On Mon, Jan 24, 2022 at 2:18 PM Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > > On Mon, Jan 24, 2022 at 10:54 AM Kenny Yu <kennyyu@xxxxxx> wrote: > > > > This adds a helper for bpf programs to read the memory of other > > tasks. > > > > As an example use case at Meta, we are using a bpf task iterator program > > and this new helper to print C++ async stack traces for all threads of > > a given process. > > > > Signed-off-by: Kenny Yu <kennyyu@xxxxxx> > > --- > > LGTM. > > Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > > > include/linux/bpf.h | 1 + > > include/uapi/linux/bpf.h | 11 +++++++++++ > > kernel/bpf/helpers.c | 34 ++++++++++++++++++++++++++++++++++ > > kernel/trace/bpf_trace.c | 2 ++ > > tools/include/uapi/linux/bpf.h | 11 +++++++++++ > > 5 files changed, 59 insertions(+) > > > > [...] > > > + ret = access_process_vm(tsk, (unsigned long)user_ptr, dst, size, 0); > > + if (ret == size) > > + return 0; > > + > > + memset(dst, 0, size); > > + /* Return -EFAULT for partial read */ > > + return (ret < 0) ? ret : -EFAULT; > > nit: unnecessary () I fixed it while applying. Also added a few unlikely(). Thanks everyone!
