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Fri, 06 Mar 2020 20:16:49 +0000 Received: from b01ledav002.gho.pok.ibm.com (b01ledav002.gho.pok.ibm.com [9.57.199.107]) by b01cxnp22033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 026KGnHP46137758 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 6 Mar 2020 20:16:49 GMT Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1EF7D124053; Fri, 6 Mar 2020 20:16:49 +0000 (GMT) Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5344C124052; Fri, 6 Mar 2020 20:16:48 +0000 (GMT) Received: from [9.70.82.143] (unknown [9.70.82.143]) by b01ledav002.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 6 Mar 2020 20:16:48 +0000 (GMT) Subject: [PATCH V7 09/14] powerpc/vas: Update CSB and notify process for fault CRBs From: Haren Myneni To: mpe@ellerman.id.au In-Reply-To: <1583525239.9256.5.camel@hbabu-laptop> References: <1583525239.9256.5.camel@hbabu-laptop> Content-Type: text/plain; charset="UTF-8" Date: Fri, 06 Mar 2020 12:16:45 -0800 Message-ID: <1583525805.9256.14.camel@hbabu-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.572 definitions=2020-03-06_07:2020-03-06, 2020-03-06 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 spamscore=0 malwarescore=0 priorityscore=1501 mlxscore=0 adultscore=0 lowpriorityscore=0 suspectscore=1 impostorscore=0 clxscore=1015 bulkscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2003060121 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mikey@neuling.org, herbert@gondor.apana.org.au, npiggin@gmail.com, hch@infradead.org, oohall@gmail.com, sukadev@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, ajd@linux.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" For each fault CRB, update fault address in CRB (fault_storage_addr) and translation error status in CSB so that user space can touch the fault address and resend the request. If the user space passed invalid CSB address send signal to process with SIGSEGV. Signed-off-by: Sukadev Bhattiprolu Signed-off-by: Haren Myneni --- arch/powerpc/platforms/powernv/vas-fault.c | 114 +++++++++++++++++++++++++++++ 1 file changed, 114 insertions(+) diff --git a/arch/powerpc/platforms/powernv/vas-fault.c b/arch/powerpc/platforms/powernv/vas-fault.c index 1c6d5cc..751ce48 100644 --- a/arch/powerpc/platforms/powernv/vas-fault.c +++ b/arch/powerpc/platforms/powernv/vas-fault.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include @@ -26,6 +27,118 @@ #define VAS_FAULT_WIN_FIFO_SIZE (4 << 20) /* + * Update the CSB to indicate a translation error. + * + * If we are unable to update the CSB means copy_to_user failed due to + * invalid csb_addr, send a signal to the process. + * + * Remaining settings in the CSB are based on wait_for_csb() of + * NX-GZIP. + */ +static void update_csb(struct vas_window *window, + struct coprocessor_request_block *crb) +{ + int rc; + struct pid *pid; + void __user *csb_addr; + struct task_struct *tsk; + struct kernel_siginfo info; + struct coprocessor_status_block csb; + + /* + * NX user space windows can not be opened for task->mm=NULL + * and faults will not be generated for kernel requests. + */ + if (!window->mm || !window->user_win) + return; + + csb_addr = (void __user *)be64_to_cpu(crb->csb_addr); + + csb.cc = CSB_CC_TRANSLATION; + csb.ce = CSB_CE_TERMINATION; + csb.cs = 0; + csb.count = 0; + + /* + * NX operates and returns in BE format as defined CRB struct. + * So return fault_storage_addr in BE as NX pastes in FIFO and + * expects user space to convert to CPU format. + */ + csb.address = crb->stamp.nx.fault_storage_addr; + csb.flags = 0; + + pid = window->pid; + tsk = get_pid_task(pid, PIDTYPE_PID); + /* + * Send window will be closed after processing all NX requests + * and process exits after closing all windows. In multi-thread + * applications, thread may not exists, but does not close FD + * (means send window) upon exit. Parent thread (tgid) can use + * and close the window later. + * pid and mm references are taken when window is opened by + * process (pid). So tgid is used only when child thread opens + * a window and exits without closing it in multithread tasks. + */ + if (!tsk) { + pid = window->tgid; + tsk = get_pid_task(pid, PIDTYPE_PID); + /* + * Parent thread will be closing window during its exit. + * So should not get here. + */ + if (!tsk) + return; + } + + /* Return if the task is exiting. */ + if (tsk->flags & PF_EXITING) { + put_task_struct(tsk); + return; + } + + use_mm(window->mm); + rc = copy_to_user(csb_addr, &csb, sizeof(csb)); + /* + * User space polls on csb.flags (first byte). So add barrier + * then copy first byte with csb flags update. + */ + smp_mb(); + if (!rc) { + csb.flags = CSB_V; + rc = copy_to_user(csb_addr, &csb, sizeof(u8)); + } + unuse_mm(window->mm); + put_task_struct(tsk); + + /* Success */ + if (!rc) + return; + + pr_debug("Invalid CSB address 0x%p signalling pid(%d)\n", + csb_addr, pid_vnr(pid)); + + clear_siginfo(&info); + info.si_signo = SIGSEGV; + info.si_errno = EFAULT; + info.si_code = SEGV_MAPERR; + info.si_addr = csb_addr; + + /* + * process will be polling on csb.flags after request is sent to + * NX. So generally CSB update should not fail except when an + * application does not follow the process properly. So an error + * message will be displayed and leave it to user space whether + * to ignore or handle this signal. + */ + rcu_read_lock(); + rc = kill_pid_info(SIGSEGV, &info, pid); + rcu_read_unlock(); + + pr_devel("%s(): pid %d kill_proc_info() rc %d\n", __func__, + pid_vnr(pid), rc); +} + +/* * Process valid CRBs in fault FIFO. */ irqreturn_t vas_fault_thread_fn(int irq, void *data) @@ -111,6 +224,7 @@ irqreturn_t vas_fault_thread_fn(int irq, void *data) return IRQ_HANDLED; } + update_csb(window, crb); } while (true); } -- 1.8.3.1