBUILD_RUSTCFLAGS += -Cforce-frame-pointers=y
else
# Some targets (ARM with Thumb2, for example), can't be built with frame
# pointers. For those, we don't have FUNCTION_TRACER automatically
@@ -826,6 +887,8 @@ ifdef CONFIG_CC_IS_GCC
DEBUG_CFLAGS += $(call cc-ifversion, -lt, 0500, $(call cc-option, -fno-var-tracking-assignments))
endif

+DEBUG_RUSTCFLAGS :=
+
ifdef CONFIG_DEBUG_INFO

ifdef CONFIG_DEBUG_INFO_SPLIT
@@ -836,6 +899,11 @@ endif

ifneq ($(LLVM_IAS),1)
KBUILD_AFLAGS += -Wa,-gdwarf-2
+ifdef CONFIG_DEBUG_INFO_REDUCED
+DEBUG_RUSTCFLAGS += -Cdebuginfo=1
+else
+DEBUG_RUSTCFLAGS += -Cdebuginfo=2
+endif
endif

ifndef CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
@@ -860,6 +928,9 @@ endif # CONFIG_DEBUG_INFO
KBUILD_CFLAGS += $(DEBUG_CFLAGS)
export DEBUG_CFLAGS

+KBUILD_RUSTCFLAGS += $(DEBUG_RUSTCFLAGS)
+export DEBUG_RUSTCFLAGS
+
ifdef CONFIG_FUNCTION_TRACER
ifdef CONFIG_FTRACE_MCOUNT_USE_CC
CC_FLAGS_FTRACE += -mrecord-mcount
@@ -990,10 +1061,11 @@ include $(addprefix $(srctree)/, $(include-y))
# Do not add $(call cc-option,...) below this line. When you build the kernel
# from the clean source tree, the GCC plugins do not exist at this point.

-# Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
+# Add user supplied CPPFLAGS, AFLAGS, CFLAGS and RUSTCFLAGS as the last assignments
KBUILD_CPPFLAGS += $(KCPPFLAGS)
KBUILD_AFLAGS += $(KAFLAGS)
KBUILD_CFLAGS += $(KCFLAGS)
+KBUILD_RUSTCFLAGS += $(KRUSTCFLAGS)

KBUILD_LDFLAGS_MODULE += --build-id=sha1
LDFLAGS_vmlinux += --build-id=sha1
@@ -1138,6 +1210,10 @@ export MODULES_NSDEPS := $(extmod-prefix)modules.nsdeps
ifeq ($(KBUILD_EXTMOD),)
core-y += kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ block/

+ifdef CONFIG_RUST
+core-y += rust/
+endif
+
vmlinux-dirs := $(patsubst %/,%,$(filter %/, \
$(core-y) $(core-m) $(drivers-y) $(drivers-m) \
$(libs-y) $(libs-m)))
@@ -1238,6 +1314,9 @@ archprepare: outputmakefile archheaders archscripts scripts include/config/kerne
prepare0: archprepare
$(Q)$(MAKE) $(build)=scripts/mod
$(Q)$(MAKE) $(build)=.
+ifdef CONFIG_RUST
+ $(Q)$(MAKE) $(build)=rust
+endif

# All the preparing..
prepare: prepare0 prepare-objtool prepare-resolve_btfids
@@ -1648,6 +1727,13 @@ help:
@echo ' kselftest-merge - Merge all the config dependencies of'
@echo ' kselftest to existing .config.'
@echo ''
+ @echo 'Rust targets:'
+ @echo ' rustfmt - Reformat all the Rust code in the kernel'
+ @echo ' rustfmtcheck - Checks if all the Rust code in the kernel'
+ @echo ' is formatted, printing a diff otherwise.'
+ @echo ' rustdoc - Generate Rust documentation'
+ @echo ' (requires kernel .config)'
+ @echo ''
@$(if $(dtstree), \
echo 'Devicetree:'; \
echo '* dtbs - Build device tree blobs for enabled boards'; \
@@ -1719,6 +1805,27 @@ PHONY += $(DOC_TARGETS)
$(DOC_TARGETS):
$(Q)$(MAKE) $(build)=Documentation $@

