From patchwork Fri Nov 8 18:37:09 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ben Dooks X-Patchwork-Id: 3159311 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 08C10C045B for ; Fri, 8 Nov 2013 18:41:08 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 0690E204AD for ; Fri, 8 Nov 2013 18:41:07 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DDCE720499 for ; Fri, 8 Nov 2013 18:41:05 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Veqxi-0001pA-Vg; Fri, 08 Nov 2013 18:39:19 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VeqxB-0002ez-Iu; Fri, 08 Nov 2013 18:38:45 +0000 Received: from 82-68-191-81.dsl.posilan.com ([82.68.191.81] helo=rainbowdash.ducie.codethink.co.uk) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Veqw9-0002Y0-Nt for linux-arm-kernel@lists.infradead.org; Fri, 08 Nov 2013 18:37:47 +0000 Received: from ben by rainbowdash.ducie.codethink.co.uk with local (Exim 4.80) (envelope-from ) id 1Veqvn-0005U3-GX; Fri, 08 Nov 2013 18:37:19 +0000 From: Ben Dooks To: linux-arm-kernel@lists.infradead.org, victor.kamensky@linaro.org, taras.kondratiuk@linaro.org Subject: [PATCH 6/9] ARM: kprobes-test: Workaround GAS .align bug Date: Fri, 8 Nov 2013 18:37:09 +0000 Message-Id: <1383935832-20865-7-git-send-email-ben.dooks@codethink.co.uk> X-Mailer: git-send-email 1.8.4.rc3 In-Reply-To: <1383935832-20865-1-git-send-email-ben.dooks@codethink.co.uk> References: <1383935832-20865-1-git-send-email-ben.dooks@codethink.co.uk> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20131108_133742_197596_CCFF39D1 X-CRM114-Status: GOOD ( 13.98 ) X-Spam-Score: -0.3 (/) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Taras Kondratiuk By default if no fill symbol is given to .align directive in a code section it fills gap with NOPs. If previous fragment is not instruction-aligned, additional pre-alignment is done by zero bytes before NOPs. These zero bytes are marked as data by special symbol $d in symbol table. Unfortunately GAS assumes that there is only code in the code section so it "puts back" code symbol $a at the end of this pre-alignment. So if there is some data after alignment it will be interpreted as code and will be swapped back to LE for BE8 system during a final linking. If explicit fill value is given to .align, the NOP-padding code is skipped and symbol table does not get messed-up. So the workaround for this issue: Use explicit fill value if data should be aligned in the code section. Signed-off-by: Taras Kondratiuk --- arch/arm/kernel/kprobes-test.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/kernel/kprobes-test.h b/arch/arm/kernel/kprobes-test.h index e28a869..eecc90a 100644 --- a/arch/arm/kernel/kprobes-test.h +++ b/arch/arm/kernel/kprobes-test.h @@ -115,7 +115,7 @@ struct test_arg_end { /* multiple strings to be concatenated. */ \ ".ascii "#title" \n\t" \ ".byte 0 \n\t" \ - ".align 2 \n\t" + ".align 2, 0 \n\t" #define TEST_ARG_REG(reg, val) \ ".byte "__stringify(ARG_TYPE_REG)" \n\t" \