On Fri, Oct 9, 2020 at 12:32 PM Yaniv Agman <yanivagman@xxxxxxxxx> wrote: > > בתאריך יום ו׳, 9 באוק׳ 2020 ב-21:39 מאת Andrii Nakryiko > <andrii.nakryiko@xxxxxxxxx>: > > > > On Fri, Oct 9, 2020 at 11:33 AM Yaniv Agman <yanivagman@xxxxxxxxx> wrote: > > > > > > בתאריך יום ו׳, 9 באוק׳ 2020 ב-21:21 מאת Daniel Borkmann > > > <daniel@xxxxxxxxxxxxx>: > > > > > > > > On 10/9/20 8:09 PM, Yaniv Agman wrote: > > > > > בתאריך יום ו׳, 9 באוק׳ 2020 ב-20:39 מאת Daniel Borkmann > > > > > <daniel@xxxxxxxxxxxxx>: > > > > >> > > > > >> On 10/9/20 6:56 PM, Yaniv Agman wrote: > > > > >>> בתאריך יום ו׳, 9 באוק׳ 2020 ב-19:27 מאת Daniel Borkmann > > > > >>> <daniel@xxxxxxxxxxxxx>: > > > > >>>> > > > > >>>> [ Cc +Yonghong ] > > > > >>>> > > > > >>>> On 10/9/20 6:05 PM, Yaniv Agman wrote: > > > > >>>>> Pulling the latest changes of libbpf and compiling my application with it, > > > > >>>>> I see the following error: > > > > >>>>> > > > > >>>>> ../libbpf/src//root/usr/include/bpf/bpf_helpers.h:99:10: error: > > > > >>>>> unknown register name 'r0' in asm > > > > >>>>> : "r0", "r1", "r2", "r3", "r4", "r5"); > > > > >>>>> > > > > >>>>> The commit which introduced this change is: > > > > >>>>> 80c7838600d39891f274e2f7508b95a75e4227c1 > > > > >>>>> > > > > >>>>> I'm not sure if I'm doing something wrong (missing include?), or this > > > > >>>>> is a genuine error > > > > >>>> > > > > >>>> Seems like your clang/llvm version might be too old. > > > > >>> > > > > >>> I'm using clang 10.0.1 > > > > >> > > > > >> Ah, okay, I see. Would this diff do the trick for you? > > > > > > > > > > Yes! Now it compiles without any problems! > > > > > > > > Great, thx, I'll cook proper fix and check with clang6 as Yonghong mentioned. > > > > > > > > > > Thanks! > > > Does this happen because I'm first compiling using "emit-llvm" and > > > then using llc? > > > > So this must be the reason, but I'll wait for Yonghong to confirm. > > > > > I wish I could use bpf target directly, but I'm then having problems > > > with includes of asm code (like pt_regs and other stuff) > > > > Are you developing for a 32-bit platform? Or what exactly is the > > problem? I've been trying to solve problems for 32-bit arches recently > > by making libbpf smarter, that relies on CO-RE though. Is CO-RE an > > option for you? > > > > Examples for the errors I'm getting: > /lib/modules/4.14.199-1-MANJARO/build/arch/x86/include/asm/atomic.h:177:9: > error: invalid output constraint '+q' in asm > return xadd(&v->counter, i); > ^ > /lib/modules/4.14.199-1-MANJARO/build/arch/x86/include/asm/cmpxchg.h:234:25: > note: expanded from macro 'xadd' > #define xadd(ptr, inc) __xadd((ptr), (inc), LOCK_PREFIX) > ... > > From What I understood, this is a known issue for tracing programs > (like the one I'm developing) We do have a bunch of selftests that use pt_regs and include, say, linux/ptrace.h header. I wonder why we are not seeing these problems. Selftests, btw, are also built with -emit-llvm and then piping output to llc. So.. there must be something else going on. It's hard to guess like this without seeing the code, but maybe -D__TARGET_ARCH_$(SRCARCH) during compilation could help, just as an idea. > Unfortunately, CO-RE is not (yet) an option. > I'm currently making the move from bcc to libbpf, and our application > needs to support kernel 4.14, and work on all environments. Kernel version is not a big problem, it's vmlinux BTF availability that could be a problem. vmlinux BTF can be added into any version of kernel with pahole -J, post factum, but that assumes you have some control over how kernels are built and distributed, of course. > > > [...]
