On Mon, Aug 3, 2020 at 10:40 AM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote: > > On 8/3/20 7:34 PM, Daniel Borkmann wrote: > > On 8/3/20 7:15 PM, Daniel Borkmann wrote: > >> On 8/3/20 12:29 AM, Alexei Starovoitov wrote: > >>> From: Alexei Starovoitov <ast@xxxxxxxxxx> > >>> > >>> Add kernel module with user mode driver that populates bpffs with > >>> BPF iterators. > >>> > >>> $ mount bpffs /my/bpffs/ -t bpf > >>> $ ls -la /my/bpffs/ > >>> total 4 > >>> drwxrwxrwt 2 root root 0 Jul 2 00:27 . > >>> drwxr-xr-x 19 root root 4096 Jul 2 00:09 .. > >>> -rw------- 1 root root 0 Jul 2 00:27 maps.debug > >>> -rw------- 1 root root 0 Jul 2 00:27 progs.debug > >>> > >>> The user mode driver will load BPF Type Formats, create BPF maps, populate BPF > >>> maps, load two BPF programs, attach them to BPF iterators, and finally send two > >>> bpf_link IDs back to the kernel. > >>> The kernel will pin two bpf_links into newly mounted bpffs instance under > >>> names "progs.debug" and "maps.debug". These two files become human readable. > >>> > >>> $ cat /my/bpffs/progs.debug > >>> id name attached > >>> 11 dump_bpf_map bpf_iter_bpf_map > >>> 12 dump_bpf_prog bpf_iter_bpf_prog > >>> 27 test_pkt_access > >>> 32 test_main test_pkt_access test_pkt_access > >>> 33 test_subprog1 test_pkt_access_subprog1 test_pkt_access > >>> 34 test_subprog2 test_pkt_access_subprog2 test_pkt_access > >>> 35 test_subprog3 test_pkt_access_subprog3 test_pkt_access > >>> 36 new_get_skb_len get_skb_len test_pkt_access > >>> 37 new_get_skb_ifindex get_skb_ifindex test_pkt_access > >>> 38 new_get_constant get_constant test_pkt_access > >>> > >>> The BPF program dump_bpf_prog() in iterators.bpf.c is printing this data about > >>> all BPF programs currently loaded in the system. This information is unstable > >>> and will change from kernel to kernel as ".debug" suffix conveys. > >>> > >>> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx> > >> [...] > >>> diff --git a/kernel/bpf/preload/Kconfig b/kernel/bpf/preload/Kconfig > >>> new file mode 100644 > >>> index 000000000000..b8ba5a9398ed > >>> --- /dev/null > >>> +++ b/kernel/bpf/preload/Kconfig > >>> @@ -0,0 +1,18 @@ > >>> +# SPDX-License-Identifier: GPL-2.0-only > >>> +menuconfig BPF_PRELOAD > >>> + bool "Preload BPF file system with kernel specific program and map iterators" > >>> + depends on BPF > >>> + help > >>> + This builds kernel module with several embedded BPF programs that are > >>> + pinned into BPF FS mount point as human readable files that are > >>> + useful in debugging and introspection of BPF programs and maps. > >>> + > >>> +if BPF_PRELOAD > >>> +config BPF_PRELOAD_UMD > >>> + tristate "bpf_preload kernel module with user mode driver" > >>> + depends on CC_CAN_LINK > >>> + depends on m || CC_CAN_LINK_STATIC > >>> + default m > >>> + help > >>> + This builds bpf_preload kernel module with embedded user mode driver. > >>> +endif > >> [...] > >> When I applied this set locally to run build & selftests I noticed that the above > >> kconfig will appear in the top-level menuconfig. This is how it looks in menuconfig: > >> > >> │ ┌────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐ │ > >> │ │ General setup ---> │ │ > >> │ │ [*] 64-bit kernel │ │ > >> │ │ Processor type and features ---> │ │ > >> │ │ Power management and ACPI options ---> │ │ > >> │ │ Bus options (PCI etc.) ---> │ │ > >> │ │ Binary Emulations ---> │ │ > >> │ │ Firmware Drivers ---> │ │ > >> │ │ [*] Virtualization ---> │ │ > >> │ │ General architecture-dependent options ---> │ │ > >> │ │ [*] Enable loadable module support ---> │ │ > >> │ │ -*- Enable the block layer ---> │ │ > >> │ │ IO Schedulers ---> │ │ > >> │ │ [ ] Preload BPF file system with kernel specific program and map iterators ---- │ │ > >> │ │ Executable file formats ---> │ │ > >> │ │ Memory Management options ---> │ │ > >> │ │ [*] Networking support ---> │ │ > >> │ │ Device Drivers ---> │ │ > >> │ │ File systems ---> │ │ > >> │ │ Security options ---> │ │ > >> [...] > >> > >> I assume the original intention was to have it under 'general setup' on a similar level for > >> the JIT settings, or is this intentional to have it at this high level next to 'networking > >> support' and others? I don't remember