When reviewing test results on aarch64 I found that the systemtap lwtools examples fslatency-nd.stp and fsslower-nd.stp were not using correct values of arguments for return probe. This is because the aarch64 arguments are stored in registers that can be overwritten in the function. These uses should be wrapped by @entry to make sure the value from the function entry is used. It would be very wise to review the other scripts and tapsets in systemtap to ensure that this problem is not lurking elsewhere. For problem entries do something like what is done in: https://sourceware.org/git/gitweb.cgi?p=systemtap.git;a=commit;h=3d0c2f452f09a64b800aabe68508f8f0183f0ea1
Reviewed the examples in testsuite/systmetap.examples. Found a couple corrections needed to be made in fslatency-nd.stp and fsslower-nd.stp. commit 01261944787df5c757d55fe2ec081b70a1723ab0 (HEAD -> master, origin/master, origin/HEAD) Author: William Cohen <wcohen@redhat.com> Date: Thu Feb 15 15:01:53 2024 -0500 PR19360: Correct lwtools fslatency-nd.stp and fsslower-nd.stp Reviewed examples to ensure that the entry value for a function argument is used for function return probes. Found that __vfs_write.return probes aliases were missing ".return" and needed an @entry() for the argument fetch in fslatency-nd.stp and fsslower-nd.stp.