From mboxrd@z Thu Jan 1 00:00:00 1970 From: Khalid Aziz Subject: [RFC PATCH v9 02/13] x86: always set IF before oopsing from page fault Date: Wed, 3 Apr 2019 11:34:03 -0600 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: In-Reply-To: References: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: juergh-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, tycho-E0fblnxP3wo@public.gmane.org, jsteckli-ebkRAfMGSJGzQB+pC5nmwQ@public.gmane.org, ak-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, liran.alon-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, keescook-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, konrad.wilk-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org Cc: catalin.marinas-5wv7dgnIgG8@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, khalid.aziz-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, steven.sistare-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, hch-jcswGhMUV9g@public.gmane.org, aneesh.kumar-tEXmvtCZX7AybS5Ee8rs3A@public.gmane.org, jmorris-gx6/JNMH7DfYtjvyW6yDsg@public.gmane.org, rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, anthony.yznaga-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, riel-ebMLmSuQjDVBDgjK7y7TUQ@public.gmane.org, npiggin-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, rppt-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org, jkosina-AlSwsSmVLrQ@public.gmane.org, rdunlap-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, jrdr.linux-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, joe-6d6DIl74uiNBDgjK7y7TUQ@public.gmane.org, arunks-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, dwmw-vV1OtcyAfmbQXOPxS62xeg@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, keith.busch-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, joao.m.martins-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org, brgl-ARrdPY/1zhM@public.gmane.org, jroedel-l3A5Bk7waGM@public.gmane.org, zhangshaokun-C8/M+/jPZTeaMJb+Lgu22Q@public.gmane.org, boris.ostrovsky-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, chris.hyser-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Khalid Aziz , aaron.lu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, steve.capper-5wv7dgnIgG8@public.gmane.org, james.morse-5wv7dgnIgG8@public.gmane.org, iamjoo List-Id: iommu@lists.linux-foundation.org From: Tycho Andersen Oopsing might kill the task, via rewind_stack_do_exit() at the bottom, and that might sleep: Aug 23 19:30:27 xpfo kernel: [ 38.302714] BUG: sleeping function called from invalid context at ./include/linux/percpu-rwsem.h:33 Aug 23 19:30:27 xpfo kernel: [ 38.303837] in_atomic(): 0, irqs_disabled(): 1, pid: 1970, name: lkdtm_xpfo_test Aug 23 19:30:27 xpfo kernel: [ 38.304758] CPU: 3 PID: 1970 Comm: lkdtm_xpfo_test Tainted: G D 4.13.0-rc5+ #228 Aug 23 19:30:27 xpfo kernel: [ 38.305813] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-1ubuntu1 04/01/2014 Aug 23 19:30:27 xpfo kernel: [ 38.306926] Call Trace: Aug 23 19:30:27 xpfo kernel: [ 38.307243] dump_stack+0x63/0x8b Aug 23 19:30:27 xpfo kernel: [ 38.307665] ___might_sleep+0xec/0x110 Aug 23 19:30:27 xpfo kernel: [ 38.308139] __might_sleep+0x45/0x80 Aug 23 19:30:27 xpfo kernel: [ 38.308593] exit_signals+0x21/0x1c0 Aug 23 19:30:27 xpfo kernel: [ 38.309046] ? blocking_notifier_call_chain+0x11/0x20 Aug 23 19:30:27 xpfo kernel: [ 38.309677] do_exit+0x98/0xbf0 Aug 23 19:30:27 xpfo kernel: [ 38.310078] ? smp_reader+0x27/0x40 [lkdtm] Aug 23 19:30:27 xpfo kernel: [ 38.310604] ? kthread+0x10f/0x150 Aug 23 19:30:27 xpfo kernel: [ 38.311045] ? read_user_with_flags+0x60/0x60 [lkdtm] Aug 23 19:30:27 xpfo kernel: [ 38.311680] rewind_stack_do_exit+0x17/0x20 To be safe, let's just always enable irqs. The particular case I'm hitting is: Aug 23 19:30:27 xpfo kernel: [ 38.278615] __bad_area_nosemaphore+0x1a9/0x1d0 Aug 23 19:30:27 xpfo kernel: [ 38.278617] bad_area_nosemaphore+0xf/0x20 Aug 23 19:30:27 xpfo kernel: [ 38.278618] __do_page_fault+0xd1/0x540 Aug 23 19:30:27 xpfo kernel: [ 38.278620] ? irq_work_queue+0x9b/0xb0 Aug 23 19:30:27 xpfo kernel: [ 38.278623] ? wake_up_klogd+0x36/0x40 Aug 23 19:30:27 xpfo kernel: [ 38.278624] trace_do_page_fault+0x3c/0xf0 Aug 23 19:30:27 xpfo kernel: [ 38.278625] do_async_page_fault+0x14/0x60 Aug 23 19:30:27 xpfo kernel: [ 38.278627] async_page_fault+0x28/0x30 When a fault is in kernel space which has been triggered by XPFO. Signed-off-by: Tycho Andersen CC: x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org Tested-by: Khalid Aziz Cc: Khalid Aziz --- arch/x86/mm/fault.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 9d5c75f02295..7891add0913f 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -858,6 +858,12 @@ no_context(struct pt_regs *regs, unsigned long error_code, /* Executive summary in case the body of the oops scrolled away */ printk(KERN_DEFAULT "CR2: %016lx\n", address); + /* + * We're about to oops, which might kill the task. Make sure we're + * allowed to sleep. + */ + flags |= X86_EFLAGS_IF; + oops_end(flags, regs, sig); } -- 2.17.1