Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1349151

[BUG ARM64/perf] Perf record on hardware breakpoint causes application to hang

Show all headers | View raw

This problem can be reproduced as follows:

We know cat /proc/version will read the memory of symbol
linux_proc_banner, then we make a hardware memory access
breakpoint on that address.

on terminal 1:

   $ perf record -e mem:0x$(cat /proc/kallsyms|grep 
linux_proc_banner|cut -d " " -f 1):rw --no-buffer -a

on terminal 2:

   $ cat /proc/version

Then our 'cat' process on terminal 2 will be hanged, until we press
'^C' to stop perf from recording events.

The sample numbers recorded by perf is extraordinary too:

   [ perf record: Captured and wrote 0.879 MB perf.data (22691 samples) ]

The right result can be produced by removing the 'no-buffer'
argument in perf command line, and the result should be like
this:

   $ perf record -e mem:0x$(cat /proc/kallsyms|grep linux_proc_
                            banner|cut -d " " -f 1):rw  -a
   ^C
   [ perf record: Woken up 1 times to write data ]
   [ perf record: Captured and wrote 0.013 MB perf.data (10 samples) ]

Report this bug to you and hope for answers.

Thanks.

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[BUG ARM64/perf] Perf record on hardware breakpoint causes  application to hang Hekuang <hekuang@huawei.com> - 2016-03-03 14:20 +0100
  Re: [BUG ARM64/perf] Perf record on hardware breakpoint causes  application to hang Will Deacon <will.deacon@arm.com> - 2016-03-03 16:10 +0100

csiph-web