Re: [PATCH dwarves] dwarf_loader: handle DWARF5 DW_OP_addrx properly

From: Yonghong Song <yhs@fb.com>
To: <sedat.dilek@gmail.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
	<dwarves@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
	Bill Wendling <morbo@google.com>, <bpf@vger.kernel.org>,
	David Blaikie <dblaikie@gmail.com>, <kernel-team@fb.com>,
	Nick Desaulniers <ndesaulniers@google.com>
Subject: Re: [PATCH dwarves] dwarf_loader: handle DWARF5 DW_OP_addrx properly
Date: Sun, 4 Apr 2021 19:30:52 -0700	[thread overview]
Message-ID: <dfc28e40-5ce9-c6df-2e12-7840195ab570@fb.com> (raw)
In-Reply-To: <CA+icZUVp3UTPUS-ZjCOnHbNXxaA7DN=4x_08jc8BExFe4Nf2ZQ@mail.gmail.com>

On 4/4/21 5:20 PM, Sedat Dilek wrote:
> On Sun, Apr 4, 2021 at 7:25 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> [ ... ]
>>>> Yonghong Song as you described your build-environment and checking
>>>> requirements for clang-13 in bpf-next (see [1]), I am unsure if I want
>>>> to upgrade LLVM toolchain to v13-git and use bpf-next as the new
>>>> kernel base.
>>>> Lemme see if I get LLVM/Clang v13-git from Debian/experimental and/or
>>>> <apt.llvm.org>.
>>>
>>> If you want to run bpf-next, clang v13 definitely recommended.
>>> But I think if you use clang v13 to run linus linux, you may
>>> hit DWARF5 DW_OP_addrx as well. But unfortunately you will
>>> may hit a few selftest issues (e.g., BPF_TCP_CLOSE issue).
>>>
>>
>> OK, I started a fresh build with LLVM/Clang v13-git from <apt.llvm.org>...
>>
>> $ /usr/lib/llvm-13/bin/clang --version
>> Debian clang version
>> 13.0.0-++20210404092853+c4c511337247-1~exp1~20210404073605.3891
>> Target: x86_64-pc-linux-gnu
>> Thread model: posix
>> InstalledDir: /usr/lib/llvm-13/bin
>>
>> ...with latest bpf-next as new base.
>>
>> I applied your/this pahole patch "[PATCH dwarves] dwarf_loader: handle
>> DWARF5 DW_OP_addrx properly".
>>
>> Will report later...
>>
> 
> Yupp, works.
> 
> $ cat /proc/version
> Linux version 5.12.0-rc5-13-amd64-clang13-lto
> (sedat.dilek@gmail.com@iniza) (Debian clang version
> 13.0.0-++20210404092853+c4c511337247-1~exp1~20210404073605.3891, LLD
> 13.0.0) #13~bullseye+dileks1 SMP 2021-04-04
> 
> MAKE="make V=1"
> MAKE_OPTS="LLVM=1 LLVM_IAS=1"
> MAKE_OPTS="$MAKE_OPTS PAHOLE=/opt/pahole/bin/pahole"
> 
> $ LC_ALL=C $MAKE $MAKE_OPTS -C tools/testing/selftests/bpf/ 2>&1 | tee
> ../make-log_tools-testing-selftests-bpf_llvm-1-llvm_ias-1.txt
> 
> dileks@iniza:~/src/linux-kernel/git/tools/testing/selftests/bpf$ sudo
> ./test_progs -n 55/2
> #55/2 subprog:OK
> #55 kfunc_call:OK
> Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED
> 
> My linux-config and
> make-log_tools-testing-selftests-bpf_llvm-1_llvm_ias-1.txt.gz files
> are attached.
> 
> Feel free to add my:
> 
> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13-git (x86-64)

Great! Thanks for the help to test the pahole/kernel patches.

> 
> - Sedat -
> 
> P.S.: List of some relevant Linux Kconfigs
> 
> $ grep 'LTO_|_BTF|DWARF' /boot/config-5.12.0-rc5-13-amd64-clang13-lto
> | grep ^CONFIG | sort
> CONFIG_ARCH_SUPPORTS_LTO_CLANG_THIN=y
> CONFIG_ARCH_SUPPORTS_LTO_CLANG=y
> CONFIG_DEBUG_INFO_BTF_MODULES=y
> CONFIG_DEBUG_INFO_BTF=y
> CONFIG_DEBUG_INFO_DWARF5=y
> CONFIG_HAS_LTO_CLANG=y
> CONFIG_LTO_CLANG_THIN=y
> CONFIG_LTO_CLANG=y
> CONFIG_PAHOLE_HAS_SPLIT_BTF=y
> 
> - EOT -
> 