Re: [PATCH dwarves 0/2] dwarf_loader: improve cus__merging_cu()

[Yonghong Song <yhs@fb.com>]

On 4/6/21 10:03 AM, Arnaldo Carvalho de Melo wrote:
> Em Tue, Apr 06, 2021 at 01:59:30PM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Tue, Apr 06, 2021 at 01:55:54PM -0300, Arnaldo Carvalho de Melo escreveu:
>>> Em Tue, Apr 06, 2021 at 01:40:20PM -0300, Arnaldo Carvalho de Melo escreveu:
>>>> Em Tue, Apr 06, 2021 at 10:22:37AM -0300, Arnaldo Carvalho de Melo escreveu:
>>>>> I'm seeing these here:
>>>
>>>>> [acme@five bpf]$ rm -f ../build/bpf_clang_thin_lto/*vmlinu*
>>>>> [acme@five bpf]$ time make -j28 LLVM=1 LLVM_IAS=1 O=../build/bpf_clang_thin_lto/ vmlinux
>>>>> make[1]: Entering directory '/home/acme/git/build/bpf_clang_thin_lto'
>>>>>    GEN     Makefile
>>>>>    DESCEND  objtool
>>>>>    DESCEND  bpf/resolve_btfids
>>>>>    CALL    /home/acme/git/bpf/scripts/atomic/check-atomics.sh
>>>>>    CALL    /home/acme/git/bpf/scripts/checksyscalls.sh
>>>>>    CHK     include/generated/compile.h
>>>>>    GEN     .version
>>>>>    CHK     include/generated/compile.h
>>>>>    UPD     include/generated/compile.h
>>>>>    CC      init/version.o
>>>>>    AR      init/built-in.a
>>>>>    GEN     .tmp_initcalls.lds
>>>>>    LTO     vmlinux.o
>>>>>    OBJTOOL vmlinux.o
>>>>> vmlinux.o: warning: objtool: aesni_gcm_init_avx_gen2()+0x12: unsupported stack pointer realignment
>>>>> vmlinux.o: warning: objtool: aesni_gcm_enc_update_avx_gen2()+0x12: unsupported stack pointer realignment
>>>>> vmlinux.o: warning: objtool: aesni_gcm_dec_update_avx_gen2()+0x12: unsupported stack pointer realignment
>>>>> vmlinux.o: warning: objtool: aesni_gcm_finalize_avx_gen2()+0x12: unsupported stack pointer realignment
>>>>> vmlinux.o: warning: objtool: aesni_gcm_init_avx_gen4()+0x12: unsupported stack pointer realignment
>>>>> vmlinux.o: warning: objtool: aesni_gcm_enc_update_avx_gen4()+0x12: unsupported stack pointer realignment
>>>>> vmlinux.o: warning: objtool: aesni_gcm_dec_update_avx_gen4()+0x12: unsupported stack pointer realignment
>>>>> vmlinux.o: warning: objtool: aesni_gcm_finalize_avx_gen4()+0x12: unsupported stack pointer realignment
>>>>>    MODPOST vmlinux.symvers
>>>>>    MODINFO modules.builtin.modinfo
>>>>>    GEN     modules.builtin
>>>>>    LD      .tmp_vmlinux.btf
>>>>>    BTF     .btf.vmlinux.bin.o
>>>>>    LD      .tmp_vmlinux.kallsyms1
>>>>>    KSYMS   .tmp_vmlinux.kallsyms1.S
>>>>>    AS      .tmp_vmlinux.kallsyms1.S
>>>>>    LD      .tmp_vmlinux.kallsyms2
>>>>>    KSYMS   .tmp_vmlinux.kallsyms2.S
>>>>>    AS      .tmp_vmlinux.kallsyms2.S
>>>>>    LD      vmlinux
>>>>>    BTFIDS  vmlinux
>>>>> WARN: multiple IDs found for 'inode': 232, 28822 - using 232
>>>>> WARN: multiple IDs found for 'file': 374, 28855 - using 374
>>>>> WARN: multiple IDs found for 'path': 379, 28856 - using 379
>>>>> WARN: multiple IDs found for 'vm_area_struct': 177, 28929 - using 177
>>>>> WARN: multiple IDs found for 'task_struct': 97, 28966 - using 97
>>>>> WARN: multiple IDs found for 'seq_file': 510, 29059 - using 510
>>>>> WARN: multiple IDs found for 'inode': 232, 29345 - using 232
>>>>> WARN: multiple IDs found for 'file': 374, 29429 - using 374
>>>>> WARN: multiple IDs found for 'path': 379, 29430 - using 379
>>>>> WARN: multiple IDs found for 'vm_area_struct': 177, 29471 - using 177
>>>>> WARN: multiple IDs found for 'task_struct': 97, 29481 - using 97
>>>>> WARN: multiple IDs found for 'seq_file': 510, 29512 - using 510
>>>>>    SORTTAB vmlinux
>>>>>    SYSMAP  System.map
>>>>> make[1]: Leaving directory '/home/acme/git/build/bpf_clang_thin_lto'
>>>>>
>>>>> [acme@five pahole]$ clang -v
>>>>> clang version 11.0.0 (Fedora 11.0.0-2.fc33)

