| Message ID | 1466432741-24452-1-git-send-email-sudeep.holla@arm.com |
|---|---|
| State | Accepted |
| Commit | b1149ad917b7808ba0023fd80a6631f10b1a14f2 |
| Headers | show |
On 21 June 2016 at 11:32, Sudeep Holla <sudeep.holla@arm.com> wrote: > > > On 21/06/16 18:05, Mathieu Poirier wrote: >> >> On 20 June 2016 at 08:25, Sudeep Holla <sudeep.holla@arm.com> wrote: >>> >>> etm4_trace_id is not guaranteed to be executed on the CPU whose ETM is >>> being accessed. This leads to exception similar to below one if the >>> CPU whose ETM is being accessed is in deeper idle states. So it must >>> be executed on the CPU whose ETM is being accessed. >>> >>> Unhandled fault: synchronous external abort (0x96000210) at >>> 0xffff000008db4040 >>> Internal error: : 96000210 [#1] PREEMPT SMP >>> Modules linked in: >>> CPU: 5 PID: 5979 Comm: etm.sh Not tainted 4.7.0-rc3 #159 >>> Hardware name: ARM Juno development board (r2) (DT) >>> task: ffff80096dd34b00 ti: ffff80096dfe4000 task.ti: ffff80096dfe4000 >>> PC is at etm4_trace_id+0x5c/0x90 >>> LR is at etm4_trace_id+0x3c/0x90 >>> Call trace: >>> etm4_trace_id+0x5c/0x90 >>> coresight_id_match+0x78/0xa8 >>> bus_for_each_dev+0x60/0xa0 >>> coresight_enable+0xc0/0x1b8 >>> enable_source_store+0x3c/0x70 >>> dev_attr_store+0x18/0x28 >>> sysfs_kf_write+0x48/0x58 >>> kernfs_fop_write+0x14c/0x1e0 >>> __vfs_write+0x1c/0x100 >>> vfs_write+0xa0/0x1b8 >>> SyS_write+0x44/0xa0 >>> el0_svc_naked+0x24/0x28 >>> >>> However, TRCTRACEIDR is not guaranteed to hold the previous programmed >>> trace id if it enters deeper idle states. Further, the trace id that is >>> computed in etm4_init_trace_id is programmed into TRCTRACEIDR only in >>> etm4_enable_hw which happens much later in the sequence after >>> coresight_id_match is executed from enable_source_store. >>> >>> This patch simplifies etm4_trace_id by returning the stashed trace id >>> value similar to etm4_cpu_id. >>> >>> Cc: Mathieu Poirier <mathieu.poirier@linaro.org> >>> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> >>> --- >>> drivers/hwtracing/coresight/coresight-etm4x.c | 16 +--------------- >>> 1 file changed, 1 insertion(+), 15 deletions(-) >>> >>> Hi Mathieu, >>> >>> While trying to support ETM with CPUIdle active, I faced this issue. >>> >>> Regards, >>> Sudeep >>> >>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c >>> b/drivers/hwtracing/coresight/coresight-etm4x.c >>> index 43fa3beaa0df..d6f1d6d874eb 100644 >>> --- a/drivers/hwtracing/coresight/coresight-etm4x.c >>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.c >>> @@ -77,22 +77,8 @@ static int etm4_cpu_id(struct coresight_device *csdev) >>> static int etm4_trace_id(struct coresight_device *csdev) >>> { >>> struct etmv4_drvdata *drvdata = >>> dev_get_drvdata(csdev->dev.parent); >>> - unsigned long flags; >>> - int trace_id = -1; >>> >>> - if (!local_read(&drvdata->mode)) >>> - return drvdata->trcid; >>> - >>> - spin_lock_irqsave(&drvdata->spinlock, flags); >>> - >>> - CS_UNLOCK(drvdata->base); >>> - trace_id = readl_relaxed(drvdata->base + TRCTRACEIDR); >>> - trace_id &= ETM_TRACEID_MASK; >>> - CS_LOCK(drvdata->base); >>> - >>> - spin_unlock_irqrestore(&drvdata->spinlock, flags); >>> - >>> - return trace_id; >>> + return drvdata->trcid; >>> } >> >> >> This code was written prior to the integration with the Perf core. To >> make sure the correct active value was return to users it goes to the >> HW if the IP is in use. With the integration with