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Date: Fri, 12 Dec 2014 06:14:25 +0000 From: Ben Hutchings <ben@...adent.org.uk> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org CC: akpm@...ux-foundation.org Subject: [PATCH 3.2 064/164] compiler: Define OPTIMIZER_HIDE_VAR 3.2.65-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Ben Hutchings <ben@...adent.org.uk> Part of upstream commit fe8c8a126806 ('crypto: more robust crypto_memneq'), needed by commit d4c5efdb9777 ('random: add and use memzero_explicit() for clearing data'). --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -37,6 +37,9 @@ __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \ (typeof(ptr)) (__ptr + (off)); }) +/* Make the optimizer believe the variable can be manipulated arbitrarily. */ +#define OPTIMIZER_HIDE_VAR(var) __asm__ ("" : "=r" (var) : "0" (var)) + #ifdef __CHECKER__ #define __must_be_array(arr) 0 #else --- a/include/linux/compiler-intel.h +++ b/include/linux/compiler-intel.h @@ -15,6 +15,7 @@ */ #undef barrier #undef RELOC_HIDE +#undef OPTIMIZER_HIDE_VAR #define barrier() __memory_barrier() @@ -23,6 +24,12 @@ __ptr = (unsigned long) (ptr); \ (typeof(ptr)) (__ptr + (off)); }) +/* This should act as an optimization barrier on var. + * Given that this compiler does not have inline assembly, a compiler barrier + * is the best we can do. + */ +#define OPTIMIZER_HIDE_VAR(var) barrier() + /* Intel ECC compiler doesn't support __builtin_types_compatible_p() */ #define __must_be_array(a) 0 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -164,6 +164,10 @@ void ftrace_likely_update(struct ftrace_ (typeof(ptr)) (__ptr + (off)); }) #endif +#ifndef OPTIMIZER_HIDE_VAR +#define OPTIMIZER_HIDE_VAR(var) barrier() +#endif + #endif /* __KERNEL__ */ #endif /* __ASSEMBLY__ */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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