From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752630AbcBOI6h (ORCPT ); Mon, 15 Feb 2016 03:58:37 -0500 Received: from mailout1.samsung.com ([203.254.224.24]:39437 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752333AbcBOI6e (ORCPT ); Mon, 15 Feb 2016 03:58:34 -0500 X-AuditID: cbfee68e-f793c6d00000136c-73-56c19338f4d0 Date: Mon, 15 Feb 2016 08:58:32 +0000 (GMT) From: EunTaik Lee Subject: [PATCH RESEND] arm64: add alignment fault hanling To: catalin.marinas@arm.com, will.deacon@arm.com, vladimir.murzin@arm.com, suzuki.poulose@arm.com, riandrews@android.com, james.morse@arm.com, salyzyn@android.com, eun.taik.lee@samsung.com, Dave.Martin@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Reply-to: eun.taik.lee@samsung.com MIME-version: 1.0 X-MTR: 20160215085337348@eun.taik.lee Msgkey: 20160215085337348@eun.taik.lee X-EPLocale: ko_KR.euc-kr X-Priority: 3 X-EPWebmail-Msg-Type: personal X-EPWebmail-Reply-Demand: 0 X-EPApproval-Locale: X-EPHeader: ML X-MLAttribute: X-RootMTR: 20160215084603773@eun.taik.lee X-ParentMTR: 20160215084855965@eun.taik.lee X-ArchiveUser: EV X-CPGSPASS: Y X-ConfirmMail: N,general Content-type: text/plain; charset=euc-kr MIME-version: 1.0 Message-id: <2039801453.916991455526707908.JavaMail.weblogic@epmlwas09b> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprDJsWRmVeSWpSXmKPExsVy+t8zTV2LyQfDDPonKltc3jWHzYHR4/Mm uQDGqAZGm8Si5IzMslSF1Lzk/JTMvHRbpdAQN10LJYWM/OISW6VoIwNjPSNTEz0jE3M9S4NY KyNTJYW8xNxUW6UKXaheJYWi5AKg2tzKYqABOal6UHG94tS8FIes/FKQS/SKE3OLS/PS9ZLz c5UUyhJzSoFGKOknTGXMeHR+FUtBk1jFp707mRsYt4h2MXJyCAmoS5zYvYYFxJYQMJHoeNzM DmGLSVy4t56ti5ELqGYZo8SiX+3MMEV3nuxjgkjMYZSY07qVDSTBIqAqceTeKiYQm01AV+L/ xy6wScICVhJfpu5gBmkQEXjAJPGs+QorxGolifmHG8BW8woISpyc+QTI5gDaoCrRfJwDIqwm MaejkRVisYTErOkXoGxeiRntT6GulpOY9nUN1HHSEudnbWCE+WDx98dQcX6JY7d3MEHYAhJT zxyEqtGSONvzEsrWkTjyaAsbhC0ocfpaNzPMroaNv9lhbtja8gTsBmYBRYkp3Q/ZIWwtiS8/ 9rGhegXE9pDoav0BDiwJgU4OiVOrIA5lATri2+RDLBMYFWch6ZmFZO4sJHOR1SxgZFnFKJpa kFxQnJReZIQc35sYIcmwbwfjzQPWhxgFOBiVeHgjzhwIE2JNLCuuzD3EmAy0eiKzlGhyPjDl 5pXEGxqbGVmYmpgaG5lbmmEIm5haWJgY4RBWEudNkPoZLCSQnliSmp2aWpBaFF9UmpNafIiR iYNTqoFxulGH1E/P21UaKdkB221TuW2DDLtYbu5OTaw9l7G7dfVlJf7FSstiA+cnbrsUV9RU uuNaxcM5c7I+GJo/Z677KRZ/wGOieqfmgd8Jk2Pb8me91bdgldn7n821fkemkD9b5wTnsobz MgGRKc5vql1Ludez7p/hKuGTtyxSdnll9JkN8Teu7ldiKc5INNRiLipOBAC0Cz4trwMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrLKsWRmVeSWpSXmKPExsVy+t/tXl2LyQfDDPbelbe4vGsOmwOjx+dN cgGMURk2GamJKalFCql5yfkpmXnptkrewfHO8aZmBoa6hpYW5koKeYm5qbZKLj4Bum6ZOUBD lRTKEnNKgUIBicXFSvp2NkX5pSWpChn5xSW2StFGBsZ6RqYmekbGBnomBrFWhgYGRqZAVQkZ GY/Or2IpaBKr+LR3J3MD4xbRLkZODiEBdYkTu9ewgNgSAiYSd57sY4KwxSQu3FvP1sXIBVQz