On 12.03.2021 23:41, Nick Desaulniers wrote:
LLVM changed the expected function signatures for llvm_gcda_start_file() and llvm_gcda_emit_function() in the clang-11 release. Users of clang-11 or newer may have noticed their kernels failing to boot due to a panic when enabling CONFIG_GCOV_KERNEL=y +CONFIG_GCOV_PROFILE_ALL=y. Fix up the function signatures so calling these functions doesn't panic the kernel.
Link: https://reviews.llvm.org/rGcdd683b516d147925212724b09ec6fb792a40041 Link: https://reviews.llvm.org/rG13a633b438b6500ecad9e4f936ebadf3411d0f44 Cc: stable@vger.kernel.org # 5.4 Reported-by: Prasad Sodagudi psodagud@quicinc.com Suggested-by: Nathan Chancellor nathan@kernel.org Reviewed-by: Fangrui Song maskray@google.com Signed-off-by: Nick Desaulniers ndesaulniers@google.com Tested-by: Nathan Chancellor nathan@kernel.org
Looks good to me (minus the code duplication - but that's IMO acceptable since it's cleaned up again with patch 2).
Acked-by: Peter Oberparleiter oberpar@linux.ibm.com
That said, I'm currently thinking of adding a compile time check that performs a dry-run gcov_info => gcda conversion in user space to detect these kind of issues before kernels fail unpredictably [1]. I'm confident that this could work for the GCC gcov kernel code, not sure about the Clang version though. But if it's possible I guess it would make sense to extend this to include the Clang code as well.
Note that this check wouldn't work for cross-compiles since the build machine must be able to run code for the target machine.
[1] https://lore.kernel.org/lkml/1c7a49e7-0e27-561b-a2f9-d42a83dc4c29@linux.ibm....
Regards, Peter