2023-01-17 14:25 UTC+0000 ~ Christophe Leroy <christophe.leroy@xxxxxxxxxx> > > > Le 17/01/2023 à 15:18, Tonghao Zhang a écrit : >> >> >>> On Jan 17, 2023, at 7:36 PM, Christophe Leroy <christophe.leroy@xxxxxxxxxx> wrote: >>> >>> >>> >>> Le 17/01/2023 à 08:30, Christophe Leroy a écrit : >>>> >>>> >>>> Le 17/01/2023 à 06:30, Tonghao Zhang a écrit : >>>>> >>>>> >>>>>> On Jan 9, 2023, at 4:15 PM, Christophe Leroy >>>>>> <christophe.leroy@xxxxxxxxxx> wrote: [...] >>>>>> Sure I will try to test bpftool again in the coming days. >>>>>> >>>>>> Previous discussion about that subject is here: >>>>>> https://patchwork.kernel.org/project/linux-riscv/patch/20210415093250.3391257-1-Jianlin.Lv@xxxxxxx/#24176847= Christophe, apologies from dropping the discussion the last time, it seems your last message on that thread didn't make it to my inbox at the time :/. Thanks a lot for looking into that again! >>>>> Hi Christophe >>>>> Any progress? We discuss to deprecate the bpf_jit_enable == 2 in 2021, >>>>> but bpftool can not run on powerpc. >>>>> Now can we fix this issue? >>>> >>>> Hi Tong, >>>> >>>> I have started to look at it but I don't have any fruitfull feedback yet. >>> >>> Hi Again, >>> >>> I tested again, the problem is still the same as one year ago: >>> >>> root@vgoip:~# ./bpftool prog >>> libbpf: elf: endianness mismatch in pid_iter_bpf. >> It seem to be not right ehdr->e_ident[EI_DATA]. Do we can print the real value? >> /* >> * e_ident[EI_DATA] >> */ >> #define ELFDATANONE 0 >> #define ELFDATA2LSB 1 >> #define ELFDATA2MSB 2 >> #define ELFDATANUM 3 >> >> bpf_object__elf_init: >> obj->efile.ehdr = ehdr = elf64_getehdr(elf); >> >>> libbpf: failed to initialize skeleton BPF object 'pid_iter_bpf': -4003 >>> Error: failed to open PID iterator skeleton >>> >>> root@vgoip:~# uname -a >>> Linux vgoip 6.2.0-rc3-02596-g1c2c9c13e256 #242 PREEMPT Tue Jan 17 >>> 09:36:08 CET 2023 ppc GNU/Linux >> On my pc, elf is little endian. >> # readelf -h tools/bpf/bpftool/pid_iter.bpf.o >> ELF Header: >> Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 >> Class: ELF64 >> Data: 2's complement, little endian # x86_64 >> Version: 1 (current) >> OS/ABI: UNIX - System V >> ABI Version: 0 >> Type: REL (Relocatable file) >> Machine: Linux BPF >> Version: 0x1 >> Entry point address: 0x0 >> Start of program headers: 0 (bytes into file) >> Start of section headers: 64832 (bytes into file) >> Flags: 0x0 >> Size of this header: 64 (bytes) >> Size of program headers: 0 (bytes) >> Number of program headers: 0 >> Size of section headers: 64 (bytes) >> Number of section headers: 13 >> Section header string table index: 1 >> > > Yes, must be something wrong with the build, I get same as you : > > $ LANG= readelf -h pid_iter.bpf.o > ELF Header: > Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 > Class: ELF64 > Data: 2's complement, little endian > Version: 1 (current) > OS/ABI: UNIX - System V > ABI Version: 0 > Type: REL (Relocatable file) > Machine: Linux BPF > Version: 0x1 > Entry point address: 0x0 > Start of program headers: 0 (bytes into file) > Start of section headers: 34704 (bytes into file) > Flags: 0x0 > Size of this header: 64 (bytes) > Size of program headers: 0 (bytes) > Number of program headers: 0 > Size of section headers: 64 (bytes) > Number of section headers: 13 > Section header string table index: 1 > > > Whereas I expect the same as bpftool I suppose, which is : > > $ LANG= readelf -h bpftool > ELF Header: > Magic: 7f 45 4c 46 01 02 01 00 00 00 00 00 00 00 00 00 > Class: ELF32 > Data: 2's complement, big endian > Version: 1 (current) > OS/ABI: UNIX - System V > ABI Version: 0 > Type: EXEC (Executable file) > Machine: PowerPC > Version: 0x1 > Entry point address: 0x100027d0 > Start of program headers: 52 (bytes into file) > Start of section headers: 1842896 (bytes into file) > Flags: 0x0 > Size of this header: 52 (bytes) > Size of program headers: 32 (bytes) > Number of program headers: 9 > Size of section headers: 40 (bytes) > Number of section headers: 39 > Section header string table index: 38 > pid_iter.bpf.o should be generated from that command in bpftool's Makefile: $(OUTPUT)%.bpf.o: skeleton/%.bpf.c $(OUTPUT)vmlinux.h \ $(LIBBPF_BOOTSTRAP) $(QUIET_CLANG)$(CLANG) \ -I$(or $(OUTPUT),.) \ -I$(srctree)/tools/include/uapi/ \ -I$(LIBBPF_BOOTSTRAP_INCLUDE) \ -g -O2 -Wall -fno-stack-protector \ -target bpf -c $< -o $@ My understanding is that "-target bpf" is supposed to pick the endianness for the host (see "llc --version | grep bpf". If that's not the case, could you please try to turn that into '-target bpfeb' in the Makefile instead? I'd be curious to see if it helps. Quentin
