Messages in this thread | | | Date | Mon, 19 Aug 2019 17:59:48 +0100 | From | Mark Rutland <> | Subject | Enabling UBSAN breaks KCOV in clang (8.0.*) on arm64 |
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Hi,
I found that when I enable both KCOV and UBSAN on arm64, clang fails to emit any __sanitizer_cov_trace_*() calls in the resulting binary, rendering KCOV useless.
For example, when building v5.3-rc3's arch/arm64/kernel/setup.o:
* With defconfig + CONFIG KCOV:
clang -Wp,-MD,arch/arm64/kernel/.setup.o.d -nostdinc -isystem /mnt/data/opt/toolchain/llvm/8.0.0/clang+llvm-8.0.0-x86_64-linux-sles11.3/lib/clang/8.0.0/include -I./arch/arm64/include -I./arch/arm64/include/generated -I./include -I./arch/arm64/include/uapi -I./arch/arm64/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -include ./include/linux/compiler_types.h -D__KERNEL__ -mlittle-endian -DKASAN_SHADOW_SCALE_SHIFT=3 -Qunused-arguments -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -Werror=implicit-function-declaration -Werror=implicit-int -Wno-format-security -std=gnu89 --target=aarch64-linux --prefix=/mnt/data/opt/toolchain/kernel-org-crosstool/gcc-8.1.0-nolibc/aarch64-linux/bin/ --gcc-toolchain=/mnt/data/opt/toolchain/kernel-org-crosstool/gcc-8.1.0-nolibc/aarch64-linux -no-integrated-as -Werror=unknown-warning-option -mgeneral-regs-only -DCONFIG_AS_LSE=1 -fno-asynchronous-unwind-tables -DKASAN_SHADOW_SCALE_SHIFT=3 -fno-delete-null-pointer-checks -Wno-address-of-packed-member -O2 -Wframe-larger-than=2048 -fstack-protector-strong -Wno-format-invalid-specifier -Wno-gnu -Wno-tautological-compare -mno-global-merge -Wno-unused-const-variable -fno-omit-frame-pointer -fno-optimize-sibling-calls -g -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -fno-strict-overflow -fno-merge-all-constants -fno-stack-check -Werror=date-time -Werror=incompatible-pointer-types -Wno-initializer-overrides -Wno-format -Wno-sign-compare -Wno-format-zero-length -fsanitize-coverage=trace-pc -DKBUILD_BASENAME='"setup"' -DKBUILD_MODNAME='"setup"' -c -o arch/arm64/kernel/setup.o arch/arm64/kernel/setup.c
... and there are 44 calls to __sanitizer_cov_trace_pc in the resulting setup.o
* with defconfig + CONFIG_KCOV + CONFIG_UBSAN:
clang -Wp,-MD,arch/arm64/kernel/.setup.o.d -nostdinc -isystem /mnt/data/opt/toolchain/llvm/8.0.0/clang+llvm-8.0.0-x86_64-linux-sles11.3/lib/clang/8.0.0/include -I./arch/arm64/include -I./arch/arm64/include/generated -I./include -I./arch/arm64/include/uapi -I./arch/arm64/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -include ./include/linux/compiler_types.h -D__KERNEL__ -mlittle-endian -DKASAN_SHADOW_SCALE_SHIFT=3 -Qunused-arguments -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -Werror=implicit-function-declaration -Werror=implicit-int -Wno-format-security -std=gnu89 --target=aarch64-linux --prefix=/mnt/data/opt/toolchain/kernel-org-crosstool/gcc-8.1.0-nolibc/aarch64-linux/bin/ --gcc-toolchain=/mnt/data/opt/toolchain/kernel-org-crosstool/gcc-8.1.0-nolibc/aarch64-linux -no-integrated-as -Werror=unknown-warning-option -mgeneral-regs-only -DCONFIG_AS_LSE=1 -fno-asynchronous-unwind-tables -DKASAN_SHADOW_SCALE_SHIFT=3 -fno-delete-null-pointer-checks -Wno-address-of-packed-member -O2 -Wframe-larger-than=2048 -fstack-protector-strong -Wno-format-invalid-specifier -Wno-gnu -Wno-tautological-compare -mno-global-merge -Wno-unused-const-variable -fno-omit-frame-pointer -fno-optimize-sibling-calls -g -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -fno-strict-overflow -fno-merge-all-constants -fno-stack-check -Werror=date-time -Werror=incompatible-pointer-types -Wno-initializer-overrides -Wno-format -Wno-sign-compare -Wno-format-zero-length -fsanitize=shift -fsanitize=integer-divide-by-zero -fsanitize=unreachable -fsanitize=signed-integer-overflow -fsanitize=bounds -fsanitize=object-size -fsanitize=bool -fsanitize=enum -fsanitize-coverage=trace-pc -DKBUILD_BASENAME='"setup"' -DKBUILD_MODNAME='"setup"' -c -o arch/arm64/kernel/setup.o arch/arm64/kernel/setup.c
... and there are 0 calls to __sanitizer_cov_trace_pc in the resulting setup.o, even though -fsanitize-coverage=trace-pc was passed to clang.
If I remove -fsanitize=bounds, there are 121 calls to __sanitizer_cov_trace_pc in setup.o. Removing the other options enabled by UBSAN didn't have any effect on setup.o.
I'm using the llvm.org 8.0.{0,1} binaries [1,2], along with the kernel.org crosstool 8.1.0 binaries [3].
Any ideas as to what's going on?
Thanks, Mark.
[1] http://releases.llvm.org/download.html#8.0.0 [2] http://releases.llvm.org/download.html#8.0.1 [3] https://mirrors.edge.kernel.org/pub/tools/crosstool/
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