+
+# Rust targets
+# ---------------------------------------------------------------------------
+
+# Documentation target
+#
+# Using the singular to avoid running afoul of `no-dot-config-targets`.
+PHONY += rustdoc
+rustdoc: prepare0
+ $(Q)$(MAKE) $(build)=rust $@
+
+# Formatting targets
+PHONY += rustfmt rustfmtcheck
+
+rustfmt:
+ find -name '*.rs' | xargs $(RUSTFMT)
+
+rustfmtcheck:
+ find -name '*.rs' | xargs $(RUSTFMT) --check
+
+
# Misc
# ---------------------------------------------------------------------------

@@ -1866,6 +1973,7 @@ clean: $(clean-dirs)
$(call cmd,rmfiles)
@find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
\( -name '*.[aios]' -o -name '*.ko' -o -name '.*.cmd' \
+ -o -name '*.rmeta' \
-o -name '*.ko.*' \
-o -name '*.dtb' -o -name '*.dtbo' -o -name '*.dtb.S' -o -name '*.dt.yaml' \
-o -name '*.dwo' -o -name '*.lst' \
diff --git a/arch/arm64/rust/target.json b/arch/arm64/rust/target.json
new file mode 100644
index 000000000000..44953e2725c4
--- /dev/null
+++ b/arch/arm64/rust/target.json
@@ -0,0 +1,40 @@
+{
+ "arch": "aarch64",
+ "data-layout": "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128",
+ "disable-redzone": true,
+ "eliminate-frame-pointer": false,
+ "emit-debug-gdb-scripts": false,
+ "env": "gnu",
+ "features": "+strict-align,+neon,+fp-armv8",
+ "function-sections": false,
+ "is-builtin": true,
+ "linker-flavor": "gcc",
+ "linker-is-gnu": true,
+ "llvm-target": "aarch64-unknown-none",
+ "max-atomic-width": 128,
+ "needs-plt": true,
+ "os": "none",
+ "panic-strategy": "abort",
+ "position-independent-executables": true,
+ "pre-link-args": {
+ "gcc": [
+ "-Wl,--as-needed",
+ "-Wl,-z,noexecstack",
+ "-m64"
+ ]
+ },
+ "relocation-model": "static",
+ "relro-level": "full",
+ "stack-probes": {
+ "kind": "inline-or-call",
+ "min-llvm-version-for-inline": [
+ 11,
+ 0,
+ 1
+ ]
+ },
+ "target-c-int-width": "32",
+ "target-endian": "little",
+ "target-pointer-width": "64",
+ "vendor": ""
+}
diff --git a/arch/powerpc/rust/target.json b/arch/powerpc/rust/target.json
new file mode 100644
index 000000000000..1e53f8308092
--- /dev/null
+++ b/arch/powerpc/rust/target.json
