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* Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
       [not found]       ` <CABtf2+RdH0dh3NyARWSOzig8euHK33h+0jL1zsey9V1HjjzB9w@mail.gmail.com>
@ 2021-01-14  6:18         ` Sedat Dilek
  2021-01-14  7:09           ` Sedat Dilek
                             ` (2 more replies)
  0 siblings, 3 replies; 13+ messages in thread
From: Sedat Dilek @ 2021-01-14  6:18 UTC (permalink / raw)
  To: Caroline Tice
  Cc: Nick Desaulniers, Masahiro Yamada, Arvind Sankar, Jakub Jelinek,
	Fangrui Song, Clang-Built-Linux ML, Nick Clifton, bpf,
	Andrii Nakryiko, Jiri Olsa

On Wed, Jan 13, 2021 at 11:25 PM Caroline Tice <cmtice@google.com> wrote:
>
>
>
>
>
> On Tue, Jan 12, 2021 at 3:17 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>>
>> On Mon, Jan 11, 2021 at 9:27 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>> >
>> > On Fri, Dec 4, 2020 at 2:11 AM 'Nick Desaulniers' via Clang Built
>> > Linux <clang-built-linux@googlegroups.com> wrote:
>> > >
>> > > DWARF v5 is the latest standard of the DWARF debug info format.
>> > >
>> > > DWARF5 wins significantly in terms of size when mixed with compression
>> > > (CONFIG_DEBUG_INFO_COMPRESSED).
>> > >
>> >
>> > Is this patchset bulletproof with CONFIG_DEBUG_INFO_BTF=y (and clang-cfi)?
>> >
>> > Debian has enabled this Kconfig in recent Linux v5.10 kernels which is
>> > a base for my custom kernels.
>> >
>> > It was fu**ing annoying to see I have no pahole binary installed and
>> > my build got broken after 3 hours of build.
>> > OK, I see that requirements is coded in scripts/link-vmlinux.sh.
>> >
>> > I needed to install dwarves package which provides pahole binary.
>> >
>> > I would like to see a prereq-checking for needed binaries with certain
>> > Kconfig set.
>> >
>> > After I calmed down I will - maybe - write to linux-kbuild mailing-list.
>> > Hope this will be a friendly email.
>> >
>>
>> After linux-bpf folks recommended not to use LLVM I jumped to gcc-10.
>>
>> I tried with ld.bfd first and then in a next run with LLVM=1.
>>
>> Upgraded pahole binary to latest Git plus a recommended patch from
>> linux-btf folks.
>>
>> Unfortunately, I see with CONFIG_DEBUG_INFO_DWARF5=y and
>> CONFIG_DEBUG_INFO_BTF=y:
>>
>> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x3f0dd5a> not handled!
>> die__process_function: DW_TAG_INVALID (0x48) @ <0x3f0dd69> not handled!
>>
>> In /usr/include/dwarf.h I found:
>>
>> 498:    DW_OP_lit24 = 0x48,                /* Literal 24.  *
>
>
> There are multiple dwarf objects with the value 0x48, depending on which section of the dwarf.h file you search:
>
> DW_TAG_call_site = 0x48
> DW_AT_static_link = 0x48
> DW_OP_lit24 = 0x48.
>
> In this case, since the error message was about a DW_TAG, it would be complaining about DW_TAG_call_site, which is new to DWARR v5.
>

[ CC linux-bpf & Andrii and Jiri ]

Thanks for your feedback Caroline.

I ran several builds in the last 24 hours with Linux v5.11-rc3.

Setting DWARF version 2 (CONFIG_DEBUG_INFO_DWARF2=y) or version 4
(CONFIG_DEBUG_INFO_DWARF4=y) with this patchset together with GCC
v10.2.1 plus LLVM=1 does NOT show this.
BTW, it does not matter when LLVM/Clang v12 and LLVM/Clang v11 is used.
But again my compiler is here GCC plus LLVM utils like llvm-objcopy,
ld.lld, lllvm-ar, llvm-nm, etc.
( My initial problem was also seen with Clang v11.0.1 - I switched to
GCC as Debian's linux-kernel uses CONFIG_DEBUG_INFO_BTF=y
successfully. )

So, this is definitely a DWARF version 5 issue when
CONFIG_DEBUG_INFO_BTF=y (and CONFIG_DEBUG_INFO_BTF_MODULES=y).

Furthermore, my build-log says with pahole (see post-scriptum) from
dwarves package - here as an example:

WARN: multiple IDs found for 'bpf_map': 3860, 369255 - using 3860

$ grep 'WARN: multiple IDs found for'
build-log_5.11.0-rc3-6-amd64-gcc10-llvm11.txt | wc -l
1621

In the Linux code this derives from tools/bpf/resolve_btfids:

static int symbols_resolve(struct object *obj)
...
                                pr_info("WARN: multiple IDs found for
'%s': %d, %d - using %d\n",

( Cut-n-paste into Gmail truncates the lines and indentation, so I dropped it. )

Please see:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/bpf/resolve_btfids/main.c#n469
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/bpf/resolve_btfids/main.c#n532

I looked with llvm-dwarf tool and saw some errors concerning
".debug-ranges" (cannot remember the exact output and the command-line
I used).

Example for "DW_TAG_INVALID (0x48)" from my build-log:

die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x1f671e7> not handled!

$ llvm-dwarfdump-11 --debug-info=0x1f671e7 vmlinux
vmlinux:        file format elf64-x86-64

.debug_info contents:

0x01f671e7: DW_TAG_call_site
             DW_AT_call_return_pc      (0xffffffff811b16f2)
             DW_AT_call_origin (0x01f67f1d)

Looking for "DW_AT_call_origin (0x01f67f1d)":

$ llvm-dwarfdump-11 --debug-info=0x01f67f1d vmlinux
vmlinux:        file format elf64-x86-64

.debug_info contents:

0x01f67f1d: DW_TAG_subprogram
             DW_AT_external    (true)
             DW_AT_declaration (true)
             DW_AT_linkage_name        ("fput")
             DW_AT_name        ("fput")
             DW_AT_decl_file
("/home/dileks/src/linux-kernel/git/./include/linux/file.h")
             DW_AT_decl_line   (16)
             DW_AT_decl_column (0x0d)

I have no experience in digging into DWARF (version 5) issues and how
to use llvm-dwarf or another appropriate tool.
If you give me a hand...
So all the above says - to be honest - nothing to me.
I hope it says something to you experts.