This could be due to the compiler. The clang 11 is used here. Sedat is
using clang 12 and didn't see warnings and I am using clang dev branch 
(clang 13) and didn't see warnings either. clang 11 could generate
some debuginfo where pahole didn't handle it properly.

I tried to build locally with clang 11 but it crashed as I enabled
assert during compiler build. Will try a little bit more.

>>>>> Target: x86_64-unknown-linux-gnu
>>>>> Thread model: posix
>>>>> InstalledDir: /usr/bin
>>>>> Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-redhat-linux/10
>>>>> Found candidate GCC installation: /usr/lib/gcc/x86_64-redhat-linux/10
>>>>> Selected GCC installation: /usr/lib/gcc/x86_64-redhat-linux/10
>>>>> Candidate multilib: .;@m64
>>>>> Candidate multilib: 32;@m32
>>>>> Selected multilib: .;@m64
>>>>> [acme@five pahole]$
>>>>>
>>>>> [acme@five bpf]$ git log --oneline -10
>>>>> 49b9da70941c3c8a (HEAD -> bpf_perf_enable) kbuild: add an elfnote with type BUILD_COMPILER_LTO_INFO
>>>>> 5c4f082a143c786e kbuild: move LINUX_ELFNOTE_BUILD_SALT to elfnote.h
>>>>> 42c8b565decb3662 bpf: Introduce helpers to enable/disable perf event fds in a map
>>>>> f73ea1eb4cce6637 (bpf-next/master, bpf-next/for-next) bpf: selftests: Specify CONFIG_DYNAMIC_FTRACE in the testing config
>>>>> f07669df4c8df0b7 libbpf: Remove redundant semi-colon
>>>>> 6ac4c6f887f5a8ef bpf: Remove repeated struct btf_type declaration
>>>>> 2daae89666ad2532 bpf, cgroup: Delete repeated struct bpf_prog declaration
>>>>> 2ec9898e9c70b93a bpf: Remove unused parameter from ___bpf_prog_run
>>>>> 007bdc12d4b46656 bpf, selftests: test_maps generating unrecognized data section
>>>>> 82506665179209e4 tcp: reorder tcp_congestion_ops for better cache locality
>>>>> [acme@five bpf]$
>>>>>
>>>>> I'll try after a 'make mrproper'
>>>>
>>>> Same thing, trying now with gcc.
>>>
>>> With gcc no such messages:
>>>
>>>    CC [M]  drivers/gpu/drm/nouveau/nv84_fence.o
>>>    CC [M]  drivers/gpu/drm/nouveau/nvc0_fence.o
>>>    LD [M]  drivers/gpu/drm/nouveau/nouveau.o
>>>    AR      drivers/gpu/built-in.a
>>>    AR      drivers/built-in.a
>>>    GEN     .version
>>>    CHK     include/generated/compile.h
>>>    LD      vmlinux.o
>>>    MODPOST vmlinux.symvers
