Re: Encountered error while encoding BTF due to Unsupported DW_TAG_unspecified_type(0x3b)

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Wed, Oct 05, 2022 at 11:37:13AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Wed, Oct 05, 2022 at 09:23:32AM +0200, Martin Liška escreveu:
> > On 10/4/22 23:44, Arnaldo Carvalho de Melo wrote:
> > > I assume "binutils master" means:
> > > 
> > > git://sourceware.org/git/binutils-gdb.git master?
> > 
> > Yes.
> 
> Taking notes:
> 
> Using what is in opensuse:tumbleweed it works:

So I built and installed from git://sourceware.org/git/binutils-gdb.git,
it got on /usr/local/bin, taking precedence above /usr/bin/, and didn't
get any DW_TAG_unspecified_type:

15e20ce2324a:~/git/linux # type readelf
readelf is hashed (/usr/local/bin/readelf)
15e20ce2324a:~/git/linux # /usr/local/bin/readelf -v
GNU readelf (GNU Binutils) 2.39.50.20221005
Copyright (C) 2022 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) any later version.
This program has absolutely no warranty.
15e20ce2324a:~/git/linux # rpm -q binutils
binutils-2.38-6.2.x86_64
15e20ce2324a:~/git/linux #

15e20ce2324a:~/git/linux # readelf -wi ../build/v6.0.0+binutils-latest/vmlinux|grep DW_TAG_unspecified_type
15e20ce2324a:~/git/linux #

15e20ce2324a:~/git/linux # egrep BTF\|DWARF\|PAHOLE ../build/v6.0.0+binutils-latest/.config
CONFIG_PAHOLE_VERSION=122
CONFIG_VIDEO_SONY_BTF_MPX=m
CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
# CONFIG_DEBUG_INFO_DWARF4 is not set
# CONFIG_DEBUG_INFO_DWARF5 is not set
CONFIG_DEBUG_INFO_BTF=y
CONFIG_PAHOLE_HAS_SPLIT_BTF=y
CONFIG_DEBUG_INFO_BTF_MODULES=y
# CONFIG_MODULE_ALLOW_BTF_MISMATCH is not set
15e20ce2324a:~/git/linux #


Its CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y and it ends up being
DWARF5 as its the toolchain default, at least from the
/usr/local/bin/readelf -wi output below.

Can you hand me your kernel .config file, please?


 <1><92163>: Abbrev Number: 0
  Compilation Unit @ offset 0x92164:
   Length:        0x24 (32-bit)
   Version:       5
   Unit Type:     DW_UT_compile (1)
   Abbrev Offset: 0x5555
   Pointer Size:  8
 <0><92170>: Abbrev Number: 1 (DW_TAG_compile_unit)
    <92171>   DW_AT_stmt_list   : 0x7df2
    <92175>   DW_AT_low_pc      : 0xffffffff81c62000
    <9217d>   DW_AT_high_pc     : 19
    <9217e>   DW_AT_name        : (indirect string, offset: 0x1878d): /root/git/linux/arch/x86/entry/entry.S
    <92182>   DW_AT_comp_dir    : (indirect string, offset: 0x2a): /root/git/build/v6.0.0+binutils-latest
    <92186>   DW_AT_producer    : (indirect string, offset: 0x51): GNU AS 2.38
    <9218a>   DW_AT_language    : 32769 (MIPS assembler)
  Compilation Unit @ offset 0x9218c:
   Length:        0x1f (32-bit)
   Version:       5
   Unit Type:     DW_UT_compile (1)
   Abbrev Offset: 0x5569
   Pointer Size:  8
 <0><92198>: Abbrev Number: 1 (DW_TAG_compile_unit)
    <92199>   DW_AT_stmt_list   : 0x7e43
    <9219d>   DW_AT_ranges      : 0x12e3
    <921a1>   DW_AT_name        : (indirect string, offset: 0x187b4): /root/git/linux/arch/x86/entry/entry_64.S
    <921a5>   DW_AT_comp_dir    : (indirect string, offset: 0x2a): /root/git/build/v6.0.0+binutils-latest
    <921a9>   DW_AT_producer    : (indirect string, offset: 0x51): GNU AS 2.38
    <921ad>   DW_AT_language    : 32769 (MIPS assembler)
  Compilation Unit @ offset 0x921af:
   Length:        0x1e93 (32-bit)
   Version:       5
   Unit Type:     DW_UT_compile (1)
   Abbrev Offset: 0x557b
   Pointer Size:  8
 <0><921bb>: Abbrev Number: 13 (DW_TAG_compile_unit)
    <921bc>   DW_AT_producer    : (indirect string, offset: 0x6622): GNU C11 12.1.1 20220629 [revision 7811663964aa7e31c3939b859bbfa2e16919639f] -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -m64 -mno-80387 -mno-fp-ret-in-387 -mpreferred-stack-boundary=3 -mskip-rax-setup -mtune=generic -mno-red-zone -mcmodel=kernel -mindirect-branch=thunk-extern -mindirect-branch-register -mindirect-branch-cs-prefix -mfunction-return=thunk-extern -mharden-sls=all -mrecord-mcount -mfentry -march=x86-64 -g -O2 -std=gnu11 -p -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -fcf-protection=none -falign-jumps=1 -falign-loops=1 -fno-asynchronous-unwind-tables -fno-jump-tables -fno-delete-null-pointer-checks -fno-allow-store-data-races -fstack-protector-strong -fno-stack-clash-protection -fzero-call-used-regs=used-gpr -fno-strict-overflow -fstack-check=no -fconserve-stack
    <921c0>   DW_AT_language    : 29    (C11)
    <921c1>   DW_AT_name        : (indirect line string, offset: 0x14b6): /root/git/linux/arch/x86/entry/syscall_64.c
    <921c5>   DW_AT_comp_dir    : (indirect line string, offset: 0): /root/git/build/v6.0.0+binutils-latest
    <921c9>   DW_AT_stmt_list   : 0x8110
 <1><921cd>: Abbrev Number: 6 (DW_TAG_base_type)
    <921ce>   DW_AT_byte_size   : 8
    <921cf>   DW_AT_encoding    : 7     (unsigned)
    <921d0>   DW_AT_name        : (indirect string, offset: 0x4dc4): long unsigned int