On Wed, Mar 01, 2023 at 08:00:52PM -0500, Steven Rostedt wrote:
From: "Steven Rostedt (Google)" rostedt@goodmis.org
Histogram values can not be strings, stacktraces, graphs, symbols, syscalls, or grouped in buckets or log. Give an error if a value is set to do so.
Note, the histogram code was not prepared to handle these modifiers for histograms and caused a bug.
Cc: stable@vger.kernel.org Fixes: c6afad49d127f ("tracing: Add hist trigger 'sym' and 'sym-offset' modifiers") Reported-by: Mark Rutland mark.rutland@arm.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org
Tested-by: Mark Rutland mark.rutland@arm.com
I gave this a spin, and I see that the buckets modifier gerts rejected for hitcount, but is usable for other values as it should be:
| # echo 'p:copy_to_user __arch_copy_to_user n=$arg3' >> /sys/kernel/tracing/kprobe_events | # echo 'hist:keys=n:vals=hitcount.buckets=8:sort=hitcount' > /sys/kernel/tracing/events/kprobes/copy_to_user/trigger | sh: write error: Invalid argument | # echo 'hist:keys=n.buckets=8:vals=hitcount:sort=hitcount' > /sys/kernel/tracing/events/kprobes/copy_to_user/trigger | # cat /sys/kernel/tracing/events/kprobes/copy_to_user/hist | # event histogram | # | # trigger info: hist:keys=n.buckets=8:vals=hitcount:sort=hitcount:size=2048 [active] | # | | { n: ~ 336-343 } hitcount: 1 | { n: ~ 16-23 } hitcount: 2 | { n: ~ 32-39 } hitcount: 2 | { n: ~ 832-839 } hitcount: 3 | { n: ~ 8-15 } hitcount: 3 | { n: ~ 128-135 } hitcount: 5 | { n: ~ 0-7 } hitcount: 57 | | Totals: | Hits: 73 | Entries: 7 | Dropped: 0
Thanks, Mark.
kernel/trace/trace_events_hist.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 89877a18f933..6e8ab726a7b5 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -4235,6 +4235,15 @@ static int __create_val_field(struct hist_trigger_data *hist_data, goto out; }
- /* Some types cannot be a value */
- if (hist_field->flags & (HIST_FIELD_FL_GRAPH | HIST_FIELD_FL_PERCENT |
HIST_FIELD_FL_BUCKET | HIST_FIELD_FL_LOG2 |HIST_FIELD_FL_SYM | HIST_FIELD_FL_SYM_OFFSET |HIST_FIELD_FL_SYSCALL | HIST_FIELD_FL_STACKTRACE)) {hist_err(file->tr, HIST_ERR_BAD_FIELD_MODIFIER, errpos(field_str));ret = -EINVAL;- }
- hist_data->fields[val_idx] = hist_field;
++hist_data->n_vals;
2.39.1