Message-ID: <e9c299c4-caeb-9eb8-f019-b311bfce756a@arm.com>
Date:   Tue, 7 Apr 2020 15:53:11 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     saiprakash.ranjan@...eaurora.org
Cc:     mike.leach@...aro.org, mathieu.poirier@...aro.org,
        leo.yan@...aro.org, alexander.shishkin@...ux.intel.com,
        swboyd@...omium.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [RFC PATCH] coresight: dynamic-replicator: Fix handling of
 multiple connections

On 04/07/2020 02:56 PM, Sai Prakash Ranjan wrote:
> Hi Suzuki,
> 
> On 2020-04-07 18:38, Suzuki K Poulose wrote:
>> On 04/07/2020 12:29 PM, Sai Prakash Ranjan wrote:
>>> Hi Suzuki,
>>>
>>> Thanks for looking into this issue.
>>>
>>> On 2020-04-07 15:54, Suzuki K Poulose wrote:
>>>> On 04/07/2020 10:46 AM, Sai Prakash Ranjan wrote:
>>>>
>>>> There seems to be two replicators back to back here. What is connected
>>>> to the other output of both of them ? Are there any TPIUs ? What 
>>>> happens
>>>> if you choose a sink on the other end of "swao_replicator" (ETB ?)
>>>>
>>>
>>> The other outport of swao replicator is connected to EUD which is a
>>> QCOM specific HW which can be used as a sink like USB.
>>> And the other outport of other replicator(replicator_out) is 
>>> connected to
>>> TPIU.
>>>
>>>> After boot, what do the idfilter registers read for both the 
>>>> replicators ?
>>>>
>>>
>>> Added some prints in replicator_probe.
>>>
>>>   replicator probe ret=-517 devname=6046000.replicator idfilter0=0x0 
>>> idfilter1=0x0
>>>   replicator probe ret=0 devname=6b06000.replicator idfilter0=0xff 
>>> idfilter1=0xff
>>>   replicator probe ret=0 devname=6046000.replicator idfilter0=0xff 
>>> idfilter1=0xff
>>
>> Curious to see how the idfilterX is set to 0:
>>      if that is never used.
>>         Or
>>      if the user doesn't reset it back to 0xff.
>>
> 
> For both replicators, the default value seems to be 0x0.
> 
>   replicator probe in res ret=0 devname=6046000.replicator idfilter0=0x0 
> idfilter1=0x0
>   replicator probe ret=-517 devname=6046000.replicator idfilter0=0x0 
> idfilter1=0x0
>   replicator probe in res ret=0 devname=6b06000.replicator idfilter0=0x0 
> idfilter1=0x0
>   replicator probe ret=0 devname=6b06000.replicator idfilter0=0xff 
> idfilter1=0xff
>   replicator probe in res ret=0 devname=6046000.replicator idfilter0=0x0 
> idfilter1=0x0
>   replicator probe ret=0 devname=6046000.replicator idfilter0=0xff 
> idfilter1=0xff

I am not sure how you have added the debugs, but it looks like the
drivers set 0xff for both the port filters on a successful probe.

> 
>> Does your test ever touch EUD (enable the port for EUD at
>> swao-replicator) ? What are the values before you run your test ?
>>
>>
> 
> No, we do not use EUD, downstream it is used as dummy sink.
> And I just try to select the ETR as the sink and enable ETM0 as the 
> trace source.
> 
> echo 1 > /sys/bus/coresight/devices/tmc_etr0/enable_sink
> echo 1 > /sys/bus/coresight/devices/etm0/enable_source
> 
> Also I see the KASAN warning but that seems like some other issue.
> 

Does your funnel have sparse input described ? I think we have an
issue with the "refcnt" tracking for funnels (especially). When we
have a sparse input ports described (ie. if only input ports 0, 3,
5 are described to protect the secure side connections), we could
end up accessing beyond the memory allocated for csdev->refcnts.
i.e, csdev->pdata->nr_inport = 3, and we could access csdev->refcnts[5],
while sizeof(csdev->refcnts) = sizeof(atomic_t) * 3.

I will send a patch.


> [  526.110401] 
> ==================================================================
> [  526.117988] BUG: KASAN: slab-out-of-bounds in funnel_enable+0x54/0x1b0
> [  526.124706] Read of size 4 at addr ffffff8135f9549c by task bash/1114
> [  526.131324]
> [  526.132886] CPU: 3 PID: 1114 Comm: bash Tainted: G S 5.4.25 #232
> [  526.140397] Hardware name: Qualcomm Technologies, Inc. SC7180 IDP (DT)
> [  526.147113] Call trace:
> [  526.149653]  dump_backtrace+0x0/0x188
> [  526.153431]  show_stack+0x20/0x2c
> [  526.156852]  dump_stack+0xdc/0x144
> [  526.160370]  print_address_description+0x3c/0x494
> [  526.165211]  __kasan_report+0x144/0x168
> [  526.169170]  kasan_report+0x10/0x18
> [  526.172769]  check_memory_region+0x1a4/0x1b4
> [  526.177164]  __kasan_check_read+0x18/0x24
> [  526.181292]  funnel_enable+0x54/0x1b0
> [  526.185072]  coresight_enable_path+0x104/0x198
> [  526.189649]  coresight_enable+0x118/0x26c
> [  526.193778]  enable_source_store+0x64/0xa8
> [  526.198007]  dev_attr_store+0x40/0x58
> [  526.201788]  sysfs_kf_write+0x4c/0x64
> [  526.205567]  kernfs_fop_write+0x16c/0x210
> [  526.209700]  __vfs_write+0x54/0x1a8
> [  526.213297]  vfs_write+0xe4/0x1a4
> [  526.216714]  ksys_write+0x84/0xec
> [  526.220131]  __arm64_sys_write+0x20/0x2c
> [  526.224179]  el0_svc_common+0xa8/0x160
> [  526.228040]  el0_svc_compat_handler+0x2c/0x38
> [  526.232533]  el0_svc_compat+0x8/0x10
> [  526.236225]
> [  526.237782] Allocated by task 280:
> [  526.241298]  __kasan_kmalloc+0xf0/0x1ac
> [  526.245249]  kasan_kmalloc+0xc/0x14
> [  526.248849]  __kmalloc+0x28c/0x3b4
> [  526.252361]  coresight_register+0x88/0x250
> [  526.256587]  funnel_probe+0x15c/0x228
> [  526.260365]  dynamic_funnel_probe+0x20/0x2c
> [  526.264679]  amba_probe+0xbc/0x158
> [  526.268193]  really_probe+0x144/0x408
> [  526.271970]  driver_probe_device+0x70/0x140
> [  526.276282]  __device_attach_driver+0x9c/0x110
> [  526.280861]  bus_for_each_drv+0x90/0xd8
> [  526.284822]  __device_attach+0xb4/0x164
> [  526.288772]  device_initial_probe+0x20/0x2c
> [  526.293081]  bus_probe_device+0x34/0x94
> [  526.297030]  deferred_probe_work_func+0xa4/0x100
> [  526.301794]  process_one_work+0x33c/0x640
> [  526.305922]  worker_thread+0x2a0/0x470
> [  526.309786]  kthread+0x128/0x138
> [  526.313119]  ret_from_fork+0x10/0x18
> [  526.316810]
> [  526.318364] Freed by task 0:
> [  526.321344] (stack is not available)
> [  526.325024]
> [  526.326580] The buggy address belongs to the object at ffffff8135f95480
> [  526.326580]  which belongs to the cache kmalloc-128 of size 128
> [  526.339439] The buggy address is located 28 bytes inside of
> [  526.339439]  128-byte region [ffffff8135f95480, ffffff8135f95500)
> [  526.351399] The buggy address belongs to the page:
> [  526.356342] page:ffffffff04b7e500 refcount:1 mapcount:0 
> mapping:ffffff814b00c380 index:0x0 compound_mapcount: 0
> [  526.366711] flags: 0x4000000000010200(slab|head)
> [  526.371475] raw: 4000000000010200 ffffffff05034008 ffffffff0501eb08 
> ffffff814b00c380
> [  526.379435] raw: 0000000000000000 0000000000190019 00000001ffffffff 
> 0000000000000000
> [  526.387393] page dumped because: kasan: bad access detected
> [  526.393128]
> [  526.394681] Memory state around the buggy address:
> [  526.399619]  ffffff8135f95380: fc fc fc fc fc fc fc fc fc fc fc fc fc 
> fc fc fc
> [  526.407046]  ffffff8135f95400: fc fc fc fc fc fc fc fc fc fc fc fc fc 
> fc fc fc
> [  526.414473] >ffffff8135f95480: 04 fc fc fc fc fc fc fc fc fc fc fc fc 
> fc fc fc
> [  526.421900]                             ^
> [  526.426029]  ffffff8135f95500: fc fc fc fc fc fc fc fc fc fc fc fc fc 
> fc fc fc
> [  526.433456]  ffffff8135f95580: fc fc fc fc fc fc fc fc fc fc fc fc fc 
> fc fc fc
> [  526.440883] 
> ==================================================================
> 
> Thanks,
> Sai
> 

Suzuki

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