From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938538AbeE1MC6 (ORCPT ); Mon, 28 May 2018 08:02:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:53460 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423295AbeE1LGj (ORCPT ); Mon, 28 May 2018 07:06:39 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Anshuman Khandual , Michael Ellerman , Sasha Levin Subject: [PATCH 4.16 062/272] powerpc/fscr: Enable interrupts earlier before calling get_user() Date: Mon, 28 May 2018 12:01:35 +0200 Message-Id: <20180528100246.089485193@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180528100240.256525891@linuxfoundation.org> References: <20180528100240.256525891@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Anshuman Khandual [ Upstream commit 709b973c844c0b4d115ac3a227a2e5a68722c912 ] The function get_user() can sleep while trying to fetch instruction from user address space and causes the following warning from the scheduler. BUG: sleeping function called from invalid context Though interrupts get enabled back but it happens bit later after get_user() is called. This change moves enabling these interrupts earlier covering the function get_user(). While at this, lets check for kernel mode and crash as this interrupt should not have been triggered from the kernel context. Signed-off-by: Anshuman Khandual Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/traps.c | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-) --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -1612,6 +1612,22 @@ void facility_unavailable_exception(stru value = mfspr(SPRN_FSCR); status = value >> 56; + if ((hv || status >= 2) && + (status < ARRAY_SIZE(facility_strings)) && + facility_strings[status]) + facility = facility_strings[status]; + + /* We should not have taken this interrupt in kernel */ + if (!user_mode(regs)) { + pr_emerg("Facility '%s' unavailable (%d) exception in kernel mode at %lx\n", + facility, status, regs->nip); + die("Unexpected facility unavailable exception", regs, SIGABRT); + } + + /* We restore the interrupt state now */ + if (!arch_irq_disabled_regs(regs)) + local_irq_enable(); + if (status == FSCR_DSCR_LG) { /* * User is accessing the DSCR register using the problem @@ -1678,25 +1694,11 @@ void facility_unavailable_exception(stru return; } - if ((hv || status >= 2) && - (status < ARRAY_SIZE(facility_strings)) && - facility_strings[status]) - facility = facility_strings[status]; - - /* We restore the interrupt state now */ - if (!arch_irq_disabled_regs(regs)) - local_irq_enable(); - pr_err_ratelimited("%sFacility '%s' unavailable (%d), exception at 0x%lx, MSR=%lx\n", hv ? "Hypervisor " : "", facility, status, regs->nip, regs->msr); out: - if (user_mode(regs)) { - _exception(SIGILL, regs, ILL_ILLOPC, regs->nip); - return; - } - - die("Unexpected facility unavailable exception", regs, SIGABRT); + _exception(SIGILL, regs, ILL_ILLOPC, regs->nip); } #endif