Regards,
- Sedat -

P.S.: I tried with a selfmade pahole from latest Git plus Jiri's v2
patch of "btf_encoder: Add extra checks for symbol names".

link="https://lore.kernel.org/bpf/20210113102509.1338601-1-jolsa@kernel.org/T/#t
b4 -d am $link
...
Wrote v2_20210113_jolsa_btf_encoder_add_extra_checks_for_symbol_names.am
for thanks tracking

[1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/

>>
>>
>> Can someone enlighten what is going on?
>>
>> Nick, Fangrui?
>>
>> Thanks.
>>
>> - Sedat -
>>
>> P.S.: Patch from linux-bpf
>>
>> link="https://lore.kernel.org/bpf/20210112194724.GB1291051@krava/T/#t"
>> b4 -d am $link
>>
>> - EOT -

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
  2021-01-14  6:18         ` [PATCH v3 0/2] Kbuild: DWARF v5 support Sedat Dilek
@ 2021-01-14  7:09           ` Sedat Dilek
  2021-01-14  9:36           ` Sedat Dilek
  2021-01-14 18:53           ` Nick Desaulniers
  2 siblings, 0 replies; 13+ messages in thread
From: Sedat Dilek @ 2021-01-14  7:09 UTC (permalink / raw)
  To: Caroline Tice
  Cc: Nick Desaulniers, Masahiro Yamada, Arvind Sankar, Jakub Jelinek,
	Fangrui Song, Clang-Built-Linux ML, Nick Clifton, bpf,
	Andrii Nakryiko, Jiri Olsa

On Thu, Jan 14, 2021 at 7:18 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>
> On Wed, Jan 13, 2021 at 11:25 PM Caroline Tice <cmtice@google.com> wrote:
> >
> >
> >
> >
> >
> > On Tue, Jan 12, 2021 at 3:17 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >>
> >> On Mon, Jan 11, 2021 at 9:27 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >> >
> >> > On Fri, Dec 4, 2020 at 2:11 AM 'Nick Desaulniers' via Clang Built
> >> > Linux <clang-built-linux@googlegroups.com> wrote:
> >> > >
> >> > > DWARF v5 is the latest standard of the DWARF debug info format.
> >> > >
> >> > > DWARF5 wins significantly in terms of size when mixed with compression
> >> > > (CONFIG_DEBUG_INFO_COMPRESSED).
> >> > >
> >> >
> >> > Is this patchset bulletproof with CONFIG_DEBUG_INFO_BTF=y (and clang-cfi)?
> >> >
> >> > Debian has enabled this Kconfig in recent Linux v5.10 kernels which is
> >> > a base for my custom kernels.
> >> >
> >> > It was fu**ing annoying to see I have no pahole binary installed and
> >> > my build got broken after 3 hours of build.
> >> > OK, I see that requirements is coded in scripts/link-vmlinux.sh.
> >> >
> >> > I needed to install dwarves package which provides pahole binary.
> >> >
> >> > I would like to see a prereq-checking for needed binaries with certain
> >> > Kconfig set.
> >> >
> >> > After I calmed down I will - maybe - write to linux-kbuild mailing-list.
> >> > Hope this will be a friendly email.
> >> >
> >>
> >> After linux-bpf folks recommended not to use LLVM I jumped to gcc-10.
> >>
> >> I tried with ld.bfd first and then in a next run with LLVM=1.
> >>
> >> Upgraded pahole binary to latest Git plus a recommended patch from
> >> linux-btf folks.
> >>
> >> Unfortunately, I see with CONFIG_DEBUG_INFO_DWARF5=y and
> >> CONFIG_DEBUG_INFO_BTF=y:
> >>
> >> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x3f0dd5a> not handled!
> >> die__process_function: DW_TAG_INVALID (0x48) @ <0x3f0dd69> not handled!
> >>
> >> In /usr/include/dwarf.h I found:
> >>
> >> 498:    DW_OP_lit24 = 0x48,                /* Literal 24.  *
> >
> >
> > There are multiple dwarf objects with the value 0x48, depending on which section of the dwarf.h file you search:
> >
> > DW_TAG_call_site = 0x48
> > DW_AT_static_link = 0x48
> > DW_OP_lit24 = 0x48.
> >
> > In this case, since the error message was about a DW_TAG, it would be complaining about DW_TAG_call_site, which is new to DWARR v5.
> >
>
> [ CC linux-bpf & Andrii and Jiri ]
>
> Thanks for your feedback Caroline.
>
> I ran several builds in the last 24 hours with Linux v5.11-rc3.
>
> Setting DWARF version 2 (CONFIG_DEBUG_INFO_DWARF2=y) or version 4
> (CONFIG_DEBUG_INFO_DWARF4=y) with this patchset together with GCC
> v10.2.1 plus LLVM=1 does NOT show this.
> BTW, it does not matter when LLVM/Clang v12 and LLVM/Clang v11 is used.
> But again my compiler is here GCC plus LLVM utils like llvm-objcopy,
> ld.lld, lllvm-ar, llvm-nm, etc.
> ( My initial problem was also seen with Clang v11.0.1 - I switched to
> GCC as Debian's linux-kernel uses CONFIG_DEBUG_INFO_BTF=y
> successfully. )
>

I have to correct myself:
The used assembler within my GCC experiments is GNU/ld BFD version
v2.35.1 - not LLD linker!

- Sedat -

> So, this is definitely a DWARF version 5 issue when
> CONFIG_DEBUG_INFO_BTF=y (and CONFIG_DEBUG_INFO_BTF_MODULES=y).
>
> Furthermore, my build-log says with pahole (see post-scriptum) from
> dwarves package - here as an example:
>
> WARN: multiple IDs found for 'bpf_map': 3860, 369255 - using 3860
>
> $ grep 'WARN: multiple IDs found for'
> build-log_5.11.0-rc3-6-amd64-gcc10-llvm11.txt | wc -l
> 1621
>
> In the Linux code this derives from tools/bpf/resolve_btfids:
>
> static int symbols_resolve(struct object *obj)
> ...
>                                 pr_info("WARN: multiple IDs found for
> '%s': %d, %d - using %d\n",
>
> ( Cut-n-paste into Gmail truncates the lines and indentation, so I dropped it. )
>
> Please see:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/bpf/resolve_btfids/main.c#n469
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/bpf/resolve_btfids/main.c#n532
>
> I looked with llvm-dwarf tool and saw some errors concerning
> ".debug-ranges" (cannot remember the exact output and the command-line
> I used).
>
> Example for "DW_TAG_INVALID (0x48)" from my build-log:
>
> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x1f671e7> not handled!
>
> $ llvm-dwarfdump-11 --debug-info=0x1f671e7 vmlinux
> vmlinux:        file format elf64-x86-64
>
> .debug_info contents:
>
> 0x01f671e7: DW_TAG_call_site
>              DW_AT_call_return_pc      (0xffffffff811b16f2)
>              DW_AT_call_origin (0x01f67f1d)
>
> Looking for "DW_AT_call_origin (0x01f67f1d)":
>
> $ llvm-dwarfdump-11 --debug-info=0x01f67f1d vmlinux
> vmlinux:        file format elf64-x86-64
>
> .debug_info contents:
>
> 0x01f67f1d: DW_TAG_subprogram
>              DW_AT_external    (true)
>              DW_AT_declaration (true)
>              DW_AT_linkage_name        ("fput")
>              DW_AT_name        ("fput")
>              DW_AT_decl_file
> ("/home/dileks/src/linux-kernel/git/./include/linux/file.h")
>              DW_AT_decl_line   (16)
>              DW_AT_decl_column (0x0d)
>
> I have no experience in digging into DWARF (version 5) issues and how
> to use llvm-dwarf or another appropriate tool.
> If you give me a hand...
> So all the above says - to be honest - nothing to me.
> I hope it says something to you experts.
>
> Regards,
> - Sedat -
>
> P.S.: I tried with a selfmade pahole from latest Git plus Jiri's v2
> patch of "btf_encoder: Add extra checks for symbol names".
>
> link="https://lore.kernel.org/bpf/20210113102509.1338601-1-jolsa@kernel.org/T/#t
> b4 -d am $link
> ...
> Wrote v2_20210113_jolsa_btf_encoder_add_extra_checks_for_symbol_names.am
> for thanks tracking
>
> [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/
>
> >>
> >>
> >> Can someone enlighten what is going on?
> >>
> >> Nick, Fangrui?
> >>
> >> Thanks.
> >>
> >> - Sedat -
> >>
> >> P.S.: Patch from linux-bpf
> >>
> >> link="https://lore.kernel.org/bpf/20210112194724.GB1291051@krava/T/#t"
> >> b4 -d am $link
> >>
> >> - EOT -