when last time I did menuconfig. How do you propose to move it? Any particular suggestion how kconfig suppose to look like? > > > > Hm, my config has: > > > > CONFIG_BPF_PRELOAD=y > > CONFIG_BPF_PRELOAD_UMD=y > > > > I'm getting the following 3 warnings and build error below: > > > > root@tank:~/bpf-next# make -j8 > /dev/null > > arch/x86/hyperv/hv_apic.c: In function ‘hv_send_ipi_mask_allbutself’: > > arch/x86/hyperv/hv_apic.c:236:1: warning: the frame size of 1032 bytes is larger than 1024 bytes [-Wframe-larger-than=] > > } > > ^ > > make[3]: *** No rule to make target 'kernel/bpf/preload/./../../tools/lib/bpf/bpf.c', needed by 'kernel/bpf/preload/./../../tools/lib/bpf/bpf.o'. Stop. > > make[3]: *** Waiting for unfinished jobs.... > > kernel/bpf/preload/iterators/iterators.c: In function ‘main’: > > kernel/bpf/preload/iterators/iterators.c:50:2: warning: ignoring return value of ‘dup’, declared with attribute warn_unused_result [-Wunused-result] > > dup(debug_fd); > > ^~~~~~~~~~~~~ > > kernel/bpf/preload/iterators/iterators.c:53:2: warning: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Wunused-result] > > read(from_kernel, &magic, sizeof(magic)); > > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > kernel/bpf/preload/iterators/iterators.c:85:2: warning: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Wunused-result] > > read(from_kernel, &magic, sizeof(magic)); > > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > make[2]: *** [kernel/bpf/preload] Error 2 > > make[1]: *** [kernel/bpf] Error 2 > > make: *** [kernel] Error 2 > > make: *** Waiting for unfinished jobs.... > > [...] > > > > Have you seen the target error before, what am I missing? > > Looks like the path in this patch is wrong: > > diff --git a/kernel/bpf/preload/Makefile b/kernel/bpf/preload/Makefile > index 191d82209842..136c6ca0c196 100644 > --- a/kernel/bpf/preload/Makefile > +++ b/kernel/bpf/preload/Makefile > @@ -1,6 +1,6 @@ > # SPDX-License-Identifier: GPL-2.0 > > -LIBBPF := $(srctree)/../../tools/lib/bpf > +LIBBPF := $(srctree)/../../../tools/lib/bpf hmm. that's very odd. Are you building in-src-tree ? I'm building out-of-src-tree with KBUILD_OUTPUT. And two pairs of dots would be correct. make V=1 kernel/bpf/preload/ gcc -m64 -lelf -lz -o kernel/bpf/preload/bpf_preload_umd kernel/bpf/preload/iterators/iterators.o kernel/bpf/preload/../../../tools/lib/bpf/bpf.o see three pairs above. the first pair comes from $(srctree) somehow. > userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi -I $(LIBBPF) \ > -I $(srctree)/tools/lib/ \ > -I $(srctree)/kernel/bpf/preload/iterators/ -Wno-int-conversion \ > > With that, I'm now getting the following error: > > root@tank:~/bpf-next# make -j8 > DESCEND objtool > DESCEND bpf/resolve_btfids > CALL scripts/atomic/check-atomics.sh > CALL scripts/checksyscalls.sh > CHK include/generated/compile.h > CC kernel/events/core.o > CC [U] kernel/bpf/preload/iterators/iterators.o > kernel/bpf/preload/iterators/iterators.c: In function ‘main’: > kernel/bpf/preload/iterators/iterators.c:50:2: warning: ignoring return value of ‘dup’, declared with attribute warn_unused_result [-Wunused-result] > dup(debug_fd); > ^~~~~~~~~~~~~ > kernel/bpf/preload/iterators/iterators.c:53:2: warning: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Wunused-result] > read(from_kernel, &magic, sizeof(magic)); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > kernel/bpf/preload/iterators/iterators.c:85:2: warning: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Wunused-result] > read(from_kernel, &magic, sizeof(magic)); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > CC kernel/events/ring_buffer.o > CC [U] kernel/bpf/preload/./../../../tools/lib/bpf/bpf.o > CC [U] kernel/bpf/preload/./../../../tools/lib/bpf/libbpf.o > In file included from kernel/bpf/preload/./../../../tools/lib/bpf/libbpf.c:47:0: > ./tools/include/tools/libc_compat.h:11:21: error: static declaration of ‘reallocarray’ follows non-static declaration > static inline void *reallocarray(void *ptr, size_t nmemb, size_t size) > ^~~~~~~~~~~~ I saw this in the past when makefile was wrong. I suspect it's related to the above issue. Could you send me your build script / command line and make version?
