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    SubjectRe: [PATCH/RFC 03/16] perf top: Factor out warnings about kernel addresses and symbols
    Hi Arnaldo,

    On Thu, Dec 10, 2015 at 04:07:48PM -0300, Arnaldo Carvalho de Melo wrote:
    > Em Thu, Dec 10, 2015 at 04:53:22PM +0900, Namhyung Kim escreveu:
    > > Factor out warning messages into separate functions. These will be
    > > called in the display thread later.
    > >
    > > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
    > > ---
    > > tools/perf/builtin-top.c | 95 ++++++++++++++++++++++++++----------------------
    > > 1 file changed, 51 insertions(+), 44 deletions(-)
    >
    > Without applying patch 2, will check if it happens without this patch as well
    >
    >
    >
    > [root@ssdandy ~]# echo 2 > /proc/sys/kernel/kptr_restrict
    > [root@ssdandy ~]# perf top
    > perf: Segmentation fault
    > -------- backtrace --------
    > perf[0x538b3b]
    > /lib64/libc.so.6(+0x35650)[0x7f401c036650]
    > perf[0x43af66]
    > perf(cmd_top+0xedf)[0x43cdbf]
    > perf[0x47b7c3]
    > perf(main+0x617)[0x4222b7]
    > /lib64/libc.so.6(__libc_start_main+0xf5)[0x7f401c022af5]
    > perf[0x4223c9]
    > [0x0]
    > [root@ssdandy ~]#

    This patch changed the order in the condition, so if kptr_restrict is
    on, kernel map is NULL and checking al->map->dso caused the segfault.

    Will fix.

    Thanks,
    Namhyung


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