@@ -0,0 +1,30 @@
+{
+ "arch": "powerpc64",
+ "code-mode": "kernel",
+ "cpu": "ppc64le",
+ "data-layout": "e-m:e-i64:64-n32:64",
+ "env": "gnu",
+ "features": "-altivec,-vsx,-hard-float",
+ "function-sections": false,
+ "is-builtin": true,
+ "linker-flavor": "gcc",
+ "linker-is-gnu": true,
+ "llvm-target": "powerpc64le-elf",
+ "max-atomic-width": 64,
+ "os": "none",
+ "panic-strategy": "abort",
+ "position-independent-executables": true,
+ "pre-link-args": {
+ "gcc": [
+ "-Wl,--as-needed",
+ "-Wl,-z,noexecstack",
+ "-m64"
+ ]
+ },
+ "relocation-model": "static",
+ "relro-level": "full",
+ "target-family": "unix",
+ "target-mcount": "_mcount",
+ "target-endian": "little",
+ "target-pointer-width": "64"
+}
diff --git a/arch/x86/rust/target.json b/arch/x86/rust/target.json
new file mode 100644
index 000000000000..6e1759cd45bf
--- /dev/null
+++ b/arch/x86/rust/target.json
@@ -0,0 +1,42 @@
+{
+ "arch": "x86_64",
+ "code-model": "kernel",
+ "cpu": "x86-64",
+ "data-layout": "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128",
+ "disable-redzone": true,
+ "eliminate-frame-pointer": false,
+ "emit-debug-gdb-scripts": false,
+ "env": "gnu",
+ "features": "-mmx,-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-3dnow,-3dnowa,-avx,-avx2,+soft-float",
+ "function-sections": false,
+ "is-builtin": true,
+ "linker-flavor": "gcc",
+ "linker-is-gnu": true,
+ "llvm-target": "x86_64-elf",
+ "max-atomic-width": 64,
+ "needs-plt": true,
+ "os": "none",
+ "panic-strategy": "abort",
+ "position-independent-executables": true,
+ "pre-link-args": {
+ "gcc": [
+ "-Wl,--as-needed",
+ "-Wl,-z,noexecstack",
+ "-m64"
+ ]
+ },
+ "relocation-model": "static",
+ "relro-level": "full",
+ "stack-probes": {
+ "kind": "inline-or-call",
+ "min-llvm-version-for-inline": [
+ 11,
+ 0,
+ 1
+ ]
+ },
+ "target-c-int-width": "32",
+ "target-endian": "little",
+ "target-pointer-width": "64",
+ "vendor": "unknown"
+}
diff --git a/init/Kconfig b/init/Kconfig
index 5f5c776ef192..11475840c29c 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -57,6 +57,15 @@ config LLD_VERSION
default $(ld-version) if LD_IS_LLD
default 0

