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Dmytro Prokopchuk1
f951de9a3b
Rule 11.1 states as following: "Conversions shall not be performed between a pointer to a function and any other type." This deviation from Rule 11.1 relies on both ABI definitions and compiler implementations supported by Xen. The System V x86_64 ABI and the AArch64 ELF ABI define consistent and compatible representations (i.e., having the same size and memory layout) for (void *), unsigned long, and function pointers, enabling safe conversions between these types without data loss or corruption. Additionally, GCC and Clang, faithfully implement the ABI specifications, ensuring that the generated machine code conforms to these guarantees. Developers must note that this behavior is not universal and depends on platform-specific ABIs and compiler implementations. Configure Eclair to avoid reporting violations for conversions from unsigned long or (void *) to a function pointer. Add a compile-time assertion into the file 'xen/common/version.c' to confirm this conversion compatibility across X86 and ARM platforms (assuming this file is common for them). References: - System V x86_64 ABI: https://gitlab.com/x86-psABIs/x86-64-ABI/-/jobs/artifacts/master/raw/x86-64-ABI/abi.pdf?job=build - AArch64 ELF ABI: https://github.com/ARM-software/abi-aa/releases - GCC: https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html - Clang: https://clang.llvm.org/docs/CrossCompilation.html Signed-off-by: Dmytro Prokopchuk <dmytro_prokopchuk1@epam.com> Reviewed-by: Nicola Vetrini <nicola.vetrini@bugseng.com> [stefano: remove special powerpc check] Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com> Acked-by: Stefano Stabellini <sstabellini@kernel.org>
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