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
  2021-01-14  6:18         ` [PATCH v3 0/2] Kbuild: DWARF v5 support Sedat Dilek
  2021-01-14  7:09           ` Sedat Dilek
@ 2021-01-14  9:36           ` Sedat Dilek
  2021-01-14 18:53           ` Nick Desaulniers
  2 siblings, 0 replies; 13+ messages in thread
From: Sedat Dilek @ 2021-01-14  9:36 UTC (permalink / raw)
  To: Caroline Tice
  Cc: Nick Desaulniers, Masahiro Yamada, Arvind Sankar, Jakub Jelinek,
	Fangrui Song, Clang-Built-Linux ML, Nick Clifton, bpf,
	Andrii Nakryiko, Jiri Olsa

On Thu, Jan 14, 2021 at 7:18 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>
> On Wed, Jan 13, 2021 at 11:25 PM Caroline Tice <cmtice@google.com> wrote:
> >
> >
> >
> >
> >
> > On Tue, Jan 12, 2021 at 3:17 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >>
> >> On Mon, Jan 11, 2021 at 9:27 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >> >
> >> > On Fri, Dec 4, 2020 at 2:11 AM 'Nick Desaulniers' via Clang Built
> >> > Linux <clang-built-linux@googlegroups.com> wrote:
> >> > >
> >> > > DWARF v5 is the latest standard of the DWARF debug info format.
> >> > >
> >> > > DWARF5 wins significantly in terms of size when mixed with compression
> >> > > (CONFIG_DEBUG_INFO_COMPRESSED).
> >> > >
> >> >
> >> > Is this patchset bulletproof with CONFIG_DEBUG_INFO_BTF=y (and clang-cfi)?
> >> >
> >> > Debian has enabled this Kconfig in recent Linux v5.10 kernels which is
> >> > a base for my custom kernels.
> >> >
> >> > It was fu**ing annoying to see I have no pahole binary installed and
> >> > my build got broken after 3 hours of build.
> >> > OK, I see that requirements is coded in scripts/link-vmlinux.sh.
> >> >
> >> > I needed to install dwarves package which provides pahole binary.
> >> >
> >> > I would like to see a prereq-checking for needed binaries with certain
> >> > Kconfig set.
> >> >
> >> > After I calmed down I will - maybe - write to linux-kbuild mailing-list.
> >> > Hope this will be a friendly email.
> >> >
> >>
> >> After linux-bpf folks recommended not to use LLVM I jumped to gcc-10.
> >>
> >> I tried with ld.bfd first and then in a next run with LLVM=1.
> >>
> >> Upgraded pahole binary to latest Git plus a recommended patch from
> >> linux-btf folks.
> >>
> >> Unfortunately, I see with CONFIG_DEBUG_INFO_DWARF5=y and
> >> CONFIG_DEBUG_INFO_BTF=y:
> >>
> >> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x3f0dd5a> not handled!
> >> die__process_function: DW_TAG_INVALID (0x48) @ <0x3f0dd69> not handled!
> >>
> >> In /usr/include/dwarf.h I found:
> >>
> >> 498:    DW_OP_lit24 = 0x48,                /* Literal 24.  *
> >
> >
> > There are multiple dwarf objects with the value 0x48, depending on which section of the dwarf.h file you search:
> >
> > DW_TAG_call_site = 0x48
> > DW_AT_static_link = 0x48
> > DW_OP_lit24 = 0x48.
> >
> > In this case, since the error message was about a DW_TAG, it would be complaining about DW_TAG_call_site, which is new to DWARR v5.
> >
>
> [ CC linux-bpf & Andrii and Jiri ]
>
> Thanks for your feedback Caroline.
>
> I ran several builds in the last 24 hours with Linux v5.11-rc3.
>
> Setting DWARF version 2 (CONFIG_DEBUG_INFO_DWARF2=y) or version 4
> (CONFIG_DEBUG_INFO_DWARF4=y) with this patchset together with GCC
> v10.2.1 plus LLVM=1 does NOT show this.
> BTW, it does not matter when LLVM/Clang v12 and LLVM/Clang v11 is used.
> But again my compiler is here GCC plus LLVM utils like llvm-objcopy,
> ld.lld, lllvm-ar, llvm-nm, etc.
> ( My initial problem was also seen with Clang v11.0.1 - I switched to
> GCC as Debian's linux-kernel uses CONFIG_DEBUG_INFO_BTF=y
> successfully. )
>
> So, this is definitely a DWARF version 5 issue when
> CONFIG_DEBUG_INFO_BTF=y (and CONFIG_DEBUG_INFO_BTF_MODULES=y).
>
> Furthermore, my build-log says with pahole (see post-scriptum) from
> dwarves package - here as an example:
>
> WARN: multiple IDs found for 'bpf_map': 3860, 369255 - using 3860
>
> $ grep 'WARN: multiple IDs found for'
> build-log_5.11.0-rc3-6-amd64-gcc10-llvm11.txt | wc -l
> 1621
>
> In the Linux code this derives from tools/bpf/resolve_btfids:
>
> static int symbols_resolve(struct object *obj)
> ...
>                                 pr_info("WARN: multiple IDs found for
> '%s': %d, %d - using %d\n",
>
> ( Cut-n-paste into Gmail truncates the lines and indentation, so I dropped it. )
>
> Please see:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/bpf/resolve_btfids/main.c#n469
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/bpf/resolve_btfids/main.c#n532
>
> I looked with llvm-dwarf tool and saw some errors concerning
> ".debug-ranges" (cannot remember the exact output and the command-line
> I used).
>

I found in my archives:

[ error: decoding address ranges: ]

Looks like these DW_TAG_xxx are involved.

