Merge: tracing: Add division and multiplication support for hist triggers [rhel-9]

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/6586

# Merge Request Required Information

JIRA: https://issues.redhat.com/browse/RHEL-67679

## Summary of Changes

Backport support for division and multiplication in histogram triggers as well as fixes and optimizations for it. Support for creating hist trigger variables from literal is added, too, as it is a dependency of one of the fixes and is documented together with the former.

## Approved Development Ticket(s)
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Please follow the CentOS Stream [contribution documentation](https://docs.centos.org/en-US/stream-contrib/quickstart/) for how to file this ticket and have it approved.

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Signed-off-by: Tomas Glozar <tglozar@redhat.com>

Approved-by: Joe Lawrence <joe.lawrence@redhat.com>
Approved-by: Waiman Long <longman@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Augusto Caringi <acaringi@redhat.com>

Author: caringi

Documentation/trace/histogram.rst

@@ -1762,6 +1762,20 @@ using the same key and variable from yet another event::
 
   # echo 'hist:key=pid:wakeupswitch_lat=$wakeup_lat+$switchtime_lat ...' >> event3/trigger
 
+Expressions support the use of addition, subtraction, multiplication and
+division operators (+-\*/).
+
+Note that division by zero always returns -1.
+
+Numeric constants can also be used directly in an expression::
+
+  # echo 'hist:keys=next_pid:timestamp_secs=common_timestamp/1000000 ...' >> event/trigger
+
+or assigned to a variable and referenced in a subsequent expression::
+
+  # echo 'hist:keys=next_pid:us_per_sec=1000000 ...' >> event/trigger
+  # echo 'hist:keys=next_pid:timestamp_secs=common_timestamp/$us_per_sec ...' >> event/trigger
+
 2.2.2 Synthetic Events
 ----------------------