From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-x243.google.com (mail-pf0-x243.google.com [IPv6:2607:f8b0:400e:c00::243]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3y3VF63jstzDr8P for ; Fri, 29 Sep 2017 21:48:25 +1000 (AEST) Received: by mail-pf0-x243.google.com with SMTP id e69so1192252pfg.4 for ; Fri, 29 Sep 2017 04:48:25 -0700 (PDT) Message-ID: <1506685639.7352.0.camel@gmail.com> Subject: Re: [PATCH] powerpc/livepatch: Fix livepatch stack access From: Balbir Singh To: "Naveen N . Rao" , Kamalesh Babulal Cc: Michael Ellerman , linuxppc-dev@lists.ozlabs.org Date: Fri, 29 Sep 2017 21:47:19 +1000 In-Reply-To: <20170920111108.wptb7ifdbqk4ndvm@naverao1-tp.localdomain> References: <1505902791-26383-1-git-send-email-kamalesh@linux.vnet.ibm.com> <20170920111108.wptb7ifdbqk4ndvm@naverao1-tp.localdomain> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2017-09-20 at 16:41 +0530, Naveen N . Rao wrote: > On 2017/09/20 03:49PM, Kamalesh Babulal wrote: > > While running stress test with livepatch module loaded, kernel > > bug was triggered. > > > > cpu 0x5: Vector: 400 (Instruction Access) at [c0000000eb9d3b60] > > pc: c0000000eb9d3e30 > > lr: c0000000eb9d3e30 > > sp: c0000000eb9d3de0 > > msr: 800000001280b033 > > current = 0xc0000000dbd38700 > > paca = 0xc00000000fe01400 softe: 0 irq_happened: 0x01 > > pid = 8618, comm = make > > Linux version 4.13.0+ (root@ubuntu) (gcc version 6.3.0 20170406 (Ubuntu 6.3.0-12ubuntu2)) #1 SMP Wed Sep 13 03:49:27 EDT 2017 > > > > 5:mon> t > > [c0000000eb9d3de0] c0000000eb9d3e30 (unreliable) > > [c0000000eb9d3e30] c000000000008ab4 hardware_interrupt_common+0x114/0x120 > > --- Exception: 501 (Hardware Interrupt) at c000000000053040 livepatch_handler+0x4c/0x74 > > [c0000000eb9d4120] 0000000057ac6e9d (unreliable) > > [d0000000089d9f78] 2e0965747962382e > > SP (965747962342e09) is in userspace > > > > When an interrupt is served in between the livepatch_handler execution, > > there are chances of the livepatch_stack/task task getting corrupted. > > > > CPU 1 > > ============= > > Task A Interrupt Handler > > ========= ================= > > livepatch_handler: > > mr r0, r1 > > ld r1, TI_livepatch_sp(r12) > > hardware_interrupt_common > > |_do_IRQ > > |_ call_do_irq: > > mflr r0 > > std r0,16(r1) > > stdu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r4) > > ... > > lis r2, STACK_END_MAGIC@h > > ori r2, r2, STACK_END_MAGIC@l > > ld r12, -8(r1) <- livepatch stack is corrupted. > > > > Fix the corruption by using r11 register for livepatch stack manipulation, > > instead of shuffling task stack and livepatch stack into r1 register. > > Using r11 register also avoids disabling/enabling irq's while setting > > up the livepatch stack. > > > > Signed-off-by: Kamalesh Babulal > > Cc: Balbir Singh > > Cc: Naveen N. Rao > > Cc: linuxppc-dev@lists.ozlabs.org > > --- > > arch/powerpc/kernel/trace/ftrace_64_mprofile.S | 45 +++++++++----------------- > > 1 file changed, 15 insertions(+), 30 deletions(-) > > Reviewed-by: Naveen N. Rao Reviewed-by: Balbir Singh