$ egrep -B4 -n 'error: decoding address ranges:' llvm-dwarfdump.txt |
grep DW_TAG_ | awk '{ print $2 }' | sort | uniq
DW_TAG_compile_unit
DW_TAG_formal_parameter
DW_TAG_inlined_subroutine
DW_TAG_lexical_block
DW_TAG_subprogram

[ example ]

1017373-0x001a1691: DW_TAG_compile_unit
1017374-              DW_AT_producer    ("GNU C89 10.2.1 20210110
-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 -mrecord-mcount -mfentry -march=x86-
64 -g -gdwarf-5 -O2 -std=gnu90 -p -fno-strict-aliasing -fno-common
-fshort-wchar -fno-PIE -falign-jumps=1 -falign-loops=1
-fno-asynchronous-unwind-tables -fno-jump-tab
les -fno-delete-null-pointer-checks -fno-allow-store-data-races
-fstack-protector-strong -fno-strict-overflow -fstack-check=no
-fconserve-stack -fcf-protection=none")
1017375-              DW_AT_language    (DW_LANG_C11)
1017376-              DW_AT_name        ("arch/x86/events/intel/knc.c")
1017377-              DW_AT_comp_dir    ("/home/dileks/src/linux-kernel/git")
1017378:              DW_AT_ranges      (0x000080d8error: decoding
address ranges: invalid range list offset 0x80d8
1017379-)
1017380-              DW_AT_low_pc      (0x0000000000000000)
1017381-              DW_AT_stmt_list   (0x000298ec)
1017382-

Furthermore I see <decoding error>.

[ example <decoding error> ]

1016826-0x001a131b:     DW_TAG_formal_parameter
1016827-                  DW_AT_abstract_origin (0x0019dacd "event")
1016828-                  DW_AT_location        (0x00020eff:
1016829:                     [0xffffffff8100f9c0, 0xffffffff8100fa76):
<decoding error> fa 37 3e 01 00 9f)
1016830-                  DW_AT_unknown_2137    (0x00020efd)

- Sedat -

> Example for "DW_TAG_INVALID (0x48)" from my build-log:
>
> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x1f671e7> not handled!
>
> $ llvm-dwarfdump-11 --debug-info=0x1f671e7 vmlinux
> vmlinux:        file format elf64-x86-64
>
> .debug_info contents:
>
> 0x01f671e7: DW_TAG_call_site
>              DW_AT_call_return_pc      (0xffffffff811b16f2)
>              DW_AT_call_origin (0x01f67f1d)
>
> Looking for "DW_AT_call_origin (0x01f67f1d)":
>
> $ llvm-dwarfdump-11 --debug-info=0x01f67f1d vmlinux
> vmlinux:        file format elf64-x86-64
>
> .debug_info contents:
>
> 0x01f67f1d: DW_TAG_subprogram
>              DW_AT_external    (true)
>              DW_AT_declaration (true)
>              DW_AT_linkage_name        ("fput")
>              DW_AT_name        ("fput")
>              DW_AT_decl_file
> ("/home/dileks/src/linux-kernel/git/./include/linux/file.h")
>              DW_AT_decl_line   (16)
>              DW_AT_decl_column (0x0d)
>
> I have no experience in digging into DWARF (version 5) issues and how
> to use llvm-dwarf or another appropriate tool.
> If you give me a hand...
> So all the above says - to be honest - nothing to me.
> I hope it says something to you experts.
>
> Regards,
> - Sedat -
>
> P.S.: I tried with a selfmade pahole from latest Git plus Jiri's v2
> patch of "btf_encoder: Add extra checks for symbol names".
>
> link="https://lore.kernel.org/bpf/20210113102509.1338601-1-jolsa@kernel.org/T/#t
> b4 -d am $link
> ...
> Wrote v2_20210113_jolsa_btf_encoder_add_extra_checks_for_symbol_names.am
> for thanks tracking
>
> [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/
>
> >>
> >>
> >> Can someone enlighten what is going on?
> >>
> >> Nick, Fangrui?
> >>
> >> Thanks.
> >>
> >> - Sedat -
> >>
> >> P.S.: Patch from linux-bpf
> >>
> >> link="https://lore.kernel.org/bpf/20210112194724.GB1291051@krava/T/#t"
> >> b4 -d am $link
> >>
> >> - EOT -

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
  2021-01-14  6:18         ` [PATCH v3 0/2] Kbuild: DWARF v5 support Sedat Dilek
  2021-01-14  7:09           ` Sedat Dilek
  2021-01-14  9:36           ` Sedat Dilek
@ 2021-01-14 18:53           ` Nick Desaulniers
  2021-01-14 19:01             ` Nick Desaulniers
  2 siblings, 1 reply; 13+ messages in thread
From: Nick Desaulniers @ 2021-01-14 18:53 UTC (permalink / raw)
  To: Sedat Dilek, Masahiro Yamada, Jiri Olsa, Andrii Nakryiko,
	Arnaldo Carvalho de Melo
  Cc: Caroline Tice, Arvind Sankar, Jakub Jelinek, Fangrui Song,
	Clang-Built-Linux ML, Nick Clifton, bpf

On Wed, Jan 13, 2021 at 10:18 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>
> On Wed, Jan 13, 2021 at 11:25 PM Caroline Tice <cmtice@google.com> wrote:
> >
> > On Tue, Jan 12, 2021 at 3:17 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >>
> >> Unfortunately, I see with CONFIG_DEBUG_INFO_DWARF5=y and
> >> CONFIG_DEBUG_INFO_BTF=y:
> >>
> >> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x3f0dd5a> not handled!
> >> die__process_function: DW_TAG_INVALID (0x48) @ <0x3f0dd69> not handled!

I can confirm that I see a stream of these warnings when building with
this patch series applied, and those two configs enabled.

rebuilding with `make ... V=1`, it looks like the call to:

+ pahole -J .tmp_vmlinux.btf

is triggering these.

Shall I send a v4 that adds a Kconfig dependency on !DEBUG_INFO_BTF?
Does pahole have a bug tracker?

> >>
> >> In /usr/include/dwarf.h I found:
> >>
> >> 498:    DW_OP_lit24 = 0x48,                /* Literal 24.  *
> >
> >
> > There are multiple dwarf objects with the value 0x48, depending on which section of the dwarf.h file you search:
> >
> > DW_TAG_call_site = 0x48
> > DW_AT_static_link = 0x48
> > DW_OP_lit24 = 0x48.
> >
> > In this case, since the error message was about a DW_TAG, it would be complaining about DW_TAG_call_site, which is new to DWARF v5.
> >
> Example for "DW_TAG_INVALID (0x48)" from my build-log:
>
> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x1f671e7> not handled!
>
> $ llvm-dwarfdump-11 --debug-info=0x1f671e7 vmlinux
> vmlinux:        file format elf64-x86-64
>
> .debug_info contents:
>
> 0x01f671e7: DW_TAG_call_site
>              DW_AT_call_return_pc      (0xffffffff811b16f2)
>              DW_AT_call_origin (0x01f67f1d)
>
> Looking for "DW_AT_call_origin (0x01f67f1d)":
>
> $ llvm-dwarfdump-11 --debug-info=0x01f67f1d vmlinux
> vmlinux:        file format elf64-x86-64
>
> .debug_info contents:
>
> 0x01f67f1d: DW_TAG_subprogram
>              DW_AT_external    (true)
>              DW_AT_declaration (true)
>              DW_AT_linkage_name        ("fput")
>              DW_AT_name        ("fput")
>              DW_AT_decl_file
> ("/home/dileks/src/linux-kernel/git/./include/linux/file.h")
>              DW_AT_decl_line   (16)
>              DW_AT_decl_column (0x0d)

