From: "Steven Rostedt (VMware)" rostedt@goodmis.org

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

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index ba03b7d84fc2..0207aeed31e6 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -1555,6 +1555,13 @@ 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