From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965687AbdDZTBx (ORCPT ); Wed, 26 Apr 2017 15:01:53 -0400 Received: from mail-pf0-f174.google.com ([209.85.192.174]:35121 "EHLO mail-pf0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965664AbdDZTBp (ORCPT ); Wed, 26 Apr 2017 15:01:45 -0400 From: Matthias Kaehlcke To: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , Kees Cook Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Grant Grundler , Greg Hackmann , Michael Davidson , Matthias Kaehlcke Subject: [PATCH] x86/mm/kaslr: Add operand size suffix to 'mul' instruction Date: Wed, 26 Apr 2017 12:01:12 -0700 Message-Id: <20170426190112.98116-1-mka@chromium.org> X-Mailer: git-send-email 2.13.0.rc0.306.g87b477812d-goog Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In difference to gas clang doesn't seem to infer the size from the operands. Adding the suffix fixes the following error when building with clang: CC arch/x86/lib/kaslr.o /tmp/kaslr-dfe1ad.s: Assembler messages: /tmp/kaslr-dfe1ad.s:182: Error: no instruction mnemonic suffix given and no register operands; can't size instruction Signed-off-by: Matthias Kaehlcke --- arch/x86/lib/kaslr.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/x86/lib/kaslr.c b/arch/x86/lib/kaslr.c index 121f59c6ee54..947d4aa92ff7 100644 --- a/arch/x86/lib/kaslr.c +++ b/arch/x86/lib/kaslr.c @@ -79,7 +79,11 @@ unsigned long kaslr_get_random_long(const char *purpose) } /* Circular multiply for better bit diffusion */ - asm("mul %3" +#ifdef CONFIG_X86_64 + asm("mulq %3" +#else + asm("mull %3" +#endif : "=a" (random), "=d" (raw) : "a" (random), "rm" (mix_const)); random += raw; -- 2.13.0.rc0.306.g87b477812d-goog