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2019-10-10mips: Fix unroll macro when building with ClangNathan Chancellor
Building with Clang errors after commit 6baaeadae911 ("MIPS: Provide unroll() macro, use it for cache ops") since the GCC_VERSION macro is defined in include/linux/compiler-gcc.h, which is only included in compiler.h when using GCC: In file included from arch/mips/kernel/mips-mt.c:20: ./arch/mips/include/asm/r4kcache.h:254:1: error: use of undeclared identifier 'GCC_VERSION'; did you mean 'S_VERSION'? __BUILD_BLAST_CACHE(i, icache, Index_Invalidate_I, Hit_Invalidate_I, 32, ) ^ ./arch/mips/include/asm/r4kcache.h:219:4: note: expanded from macro '__BUILD_BLAST_CACHE' cache_unroll(32, kernel_cache, indexop, ^ ./arch/mips/include/asm/r4kcache.h:203:2: note: expanded from macro 'cache_unroll' unroll(times, _cache_op, insn, op, (addr) + (i++ * (lsize))); ^ ./arch/mips/include/asm/unroll.h:28:15: note: expanded from macro 'unroll' BUILD_BUG_ON(GCC_VERSION >= 40700 && \ ^ Use CONFIG_GCC_VERSION, which will always be set by Kconfig. Additionally, Clang 8 had improvements around __builtin_constant_p so use that as a lower limit for this check with Clang (although MIPS wasn't buildable until Clang 9); building a kernel with Clang 9.0.0 has no issues after this change. Fixes: 6baaeadae911 ("MIPS: Provide unroll() macro, use it for cache ops") Link: https://github.com/ClangBuiltLinux/linux/issues/736 Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: clang-built-linux@googlegroups.com Cc: Nick Desaulniers <ndesaulniers@google.com>
2019-10-09MIPS: Provide unroll() macro, use it for cache opsPaul Burton
Currently we have a lot of duplication in asm/r4kcache.h to handle manually unrolling loops of cache ops for various line sizes, and we have to explicitly handle the difference in cache op immediate width between MIPSr6 & earlier ISA revisions with further duplication. Introduce an unroll() macro in asm/unroll.h which expands to a switch statement which is used to call a function or expand a preprocessor macro a compile-time constant number of times in a row - effectively explicitly unrolling a loop. We make use of this here to remove the cache op duplication & will use it further in later patches. A nice side effect of this is that calculating the cache op offset immediate is now the compiler's responsibility, so we're no longer sensitive to the width change of that immediate in MIPSr6 & will be similarly agnostic to immediate width in any future supported ISA. Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: linux-mips@vger.kernel.org