On Thu, Dec 3, 2020 at 9:35 PM Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > > 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? You're right. The problem is that this tracepoint is inside the kernel module. I recompiled the kernel with CONFIG_MAC80211 flag set to 'y' and the program loads successfully. Thank you very much for your fast reply. > > > Best regards, > > David Marčinković > > > > > > [0] https://lore.kernel.org/bpf/20201007202946.3684483-1-andrii@xxxxxxxxxx/T/#ma08db511daa0b5978f16df9f98f4ef644b83fc96 > > > > > > [...]
