• Suzuki K Poulose's avatar
    coresight: tmc-etf: Do not call smp_processor_id from preemptible · 024c1fd9
    Suzuki K Poulose authored
    During a perf session we try to allocate buffers on the "node" associated
    with the CPU the event is bound to. If it is not bound to a CPU, we
    use the current CPU node, using smp_processor_id(). However this is unsafe
    in a pre-emptible context and could generate the splats as below :
    
     BUG: using smp_processor_id() in preemptible [00000000] code: perf/2544
     caller is tmc_alloc_etf_buffer+0x5c/0x60
     CPU: 2 PID: 2544 Comm: perf Not tainted 5.1.0-rc6-147786-g116841e #344
     Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Feb  1 2019
     Call trace:
      dump_backtrace+0x0/0x150
      show_stack+0x14/0x20
      dump_stack+0x9c/0xc4
      debug_smp_processor_id+0x10c/0x110
      tmc_alloc_etf_buffer+0x5c/0x60
      etm_setup_aux+0x1c4/0x230
      rb_alloc_aux+0x1b8/0x2b8
      perf_mmap+0x35c/0x478
      mmap_region+0x34c/0x4f0
      do_mmap+0x2d8/0x418
      vm_mmap_pgoff+0xd0/0xf8
      ksys_mmap_pgoff+0x88/0xf8
      __arm64_sys_mmap+0x28/0x38
      el0_svc_handler+0xd8/0x138
      el0_svc+0x8/0xc
    
    Use NUMA_NO_NODE hint instead of using the current node for events
    not bound to CPUs.
    
    Fixes: 2e499bbc ("coresight: tmc: implementing TMC-ETF AUX space API")
    Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
    Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
    Cc: stable <stable@vger.kernel.org> # 4.7+
    Signed-off-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
    Link: https://lore.kernel.org/r/20190620221237.3536-4-mathieu.poirier@linaro.orgSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    024c1fd9
coresight-tmc-etf.c 16.1 KB