libbpf-tools/offcputime: Use CO-RE operation to read kernel data #4471
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Use CO-RE API to read the value of a field from task_struct. Signed-off-by: Eunseon Lee <es.lee@lge.com>
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; | |||
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| if (allow_record(prev)) { | |||
| pid = prev->pid; | |||
| pid = BPF_CORE_READ(prev, pid); | |||
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tp_btf is BTF-awared, pointer chasing should work, right ?
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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.
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Ok. I got information from another engineer that tp_btf is not supported in Linux v5.4. I abandon this patch. Thank you.
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Oh..!! Thank you. I'll read it carefully.
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Use CO-RE API to read the value of a field from task_struct.
Signed-off-by: Eunseon Lee es.lee@lge.com