h1FiTutWNpAEi4CqxJF7q8CK2AR0Jf5/7GIHsYUFrCS+TN3BDNIgIvCASeJZ8xVWiA1KEvMP N4Bt4BUQlDg58wmQzQG0QVWi+TgHRFhNYk5HIyvEYgmJWdMvQNm8EjPan0IdJycx7esaZghb WuL8rA2MMIcu/v4YKs4vcez2DqgHBCSmnjkIVaMlcbbnJZStI3Hk0RY2CFtQ4vS1bmaYXQ0b f7PD3LC15QnYDcwCihJTuh+yQ9haEl9+7GND9QqI7SHR1fqDaQKjzCwkqVlI2mchaUdWs4CR ZRWjaGpBckFxUnqFoV5xYm5xaV66XnJ+7iZGcNJ5tnAH45fz1ocYBTgYlXh4I84cCBNiTSwr rsw9xCjBwawkwvus9WCYEG9KYmVValF+fFFpTmrxIUZTYExNZJYSTc4HJsS8knhDYwNjQ0NL cwNTQyMLJXHegL/rwoQE0hNLUrNTUwtSi2D6mDg4pRoYE1/5Gs84HPWw48quI76ihnemKFRs ijkSntC7oTOk9GY4p0vzV66SpUtZX4kbCUZFPDyxT+zyk5y7Qcpe7pN9vx7Relyl9Pn/5STr xX+rfzfGMFwqVAlrmXs60f2b6mKbTV/y/7h45x39KOKWrcaavXWB8pVywTyxOxP2TNRZ8vqy gGvG5Gf7lFiKMxINtZiLihMB4Dqru1ADAAA= DLP-Filter: Pass X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id u1F8wmjN013825 Userspace memory is mapped as below: F2A7F000--F2A7FFFF Normal Memory F2A80000--F2A80FFF Device nGnRnE And that userspace application makes a system call as below: -009 |do_strncpy_from_user(inline) -009 |strncpy_from_user() -010 |getname_flags() -011 |user_path_at_empty() -012 |user_path_at() -013 |SYSC_faccessat(inline) -013 |sys_faccessat() -014 |__sys_trace(asm) --> |exception The string spans from 0xF2A7FFC1 to 0xF2A7FFFB. When do_strncpy_from_user() reads the last (unsigned long) value, the alignement fault is triggered. The 8 byte from 0xF2A7FFC1 spans to the next page that is mapped as Device nGnRnE, which does not allow an unaligned access, causes the abort. The instruction which caused the alignment fault is registered in the fixup table but the exception handler does not reach there. This patch registers a alignment fault handler and fixes up the pc if appropriate. Signed-off-by: Eun Taik Lee --- arch/arm64/mm/fault.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 19211c4..8257d4f 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -371,6 +371,16 @@ static int __kprobes do_translation_fault(unsigned long addr, return 0; } +static int __kprobes do_alignment_fault(unsigned long addr, + unsigned int esr, + struct pt_regs *regs) +{ + if (addr >= TASK_SIZE && fixup_exception(regs)) + return 0; + + return 1; +} + /* * This abort handler always returns "fault". */ @@ -418,7 +428,7 @@ static struct fault_info { { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" }, { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" }, { do_bad, SIGBUS, 0, "unknown 32" }, - { do_bad, SIGBUS, BUS_ADRALN, "alignment fault" }, + { do_alignment_fault, SIGBUS, BUS_ADRALN, "alignment fault" }, { do_bad, SIGBUS, 0, "debug event" }, { do_bad, SIGBUS, 0, "unknown 35" }, { do_bad, SIGBUS, 0, "unknown 36" }, -- 1.9.1