+config HAS_RUST
+ depends on ARM64 || (PPC64 && CPU_LITTLE_ENDIAN) || X86_64
+ def_bool $(success,$(RUSTC) --version)
+
+config RUSTC_VERSION
+ depends on HAS_RUST
+ int
+ default $(shell,$(srctree)/scripts/rust-version.sh $(RUSTC))
+
config CC_CAN_LINK
bool
default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag)) if 64BIT
@@ -2027,6 +2036,24 @@ config PROFILING
Say Y here to enable the extended profiling support mechanisms used
by profilers.

+config RUST
+ bool "Rust support"
+ depends on HAS_RUST
+ depends on !COMPILE_TEST
+ default n
+ help
+ Enables Rust support in the kernel.
+
+ This allows other Rust-related options, like drivers written in Rust,
+ to be selected.
+
+ It is also required to be able to load external kernel modules
+ written in Rust.
+
+ See Documentation/rust/ for more information.
+
+ If unsure, say N.
+
#
# Place an empty function call at each tracepoint site. Can be
# dynamically changed for a probe function.
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 2779c29d9981..acf4993baddc 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2537,6 +2537,106 @@ config HYPERV_TESTING

endmenu # "Kernel Testing and Coverage"

+menu "Rust hacking"
+
+config RUST_DEBUG_ASSERTIONS
+ bool "Debug assertions"
+ default n
+ depends on RUST
+ help
+ Enables rustc's `-Cdebug-assertions` codegen option.
+
+ This flag lets you turn `cfg(debug_assertions)` conditional
+ compilation on or off. This can be used to enable extra debugging
+ code in development but not in production. For example, it controls
+ the behavior of the standard library's `debug_assert!` macro.
+
+ Note that this will apply to all Rust code, including `core`.
+
+ If unsure, say N.
+
+config RUST_OVERFLOW_CHECKS
+ bool "Overflow checks"
+ default y
+ depends on RUST
+ help
+ Enables rustc's `-Coverflow-checks` codegen option.
+
+ This flag allows you to control the behavior of runtime integer
+ overflow. When overflow-checks are enabled, a panic will occur
+ on overflow.
+
+ Note that this will apply to all Rust code, including `core`.
+
+ If unsure, say Y.
+
+choice
+ prompt "Optimization level"
+ default RUST_OPT_LEVEL_SIMILAR_AS_CHOSEN_FOR_C
+ depends on RUST
+ help
+ Controls rustc's `-Copt-level` codegen option.
+
+ This flag controls the optimization level.
+
+ If unsure, say "Similar as chosen for C".
+
+config RUST_OPT_LEVEL_SIMILAR_AS_CHOSEN_FOR_C
+ bool "Similar as chosen for C"
+ help
+ This choice will pick a similar optimization level as chosen in
+ the "Compiler optimization level" for C:
+
+ -O2 is currently mapped to -Copt-level=2
+ -O3 is currently mapped to -Copt-level=3
+ -Os is currently mapped to -Copt-level=z
+
+ The mapping may change over time to follow the intended semantics
+ of the choice for C as sensibly as possible.
+
+ This is the default.
+
+config RUST_OPT_LEVEL_0
+ bool "No optimizations (-Copt-level=0)"
+ help
+ Not recommended for most purposes. It may come in handy for debugging
+ suspected optimizer bugs, unexpected undefined behavior, etc.
+
+ Note that this level will *not* enable debug assertions nor overflow
+ checks on its own (like it happens when interacting with rustc
+ directly). Use the corresponding configuration options to control
+ that instead, orthogonally.
+
+config RUST_OPT_LEVEL_1
+ bool "Basic optimizations (-Copt-level=1)"
+ help
+ Useful for debugging without getting too lost, but without
+ the overhead and boilerplate of no optimizations at all.
+
+config RUST_OPT_LEVEL_2
+ bool "Some optimizations (-Copt-level=2)"
+ help
+ The sensible choice in most cases.
+
+config RUST_OPT_LEVEL_3
+ bool "All optimizations (-Copt-level=3)"
+ help
+ Yet more performance (hopefully).
+
+config RUST_OPT_LEVEL_S
+ bool "Optimize for size (-Copt-level=s)"
+ help
+ Smaller kernel, ideally without too much performance loss.
+
+config RUST_OPT_LEVEL_Z
+ bool "Optimize for size, no loop vectorization (-Copt-level=z)"
+ help
+ Like the previous level, but also turn off loop vectorization.
+
+endchoice
+
+endmenu # "Rust"
+
source "Documentation/Kconfig"

