kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 383 insertions, 0 deletions

diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile
new file mode 100644
index 000000000..ca068df1f
--- /dev/null
+++ b/lib/crypto/Makefile
@@ -0,0 +1,383 @@
+# SPDX-License-Identifier: GPL-2.0
+
+aflags-thumb2-$(CONFIG_THUMB2_KERNEL)  := -U__thumb2__ -D__thumb2__=1
+
+quiet_cmd_perlasm = PERLASM $@
+      cmd_perlasm = $(PERL) $(<) > $(@)
+
+quiet_cmd_perlasm_with_args = PERLASM $@
+      cmd_perlasm_with_args = $(PERL) $(<) void $(@)
+
+ppc64-perlasm-flavour-y := linux-ppc64
+ppc64-perlasm-flavour-$(CONFIG_PPC64_ELF_ABI_V2) := linux-ppc64-elfv2
+ppc64-perlasm-flavour-$(CONFIG_CPU_LITTLE_ENDIAN) := linux-ppc64le
+
+obj-$(CONFIG_KUNIT)				+= tests/
+
+obj-$(CONFIG_CRYPTO_HASH_INFO)			+= hash_info.o
+
+obj-$(CONFIG_CRYPTO_LIB_UTILS)			+= libcryptoutils.o
+libcryptoutils-y				:= memneq.o utils.o
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_AES) += libaes.o
+libaes-y := aes.o
+ifeq ($(CONFIG_CRYPTO_LIB_AES_ARCH),y)
+CFLAGS_aes.o += -I$(src)/$(SRCARCH)
+
+libaes-$(CONFIG_ARM) += arm/aes-cipher-core.o
+libaes-$(CONFIG_ARM64) += arm64/aes-cipher-core.o \
+			  arm64/aes-ce-core.o \
+			  arm64/aes-ce.o \
+			  arm64/aes-neon.o
+
+ifeq ($(CONFIG_PPC),y)
+ifeq ($(CONFIG_SPE),y)
+libaes-y += powerpc/aes-spe-core.o \
+	    powerpc/aes-spe-keys.o \
+	    powerpc/aes-spe-modes.o \
+	    powerpc/aes-tab-4k.o
+else
+libaes-y += powerpc/aesp8-ppc.o
+quiet_cmd_perlasm_aes = PERLASM $@
+      cmd_perlasm_aes = $(PERL) $< $(ppc64-perlasm-flavour-y) $@
+# Use if_changed instead of cmd, in case the flavour changed.
+$(obj)/powerpc/aesp8-ppc.S: $(src)/powerpc/aesp8-ppc.pl FORCE
+	$(call if_changed,perlasm_aes)
+targets += powerpc/aesp8-ppc.S
+OBJECT_FILES_NON_STANDARD_powerpc/aesp8-ppc.o := y
+endif # !CONFIG_SPE
+endif # CONFIG_PPC
+
+libaes-$(CONFIG_RISCV) += riscv/aes-riscv64-zvkned.o
+libaes-$(CONFIG_SPARC) += sparc/aes_asm.o
+libaes-$(CONFIG_X86) += x86/aes-aesni.o
+endif # CONFIG_CRYPTO_LIB_AES_ARCH
+
+# clean-files must be defined unconditionally
+clean-files += powerpc/aesp8-ppc.S
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_AESCFB)			+= libaescfb.o
+libaescfb-y					:= aescfb.o
+
+obj-$(CONFIG_CRYPTO_LIB_ARC4)			+= libarc4.o
+libarc4-y					:= arc4.o
+
+obj-$(CONFIG_CRYPTO_LIB_GF128MUL)		+= gf128mul.o
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_BLAKE2B) += libblake2b.o
+libblake2b-y := blake2b.o
+ifeq ($(CONFIG_CRYPTO_LIB_BLAKE2B_ARCH),y)
+CFLAGS_blake2b.o += -I$(src)/$(SRCARCH)
+libblake2b-$(CONFIG_ARM) += arm/blake2b-neon-core.o
+endif # CONFIG_CRYPTO_LIB_BLAKE2B_ARCH
+
