Le 17/01/2023 à 15:41, Quentin Monnet a écrit :

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2023-01-17 14:25 UTC+0000 ~ Christophe Leroy [off-list ref]

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Le 17/01/2023 à 15:18, Tonghao Zhang a écrit :

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On Jan 17, 2023, at 7:36 PM, Christophe Leroy [off-list ref] wrote:



Le 17/01/2023 à 08:30, Christophe Leroy a écrit :

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Le 17/01/2023 à 06:30, Tonghao Zhang a écrit :

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On Jan 9, 2023, at 4:15 PM, Christophe Leroy
[off-list ref] wrote:

[...]

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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@arm.com/#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!

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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);

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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.

I guess it cannot work if it picks the endianness for the build host. It 
should pick the endianness for the target host.

That's worse it seems with bpfeb : it fails at build :

   LINK    /home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/bpftool
   GEN     vmlinux.h
   CLANG   pid_iter.bpf.o
   GEN     pid_iter.skel.h
libbpf: elf: endianness mismatch in pid_iter_bpf.
Error: failed to open BPF object file: Endian mismatch
make: *** [Makefile:222: pid_iter.skel.h] Error 93


Complete build in case it helps:

$ LANG= make CROSS_COMPILE=ppc-linux- ARCH=powerpc

Auto-detecting system features:
...                         clang-bpf-co-re: [ on  ]
...                                    llvm: [ OFF ]
...                                  libcap: [ OFF ]
...                                  libbfd: [ OFF ]

   MKDIR   /home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/
make[1]: Entering directory '/home/chleroy/linux-powerpc/tools/lib/bpf'
   GEN 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/bpf_helper_defs.h
   MKDIR   /home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/libbpf.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/bpf.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/nlattr.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/btf.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/libbpf_errno.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/str_error.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/netlink.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/bpf_prog_linfo.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/libbpf_probes.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/hashmap.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/btf_dump.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/ringbuf.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/strset.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/linker.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/gen_loader.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/relo_core.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/usdt.o
   LD 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/staticobjs/libbpf-in.o
   LINK    /home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/libbpf.a
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/bpf.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/libbpf.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/btf.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/libbpf_common.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/libbpf_legacy.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/bpf_helpers.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/bpf_tracing.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/bpf_endian.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/bpf_core_read.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/skel_internal.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/libbpf_version.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/usdt.bpf.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/bpf_helper_defs.h
   INSTALL libbpf_headers
make[1]: Leaving directory '/home/chleroy/linux-powerpc/tools/lib/bpf'
   MKDIR   /home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/hashmap.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/nlattr.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/relo_core.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/libbpf/include/bpf/libbpf_internal.h
   CC      btf.o
   CC      btf_dumper.o
   CC      cfg.o
   CC      cgroup.o
   CC      common.o
   CC      feature.o
   CC      gen.o
   CC      iter.o
   CC      json_writer.o
   CC      link.o
   CC      main.o
   CC      map.o
   CC      map_perf_ring.o
   CC      net.o
   CC      netlink_dumper.o
   CC      perf.o
   MKDIR 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/hashmap.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/relo_core.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/libbpf_internal.h
   MKDIR   /home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/
   MKDIR   /home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/
make[1]: Entering directory '/home/chleroy/linux-powerpc/tools/lib/bpf'
   GEN 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/bpf_helper_defs.h
   MKDIR 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/libbpf.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/bpf.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/nlattr.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/btf.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/libbpf_errno.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/str_error.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/netlink.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/bpf_prog_linfo.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/libbpf_probes.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/hashmap.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/btf_dump.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/ringbuf.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/strset.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/linker.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/gen_loader.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/relo_core.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/usdt.o
   LD 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/staticobjs/libbpf-in.o
   LINK 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/libbpf.a
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/bpf.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/libbpf.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/btf.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/libbpf_common.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/libbpf_legacy.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/bpf_helpers.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/bpf_tracing.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/bpf_endian.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/bpf_core_read.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/skel_internal.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/libbpf_version.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/usdt.bpf.h
   INSTALL 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/libbpf/include/bpf/bpf_helper_defs.h
   INSTALL libbpf_headers
make[1]: Leaving directory '/home/chleroy/linux-powerpc/tools/lib/bpf'
   CC      /home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/main.o
   CC      /home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/common.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/json_writer.o
   CC      /home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/gen.o
   CC      /home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/btf.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/xlated_dumper.o
   CC 
/home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/btf_dumper.o
   CC      /home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/disasm.o
   LINK    /home/chleroy/linux-powerpc/tools/bpf/bpftool/bootstrap/bpftool
   GEN     vmlinux.h
   CLANG   pid_iter.bpf.o
   GEN     pid_iter.skel.h
libbpf: elf: endianness mismatch in pid_iter_bpf.
Error: failed to open BPF object file: Endian mismatch
make: *** [Makefile:222: pid_iter.skel.h] Error 93