Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754735AbaKYK6M (ORCPT ); Tue, 25 Nov 2014 05:58:12 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:59054 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754009AbaKYKnS (ORCPT ); Tue, 25 Nov 2014 05:43:18 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Nathan Lynch , Russell King , Luis Henriques Subject: [PATCH 3.16.y-ckt 208/254] ARM: 8198/1: make kuser helpers depend on MMU Date: Tue, 25 Nov 2014 10:39:18 +0000 Message-Id: <1416912004-5928-209-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1416912004-5928-1-git-send-email-luis.henriques@canonical.com> References: <1416912004-5928-1-git-send-email-luis.henriques@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt2 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Nathan Lynch commit 08b964ff3c51b10aaf2e6ba639f40054c09f0f7a upstream. The kuser helpers page is not set up on non-MMU systems, so it does not make sense to allow CONFIG_KUSER_HELPERS to be enabled when CONFIG_MMU=n. Allowing it to be set on !MMU results in an oops in set_tls (used in execve and the arm_syscall trap handler): Unhandled exception: IPSR = 00000005 LR = fffffff1 CPU: 0 PID: 1 Comm: swapper Not tainted 3.18.0-rc1-00041-ga30465a #216 task: 8b838000 ti: 8b82a000 task.ti: 8b82a000 PC is at flush_thread+0x32/0x40 LR is at flush_thread+0x21/0x40 pc : [<8f00157a>] lr : [<8f001569>] psr: 4100000b sp : 8b82be20 ip : 00000000 fp : 8b83c000 r10: 00000001 r9 : 88018c84 r8 : 8bb85000 r7 : 8b838000 r6 : 00000000 r5 : 8bb77400 r4 : 8b82a000 r3 : ffff0ff0 r2 : 8b82a000 r1 : 00000000 r0 : 88020354 xPSR: 4100000b CPU: 0 PID: 1 Comm: swapper Not tainted 3.18.0-rc1-00041-ga30465a #216 [<8f002bc1>] (unwind_backtrace) from [<8f002033>] (show_stack+0xb/0xc) [<8f002033>] (show_stack) from [<8f00265b>] (__invalid_entry+0x4b/0x4c) As best I can tell this issue existed for the set_tls ARM syscall before commit fbfb872f5f41 "ARM: 8148/1: flush TLS and thumbee register state during exec" consolidated the TLS manipulation code into the set_tls helper function, but now that we're using it to flush register state during execve, !MMU users encounter the oops at the first exec. Prevent CONFIG_MMU=n configurations from enabling CONFIG_KUSER_HELPERS. Fixes: fbfb872f5f41 (ARM: 8148/1: flush TLS and thumbee register state during exec) Signed-off-by: Nathan Lynch Reported-by: Stefan Agner Acked-by: Uwe Kleine-König Signed-off-by: Russell King Signed-off-by: Luis Henriques --- arch/arm/mm/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index c348eaee7ee2..b781cc7c7b6a 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -798,6 +798,7 @@ config NEED_KUSER_HELPERS config KUSER_HELPERS bool "Enable kuser helpers in vector page" if !NEED_KUSER_HELPERS + depends on MMU default y help Warning: disabling this option may break user programs. -- 2.1.0 -- 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/