Em Mon, Oct 03, 2022 at 10:56:36AM +0200, Martin Liška escreveu:
> I noticed one can't build 5.19 with latest binutils master.
>
> One see the following error:
> [ 1413s] BTF .btf.vmlinux.bin.o
> [ 1413s] Unsupported DW_TAG_unspecified_type(0x3b)
> [ 1413s] Encountered error while encoding BTF.
>
> It's caused by DWARF coming from .S files and the change is introduced since
> the following binutils revision:
>
> commit 5578fbf672ee497ea19826edeb509f4cc3e825a8
> Author: Nick Clifton <nickc@xxxxxxxxxx>
> Date: Thu Aug 25 11:48:00 2022 +0100
>
> GAS: Add a return type tag to DWARF DIEs generated for function symbols.
>
> for entry.S the output changes to:
>
> $ as-new --gdwarf-5 --64 -o entry.o entry.S && readelf -wi entry.o
> Contents of the .debug_info section:
>
> Compilation Unit @ offset 0x0:
> Length: 0x35 (32-bit)
> Version: 5
> Unit Type: DW_UT_compile (1)
> Abbrev Offset: 0x0
> Pointer Size: 8
> <0><c>: Abbrev Number: 3 (DW_TAG_unspecified_type) <--- the problematic TAG
> <0><d>: Abbrev Number: 1 (DW_TAG_compile_unit)
> <e> DW_AT_stmt_list : 0x0
> <12> DW_AT_low_pc : 0x0
> <1a> DW_AT_high_pc : 19
> <1b> DW_AT_name : (indirect string, offset: 0x0): ../arch/x86/entry/entry.S
> <1f> DW_AT_comp_dir : (indirect string, offset: 0x1a): /tmp
> <23> DW_AT_producer : (indirect string, offset: 0x1f): GNU AS 2.39.50
> <27> DW_AT_language : 32769 (MIPS assembler)
> <1><29>: Abbrev Number: 2 (DW_TAG_subprogram)
> <2a> DW_AT_name : (indirect string, offset: 0x2e): entry_ibpb
> <2e> DW_AT_external : 1
> <2e> DW_AT_type : <0xc>
> <2f> DW_AT_low_pc : 0x0
> <37> DW_AT_high_pc : 19
> <1><38>: Abbrev Number: 0
>
> Is it something pahole should handle?
So if I build with clang 14 on opensuse tumbleweed I end up with:
<2><5c234>: Abbrev Number: 0
<1><5c235>: Abbrev Number: 0
Compilation Unit @ offset 0x5c236:
Length: 0x9f (32-bit)
Version: 5
Unit Type: DW_UT_compile (1)
Abbrev Offset: 0x355b
Pointer Size: 8
<0><5c242>: Abbrev Number: 1 (DW_TAG_compile_unit)
<5c243> DW_AT_stmt_list : 0xa3b8
<5c247> DW_AT_low_pc : 0xffffffff81c22000
<5c24f> DW_AT_high_pc : 0xffffffff81c2200f
<5c257> DW_AT_name : /root/git/linux/arch/x86/entry/entry.S
<5c27e> DW_AT_comp_dir : /root/git/build/v6.0.0+binutils-latest
<5c2a5> DW_AT_producer : clang version 14.0.6
<5c2ba> DW_AT_language : 32769 (MIPS assembler)
<1><5c2bc>: Abbrev Number: 2 (DW_TAG_label)
<5c2bd> DW_AT_name : entry_ibpb
<5c2c8> DW_AT_decl_file : 0
<5c2cc> DW_AT_decl_line : 0x95
<5c2d0> DW_AT_low_pc : 0xffffffff81c22000
<1><5c2d8>: Abbrev Number: 0
clang uses DW_TAG_label for entry_ibpb, while GNU AS 2.39.50 generates
DW_TAG_subprogram.
But then the one I'm using when building with gcc, same
opensuse:tumbleweed container:
15e20ce2324a:~/git/linux # as --version
GNU assembler (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 later.
This program has absolutely no warranty.
This assembler was configured for a target of `x86_64-pc-linux-gnu'.
15e20ce2324a:~/git/linux #
Isn't producing anything for entry_ibpb :-\
- Arnaldo