That's a neat trick (using --debug-info=offset to print one element
from the stream).
-- 
Thanks,
~Nick Desaulniers

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
  2021-01-14 18:53           ` Nick Desaulniers
@ 2021-01-14 19:01             ` Nick Desaulniers
  2021-01-14 19:13               ` Yonghong Song
  0 siblings, 1 reply; 13+ messages in thread
From: Nick Desaulniers @ 2021-01-14 19:01 UTC (permalink / raw)
  To: Jiri Olsa, Andrii Nakryiko, Arnaldo Carvalho de Melo
  Cc: Caroline Tice, Arvind Sankar, Jakub Jelinek, Fangrui Song,
	Clang-Built-Linux ML, Nick Clifton, bpf, Masahiro Yamada,
	Sedat Dilek

On Thu, Jan 14, 2021 at 10:53 AM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Wed, Jan 13, 2021 at 10:18 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >
> > On Wed, Jan 13, 2021 at 11:25 PM Caroline Tice <cmtice@google.com> wrote:
> > >
> > > On Tue, Jan 12, 2021 at 3:17 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> > >>
> > >> Unfortunately, I see with CONFIG_DEBUG_INFO_DWARF5=y and
> > >> CONFIG_DEBUG_INFO_BTF=y:
> > >>
> > >> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x3f0dd5a> not handled!
> > >> die__process_function: DW_TAG_INVALID (0x48) @ <0x3f0dd69> not handled!
>
> I can confirm that I see a stream of these warnings when building with
> this patch series applied, and those two configs enabled.
>
> rebuilding with `make ... V=1`, it looks like the call to:
>
> + pahole -J .tmp_vmlinux.btf
>
> is triggering these.
>
> Shall I send a v4 that adds a Kconfig dependency on !DEBUG_INFO_BTF?
> Does pahole have a bug tracker?

FWIW, my distro packages pahole v1.17; rebuilt with ToT v1.19 from
source and also observe the issue.
-- 
Thanks,
~Nick Desaulniers

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
  2021-01-14 19:01             ` Nick Desaulniers
@ 2021-01-14 19:13               ` Yonghong Song
  2021-01-14 19:20                 ` Nick Desaulniers
  2021-01-14 20:11                 ` Sedat Dilek
  0 siblings, 2 replies; 13+ messages in thread
From: Yonghong Song @ 2021-01-14 19:13 UTC (permalink / raw)
  To: Nick Desaulniers, Jiri Olsa, Andrii Nakryiko, Arnaldo Carvalho de Melo
  Cc: Caroline Tice, Arvind Sankar, Jakub Jelinek, Fangrui Song,
	Clang-Built-Linux ML, Nick Clifton, bpf, Masahiro Yamada,
	Sedat Dilek



On 1/14/21 11:01 AM, Nick Desaulniers wrote:
> On Thu, Jan 14, 2021 at 10:53 AM Nick Desaulniers
> <ndesaulniers@google.com> wrote:
>>
>> On Wed, Jan 13, 2021 at 10:18 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>>>
>>> On Wed, Jan 13, 2021 at 11:25 PM Caroline Tice <cmtice@google.com> wrote:
>>>>
>>>> On Tue, Jan 12, 2021 at 3:17 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>>>>>
>>>>> Unfortunately, I see with CONFIG_DEBUG_INFO_DWARF5=y and
>>>>> CONFIG_DEBUG_INFO_BTF=y:
>>>>>
>>>>> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x3f0dd5a> not handled!
>>>>> die__process_function: DW_TAG_INVALID (0x48) @ <0x3f0dd69> not handled!
>>
>> I can confirm that I see a stream of these warnings when building with
>> this patch series applied, and those two configs enabled.
>>
>> rebuilding with `make ... V=1`, it looks like the call to:
>>
>> + pahole -J .tmp_vmlinux.btf
>>
>> is triggering these.
>>
>> Shall I send a v4 that adds a Kconfig dependency on !DEBUG_INFO_BTF?
>> Does pahole have a bug tracker?

pahole could have issues for dwarf5 since as far as I know, people just 
use dwarf2/dwarf4 with config functions in the kernel.

Where is the link of the patch to add CONFIG_DEBUG_INFO_DWARF5 to linux?
I think you can add CONFIG_DEBUG_INFO_DWARF5 to kernel with dependency
of !CONFIG_DEBUG_INFO_BTF. At the same time, people can debug pahole 
issues. Once it is resolved, !CONFIG_DEBUG_INFO_BTF dependency can be
removed with proper pahole version change in kernel.

> 
> FWIW, my distro packages pahole v1.17; rebuilt with ToT v1.19 from
> source and also observe the issue.
> 

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
  2021-01-14 19:13               ` Yonghong Song
@ 2021-01-14 19:20                 ` Nick Desaulniers
  2021-01-14 20:12                   ` Sedat Dilek
  2021-01-14 20:11                 ` Sedat Dilek
  1 sibling, 1 reply; 13+ messages in thread
From: Nick Desaulniers @ 2021-01-14 19:20 UTC (permalink / raw)
  To: Yonghong Song
  Cc: Jiri Olsa, Andrii Nakryiko, Arnaldo Carvalho de Melo,
	Caroline Tice, Arvind Sankar, Jakub Jelinek, Fangrui Song,
	Clang-Built-Linux ML, Nick Clifton, bpf, Masahiro Yamada,
	Sedat Dilek

On Thu, Jan 14, 2021 at 11:13 AM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> On 1/14/21 11:01 AM, Nick Desaulniers wrote:
> > On Thu, Jan 14, 2021 at 10:53 AM Nick Desaulniers
> > <ndesaulniers@google.com> wrote:
> >>
> >> On Wed, Jan 13, 2021 at 10:18 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >>>
> >>> On Wed, Jan 13, 2021 at 11:25 PM Caroline Tice <cmtice@google.com> wrote:
> >>>>
> >>>> On Tue, Jan 12, 2021 at 3:17 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >>>>>
> >>>>> Unfortunately, I see with CONFIG_DEBUG_INFO_DWARF5=y and
> >>>>> CONFIG_DEBUG_INFO_BTF=y:
> >>>>>
> >>>>> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x3f0dd5a> not handled!
> >>>>> die__process_function: DW_TAG_INVALID (0x48) @ <0x3f0dd69> not handled!
> >>
> >> I can confirm that I see a stream of these warnings when building with
> >> this patch series applied, and those two configs enabled.
> >>
> >> rebuilding with `make ... V=1`, it looks like the call to:
> >>
> >> + pahole -J .tmp_vmlinux.btf
> >>
> >> is triggering these.
> >>
> >> Shall I send a v4 that adds a Kconfig dependency on !DEBUG_INFO_BTF?
> >> Does pahole have a bug tracker?
>
> pahole could have issues for dwarf5 since as far as I know, people just
> use dwarf2/dwarf4 with config functions in the kernel.
>
> Where is the link of the patch to add CONFIG_DEBUG_INFO_DWARF5 to linux?

