On Tue, Dec 15, 2020 at 3:26 AM Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > > On Mon, Dec 14, 2020 at 1:58 AM Gilad Reti <gilad.reti@xxxxxxxxx> wrote: > > > > Hello there, > > libbpf provides BPF_CORE_READ macros for reading struct members in a > > CO-RE compatible way. By default those macros reduct to the relevant > > bpf_probe_read_kernel functions. As far as I could tell, there are no > > variants of this macros that wrap the _user variants of the read > > functions. Are there any plans to support ones? > > BPF_CORE_READ() are using BPF CO-RE and thus emit relocations, which > will be adjusted by libbpf to match kernel struct layouts by using > kernel's BTF(s). Because of this, having xxx_user() variants doesn't > make much sense, because libbpf can't relocate field offsets against > user-space types (as there is no BTF for user-space applications, > typically). Which is why there are no BPF_CORE_READ_USER()-like > macros. > > What's your use case, though? There might be a valid one that we are > not aware of, so please provide more details. Thanks. Currently my use case is tracing syscall pointer arguments (For example, "connect" has a "struct sockaddr *" argument). > > > Thanks, > > Gilad Reti.
