Em Wed, Sep 28, 2022 at 08:25:51AM -0700, Nathan Chancellor escreveu:
> On Wed, Sep 28, 2022 at 10:42:53AM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Tue, Sep 27, 2022 at 12:59:03PM -0700, Nathan Chancellor escreveu:
> > > On Tue, Sep 27, 2022 at 04:08:02PM -0300, Arnaldo Carvalho de Melo wrote:
> > > > Em Tue, Sep 27, 2022 at 11:56:34AM -0700, Nathan Chancellor escreveu:
> > > > > When building a kernel with LLVM and CONFIG_DEBUG_INFO_BTF after commit
> > > > > 32ef9e5054ec ("Makefile.debug: re-enable debug info for .S files") in
> > > > > the kernel, I see the following spew of warnings, which appear to come
> > > > > from pahole:
> > > > >
> > > > > $ clang --version
> > > > > clang version 15.0.0 (Fedora 15.0.0-3.fc38)
> > > > > Target: x86_64-redhat-linux-gnu
> > > > > Thread model: posix
> > > > > InstalledDir: /usr/bin
> > > > >
> > > > > $ pahole --version
> > > > > v1.24
> > > > >
> > > > > $ make -skj"$(nproc)" ARCH=x86_64 LLVM=1 defconfig
> > > > >
> > > > > $ scripts/config \
> > > > > -d DEBUG_INFO_NONE \
> > > > > -e BPF_SYSCALL \
> > > > > -e DEBUG_INFO_BTF \
> > > > > -e DEBUG_INFO_DWARF5
> > > > >
> > > > > $ make -skj"$(nproc)" ARCH=x86_64 LLVM=1 olddefconfig all
> > > > > ...
> > > > > die__process_unit: DW_TAG_label (0xa) @ <0x7b> not handled!
> > > > > die__process_unit: tag not supported 0xa (label)!
> > > > > die__process_unit: DW_TAG_label (0xa) @ <0x97> not handled!
> > > > > die__process_unit: DW_TAG_label (0xa) @ <0xbd> not handled!
> > > > > die__process_unit: DW_TAG_label (0xa) @ <0xed> not handled!
> > > > > die__process_unit: DW_TAG_label (0xa) @ <0x109> not handled!
> > > > > die__process_unit: DW_TAG_label (0xa) @ <0x12a> not handled!
> > > > > die__process_unit: DW_TAG_label (0xa) @ <0x146> not handled!
> > > > > die__process_unit: DW_TAG_label (0xa) @ <0x16f> not handled!
> > > > > ...
> > > > >
> > > > > Is this a problem with LLVM or pahole? I do not see this when building
> > > > > with GCC + GNU as but that could just be a red herring. I assume that
> > > > > there could be something missing for processing debug info from
> > > > > assembly, perhaps? If there is any further information I can provide or
> > > > > anything I can test, I am more than happy to do so.
> > > >
> > > > I'll try to repro, but at first sight it looks like a label in a
> > >
> > > If you need help reproducing this locally, feel free to reach out
> > > through this thread or #clangbuiltlinux on Libera.
> >
> > Can you please provide the vmlinux file where this takes place?
>
> Sure thing, it is compressed to save some bandwidth while downloading:
>
> https://1drv.ms/u/s!AsQNYeB-IEbqnnzsULjM1pXmOlI5?e=qHKjuW
>
> If there is anything else I can provide, please let me know!
Interesting, indeed it is inside a DW_TAG_compile_unit, outside
functions, so pahole has no use for it right now, I'll just ignore it
and remove that warning.
These are for arch/x86/kernel/verify_cpu.S, asm file indeed.
⬢[acme@toolbox Nathan]$ readelf -wi vmlinux-pahole-warnings
Contents of the .debug_info section:
Compilation Unit @ offset 0x0:
Length: 0x1df (32-bit)
Version: 5
Unit Type: DW_UT_compile (1)
Abbrev Offset: 0x0
Pointer Size: 8
<0><c>: Abbrev Number: 1 (DW_TAG_compile_unit)
<d> DW_AT_stmt_list : 0x0
<11> DW_AT_ranges : 0xc
<15> DW_AT_name : arch/x86/kernel/verify_cpu.S
<32> DW_AT_comp_dir : /home/nathan/cbl/src/linux
<4d> DW_AT_producer : ClangBuiltLinux clang version 16.0.0 (https://github.com/llvm/llvm-project 7e22179d38c438fedb0d9bb0cff1585843bd7082)
<c2> DW_AT_language : 32769 (MIPS assembler)
<1><c4>: Abbrev Number: 2 (DW_TAG_label)
<c5> DW_AT_name : startup_64
<d0> DW_AT_decl_file : 0x0
<d4> DW_AT_decl_line : 0x364
<d8> DW_AT_low_pc : 0xffffffff81000000
<1><e0>: Abbrev Number: 2 (DW_TAG_label)
<e1> DW_AT_name : secondary_startup_64
<f6> DW_AT_decl_file : 0x0
<fa> DW_AT_decl_line : 0x399
<fe> DW_AT_low_pc : 0xffffffff81000060
<1><106>: Abbrev Number: 2 (DW_TAG_label)
<107> DW_AT_name : secondary_startup_64_no_verify
<126> DW_AT_decl_file : 0x0
<12a> DW_AT_decl_line : 0x39f
<12e> DW_AT_low_pc : 0xffffffff81000065
<1><136>: Abbrev Number: 2 (DW_TAG_label)
<137> DW_AT_name : verify_cpu
<142> DW_AT_decl_file : 0x0
<146> DW_AT_decl_line : 0x430
<14a> DW_AT_low_pc : 0xffffffff81000150
<1><152>: Abbrev Number: 2 (DW_TAG_label)
<153> DW_AT_name : sev_verify_cbit
<163> DW_AT_decl_file : 0x1
<167> DW_AT_decl_line : 0x491
<16b> DW_AT_low_pc : 0xffffffff81000250
<1><173>: Abbrev Number: 2 (DW_TAG_label)
<174> DW_AT_name : start_cpu0
<17f> DW_AT_decl_file : 0x2
<183> DW_AT_decl_line : 0x49e
<187> DW_AT_low_pc : 0xffffffff81000260
<1><18f>: Abbrev Number: 2 (DW_TAG_label)
<190> DW_AT_name : early_idt_handler_array
<1a8> DW_AT_decl_file : 0x0
<1ac> DW_AT_decl_line : 0x4ad
<1b0> DW_AT_low_pc : 0xffffffff83796000
<1><1b8>: Abbrev Number: 2 (DW_TAG_label)
<1b9> DW_AT_name : early_idt_handler_common
<1d2> DW_AT_decl_file : 0x0
<1d6> DW_AT_decl_line : 0x4c1
<1da> DW_AT_low_pc : 0xffffffff83796120
<BIG SNIP>