+################################################################################
+
+# blake2s is used by the /dev/random driver which is always builtin
+obj-y += blake2s.o
+ifeq ($(CONFIG_CRYPTO_LIB_BLAKE2S_ARCH),y)
+CFLAGS_blake2s.o += -I$(src)/$(SRCARCH)
+obj-$(CONFIG_ARM) += arm/blake2s-core.o
+obj-$(CONFIG_X86) += x86/blake2s-core.o
+endif
+
+################################################################################
+
+# chacha20_block() is used by the /dev/random driver which is always builtin
+obj-y += chacha-block-generic.o
+
+obj-$(CONFIG_CRYPTO_LIB_CHACHA) += libchacha.o
+libchacha-y := chacha.o
+
+ifeq ($(CONFIG_CRYPTO_LIB_CHACHA_ARCH),y)
+CFLAGS_chacha.o += -I$(src)/$(SRCARCH)
+
+ifeq ($(CONFIG_ARM),y)
+libchacha-y += arm/chacha-scalar-core.o
+libchacha-$(CONFIG_KERNEL_MODE_NEON) += arm/chacha-neon-core.o
+endif
+
+libchacha-$(CONFIG_ARM64) += arm64/chacha-neon-core.o
+
+ifeq ($(CONFIG_MIPS),y)
+libchacha-y += mips/chacha-core.o
+AFLAGS_mips/chacha-core.o += -O2 # needed to fill branch delay slots
+endif
+
+libchacha-$(CONFIG_PPC) += powerpc/chacha-p10le-8x.o
+libchacha-$(CONFIG_RISCV) += riscv/chacha-riscv64-zvkb.o
+libchacha-$(CONFIG_S390) += s390/chacha-s390.o
+libchacha-$(CONFIG_X86) += x86/chacha-ssse3-x86_64.o \
+			   x86/chacha-avx2-x86_64.o \
+			   x86/chacha-avx512vl-x86_64.o
+endif # CONFIG_CRYPTO_LIB_CHACHA_ARCH
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_CHACHA20POLY1305)	+= libchacha20poly1305.o
+libchacha20poly1305-y				+= chacha20poly1305.o
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_CURVE25519) += libcurve25519.o
+libcurve25519-y := curve25519.o
+
+# Disable GCOV in odd or sensitive code
+GCOV_PROFILE_curve25519.o := n
+
+ifeq ($(CONFIG_ARCH_SUPPORTS_INT128),y)
+libcurve25519-$(CONFIG_CRYPTO_LIB_CURVE25519_GENERIC) += curve25519-hacl64.o
+else
+libcurve25519-$(CONFIG_CRYPTO_LIB_CURVE25519_GENERIC) += curve25519-fiat32.o
+endif
+# clang versions prior to 18 may blow out the stack with KASAN
+ifeq ($(CONFIG_CC_IS_CLANG)_$(call clang-min-version, 180000),y_)
+KASAN_SANITIZE_curve25519-hacl64.o := n
+endif
+
+ifeq ($(CONFIG_CRYPTO_LIB_CURVE25519_ARCH),y)
+CFLAGS_curve25519.o += -I$(src)/$(SRCARCH)
+libcurve25519-$(CONFIG_ARM) += arm/curve25519-core.o
+libcurve25519-$(CONFIG_PPC) += powerpc/curve25519-ppc64le_asm.o
+endif
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_DES)			+= libdes.o
+libdes-y					:= des.o
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_GF128HASH) += libgf128hash.o
+libgf128hash-y := gf128hash.o
+ifeq ($(CONFIG_CRYPTO_LIB_GF128HASH_ARCH),y)
+CFLAGS_gf128hash.o += -I$(src)/$(SRCARCH)
+libgf128hash-$(CONFIG_ARM) += arm/ghash-neon-core.o