Latest is v4: https://lore.kernel.org/lkml/20210113003235.716547-1-ndesaulniers@google.com/

> I think you can add CONFIG_DEBUG_INFO_DWARF5 to kernel with dependency
> of !CONFIG_DEBUG_INFO_BTF. At the same time, people can debug pahole
> issues. Once it is resolved, !CONFIG_DEBUG_INFO_BTF dependency can be
> removed with proper pahole version change in kernel.

SGTM, will send a v5 tomorrow in case there's more feedback.

>
> >
> > FWIW, my distro packages pahole v1.17; rebuilt with ToT v1.19 from
> > source and also observe the issue.
> >
-- 
Thanks,
~Nick Desaulniers

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
  2021-01-14 19:13               ` Yonghong Song
  2021-01-14 19:20                 ` Nick Desaulniers
@ 2021-01-14 20:11                 ` Sedat Dilek
  2021-01-14 21:52                   ` Sedat Dilek
  1 sibling, 1 reply; 13+ messages in thread
From: Sedat Dilek @ 2021-01-14 20:11 UTC (permalink / raw)
  To: Yonghong Song
  Cc: Nick Desaulniers, Jiri Olsa, Andrii Nakryiko,
	Arnaldo Carvalho de Melo, Caroline Tice, Arvind Sankar,
	Jakub Jelinek, Fangrui Song, Clang-Built-Linux ML, Nick Clifton,
	bpf, Masahiro Yamada

On Thu, Jan 14, 2021 at 8:13 PM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> On 1/14/21 11:01 AM, Nick Desaulniers wrote:
> > On Thu, Jan 14, 2021 at 10:53 AM Nick Desaulniers
> > <ndesaulniers@google.com> wrote:
> >>
> >> On Wed, Jan 13, 2021 at 10:18 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >>>
> >>> On Wed, Jan 13, 2021 at 11:25 PM Caroline Tice <cmtice@google.com> wrote:
> >>>>
> >>>> On Tue, Jan 12, 2021 at 3:17 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >>>>>
> >>>>> Unfortunately, I see with CONFIG_DEBUG_INFO_DWARF5=y and
> >>>>> CONFIG_DEBUG_INFO_BTF=y:
> >>>>>
> >>>>> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x3f0dd5a> not handled!
> >>>>> die__process_function: DW_TAG_INVALID (0x48) @ <0x3f0dd69> not handled!
> >>
> >> I can confirm that I see a stream of these warnings when building with
> >> this patch series applied, and those two configs enabled.
> >>
> >> rebuilding with `make ... V=1`, it looks like the call to:
> >>
> >> + pahole -J .tmp_vmlinux.btf
> >>
> >> is triggering these.
> >>
> >> Shall I send a v4 that adds a Kconfig dependency on !DEBUG_INFO_BTF?
> >> Does pahole have a bug tracker?
>
> pahole could have issues for dwarf5 since as far as I know, people just
> use dwarf2/dwarf4 with config functions in the kernel.
>
> Where is the link of the patch to add CONFIG_DEBUG_INFO_DWARF5 to linux?
> I think you can add CONFIG_DEBUG_INFO_DWARF5 to kernel with dependency
> of !CONFIG_DEBUG_INFO_BTF. At the same time, people can debug pahole
> issues. Once it is resolved, !CONFIG_DEBUG_INFO_BTF dependency can be
> removed with proper pahole version change in kernel.
>

Yeah, sounds like a good idea.

- Sedat -

> >
> > FWIW, my distro packages pahole v1.17; rebuilt with ToT v1.19 from
> > source and also observe the issue.
> >

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
  2021-01-14 19:20                 ` Nick Desaulniers
@ 2021-01-14 20:12                   ` Sedat Dilek
  0 siblings, 0 replies; 13+ messages in thread
From: Sedat Dilek @ 2021-01-14 20:12 UTC (permalink / raw)
  To: Nick Desaulniers
  Cc: Yonghong Song, Jiri Olsa, Andrii Nakryiko,
	Arnaldo Carvalho de Melo, Caroline Tice, Arvind Sankar,
	Jakub Jelinek, Fangrui Song, Clang-Built-Linux ML, Nick Clifton,
	bpf, Masahiro Yamada

On Thu, Jan 14, 2021 at 8:20 PM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Thu, Jan 14, 2021 at 11:13 AM Yonghong Song <yhs@fb.com> wrote:
> >
> >
> >
> > On 1/14/21 11:01 AM, Nick Desaulniers wrote:
> > > On Thu, Jan 14, 2021 at 10:53 AM Nick Desaulniers
> > > <ndesaulniers@google.com> wrote:
> > >>
> > >> On Wed, Jan 13, 2021 at 10:18 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> > >>>
> > >>> On Wed, Jan 13, 2021 at 11:25 PM Caroline Tice <cmtice@google.com> wrote:
> > >>>>
> > >>>> On Tue, Jan 12, 2021 at 3:17 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> > >>>>>
> > >>>>> Unfortunately, I see with CONFIG_DEBUG_INFO_DWARF5=y and
> > >>>>> CONFIG_DEBUG_INFO_BTF=y:
> > >>>>>
> > >>>>> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x3f0dd5a> not handled!
> > >>>>> die__process_function: DW_TAG_INVALID (0x48) @ <0x3f0dd69> not handled!
> > >>
> > >> I can confirm that I see a stream of these warnings when building with
> > >> this patch series applied, and those two configs enabled.
> > >>
> > >> rebuilding with `make ... V=1`, it looks like the call to:
> > >>
> > >> + pahole -J .tmp_vmlinux.btf
> > >>
> > >> is triggering these.
> > >>
> > >> Shall I send a v4 that adds a Kconfig dependency on !DEBUG_INFO_BTF?
> > >> Does pahole have a bug tracker?
> >
> > pahole could have issues for dwarf5 since as far as I know, people just
> > use dwarf2/dwarf4 with config functions in the kernel.
> >
> > Where is the link of the patch to add CONFIG_DEBUG_INFO_DWARF5 to linux?
>
> Latest is v4: https://lore.kernel.org/lkml/20210113003235.716547-1-ndesaulniers@google.com/
>
> > I think you can add CONFIG_DEBUG_INFO_DWARF5 to kernel with dependency
> > of !CONFIG_DEBUG_INFO_BTF. At the same time, people can debug pahole
> > issues. Once it is resolved, !CONFIG_DEBUG_INFO_BTF dependency can be
> > removed with proper pahole version change in kernel.
>
> SGTM, will send a v5 tomorrow in case there's more feedback.
>

Please CC me on v5.

Feel free to add my Reported-by.

