libbpf-tools/offcputime: Use CO-RE operation to read kernel data #4471
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Use CO-RE API to read the value of a field from task_struct. Signed-off-by: Eunseon Lee <[email protected]>
ekyooo
requested review from
drzaeus77,
goldshtn,
yonghong-song,
4ast,
brendangregg and
davemarchevsky
as code owners
chenhengqi
reviewed
Feb 9, 2023
| @@ -66,15 +66,15 @@ int BPF_PROG(sched_switch, bool preempt, struct task_struct *prev, struct task_s | |||
| u32 pid; | |||
|
|
|||
| if (allow_record(prev)) { | |||
| pid = prev->pid; | |||
| pid = BPF_CORE_READ(prev, pid); | |||
There was a problem hiding this comment.
tp_btf is BTF-awared, pointer chasing should work, right ?
There was a problem hiding this comment.
Oh... I didn't know that. Thank you for the information. Does tp_btf support depend on kernel version?
A segfault occurred when running the default version of offfcputime on my Linux v5.4 kernel environment. So I switched tp_btf to tracepoint as below. So this patch was needed.
-SEC("tp_btf/sched_switch")
+SEC("tracepoint/sched/sched_switch")
Could you please tell me if tp_btf is supported in Linux v5.4 as well?
Thank you in advance.
There was a problem hiding this comment.
Ok. I got information from another engineer that tp_btf is not supported in Linux v5.4. I abandon this patch. Thank you.
There was a problem hiding this comment.
Oh..!! Thank you. I'll read it carefully.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Use CO-RE API to read the value of a field from task_struct.
Signed-off-by: Eunseon Lee [email protected]