Perf the code was >> moved around and the traceID is no longer called on the CPU (as you >> noticed) and has lost the required PM runtime operation. >> > > Is the perf integration already queued ? If not, it good to have this > until then. I see crashes if I disable idle on one core and enable ETM > source on that. Yes, the patches are part of the 4.7 cycle. > > With this I don't see any crashes even if we have CPUIdle enabled. > However the trace collection halts once the core suspends and resumes > back. I have a simple solution for handling CPUIdle too, will post it soon. I am quite sure you'll be seeing a lot of crashes/weird things happening with CPUidle enabled. I never had the opportunity to test with PM runtime, even less with CPUidle. (For those who might be wondering why, this is because the FW never supported it, something Sudeep is currently fixing.) > > -- > Regards, > Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c index 43fa3beaa0df..d6f1d6d874eb 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x.c +++ b/drivers/hwtracing/coresight/coresight-etm4x.c @@ -77,22 +77,8 @@ static int etm4_cpu_id(struct coresight_device *csdev) static int etm4_trace_id(struct coresight_device *csdev) { struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); - unsigned long flags; - int trace_id = -1; - if (!local_read(&drvdata->mode)) - return drvdata->trcid; - - spin_lock_irqsave(&drvdata->spinlock, flags); - - CS_UNLOCK(drvdata->base); - trace_id = readl_relaxed(drvdata->base + TRCTRACEIDR); - trace_id &= ETM_TRACEID_MASK; - CS_LOCK(drvdata->base); - - spin_unlock_irqrestore(&drvdata->spinlock, flags); - - return trace_id; + return drvdata->trcid; } static void etm4_enable_hw(void *info)
etm4_trace_id is not guaranteed to be executed on the CPU whose ETM is being accessed. This leads to exception similar to below one if the CPU whose ETM is being accessed is in deeper idle states. So it must be executed on the CPU whose ETM is being accessed. Unhandled fault: synchronous external abort (0x96000210) at 0xffff000008db4040 Internal error: : 96000210 [#1] PREEMPT SMP Modules linked in: CPU: 5 PID: 5979 Comm: etm.sh Not tainted 4.7.0-rc3 #159 Hardware name: ARM Juno development board (r2) (DT) task: ffff80096dd34b00 ti: ffff80096dfe4000 task.ti: ffff80096dfe4000 PC is at etm4_trace_id+0x5c/0x90 LR is at etm4_trace_id+0x3c/0x90 Call trace: etm4_trace_id+0x5c/0x90 coresight_id_match+0x78/0xa8 bus_for_each_dev+0x60/0xa0 coresight_enable+0xc0/0x1b8 enable_source_store+0x3c/0x70 dev_attr_store+0x18/0x28 sysfs_kf_write+0x48/0x58 kernfs_fop_write+0x14c/0x1e0 __vfs_write+0x1c/0x100 vfs_write+0xa0/0x1b8 SyS_write+0x44/0xa0 el0_svc_naked+0x24/0x28 However, TRCTRACEIDR is not guaranteed to hold the previous programmed trace id if it enters deeper idle states. Further, the trace id that is computed in etm4_init_trace_id is programmed into TRCTRACEIDR only in etm4_enable_hw which happens much later in the sequence after coresight_id_match is executed from enable_source_store. This patch simplifies etm4_trace_id by returning the stashed trace id value similar to etm4_cpu_id. Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> --- drivers/hwtracing/coresight/coresight-etm4x.c | 16 +--------------- 1 file changed, 1 insertion(+), 15 deletions(-) Hi Mathieu, While trying to support ETM with CPUIdle active, I faced this issue. Regards, Sudeep -- 2.7.4 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel