• Suzuki K Poulose's avatar
    coresight: Fix erroneous memset in tmc_read_unprepare_etr · f3b8172f
    Suzuki K Poulose authored
    At the end of a trace collection, we try to clear the entire buffer
    and enable the ETR back if it was already enabled. But, we would have
    adjusted the drvdata->buf to point to the beginning of the trace data
    in the trace buffer @drvdata->vaddr. So, the following code which
    clears the buffer is dangerous and can cause crashes, like below :
    
    	memset(drvdata->buf, 0, drvdata->size);
    
     Unable to handle kernel paging request at virtual address ffffff800a145000
     pgd = ffffffc974726000
     *pgd=00000009f3e91003, *pud=00000009f3e91003, *pmd=0000000000000000
     PREEMPT SMP
     Modules linked in:
     CPU: 4 PID: 1692 Comm: dd Not tainted 4.7.0-rc2+ #1721
     Hardware name: ARM Juno development board (r0) (DT)
     task: ffffffc9734a0080 ti: ffffffc974460000 task.ti: ffffffc974460000
     PC is at __memset+0x1ac/0x200
     LR is at tmc_read_unprepare_etr+0x144/0x1bc
     pc : [<ffffff80083a05ac>] lr : [<ffffff800859c984>] pstate: 200001c5
     ...
     [<ffffff80083a05ac>] __memset+0x1ac/0x200
     [<ffffff800859b2e4>] tmc_release+0x90/0x94
     [<ffffff8008202f58>] __fput+0xa8/0x1ec
     [<ffffff80082030f4>] ____fput+0xc/0x14
     [<ffffff80080c3ef8>] task_work_run+0xb0/0xe4
     [<ffffff8008088bf4>] do_notify_resume+0x64/0x6c
     [<ffffff8008084d5c>] work_pending+0x10/0x14
     Code: 91010108 54ffff4a 8b040108 cb050042 (d50b7428)
    
    Since we clear the buffer anyway in the following call to
    tmc_etr_enable_hw(), remove the erroneous memset().
    
    Fixes: commit de546197 ("coresight: tmc: allocating memory when needed")
    Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
    Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
    Signed-off-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    f3b8172f
coresight-tmc-etr.c 8.2 KB