From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759959AbcAUSg2 (ORCPT ); Thu, 21 Jan 2016 13:36:28 -0500 Received: from mail.skyhub.de ([78.46.96.112]:43429 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759861AbcAUSfR (ORCPT ); Thu, 21 Jan 2016 13:35:17 -0500 From: Borislav Petkov To: "H. Peter Anvin" Cc: Andy Lutomirski , Brian Gerst , X86 ML , LKML Subject: [PATCH 5/5] x86/alternatives: Discard dynamic check after init Date: Thu, 21 Jan 2016 19:34:46 +0100 Message-Id: <1453401286-26966-6-git-send-email-bp@alien8.de> X-Mailer: git-send-email 2.3.5 In-Reply-To: <1453401286-26966-1-git-send-email-bp@alien8.de> References: <1453401286-26966-1-git-send-email-bp@alien8.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Brian Gerst Move the code to do the dynamic check to the altinstr_aux section so that it is discarded after alternatives have run and a static branch has been chosen. Boris: change it to do TESTB, as hpa suggests. Signed-off-by: Brian Gerst Cc: Andrew Morton Cc: Andy Lutomirski Cc: Boris Ostrovsky Cc: Dave Young Cc: Denys Vlasenko Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Kristen Carlson Accardi Cc: Laura Abbott Cc: Linus Torvalds Cc: "Peter Zijlstra (Intel)" Cc: Prarit Bhargava Cc: Ross Zwisler Cc: Thomas Gleixner Cc: x86-ml Link: http://lkml.kernel.org/r/1452972124-7380-1-git-send-email-brgerst@gmail.com Signed-off-by: Borislav Petkov --- arch/x86/include/asm/cpufeature.h | 17 +++++++++++------ arch/x86/kernel/cpu/common.c | 6 ------ 2 files changed, 11 insertions(+), 12 deletions(-) diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index e4759223f82c..77c51f4c15b7 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -131,7 +131,6 @@ extern const char * const x86_bug_flags[NBUGINTS*32]; #if __GNUC__ >= 4 && defined(CONFIG_X86_FAST_FEATURE_TESTS) extern void warn_pre_alternatives(void); -extern bool __static_cpu_has(u16 bit); /* * Static testing of CPU features. Used the same as boot_cpu_has(). @@ -141,7 +140,7 @@ extern bool __static_cpu_has(u16 bit); static __always_inline __pure bool _static_cpu_has(u16 bit) { #ifdef CC_HAVE_ASM_GOTO - asm_volatile_goto("1: jmp %l[t_dynamic]\n" + asm_volatile_goto("1: jmp 6f\n" "2:\n" ".skip -(((5f-4f) - (2b-1b)) > 0) * " "((5f-4f) - (2b-1b)),0x90\n" @@ -166,13 +165,19 @@ static __always_inline __pure bool _static_cpu_has(u16 bit) " .byte 0\n" /* repl len */ " .byte 0\n" /* pad len */ ".previous\n" - : : "i" (bit), "i" (X86_FEATURE_ALWAYS) - : : t_dynamic, t_no); + ".section .altinstr_aux,\"ax\"\n" + "6: testb %[bitnum],%[cap_word]\n" + " jnz %l[t_yes]\n" + " jmp %l[t_no]\n" + ".previous\n" + : : "i" (bit), "i" (X86_FEATURE_ALWAYS), + [bitnum] "i" (1 << (bit & 7)), + [cap_word] "m" (((const char *)boot_cpu_data.x86_capability)[bit >> 3]) + : : t_yes, t_no); + t_yes: return true; t_no: return false; - t_dynamic: - return __static_cpu_has(bit); #else return boot_cpu_has(bit); #endif /* CC_HAVE_ASM_GOTO */ diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index a57ec0df9cc3..897c65bd3faa 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1483,12 +1483,6 @@ void warn_pre_alternatives(void) EXPORT_SYMBOL_GPL(warn_pre_alternatives); #endif -inline bool __static_cpu_has(u16 bit) -{ - return boot_cpu_has(bit); -} -EXPORT_SYMBOL_GPL(__static_cpu_has); - static void bsp_resume(void) { if (this_cpu->c_bsp_resume) -- 2.3.5