endmenu # Kernel hacking
diff --git a/rust/.gitignore b/rust/.gitignore
new file mode 100644
index 000000000000..8875e08ed0b1
--- /dev/null
+++ b/rust/.gitignore
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+
+bindings_generated.rs
+exports_*_generated.h
+doc/
\ No newline at end of file
diff --git a/rust/Makefile b/rust/Makefile
new file mode 100644
index 000000000000..ba4b13e4fc7f
--- /dev/null
+++ b/rust/Makefile
@@ -0,0 +1,141 @@
+# SPDX-License-Identifier: GPL-2.0
+
+RUSTDOC = rustdoc
+
+quiet_cmd_rustdoc = RUSTDOC $<
+ cmd_rustdoc = \
+ RUST_BINDINGS_FILE=$(abspath $(objtree)/rust/bindings_generated.rs) \
+ $(RUSTDOC) $(filter-out --emit=%, $(rustc_flags)) \
+ $(rustdoc_target_flags) -L $(objtree)/rust/ \
+ --output $(objtree)/rust/doc --crate-name $(subst rustdoc-,,$@) \
+ -Fmissing-docs @$(objtree)/include/generated/rustc_cfg $<
+
+rustdoc: rustdoc-module rustdoc-compiler_builtins rustdoc-kernel
+
+rustdoc-module: private rustdoc_target_flags = --crate-type proc-macro \
+ --extern proc_macro
+rustdoc-module: $(srctree)/rust/module.rs FORCE
+ $(call if_changed,rustdoc)
+
+rustdoc-compiler_builtins: $(srctree)/rust/compiler_builtins.rs FORCE
+ $(call if_changed,rustdoc)
+
+rustdoc-kernel: private rustdoc_target_flags = --extern alloc \
+ --extern module=$(objtree)/rust/libmodule.so
+rustdoc-kernel: $(srctree)/rust/kernel/lib.rs rustdoc-module \
+ $(objtree)/rust/libmodule.so $(objtree)/rust/bindings_generated.rs FORCE
+ $(call if_changed,rustdoc)
+
+ifdef CONFIG_CC_IS_CLANG
+bindgen_c_flags = $(c_flags)
+else
+# bindgen relies on libclang to parse C. Ideally, bindgen would support a GCC
+# plugin backend and/or the Clang driver would be perfectly compatible with GCC.
+#
+# For the moment, here we are tweaking the flags on the fly. Some config
+# options may not work (e.g. `GCC_PLUGIN_RANDSTRUCT` if we end up using one
+# of those structs). We might want to redo how Clang flags are kept track of
+# in the general `Makefile` even for GCC builds, similar to what we did with
+# `TENTATIVE_CLANG_FLAGS`.
+bindgen_skip_c_flags := -mno-fp-ret-in-387 -mpreferred-stack-boundary=% \
+ -mskip-rax-setup -mgeneral-regs-only -msign-return-address=% \
+ -mindirect-branch=thunk-extern -mindirect-branch-register -mrecord-mcount \
+ -mabi=lp64 -mstack-protector-guard% -fconserve-stack -falign-jumps=% \
+ -falign-loops=% -fno-ipa-cp-clone -fno-partial-inlining \
+ -fno-reorder-blocks -fno-allow-store-data-races -fasan-shadow-offset=% \
+ -Wno-packed-not-aligned -Wno-format-truncation -Wno-format-overflow \
+ -Wno-stringop-truncation -Wno-unused-but-set-variable \
+ -Wno-stringop-overflow -Wno-restrict -Wno-maybe-uninitialized \
+ -Werror=designated-init -Wno-zero-length-bounds \
+ --param=% --param asan-%
+
+# PowerPC
+bindgen_skip_c_flags += -mtraceback=no -mno-pointers-to-nested-functions \
+ -mno-string -mno-strict-align
+
+bindgen_extra_c_flags = $(TENTATIVE_CLANG_FLAGS) -Wno-address-of-packed-member
+bindgen_c_flags = $(filter-out $(bindgen_skip_c_flags), $(c_flags)) \
+ $(bindgen_extra_c_flags)
+endif
+
+bindgen_opaque_types := xregs_state desc_struct arch_lbr_state
+
+# To avoid several recompilations in PowerPC, which inserts `-D_TASK_CPU`
+bindgen_c_flags_final = $(filter-out -D_TASK_CPU=%, $(bindgen_c_flags))
+
+quiet_cmd_bindgen = BINDGEN $@
+ cmd_bindgen = \
+ $(BINDGEN) $< $(addprefix --opaque-type , $(bindgen_opaque_types)) \
