scripts/mksysmap: Ignore prefixed KCFI symbols

The (relatively) new KCFI feature in LLVM/Clang encodes type information for C functions by generating symbols named __kcfi_typeid_<fname>, which can then be referenced from assembly. However, some custom build rules (e.g. nVHE or early PIE on arm64) use objcopy to add a prefix to all the symbols in their object files, making mksysmap's ignore filter miss those KCFI symbols. Therefore, explicitly list those twice-prefixed KCFI symbols as ignored. Alternatively, this could also be achieved in a less verbose way by ignoring any symbol containing the string "__kcfi_typeid_". However, listing the combined prefixes explicitly saves us from running the small risk of ignoring symbols that should be kept.

PCPierre-Clément Tosi committed 3 years ago