MbedTLS bignum module needs '__udivti3' which is a 128-bit division function provided by the compiler runtime, typically libgcc for GCC or clang_rt.builtins for Clang. Thus 'clang_rt.builtins' library is required when building using Clang.
This patch supports the location layout of clang_rt.builtins libraries from both LLVM pre-15 pattern [1] and post-15(up to 20) pattern [2]. As a fact that starts from LLVM 20, no official prebuilt multi-targets are included and users might need to cross-built it from source. [3] is an example of instructions for building. [1] <INST_DIR>/lib/clang/<REV>/lib/linux/libclang_rt.builtins-<ARCH>.a E.g. lib/clang/14.0.0/lib/linux/libclang_rt.builtins-aarch64.a lib/clang/14.0.0/lib/linux/libclang_rt.builtins-x86_64.a [2] <INST_DIR>/lib/clang/<REV_MAJOR>/lib/<CROSSTOOL>/libclang_rt.builtins.a E.g. lib/clang/20/lib/aarch64-none-linux-gnu/libclang_rt.builtins.a lib/clang/20/lib/x86_64-unknown-linux-gnu/libclang_rt.builtins.a [3] git clone https://github.com/llvm/llvm-project.git cd llvm-project git checkout -b llvmorg-20.1.6 llvmorg-20.1.6 mkdir build-builtin && cd build-builtin cmake -G Ninja ../llvm \ -DCMAKE_BUILD_TYPE=Release \ -DCMAKE_C_COMPILER=clang \ -DLLVM_ENABLE_PROJECTS="clang" \ -DLLVM_ENABLE_RUNTIMES="compiler-rt" \ -DLLVM_TARGETS_TO_BUILD="X86;AArch64" \ -DLLVM_BUILTIN_TARGETS=\ "x86_64-unknown-linux-gnu;aarch64-none-linux-gnu" \ -DBUILTINS_aarch64-none-linux-gnu_CMAKE_SYSTEM_NAME=Linux \ -DBUILTINS_aarch64-none-linux-gnu_CMAKE_C_COMPILER=\ <YOUR_TOOLCHAIN_GCC> \ -DBUILTINS_aarch64-none-linux-gnu_CMAKE_ASM_COMPILER=\ <YOUR_TOOLCHAIN_GCC> \ -DBUILTINS_aarch64-none-linux-gnu_CMAKE_SYSROOT=\ <YOUR_TOOLCHAIN_LIBC_DIR> \ -DCOMPILER_RT_BUILD_BUILTINS=ON \ -DCOMPILER_RT_BUILD_SANITIZERS=OFF \ -DCOMPILER_RT_BUILD_XRAY=OFF \ -DCOMPILER_RT_BUILD_LIBFUZZER=OFF \ -DCOMPILER_RT_BUILD_PROFILE=OFF \ -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR> \ -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF ninja builtins sudo ninja install Fixes: 13de8483388c ("mbedtls: add mbedtls into the build system") Signed-off-by: Raymond Mao <raymond....@linaro.org> --- Changes in V2: - Add support for LLVM post-15. Makefile | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index f88684947ee..6cec94e1cd3 100644 --- a/Makefile +++ b/Makefile @@ -37,7 +37,6 @@ else ifeq ("riscv32", $(MK_ARCH)) else ifeq ("riscv64", $(MK_ARCH)) export HOST_ARCH=$(HOST_ARCH_RISCV64) endif -undefine MK_ARCH # Avoid funny character set dependencies unexport LC_ALL @@ -915,8 +914,27 @@ PLATFORM_LIBGCC = arch/$(ARCH)/lib/lib.a else ifndef CONFIG_CC_IS_CLANG PLATFORM_LIBGCC := -L $(shell dirname `$(CC) $(c_flags) -print-libgcc-file-name`) -lgcc +else +# mbedtls bignum needs '__udivti3' - a 128-bit division function that's provided by clang-rt. +ifeq ($(CONFIG_RSA_PUBLIC_KEY_PARSER_MBEDTLS),y) +CLANG_RES_DIR := $(shell $(CC) --print-resource-dir) +# Find all matching libclang_rt.builtins*.a files +CLANG_RT_LIB_FULL := $(shell find $(CLANG_RES_DIR)/lib -name "libclang_rt.builtins*.a" 2>/dev/null | grep "$(MK_ARCH)" | head -n 1) +CLANG_RT_DIR := $(shell dirname $(CLANG_RT_LIB_FULL)) +ifeq ($(CLANG_RT_LIB_FULL),) +$(info libclang_rt.builtins.a not found for target $(MK_ARCH)) +else ifneq ($(findstring /linux/, $(CLANG_RT_LIB_FULL)),) +# Legacy(pre-LLVM15) layout (<INSTALLED_DIR>/lib/clang/<REV>/lib/linux/libclang_rt.builtins-<ARCH>.a) +PLATFORM_LIBGCC := -L$(CLANG_RT_DIR) -lclang_rt.builtins-$(shell echo $(MK_ARCH) | tr -d '"') +else +# New(post-LLVM15) layout (<INSTALLED_DIR>/lib/clang/<REV_MAJOR>/lib/<CROSSTOOL_NAME>/libclang_rt.builtins.a) +PLATFORM_LIBGCC := -L$(CLANG_RT_DIR) -lclang_rt.builtins endif -endif +endif # CONFIG_RSA_PUBLIC_KEY_PARSER_MBEDTLS +endif # CONFIG_CC_IS_CLANG +endif # CONFIG_USE_PRIVATE_LIBGCC + +undefine MK_ARCH PLATFORM_LIBS += $(PLATFORM_LIBGCC) ifdef CONFIG_CC_COVERAGE -- 2.25.1