- Sedat -

> >
> > >
> > > FWIW, my distro packages pahole v1.17; rebuilt with ToT v1.19 from
> > > source and also observe the issue.
> > >
> --
> Thanks,
> ~Nick Desaulniers

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
  2021-01-14 20:11                 ` Sedat Dilek
@ 2021-01-14 21:52                   ` Sedat Dilek
  2021-01-14 22:05                     ` Nick Desaulniers
  0 siblings, 1 reply; 13+ messages in thread
From: Sedat Dilek @ 2021-01-14 21:52 UTC (permalink / raw)
  To: Yonghong Song
  Cc: Nick Desaulniers, Jiri Olsa, Andrii Nakryiko,
	Arnaldo Carvalho de Melo, Caroline Tice, Arvind Sankar,
	Jakub Jelinek, Fangrui Song, Clang-Built-Linux ML, Nick Clifton,
	bpf, Masahiro Yamada

On Thu, Jan 14, 2021 at 9:11 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>
> On Thu, Jan 14, 2021 at 8:13 PM Yonghong Song <yhs@fb.com> wrote:
> >
> >
> >
> > On 1/14/21 11:01 AM, Nick Desaulniers wrote:
> > > On Thu, Jan 14, 2021 at 10:53 AM Nick Desaulniers
> > > <ndesaulniers@google.com> wrote:
> > >>
> > >> On Wed, Jan 13, 2021 at 10:18 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> > >>>
> > >>> On Wed, Jan 13, 2021 at 11:25 PM Caroline Tice <cmtice@google.com> wrote:
> > >>>>
> > >>>> On Tue, Jan 12, 2021 at 3:17 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> > >>>>>
> > >>>>> Unfortunately, I see with CONFIG_DEBUG_INFO_DWARF5=y and
> > >>>>> CONFIG_DEBUG_INFO_BTF=y:
> > >>>>>
> > >>>>> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x3f0dd5a> not handled!
> > >>>>> die__process_function: DW_TAG_INVALID (0x48) @ <0x3f0dd69> not handled!
> > >>
> > >> I can confirm that I see a stream of these warnings when building with
> > >> this patch series applied, and those two configs enabled.
> > >>
> > >> rebuilding with `make ... V=1`, it looks like the call to:
> > >>
> > >> + pahole -J .tmp_vmlinux.btf
> > >>
> > >> is triggering these.
> > >>
> > >> Shall I send a v4 that adds a Kconfig dependency on !DEBUG_INFO_BTF?
> > >> Does pahole have a bug tracker?
> >
> > pahole could have issues for dwarf5 since as far as I know, people just
> > use dwarf2/dwarf4 with config functions in the kernel.
> >
> > Where is the link of the patch to add CONFIG_DEBUG_INFO_DWARF5 to linux?
> > I think you can add CONFIG_DEBUG_INFO_DWARF5 to kernel with dependency
> > of !CONFIG_DEBUG_INFO_BTF. At the same time, people can debug pahole
> > issues. Once it is resolved, !CONFIG_DEBUG_INFO_BTF dependency can be
> > removed with proper pahole version change in kernel.
> >
>
> Yeah, sounds like a good idea.
>

Today, I have observed and reported (see [1]) bpf/btf/pahole issues
with Clang v12 (from apt.llvm.org) and DWARF-4 ("four").
Cannot speak for other compilers and its version.

- Sedat -

[1] https://lore.kernel.org/bpf/CA+icZUWb3OyaSQAso8LhsRifZnpxAfDtuRwgB786qEJ3GQ+kRw@mail.gmail.com/T/#m6d05cc6c634e9cee89060b2522abc78c3705ea4c


>
> > >
> > > FWIW, my distro packages pahole v1.17; rebuilt with ToT v1.19 from
> > > source and also observe the issue.
> > >

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
  2021-01-14 21:52                   ` Sedat Dilek
@ 2021-01-14 22:05                     ` Nick Desaulniers
  2021-01-14 22:21                       ` Sedat Dilek
  0 siblings, 1 reply; 13+ messages in thread
From: Nick Desaulniers @ 2021-01-14 22:05 UTC (permalink / raw)
  To: Sedat Dilek
  Cc: Yonghong Song, Jiri Olsa, Andrii Nakryiko,
	Arnaldo Carvalho de Melo, Caroline Tice, Arvind Sankar,
	Jakub Jelinek, Fangrui Song, Clang-Built-Linux ML, Nick Clifton,
	bpf, Masahiro Yamada

On Thu, Jan 14, 2021 at 1:52 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>
> Today, I have observed and reported (see [1]) bpf/btf/pahole issues
> with Clang v12 (from apt.llvm.org) and DWARF-4 ("four").
> Cannot speak for other compilers and its version.

If these are not specific to DWARF5, then it sounds like
CONFIG_DEBUG_INFO_DWARF4 should also be marked as `depends on
!DEBUG_INFO_BTF`? (or !BTF && CC=clang)

>
> - Sedat -
>
> [1] https://lore.kernel.org/bpf/CA+icZUWb3OyaSQAso8LhsRifZnpxAfDtuRwgB786qEJ3GQ+kRw@mail.gmail.com/T/#m6d05cc6c634e9cee89060b2522abc78c3705ea4c
-- 
Thanks,
~Nick Desaulniers

^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
  2021-01-14 22:05                     ` Nick Desaulniers
@ 2021-01-14 22:21                       ` Sedat Dilek
  2021-01-14 23:45                         ` Yonghong Song
  0 siblings, 1 reply; 13+ messages in thread
From: Sedat Dilek @ 2021-01-14 22:21 UTC (permalink / raw)
  To: Nick Desaulniers
  Cc: Yonghong Song, Jiri Olsa, Andrii Nakryiko,
	Arnaldo Carvalho de Melo, Caroline Tice, Arvind Sankar,
	Jakub Jelinek, Fangrui Song, Clang-Built-Linux ML, Nick Clifton,
	bpf, Masahiro Yamada


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On Thu, Jan 14, 2021 at 11:05 PM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Thu, Jan 14, 2021 at 1:52 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >
> > Today, I have observed and reported (see [1]) bpf/btf/pahole issues
> > with Clang v12 (from apt.llvm.org) and DWARF-4 ("four").
> > Cannot speak for other compilers and its version.
>
> If these are not specific to DWARF5, then it sounds like
> CONFIG_DEBUG_INFO_DWARF4 should also be marked as `depends on
> !DEBUG_INFO_BTF`? (or !BTF && CC=clang)
>

My experiments yesterday on Wednesday were with GCC v10.2.1 plus LLVM=1.
There were no issues with DWARF v2 and v4 but v5.

Unfortunately, build-time is long here on my systems.

For now, I did CONFIG_DEBUG_INFO_BTF=n.

I have applied attached patch.

Is it possible to re-arrange CC depends?

