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    Subject[PATCH 5.12 102/700] tracing/histograms: Fix parsing of "sym-offset" modifier
    Date
    From: Steven Rostedt (VMware) <rostedt@goodmis.org>

    commit 26c563731056c3ee66f91106c3078a8c36bb7a9e upstream.

    With the addition of simple mathematical operations (plus and minus), the
    parsing of the "sym-offset" modifier broke, as it took the '-' part of the
    "sym-offset" as a minus, and tried to break it up into a mathematical
    operation of "field.sym - offset", in which case it failed to parse
    (unless the event had a field called "offset").

    Both .sym and .sym-offset modifiers should not be entered into
    mathematical calculations anyway. If ".sym-offset" is found in the
    modifier, then simply make it not an operation that can be calculated on.

    Link: https://lkml.kernel.org/r/20210707110821.188ae255@oasis.local.home

    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Masami Hiramatsu <mhiramat@kernel.org>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
    Cc: stable@vger.kernel.org
    Fixes: 100719dcef447 ("tracing: Add simple expression support to hist triggers")
    Reviewed-by: Tom Zanussi <zanussi@kernel.org>
    Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    kernel/trace/trace_events_hist.c | 7 +++++++
    1 file changed, 7 insertions(+)

    --- a/kernel/trace/trace_events_hist.c
    +++ b/kernel/trace/trace_events_hist.c
    @@ -1539,6 +1539,13 @@ static int contains_operator(char *str)

    switch (*op) {
    case '-':
    + /*
    + * Unfortunately, the modifier ".sym-offset"
    + * can confuse things.
    + */
    + if (op - str >= 4 && !strncmp(op - 4, ".sym-offset", 11))
    + return FIELD_OP_NONE;
    +
    if (*str == '-')
    field_op = FIELD_OP_UNARY_MINUS;
    else

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