+libgf128hash-$(CONFIG_ARM64) += arm64/ghash-neon-core.o \
+				arm64/polyval-ce-core.o
+
+ifeq ($(CONFIG_PPC),y)
+libgf128hash-y += powerpc/ghashp8-ppc.o
+quiet_cmd_perlasm_ghash = PERLASM $@
+      cmd_perlasm_ghash = $(PERL) $< $(ppc64-perlasm-flavour-y) $@
+$(obj)/powerpc/ghashp8-ppc.S: $(src)/powerpc/ghashp8-ppc.pl FORCE
+	$(call if_changed,perlasm_ghash)
+targets += powerpc/ghashp8-ppc.S
+OBJECT_FILES_NON_STANDARD_powerpc/ghashp8-ppc.o := y
+endif
+
+libgf128hash-$(CONFIG_RISCV) += riscv/ghash-riscv64-zvkg.o
+libgf128hash-$(CONFIG_X86) += x86/ghash-pclmul.o \
+			      x86/polyval-pclmul-avx.o
+endif # CONFIG_CRYPTO_LIB_GF128HASH_ARCH
+
+# clean-files must be defined unconditionally
+clean-files += powerpc/ghashp8-ppc.S
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_MD5) += libmd5.o
+libmd5-y := md5.o
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_MLDSA) += libmldsa.o
+libmldsa-y := mldsa.o
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_NH) += libnh.o
+libnh-y := nh.o
+ifeq ($(CONFIG_CRYPTO_LIB_NH_ARCH),y)
+CFLAGS_nh.o += -I$(src)/$(SRCARCH)
+libnh-$(CONFIG_ARM) += arm/nh-neon-core.o
+libnh-$(CONFIG_ARM64) += arm64/nh-neon-core.o
+libnh-$(CONFIG_X86) += x86/nh-sse2.o x86/nh-avx2.o
+endif
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_POLY1305) += libpoly1305.o
+libpoly1305-y := poly1305.o
+ifeq ($(CONFIG_ARCH_SUPPORTS_INT128),y)
+libpoly1305-$(CONFIG_CRYPTO_LIB_POLY1305_GENERIC) += poly1305-donna64.o
+else
+libpoly1305-$(CONFIG_CRYPTO_LIB_POLY1305_GENERIC) += poly1305-donna32.o
+endif
+
+ifeq ($(CONFIG_CRYPTO_LIB_POLY1305_ARCH),y)
+CFLAGS_poly1305.o += -I$(src)/$(SRCARCH)
+
+ifeq ($(CONFIG_ARM),y)
+libpoly1305-y += arm/poly1305-core.o
+$(obj)/arm/poly1305-core.S: $(src)/arm/poly1305-armv4.pl
+	$(call cmd,perlasm)
+# massage the perlasm code a bit so we only get the NEON routine if we need it
+poly1305-aflags-$(CONFIG_CPU_V7) := -U__LINUX_ARM_ARCH__ -D__LINUX_ARM_ARCH__=5
+poly1305-aflags-$(CONFIG_KERNEL_MODE_NEON) := -U__LINUX_ARM_ARCH__ -D__LINUX_ARM_ARCH__=7
+AFLAGS_arm/poly1305-core.o += $(poly1305-aflags-y) $(aflags-thumb2-y)
+endif
+
+ifeq ($(CONFIG_ARM64),y)
+libpoly1305-y += arm64/poly1305-core.o
+$(obj)/arm64/poly1305-core.S: $(src)/arm64/poly1305-armv8.pl
+	$(call cmd,perlasm_with_args)
+endif
+
+ifeq ($(CONFIG_MIPS),y)
+libpoly1305-y += mips/poly1305-core.o
+poly1305-perlasm-flavour-$(CONFIG_32BIT) := o32
+poly1305-perlasm-flavour-$(CONFIG_64BIT) := 64
+quiet_cmd_perlasm_poly1305 = PERLASM $@
+      cmd_perlasm_poly1305 = $(PERL) $< $(poly1305-perlasm-flavour-y) $@
+# Use if_changed instead of cmd, in case the flavour changed.
