From 101b29a204f87c99377faa53bd378f101ebb1824 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 25 Aug 2016 15:16:45 -0700 Subject: [PATCH] byteswap: don't use __builtin_bswap*() with sparse Although sparse declares __builtin_bswap*(), it can't actually do constant folding inside them (yet). As such, things like switch (protocol) { case htons(ETH_P_IP): break; } which we do all over the place cause sparse to warn that it expects a constant instead of a function call. Disable __HAVE_BUILTIN_BSWAP*__ if __CHECKER__ is defined to avoid this. Fixes: 7322dd755e7d ("byteswap: try to avoid __builtin_constant_p gcc bug") Link: http://lkml.kernel.org/r/1470914102-26389-1-git-send-email-johannes@sipsolutions.net Signed-off-by: Johannes Berg Acked-by: Arnd Bergmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/compiler-gcc.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index e294939..8dbc892 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -242,7 +242,11 @@ */ #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0) -#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP +/* + * sparse (__CHECKER__) pretends to be gcc, but can't do constant + * folding in __builtin_bswap*() (yet), so don't set these for it. + */ +#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__) #if GCC_VERSION >= 40400 #define __HAVE_BUILTIN_BSWAP32__ #define __HAVE_BUILTIN_BSWAP64__ @@ -250,7 +254,7 @@ #if GCC_VERSION >= 40800 #define __HAVE_BUILTIN_BSWAP16__ #endif -#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */ +#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */ #if GCC_VERSION >= 50000 #define KASAN_ABI_VERSION 4 -- 2.7.4