+ --use-core --with-derive-default --ctypes-prefix c_types \
+ --size_t-is-usize -o $@ -- $(bindgen_c_flags_final) -DMODULE
+
+$(objtree)/rust/bindings_generated.rs: $(srctree)/rust/kernel/bindings_helper.h FORCE
+ $(call if_changed_dep,bindgen)
+
+quiet_cmd_exports = EXPORTS $@
+ cmd_exports = \
+ $(NM) -p --defined-only $< \
+ | grep -E ' (T|R|D) ' | cut -d ' ' -f 3 | grep -E '^(__rust_|_R)' \
+ | xargs -Isymbol \
+ echo 'EXPORT_SYMBOL_RUST_GPL(symbol);' > $@
+
+$(objtree)/rust/exports_core_generated.h: $(objtree)/rust/core.o FORCE
+ $(call if_changed,exports)
+
+$(objtree)/rust/exports_alloc_generated.h: $(objtree)/rust/alloc.o FORCE
+ $(call if_changed,exports)
+
+$(objtree)/rust/exports_kernel_generated.h: $(objtree)/rust/kernel.o FORCE
+ $(call if_changed,exports)
+
+# `-Cpanic=unwind -Cforce-unwind-tables=y` overrides `rustc_flags` in order to
+# avoid the https://github.com/rust-lang/rust/issues/82320 rustc crash.
+quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@
+ cmd_rustc_procmacro = \
+ $(RUSTC_OR_CLIPPY) $(rustc_flags) \
+ --emit=dep-info,link --extern proc_macro \
+ -Cpanic=unwind -Cforce-unwind-tables=y \
+ --crate-type proc-macro --out-dir $(objtree)/rust/ \
+ --crate-name $(patsubst lib%.so,%,$(notdir $@)) $<; \
+ mv $(objtree)/rust/$(patsubst lib%.so,%,$(notdir $@)).d $(depfile); \
+ sed -i '/^\#/d' $(depfile)
+
+$(objtree)/rust/libmodule.so: $(srctree)/rust/module.rs FORCE
+ $(call if_changed_dep,rustc_procmacro)
+
+quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L $@
+ cmd_rustc_library = \
+ RUST_BINDINGS_FILE=$(abspath $(objtree)/rust/bindings_generated.rs) \
+ $(if $(skip_clippy),$(RUSTC),$(RUSTC_OR_CLIPPY)) \
+ $(rustc_flags) $(rustc_cross_flags) $(rustc_target_flags) \
+ --crate-type rlib --out-dir $(objtree)/rust/ -L $(objtree)/rust/ \
+ --crate-name $(patsubst %.o,%,$(notdir $@)) $<; \
+ mv $(objtree)/rust/$(patsubst %.o,%,$(notdir $@)).d $(depfile); \
+ sed -i '/^\#/d' $(depfile) \
+ $(if $(rustc_objcopy),;$(OBJCOPY) $(rustc_objcopy) $@)
+
+# `$(rustc_flags)` is passed in case the user added `--sysroot`.
+rustc_sysroot = $(shell $(RUSTC) $(rustc_flags) --print sysroot)
+rustc_src = $(rustc_sysroot)/lib/rustlib/src/rust
+
+.SECONDEXPANSION:
+$(objtree)/rust/core.o: private skip_clippy = 1
+$(objtree)/rust/core.o: $$(rustc_src)/library/core/src/lib.rs FORCE
+ $(call if_changed_dep,rustc_library)
+
+$(objtree)/rust/compiler_builtins.o: private rustc_objcopy = -w -W '__*'
+$(objtree)/rust/compiler_builtins.o: $(srctree)/rust/compiler_builtins.rs \
+ $(objtree)/rust/core.o FORCE
+ $(call if_changed_dep,rustc_library)
+
+$(objtree)/rust/alloc.o: private skip_clippy = 1
+$(objtree)/rust/alloc.o: $$(rustc_src)/library/alloc/src/lib.rs \
+ $(objtree)/rust/compiler_builtins.o FORCE
+ $(call if_changed_dep,rustc_library)
+
+# ICE on `--extern module`: https://github.com/rust-lang/rust/issues/56935
+$(objtree)/rust/kernel.o: private rustc_target_flags = --extern alloc \
+ --extern module=$(objtree)/rust/libmodule.so
+$(objtree)/rust/kernel.o: $(srctree)/rust/kernel/lib.rs $(objtree)/rust/alloc.o \
+ $(objtree)/rust/libmodule.so $(objtree)/rust/bindings_generated.rs FORCE
+ $(call if_changed_dep,rustc_library)
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 1b6094a13034..3665c49c4dcf 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -26,6 +26,7 @@ EXTRA_CPPFLAGS :=
EXTRA_LDFLAGS :=
asflags-y :=
ccflags-y :=
+rustcflags-y :=
cppflags-y :=
ldflags-y :=