+$(obj)/mips/poly1305-core.S: $(src)/mips/poly1305-mips.pl FORCE
+	$(call if_changed,perlasm_poly1305)
+targets += mips/poly1305-core.S
+endif
+
+libpoly1305-$(CONFIG_PPC) += powerpc/poly1305-p10le_64.o
+
+ifeq ($(CONFIG_RISCV),y)
+libpoly1305-y += riscv/poly1305-core.o
+poly1305-perlasm-flavour-$(CONFIG_32BIT) := 32
+poly1305-perlasm-flavour-$(CONFIG_64BIT) := 64
+quiet_cmd_perlasm_poly1305 = PERLASM $@
+      cmd_perlasm_poly1305 = $(PERL) $< $(poly1305-perlasm-flavour-y) $@
+# Use if_changed instead of cmd, in case the flavour changed.
+$(obj)/riscv/poly1305-core.S: $(src)/riscv/poly1305-riscv.pl FORCE
+	$(call if_changed,perlasm_poly1305)
+targets += riscv/poly1305-core.S
+AFLAGS_riscv/poly1305-core.o += -Dpoly1305_init=poly1305_block_init
+endif
+
+ifeq ($(CONFIG_X86),y)
+libpoly1305-y += x86/poly1305-x86_64-cryptogams.o
+$(obj)/x86/poly1305-x86_64-cryptogams.S: $(src)/x86/poly1305-x86_64-cryptogams.pl
+	$(call cmd,perlasm)
+endif
+
+endif # CONFIG_CRYPTO_LIB_POLY1305_ARCH
+
+# clean-files must be defined unconditionally
+clean-files += arm/poly1305-core.S \
+	       arm64/poly1305-core.S \
+	       mips/poly1305-core.S \
+	       riscv/poly1305-core.S \
+	       x86/poly1305-x86_64-cryptogams.S
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_SHA1) += libsha1.o
+libsha1-y := sha1.o
+ifeq ($(CONFIG_CRYPTO_LIB_SHA1_ARCH),y)
+CFLAGS_sha1.o += -I$(src)/$(SRCARCH)
+ifeq ($(CONFIG_ARM),y)
+libsha1-y += arm/sha1-armv4-large.o
+libsha1-$(CONFIG_KERNEL_MODE_NEON) += arm/sha1-armv7-neon.o \
+				      arm/sha1-ce-core.o
+endif
+libsha1-$(CONFIG_ARM64) += arm64/sha1-ce-core.o
+ifeq ($(CONFIG_PPC),y)
+libsha1-y += powerpc/sha1-powerpc-asm.o
+libsha1-$(CONFIG_SPE) += powerpc/sha1-spe-asm.o
+endif
+libsha1-$(CONFIG_SPARC) += sparc/sha1_asm.o
+libsha1-$(CONFIG_X86) += x86/sha1-ssse3-and-avx.o \
+			 x86/sha1-avx2-asm.o \
+			 x86/sha1-ni-asm.o
+endif # CONFIG_CRYPTO_LIB_SHA1_ARCH
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_SHA256) += libsha256.o
+libsha256-y := sha256.o
+ifeq ($(CONFIG_CRYPTO_LIB_SHA256_ARCH),y)
+CFLAGS_sha256.o += -I$(src)/$(SRCARCH)
+
+ifeq ($(CONFIG_ARM),y)
+libsha256-y += arm/sha256-ce.o arm/sha256-core.o
+$(obj)/arm/sha256-core.S: $(src)/arm/sha256-armv4.pl
+	$(call cmd,perlasm)
+AFLAGS_arm/sha256-core.o += $(aflags-thumb2-y)
+endif
+
+ifeq ($(CONFIG_ARM64),y)