[ /lib/Kconfig.debug ]

config DEBUG_INFO_DWARF5
       bool "Generate DWARF Version 5 debuginfo"
-       depends on GCC_VERSION >= 50000 || CC_IS_CLANG
-       depends on CC_IS_GCC ||
$(success,$(srctree)/scripts/test_dwarf5_support.sh $(CC)
$(CLANG_FLAGS))
+      depends on CC_IS_GCC && GCC_VERSION >= 50000 || CC_IS_CLANG
+      depends on $(success,$(srctree)/scripts/test_dwarf5_support.sh
$(CC) $(CLANG_FLAGS))
+       depends on !DEBUG_INFO_BTF
       help
         Generate DWARF v5 debug info. Requires binutils 2.35, gcc 5.0+ (gcc
         5.0+ accepts the -gdwarf-5 flag but only had partial support for some

And adding text to help concerning DEBUG_INFO_BTF is no good these days.

BTW, if you do not mind:

Label your patches with "*k*build:" not "*K*build:".

Use "DWARF *v*ersion" not "DWARF *V*ersion" - everywhere.

One patch missed the label "kbuild:" (guess the subject has too many
characters).

From what I remember - but these are small nits.

Thanks for DWARF v5 support in Linux.

- Sedat -

> >
> > - Sedat -
> >
> > [1] https://lore.kernel.org/bpf/CA+icZUWb3OyaSQAso8LhsRifZnpxAfDtuRwgB786qEJ3GQ+kRw@mail.gmail.com/T/#m6d05cc6c634e9cee89060b2522abc78c3705ea4c
> --
> Thanks,
> ~Nick Desaulniers

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From 7f71b48a8a30077e385f00614af5158732092b90 Mon Sep 17 00:00:00 2001
From: Sedat Dilek <sedat.dilek@gmail.com>
Date: Thu, 14 Jan 2021 21:54:36 +0100
Subject: [PATCH] kbuild: dwarf-5: Do not depend on CONFIG_DEBUG_INFO_BTF

---
 lib/Kconfig.debug | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index eda76af4328e..1d6a526b6344 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -277,6 +277,7 @@ config DEBUG_INFO_DWARF5
 	bool "Generate DWARF Version 5 debuginfo"
 	depends on GCC_VERSION >= 50000 || CC_IS_CLANG
 	depends on CC_IS_GCC || $(success,$(srctree)/scripts/test_dwarf5_support.sh $(CC) $(CLANG_FLAGS))
+	depends on !DEBUG_INFO_BTF
 	help
 	  Generate DWARF v5 debug info. Requires binutils 2.35, gcc 5.0+ (gcc
 	  5.0+ accepts the -gdwarf-5 flag but only had partial support for some
-- 
2.30.0


^ permalink raw reply	[flat|nested] 13+ messages in thread

* Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
  2021-01-14 22:21                       ` Sedat Dilek
@ 2021-01-14 23:45                         ` Yonghong Song
  0 siblings, 0 replies; 13+ messages in thread
From: Yonghong Song @ 2021-01-14 23:45 UTC (permalink / raw)
  To: sedat.dilek, Nick Desaulniers
  Cc: Jiri Olsa, Andrii Nakryiko, Arnaldo Carvalho de Melo,
	Caroline Tice, Arvind Sankar, Jakub Jelinek, Fangrui Song,
	Clang-Built-Linux ML, Nick Clifton, bpf, Masahiro Yamada



On 1/14/21 2:21 PM, Sedat Dilek wrote:
> On Thu, Jan 14, 2021 at 11:05 PM Nick Desaulniers
> <ndesaulniers@google.com> wrote:
>>
>> On Thu, Jan 14, 2021 at 1:52 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>>>
>>> Today, I have observed and reported (see [1]) bpf/btf/pahole issues
>>> with Clang v12 (from apt.llvm.org) and DWARF-4 ("four").
>>> Cannot speak for other compilers and its version.
>>
>> If these are not specific to DWARF5, then it sounds like
>> CONFIG_DEBUG_INFO_DWARF4 should also be marked as `depends on
>> !DEBUG_INFO_BTF`? (or !BTF && CC=clang)
>>
> 
> My experiments yesterday on Wednesday were with GCC v10.2.1 plus LLVM=1.
> There were no issues with DWARF v2 and v4 but v5.
> 
> Unfortunately, build-time is long here on my systems.
> 
> For now, I did CONFIG_DEBUG_INFO_BTF=n.
> 
> I have applied attached patch.
> 
> Is it possible to re-arrange CC depends?
> 
> [ /lib/Kconfig.debug ]
> 
> config DEBUG_INFO_DWARF5
>         bool "Generate DWARF Version 5 debuginfo"
> -       depends on GCC_VERSION >= 50000 || CC_IS_CLANG
> -       depends on CC_IS_GCC ||
> $(success,$(srctree)/scripts/test_dwarf5_support.sh $(CC)
> $(CLANG_FLAGS))
> +      depends on CC_IS_GCC && GCC_VERSION >= 50000 || CC_IS_CLANG
> +      depends on $(success,$(srctree)/scripts/test_dwarf5_support.sh
> $(CC) $(CLANG_FLAGS))
> +       depends on !DEBUG_INFO_BTF
>         help
>           Generate DWARF v5 debug info. Requires binutils 2.35, gcc 5.0+ (gcc
>           5.0+ accepts the -gdwarf-5 flag but only had partial support for some
> 
> And adding text to help concerning DEBUG_INFO_BTF is no good these days.

Thanks, the above change looks good to me as well as the suggestion to 
add some explanation why disabling DEBUG_INFO_BTF.

> 
> BTW, if you do not mind:
> 
> Label your patches with "*k*build:" not "*K*build:".
> 
> Use "DWARF *v*ersion" not "DWARF *V*ersion" - everywhere.
> 
> One patch missed the label "kbuild:" (guess the subject has too many
> characters).
> 
>>From what I remember - but these are small nits.
> 
> Thanks for DWARF v5 support in Linux.
> 
> - Sedat -
> 
>>>
>>> - Sedat -
>>>
>>> [1] https://lore.kernel.org/bpf/CA+icZUWb3OyaSQAso8LhsRifZnpxAfDtuRwgB786qEJ3GQ+kRw@mail.gmail.com/T/#m6d05cc6c634e9cee89060b2522abc78c3705ea4c
>> --
>> Thanks,
>> ~Nick Desaulniers

^ permalink raw reply	[flat|nested] 13+ messages in thread

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2021-01-14  6:18         ` [PATCH v3 0/2] Kbuild: DWARF v5 support Sedat Dilek
2021-01-14  7:09           ` Sedat Dilek
2021-01-14  9:36           ` Sedat Dilek
2021-01-14 18:53           ` Nick Desaulniers
2021-01-14 19:01             ` Nick Desaulniers
2021-01-14 19:13               ` Yonghong Song
2021-01-14 19:20                 ` Nick Desaulniers
2021-01-14 20:12                   ` Sedat Dilek
2021-01-14 20:11                 ` Sedat Dilek
2021-01-14 21:52                   ` Sedat Dilek
2021-01-14 22:05                     ` Nick Desaulniers
2021-01-14 22:21                       ` Sedat Dilek
2021-01-14 23:45                         ` Yonghong Song

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