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Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kInGx-0003LG-UJ; Thu, 17 Sep 2020 06:20:00 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kInGv-0003Kq-Ma for linux-arm-kernel@lists.infradead.org; Thu, 17 Sep 2020 06:19:58 +0000 Received: from e123331-lin.nice.arm.com (unknown [91.140.120.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9D4CD20707; Thu, 17 Sep 2020 06:19:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600323596; bh=ziD1S262d4AhvP0HlkLo4WCfu8gkBuZJo+18GfJki9c=; h=From:To:Cc:Subject:Date:From; b=Dfh0zH+QgFdYO0gLoboRtZhySJAl+bjUHgIo8kCQVGjvzCWF7i2BSPEKZiFbSIEGm fFSTDES62ApoJHYwFnIAtXQMpjV7DYbIoeuFScbKPT4lMxCYpo/X7ffl/+OEWMkRAK 4Unu4CMR1SVL+8a4DZhSoF74nrvGspRqV5Nh1iTI= From: Ard Biesheuvel <ardb@kernel.org> To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] ARM: vfp: force non-conditional encoding for external Thumb2 tail call Date: Thu, 17 Sep 2020 09:19:48 +0300 Message-Id: <20200917061948.12403-1-ardb@kernel.org> X-Mailer: git-send-email 2.17.1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200917_021957_811961_126E0A54 X-CRM114-Status: GOOD ( 13.51 ) X-Spam-Score: -8.2 (--------) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-8.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at https://www.dnswl.org/, high trust [198.145.29.99 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -3.0 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: <linux-arm-kernel.lists.infradead.org> List-Unsubscribe: <http://lists.infradead.org/mailman/options/linux-arm-kernel>, <mailto:linux-arm-kernel-request@lists.infradead.org?subject=unsubscribe> List-Archive: <http://lists.infradead.org/pipermail/linux-arm-kernel/> List-Post: <mailto:linux-arm-kernel@lists.infradead.org> List-Help: <mailto:linux-arm-kernel-request@lists.infradead.org?subject=help> List-Subscribe: <http://lists.infradead.org/mailman/listinfo/linux-arm-kernel>, <mailto:linux-arm-kernel-request@lists.infradead.org?subject=subscribe> Cc: ndesaulniers@google.com, linux@armlinux.org.uk, stable@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org> MIME-Version: 1.0 Sender: "linux-arm-kernel" <linux-arm-kernel-bounces@lists.infradead.org> Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Nick reports that the following error is produced in some cases when using GCC+ld.bfd to build the ARM defconfig with Thumb2 enabled: arch/arm/vfp/vfphw.o: in function `vfp_support_entry': (.text+0xa): relocation truncated to fit: R_ARM_THM_JUMP19 against symbol `vfp_kmode_exception' defined in .text.unlikely section in arch/arm/vfp/vfpmodule.o $ arm-linux-gnueabihf-ld --version GNU ld (GNU Binutils for Debian) 2.34 Generally, the linker should be able to fix up out of range branches by emitting veneers, but apparently, it fails to do so in this particular case, i.e., a conditional 'tail call' to vfp_kmode_exception(), which is not defined in the same object file. So let's force the use of a non-conditional encoding of the B instruction, which has more space for an immediate offset. Cc: <stable@vger.kernel.org> Reported-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- arch/arm/vfp/vfphw.S | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S index 4fcff9f59947..f1468702fbc9 100644 --- a/arch/arm/vfp/vfphw.S +++ b/arch/arm/vfp/vfphw.S @@ -82,6 +82,7 @@ ENTRY(vfp_support_entry) ldr r3, [sp, #S_PSR] @ Neither lazy restore nor FP exceptions and r3, r3, #MODE_MASK @ are supported in kernel mode teq r3, #USR_MODE +THUMB( it ne ) bne vfp_kmode_exception @ Returns through lr VFPFMRX r1, FPEXC @ Is the VFP enabled?