Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753535AbaKFWtW (ORCPT ); Thu, 6 Nov 2014 17:49:22 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:59122 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753288AbaKFWoQ (ORCPT ); Thu, 6 Nov 2014 17:44:16 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Cesar Eduardo Barros , Kamal Mostafa Subject: [PATCH 3.13 077/162] compiler: define OPTIMIZER_HIDE_VAR() macro Date: Thu, 6 Nov 2014 14:35:41 -0800 Message-Id: <1415313426-9622-78-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1415313426-9622-1-git-send-email-kamal@canonical.com> References: <1415313426-9622-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11.11 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Cesar Eduardo Barros [ 3.13-stable only: OPTIMIZER_HIDE_VAR() macro extracted from fe8c8a1 "crypto: more robust crypto_memneq" ] [...] dummy inline assembly (based on RELOC_HIDE) to block the problematic kinds of optimization, while still allowing other optimizations to be applied to the code. Signed-off-by: Cesar Eduardo Barros [ kamal: 3.13-stable prereq for d4c5efd "random: add and use memzero_explicit() for clearing data" ] Signed-off-by: Kamal Mostafa --- include/linux/compiler-gcc.h | 3 +++ include/linux/compiler-intel.h | 7 +++++++ include/linux/compiler.h | 4 ++++ 3 files changed, 14 insertions(+) diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 24545cd..02ae99e 100644 --- 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 diff --git a/include/linux/compiler-intel.h b/include/linux/compiler-intel.h index dc1bd3d..5529c52 100644 --- 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 diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 92669cd..a2329c5 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -170,6 +170,10 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); (typeof(ptr)) (__ptr + (off)); }) #endif +#ifndef OPTIMIZER_HIDE_VAR +#define OPTIMIZER_HIDE_VAR(var) barrier() +#endif + /* Not-quite-unique ID. */ #ifndef __UNIQUE_ID # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/