Messages in this thread | | | From | Andrii Nakryiko <> | Date | Sat, 27 Jun 2020 13:35:55 -0700 | Subject | Re: [PATCH v3 bpf-next 2/4] bpf: introduce helper bpf_get_task_stack() |
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On Fri, Jun 26, 2020 at 5:29 PM Song Liu <songliubraving@fb.com> wrote: > > Introduce helper bpf_get_task_stack(), which dumps stack trace of given > task. This is different to bpf_get_stack(), which gets stack track of > current task. One potential use case of bpf_get_task_stack() is to call > it from bpf_iter__task and dump all /proc/<pid>/stack to a seq_file. > > bpf_get_task_stack() uses stack_trace_save_tsk() instead of > get_perf_callchain() for kernel stack. The benefit of this choice is that > stack_trace_save_tsk() doesn't require changes in arch/. The downside of > using stack_trace_save_tsk() is that stack_trace_save_tsk() dumps the > stack trace to unsigned long array. For 32-bit systems, we need to > translate it to u64 array. > > Acked-by: Andrii Nakryiko <andriin@fb.com> > Signed-off-by: Song Liu <songliubraving@fb.com> > --- > include/linux/bpf.h | 1 + > include/uapi/linux/bpf.h | 36 +++++++++++++++- > kernel/bpf/stackmap.c | 75 ++++++++++++++++++++++++++++++++-- > kernel/bpf/verifier.c | 4 +- > kernel/trace/bpf_trace.c | 2 + > scripts/bpf_helpers_doc.py | 2 + > tools/include/uapi/linux/bpf.h | 36 +++++++++++++++- > 7 files changed, 150 insertions(+), 6 deletions(-) >
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> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 7de98906ddf4a..b608185e1ffd5 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -4864,7 +4864,9 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn > if (err) > return err; > > - if (func_id == BPF_FUNC_get_stack && !env->prog->has_callchain_buf) { > + if ((func_id == BPF_FUNC_get_stack || > + func_id == BPF_FUNC_get_task_stack) && > + !env->prog->has_callchain_buf) { > const char *err_str; >
I'm glad it was so simple :) Thanks for checking!
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