@@ -287,6 +288,24 @@ quiet_cmd_cc_lst_c = MKLST $@
$(obj)/%.lst: $(src)/%.c FORCE
$(call if_changed_dep,cc_lst_c)

+# Compile Rust sources (.rs)
+# ---------------------------------------------------------------------------
+
+rustc_cross_flags := --target=$(srctree)/arch/$(SRCARCH)/rust/target.json
+
+quiet_cmd_rustc_o_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
+ cmd_rustc_o_rs = \
+ RUST_MODFILE=$(modfile) \
+ $(RUSTC_OR_CLIPPY) $(rustc_flags) $(rustc_cross_flags) \
+ --extern alloc --extern kernel \
+ --crate-type rlib --out-dir $(obj) -L $(objtree)/rust/ \
+ --crate-name $(patsubst %.o,%,$(notdir $@)) $<; \
+ mv $(obj)/$(subst .o,,$(notdir $@)).d $(depfile); \
+ sed -i '/^\#/d' $(depfile)
+
+$(obj)/%.o: $(src)/%.rs FORCE
+ $(call if_changed_dep,rustc_o_rs)
+
# Compile assembler sources (.S)
# ---------------------------------------------------------------------------

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 8cd67b1b6d15..bd6cb3562fb4 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -8,6 +8,7 @@ ldflags-y += $(EXTRA_LDFLAGS)
# flags that take effect in current and sub directories
KBUILD_AFLAGS += $(subdir-asflags-y)
KBUILD_CFLAGS += $(subdir-ccflags-y)
+KBUILD_RUSTCFLAGS += $(subdir-rustcflags-y)

# Figure out what we need to build from the various variables
# ===========================================================================
@@ -122,6 +123,10 @@ _c_flags = $(filter-out $(CFLAGS_REMOVE_$(target-stem).o), \
$(filter-out $(ccflags-remove-y), \
$(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(ccflags-y)) \
$(CFLAGS_$(target-stem).o))
+_rustc_flags = $(filter-out $(RUSTCFLAGS_REMOVE_$(target-stem).o), \
+ $(filter-out $(rustcflags-remove-y), \
+ $(KBUILD_RUSTCFLAGS) $(rustcflags-y)) \
+ $(RUSTCFLAGS_$(target-stem).o))
_a_flags = $(filter-out $(AFLAGS_REMOVE_$(target-stem).o), \
$(filter-out $(asflags-remove-y), \
$(KBUILD_CPPFLAGS) $(KBUILD_AFLAGS) $(asflags-y)) \
@@ -191,6 +196,11 @@ modkern_cflags = \
$(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE), \
$(KBUILD_CFLAGS_KERNEL) $(CFLAGS_KERNEL) $(modfile_flags))

+modkern_rustcflags = \
+ $(if $(part-of-module), \
+ $(KBUILD_RUSTCFLAGS_MODULE) $(RUSTCFLAGS_MODULE), \
+ $(KBUILD_RUSTCFLAGS_KERNEL) $(RUSTCFLAGS_KERNEL))
+
modkern_aflags = $(if $(part-of-module), \
$(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE), \
$(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL))
@@ -200,6 +210,8 @@ c_flags = -Wp,-MMD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) \
$(_c_flags) $(modkern_cflags) \
$(basename_flags) $(modname_flags)

+rustc_flags = $(_rustc_flags) $(modkern_rustcflags) @$(objtree)/include/generated/rustc_cfg
+
a_flags = -Wp,-MMD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) \
$(_a_flags) $(modkern_aflags)

diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
index 2568dbe16ed6..a83d646ecef5 100644
--- a/scripts/kconfig/confdata.c
+++ b/scripts/kconfig/confdata.c
@@ -637,6 +637,56 @@ static struct conf_printer kconfig_printer_cb =
.print_comment = kconfig_print_comment,
};

