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In iommu_range_alloc() we generate a mask by right shifting ~0, however if the specified alignment is 0 then we right shift by 64, which is undefined. UBSAN tells us so: UBSAN: Undefined behaviour in ../arch/powerpc/kernel/iommu.c:193:35 shift exponent 64 is too large for 64-bit type 'long unsigned int' We can avoid it by instead generating the mask with: align_mask = (1ull << align_order) - 1; That will also generate an undefined shift if align_order is 64 or greater, but that shouldn't be a problem for a while. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.