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Description of problem:
I have written a script that tries print current working directory, e.g.:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
stap -v -e 'probe syscall.openat { printf("PID %lu CWD %s\n", pid(), fullpath_struct_path(task_cwd_path(task_current()))) }'
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
This works fine on RHEL7 but not on RHEL8.
First I see warnings:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
WARNING: Potential type mismatch in reassignment: identifier 'root_dentry' at /usr/share/systemtap/tapset/linux/dentry.stp:246:3
source: root_dentry = @cast(task, "task_struct", "kernel")->fs->root->dentry
^
WARNING: Potential type mismatch in reassignment: identifier 'root_dentry' at :242:3
source: root_dentry = & @cast(task, "task_struct", "kernel")->fs->root
^
...
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
Then once I get a hit (on "openat" here), script dies:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
ERROR: read fault [man error::fault] at 0x10 near operator '->' at /usr/share/systemtap/tapset/linux/dentry.stp:267:19
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
task_cwd_path() returns the pointer to path struct and
fullpath_struct_path() expects the arg to be a pointer to "struct path".
Version-Release number of selected component (if applicable):
systemtap-4.5-3.el8.x86_64
How reproducible:
Always see above.
stap 4.6 already built for rhel8 corrects the first WARNING diagnostics, but the read-fault is still there. Chances are some more tapset porting for kernel changes needs to be done.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory (systemtap bug fix and enhancement update), and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2022:7538
Description of problem: I have written a script that tries print current working directory, e.g.: -------- 8< ---------------- 8< ---------------- 8< ---------------- 8< -------- stap -v -e 'probe syscall.openat { printf("PID %lu CWD %s\n", pid(), fullpath_struct_path(task_cwd_path(task_current()))) }' -------- 8< ---------------- 8< ---------------- 8< ---------------- 8< -------- This works fine on RHEL7 but not on RHEL8. First I see warnings: -------- 8< ---------------- 8< ---------------- 8< ---------------- 8< -------- WARNING: Potential type mismatch in reassignment: identifier 'root_dentry' at /usr/share/systemtap/tapset/linux/dentry.stp:246:3 source: root_dentry = @cast(task, "task_struct", "kernel")->fs->root->dentry ^ WARNING: Potential type mismatch in reassignment: identifier 'root_dentry' at :242:3 source: root_dentry = & @cast(task, "task_struct", "kernel")->fs->root ^ ... -------- 8< ---------------- 8< ---------------- 8< ---------------- 8< -------- Then once I get a hit (on "openat" here), script dies: -------- 8< ---------------- 8< ---------------- 8< ---------------- 8< -------- ERROR: read fault [man error::fault] at 0x10 near operator '->' at /usr/share/systemtap/tapset/linux/dentry.stp:267:19 -------- 8< ---------------- 8< ---------------- 8< ---------------- 8< -------- task_cwd_path() returns the pointer to path struct and fullpath_struct_path() expects the arg to be a pointer to "struct path". Version-Release number of selected component (if applicable): systemtap-4.5-3.el8.x86_64 How reproducible: Always see above.