+/*
+ * rustc cfg printer
+ *
+ * This printer is used when generating the resulting rustc configuration
+ * after kconfig invocation and `defconfig` files.
+ */
+static void rustc_cfg_print_symbol(FILE *fp, struct symbol *sym, const char *value, void *arg)
+{
+ const char *str;
+
+ switch (sym->type) {
+ case S_INT:
+ case S_HEX:
+ case S_BOOLEAN:
+ case S_TRISTATE:
+ str = sym_escape_string_value(value);
+
+ /*
+ * We don't care about disabled ones, i.e. no need for
+ * what otherwise are "comments" in other printers.
+ */
+ if (*value == 'n')
+ return;
+
+ /*
+ * To have similar functionality to the C macro `IS_ENABLED()`
+ * we provide an empty `--cfg CONFIG_X` here in both `y`
+ * and `m` cases.
+ *
+ * Then, the common `fprintf()` below will also give us
+ * a `--cfg CONFIG_X="y"` or `--cfg CONFIG_X="m"`, which can
+ * be used as the equivalent of `IS_BUILTIN()`/`IS_MODULE()`.
+ */
+ if (*value == 'y' || *value == 'm')
+ fprintf(fp, "--cfg=%s%s\n", CONFIG_, sym->name);
+
+ break;
+ default:
+ str = value;
+ break;
+ }
+
+ fprintf(fp, "--cfg=%s%s=%s\n", CONFIG_, sym->name, str);
+}
+
+static struct conf_printer rustc_cfg_printer_cb =
+{
+ .print_symbol = rustc_cfg_print_symbol,
+};
+
/*
* Header printer
*
@@ -1044,7 +1094,7 @@ int conf_write_autoconf(int overwrite)
struct symbol *sym;
const char *name;
const char *autoconf_name = conf_get_autoconfig_name();
- FILE *out, *out_h;
+ FILE *out, *out_h, *out_rustc_cfg;
int i;

if (!overwrite && is_present(autoconf_name))
@@ -1065,6 +1115,13 @@ int conf_write_autoconf(int overwrite)
return 1;
}

+ out_rustc_cfg = fopen(".tmp_rustc_cfg", "w");
+ if (!out_rustc_cfg) {
+ fclose(out);
+ fclose(out_h);
+ return 1;
+ }
+
conf_write_heading(out, &kconfig_printer_cb, NULL);
conf_write_heading(out_h, &header_printer_cb, NULL);

@@ -1076,9 +1133,11 @@ int conf_write_autoconf(int overwrite)
/* write symbols to auto.conf and autoconf.h */
conf_write_symbol(out, sym, &kconfig_printer_cb, (void *)1);
conf_write_symbol(out_h, sym, &header_printer_cb, NULL);
+ conf_write_symbol(out_rustc_cfg, sym, &rustc_cfg_printer_cb, NULL);
}
fclose(out);
fclose(out_h);
+ fclose(out_rustc_cfg);

name = getenv("KCONFIG_AUTOHEADER");
if (!name)
@@ -1097,6 +1156,12 @@ int conf_write_autoconf(int overwrite)
if (rename(".tmpconfig", autoconf_name))
return 1;

+ name = "include/generated/rustc_cfg";
+ if (make_parent_dir(name))
+ return 1;
+ if (rename(".tmp_rustc_cfg", name))
+ return 1;
+
return 0;
}

diff --git a/scripts/rust-version.sh b/scripts/rust-version.sh
new file mode 100755
index 000000000000..67b6d31688e2
--- /dev/null
+++ b/scripts/rust-version.sh
@@ -0,0 +1,31 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# rust-version rust-command
+#
+# Print the compiler version of `rust-command' in a 5 or 6-digit form
+# such as `14502' for rustc-1.45.2 etc.
+#
+# Returns 0 if not found (so that Kconfig does not complain)
+compiler="$*"
+
+if [ ${#compiler} -eq 0 ]; then
+ echo "Error: No compiler specified." >&2
+ printf "Usage:\n\t$0 <rust-command>\n" >&2
+ exit 1
+fi
+
+if ! command -v $compiler >/dev/null 2>&1; then
+ echo 0
+ exit 0
+fi
+
+VERSION=$($compiler --version | cut -f2 -d' ')
+
+# Cut suffix if any (e.g. `-dev`)
+VERSION=$(echo $VERSION | cut -f1 -d'-')
+
+MAJOR=$(echo $VERSION | cut -f1 -d'.')
+MINOR=$(echo $VERSION | cut -f2 -d'.')
+PATCHLEVEL=$(echo $VERSION | cut -f3 -d'.')
+printf "%d%02d%02d\\n" $MAJOR $MINOR $PATCHLEVEL
--
2.17.1
\
 
 \ /
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