lkml.org 
[lkml]   [2020]   [Jan]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.4 118/191] tracing: Fix endianness bug in histogram trigger
    Date
    From: Sven Schnelle <svens@linux.ibm.com>

    commit fe6e096a5bbf73a142f09c72e7aa2835026eb1a3 upstream.

    At least on PA-RISC and s390 synthetic histogram triggers are failing
    selftests because trace_event_raw_event_synth() always writes a 64 bit
    values, but the reader expects a field->size sized value. On little endian
    machines this doesn't hurt, but on big endian this makes the reader always
    read zero values.

    Link: http://lore.kernel.org/linux-trace-devel/20191218074427.96184-4-svens@linux.ibm.com

    Cc: stable@vger.kernel.org
    Fixes: 4b147936fa509 ("tracing: Add support for 'synthetic' events")
    Acked-by: Tom Zanussi <tom.zanussi@linux.intel.com>
    Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
    Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    kernel/trace/trace_events_hist.c | 21 ++++++++++++++++++++-
    1 file changed, 20 insertions(+), 1 deletion(-)

    --- a/kernel/trace/trace_events_hist.c
    +++ b/kernel/trace/trace_events_hist.c
    @@ -911,7 +911,26 @@ static notrace void trace_event_raw_even
    strscpy(str_field, str_val, STR_VAR_LEN_MAX);
    n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
    } else {
    - entry->fields[n_u64] = var_ref_vals[var_ref_idx + i];
    + struct synth_field *field = event->fields[i];
    + u64 val = var_ref_vals[var_ref_idx + i];
    +
    + switch (field->size) {
    + case 1:
    + *(u8 *)&entry->fields[n_u64] = (u8)val;
    + break;
    +
    + case 2:
    + *(u16 *)&entry->fields[n_u64] = (u16)val;
    + break;
    +
    + case 4:
    + *(u32 *)&entry->fields[n_u64] = (u32)val;
    + break;
    +
    + default:
    + entry->fields[n_u64] = val;
    + break;
    + }
    n_u64++;
    }
    }

    \
     
     \ /
      Last update: 2020-01-07 22:40    [W:6.943 / U:0.140 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site