Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755060AbcD0ARy (ORCPT ); Tue, 26 Apr 2016 20:17:54 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:40076 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753960AbcDZXN4 (ORCPT ); Tue, 26 Apr 2016 19:13:56 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Helge Deller" Date: Wed, 27 Apr 2016 01:02:21 +0200 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 178/217] parisc: Unbreak handling exceptions from kernel modules In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8426:ae4:c500:9cba:69ae:962d:6167 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2753 Lines: 87 3.16.35-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Helge Deller commit 2ef4dfd9d9f288943e249b78365a69e3ea3ec072 upstream. Handling exceptions from modules never worked on parisc. It was just masked by the fact that exceptions from modules don't happen during normal use. When a module triggers an exception in get_user() we need to load the main kernel dp value before accessing the exception_data structure, and afterwards restore the original dp value of the module on exit. Noticed-by: Mikulas Patocka Signed-off-by: Helge Deller [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- arch/parisc/include/asm/uaccess.h | 1 + arch/parisc/kernel/asm-offsets.c | 1 + arch/parisc/lib/fixup.S | 6 ++++++ arch/parisc/mm/fault.c | 1 + 4 files changed, 9 insertions(+) --- a/arch/parisc/include/asm/uaccess.h +++ b/arch/parisc/include/asm/uaccess.h @@ -79,6 +79,7 @@ struct exception_table_entry { */ struct exception_data { unsigned long fault_ip; + unsigned long fault_gp; unsigned long fault_space; unsigned long fault_addr; }; --- a/arch/parisc/kernel/asm-offsets.c +++ b/arch/parisc/kernel/asm-offsets.c @@ -292,6 +292,7 @@ int main(void) DEFINE(ASM_PT_INITIAL, PT_INITIAL); BLANK(); DEFINE(EXCDATA_IP, offsetof(struct exception_data, fault_ip)); + DEFINE(EXCDATA_GP, offsetof(struct exception_data, fault_gp)); DEFINE(EXCDATA_SPACE, offsetof(struct exception_data, fault_space)); DEFINE(EXCDATA_ADDR, offsetof(struct exception_data, fault_addr)); BLANK(); --- a/arch/parisc/lib/fixup.S +++ b/arch/parisc/lib/fixup.S @@ -26,6 +26,7 @@ #ifdef CONFIG_SMP .macro get_fault_ip t1 t2 + loadgp addil LT%__per_cpu_offset,%r27 LDREG RT%__per_cpu_offset(%r1),\t1 /* t2 = smp_processor_id() */ @@ -40,14 +41,19 @@ LDREG RT%exception_data(%r1),\t1 /* t1 = &__get_cpu_var(exception_data) */ add,l \t1,\t2,\t1 + /* %r27 = t1->fault_gp - restore gp */ + LDREG EXCDATA_GP(\t1), %r27 /* t1 = t1->fault_ip */ LDREG EXCDATA_IP(\t1), \t1 .endm #else .macro get_fault_ip t1 t2 + loadgp /* t1 = &__get_cpu_var(exception_data) */ addil LT%exception_data,%r27 LDREG RT%exception_data(%r1),\t2 + /* %r27 = t2->fault_gp - restore gp */ + LDREG EXCDATA_GP(\t2), %r27 /* t1 = t2->fault_ip */ LDREG EXCDATA_IP(\t2), \t1 .endm --- a/arch/parisc/mm/fault.c +++ b/arch/parisc/mm/fault.c @@ -151,6 +151,7 @@ int fixup_exception(struct pt_regs *regs struct exception_data *d; d = this_cpu_ptr(&exception_data); d->fault_ip = regs->iaoq[0]; + d->fault_gp = regs->gr[27]; d->fault_space = regs->isr; d->fault_addr = regs->ior;