On Thu, Dec 3, 2020 at 4:20 AM David Marcinkovic <david.marcinkovic@xxxxxxxxxx> wrote: > > Hello everyone, > > I am trying to run a simple BPF program that hooks onto > `mac80211/drv_sta_state` tracepoint. When I run the program on the arm > 32 bit architecture, > the verifier rejects to load the program and outputs the following error > message: > > Unrecognized arg#0 type PTR > ; int tp__mac80211_drv_sta_state(struct trace_event_raw_drv_sta_state* ctx) > 0: (bf) r3 = r1 > 1: (85) call unknown#195896080 > invalid func unknown#195896080 > > This error does not seem to occur on the amd64 architecture. I am > using clang version 10 for both, compiling on amd64 and > cross-compiling for arm32. > > > I have prepared a simple program that hooks onto the > `mac80211/drv_sta_state` tracepoint. > In this example, `BPF_CORE_READ` macro function seems to cause the > verifier to reject to load the program. > I've been using this macro in various different programs and it didn't > cause any problems. > Also, I've been using packed structs and bit fields in other programs > and they also didn't cause any problems. > > I tried to use BPF_CORE_READ_BITFIELD as stated in this patch [0] and > got a similar error. > > Any input is much appreciated, > Can you provide libbpf debug output, especially the section about CO-RE relocations? Could it be that this tracepoint is inside the kernel module? > Best regards, > David Marčinković > > > [0] https://lore.kernel.org/bpf/20201007202946.3684483-1-andrii@xxxxxxxxxx/T/#ma08db511daa0b5978f16df9f98f4ef644b83fc96 > > [...]