>>>    MODINFO modules.builtin.modinfo
>>>    GEN     modules.builtin
>>>    LD      .tmp_vmlinux.btf
>>>    BTF     .btf.vmlinux.bin.o
>>>    LD      .tmp_vmlinux.kallsyms1
>>>    KSYMS   .tmp_vmlinux.kallsyms1.S
>>>    AS      .tmp_vmlinux.kallsyms1.S
>>>    LD      .tmp_vmlinux.kallsyms2
>>>    KSYMS   .tmp_vmlinux.kallsyms2.S
>>>    AS      .tmp_vmlinux.kallsyms2.S
>>>    LD      vmlinux
>>>    BTFIDS  vmlinux
>>>    SORTTAB vmlinux
>>>    SYSMAP  System.map
>>>    HOSTCC  arch/x86/tools/insn_decoder_test
>>>    HOSTCC  arch/x86/tools/insn_sanity
>>>    MODPOST Module.symvers
>>>    TEST    posttest
>>>    CC [M]  arch/x86/crypto/aegis128-aesni.mod.o
>>>    CC [M]  arch/x86/crypto/blake2s-x86_64.mod.o
>>>
>>> Now will try with clang non-LTO.
>>
>> Works:
>>
>>    AR      drivers/usb/built-in.a
>>    AR      lib/built-in.a
>>    AR      drivers/md/built-in.a
>>    AR      drivers/built-in.a
>>    GEN     .version
>>    CHK     include/generated/compile.h
>>    LD      vmlinux.o
>>    MODPOST vmlinux.symvers
>>    MODINFO modules.builtin.modinfo
>>    GEN     modules.builtin
>>    LD      .tmp_vmlinux.btf
>>    BTF     .btf.vmlinux.bin.o
>>    LD      .tmp_vmlinux.kallsyms1
>>    KSYMS   .tmp_vmlinux.kallsyms1.S
>>    AS      .tmp_vmlinux.kallsyms1.S
>>    LD      .tmp_vmlinux.kallsyms2
>>    KSYMS   .tmp_vmlinux.kallsyms2.S
>>    AS      .tmp_vmlinux.kallsyms2.S
>>    LD      vmlinux
>>    BTFIDS  vmlinux
>>    SORTTAB vmlinux
>>    SYSMAP  System.map
>> make[1]: Leaving directory '/home/acme/git/build/bpf_clang_no_lto'
>>
>> [acme@five bpf]$ grep LTO ../build/bpf_clang_no_lto/.config
>> CONFIG_ARCH_SUPPORTS_LTO_CLANG=y
>> CONFIG_ARCH_SUPPORTS_LTO_CLANG_THIN=y
>> CONFIG_LTO_NONE=y
>> CONFIG_HID_WALTOP=m
>> [acme@five bpf]$
> 
> Sorry, I forgot to use clang on this no-lto build... doing it now with:
> 
> [acme@five bpf]$ grep LTO ../build/bpf_clang_no_lto/.config
> CONFIG_ARCH_SUPPORTS_LTO_CLANG=y
> CONFIG_ARCH_SUPPORTS_LTO_CLANG_THIN=y
> CONFIG_HAS_LTO_CLANG=y
> CONFIG_LTO_NONE=y
> # CONFIG_LTO_CLANG_FULL is not set
> # CONFIG_LTO_CLANG_THIN is not set
> CONFIG_HID_WALTOP=m
> [acme@five bpf]$
> [acme@five bpf]$ make -j28 LLVM=1 LLVM_IAS=1 O=../build/bpf_clang_no_lto/ vmlinux
> 
> - Arnaldo
> 
>