+libsha256-y += arm64/sha256-ce.o arm64/sha256-core.o
+$(obj)/arm64/sha256-core.S: $(src)/arm64/sha2-armv8.pl
+	$(call cmd,perlasm_with_args)
+endif
+
+libsha256-$(CONFIG_PPC) += powerpc/sha256-spe-asm.o
+libsha256-$(CONFIG_RISCV) += riscv/sha256-riscv64-zvknha_or_zvknhb-zvkb.o
+libsha256-$(CONFIG_SPARC) += sparc/sha256_asm.o
+libsha256-$(CONFIG_X86) += x86/sha256-ssse3-asm.o \
+			   x86/sha256-avx-asm.o \
+			   x86/sha256-avx2-asm.o \
+			   x86/sha256-ni-asm.o
+endif # CONFIG_CRYPTO_LIB_SHA256_ARCH
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_SHA512) += libsha512.o
+libsha512-y := sha512.o
+ifeq ($(CONFIG_CRYPTO_LIB_SHA512_ARCH),y)
+CFLAGS_sha512.o += -I$(src)/$(SRCARCH)
+
+ifeq ($(CONFIG_ARM),y)
+libsha512-y += arm/sha512-core.o
+$(obj)/arm/sha512-core.S: $(src)/arm/sha512-armv4.pl
+	$(call cmd,perlasm)
+AFLAGS_arm/sha512-core.o += $(aflags-thumb2-y)
+endif
+
+ifeq ($(CONFIG_ARM64),y)
+libsha512-y += arm64/sha512-ce-core.o arm64/sha512-core.o
+$(obj)/arm64/sha512-core.S: $(src)/arm64/sha2-armv8.pl
+	$(call cmd,perlasm_with_args)
+endif
+
+libsha512-$(CONFIG_RISCV) += riscv/sha512-riscv64-zvknhb-zvkb.o
+libsha512-$(CONFIG_SPARC) += sparc/sha512_asm.o
+libsha512-$(CONFIG_X86) += x86/sha512-ssse3-asm.o \
+			   x86/sha512-avx-asm.o \
+			   x86/sha512-avx2-asm.o
+endif # CONFIG_CRYPTO_LIB_SHA512_ARCH
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_SHA3) += libsha3.o
+libsha3-y := sha3.o
+
+ifeq ($(CONFIG_CRYPTO_LIB_SHA3_ARCH),y)
+CFLAGS_sha3.o += -I$(src)/$(SRCARCH)
+libsha3-$(CONFIG_ARM64) += arm64/sha3-ce-core.o
+endif # CONFIG_CRYPTO_LIB_SHA3_ARCH
+
+################################################################################
+
+obj-$(CONFIG_CRYPTO_LIB_SM3) += libsm3.o
+libsm3-y := sm3.o
+ifeq ($(CONFIG_CRYPTO_LIB_SM3_ARCH),y)
+CFLAGS_sm3.o += -I$(src)/$(SRCARCH)
+libsm3-$(CONFIG_ARM64) += arm64/sm3-ce-core.o \
+			  arm64/sm3-neon-core.o
+libsm3-$(CONFIG_RISCV) += riscv/sm3-riscv64-zvksh-zvkb.o
+libsm3-$(CONFIG_X86) += x86/sm3-avx-asm_64.o
+endif # CONFIG_CRYPTO_LIB_SM3_ARCH
+
+################################################################################
+
+obj-$(CONFIG_MPILIB) += mpi/
+
+obj-$(CONFIG_CRYPTO_SELFTESTS_FULL)		+= simd.o
+
+# clean-files must be defined unconditionally
+clean-files += arm/sha256-core.S arm/sha512-core.S
+clean-files += arm64/sha256-core.S arm64/sha512-core.S