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tracing/histograms: Fix parsing of "sym-offset" modifier

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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>
This commit is contained in:
Steven Rostedt (VMware) 2021-07-07 11:08:21 -04:00 committed by Greg Kroah-Hartman
parent 998de999ba
commit 2aedacfaf6
1 changed files with 7 additions and 0 deletions
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7
kernel/trace/trace_events_hist.c
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@ -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