From: Jiri Slaby <jirislaby@kernel.org>
To: "Michal Suchánek" <msuchanek@suse.de>, "Jiri Olsa" <jolsa@redhat.com>
Cc: Yonghong Song <yhs@fb.com>,
linux-kernel@vger.kernel.org, Martin KaFai Lau <kafai@fb.com>,
"David S. Miller" <davem@davemloft.net>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
David Ahern <dsahern@kernel.org>,
Jakub Kicinski <kuba@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Song Liu <songliubraving@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
Jiri Olsa <jolsa@kernel.org>,
Jesper Dangaard Brouer <brouer@redhat.com>
Subject: Re: linux-next failing build due to missing cubictcp_state symbol
Date: Mon, 3 May 2021 09:59:37 +0200 [thread overview]
Message-ID: <4e051459-8532-7b61-c815-f3435767f8a0@kernel.org> (raw)
In-Reply-To: <6c14f3c8-7474-9f3f-b4a6-2966cb19e1ed@kernel.org>
On 03. 05. 21, 8:11, Jiri Slaby wrote:
>>>>>> looks like vfs_truncate did not get into BTF data,
>>>>>> I'll try to reproduce
>>
>> _None_ of the functions are generated by pahole -J from debuginfo on
>> ppc64. debuginfo appears to be correct. Neither pahole -J fs/open.o
>> works correctly. collect_functions in dwarves seems to be defunct on
>> ppc64... "functions" array is bogus (so find_function -- the bsearch
>> -- fails).
>
> It's not that bogus. I forgot an asterisk:
>> #0 find_function (btfe=0x100269f80, name=0x10024631c "stream_open")
>> at /usr/src/debug/dwarves-1.21-1.1.ppc64/btf_encoder.c:350
>> (gdb) p (*functions)@84
>> $5 = {{name = 0x7ffff68e0922 ".__se_compat_sys_ftruncate", addr =
>> 75232, size = 72, sh_addr = 65536, generated = false}, {
>> name = 0x7ffff68e019e ".__se_compat_sys_open", addr = 80592, size
>> = 216, sh_addr = 65536, generated = false}, {
>> name = 0x7ffff68e0076 ".__se_compat_sys_openat", addr = 80816,
>> size = 232, sh_addr = 65536, generated = false}, {
>> name = 0x7ffff68e0908 ".__se_compat_sys_truncate", addr = 74304,
>> size = 100, sh_addr = 65536, generated = false}, {
> ...
>> name = 0x7ffff68e0808 ".stream_open", addr = 65824, size = 72,
>> sh_addr = 65536, generated = false}, {
> ...
>> name = 0x7ffff68e0751 ".vfs_truncate", addr = 73392, size = 544,
>> sh_addr = 65536, generated = false}}
>
> The dot makes the difference, of course. The question is why is it
> there? I keep looking into it. Only if someone has an immediate idea...
Well, .vfs_truncate is in .text (and contains an ._mcount call). And
vfs_truncate is in .opd (w/o an ._mcount call). Since setup_functions
excludes all functions without the ._mcount call, is_ftrace_func later
returns false for such functions and they are filtered before the BTF
processing.
Technically, get_vmlinux_addrs looks at a list of functions between
__start_mcount_loc and __stop_mcount_loc and considers only the listed.
I don't know what the correct fix is (exclude .opd functions from the
filter?). Neither why cross compiler doesn't fail, nor why ebi v2 avoids
this too.
regards,
--
js
next prev parent reply other threads:[~2021-05-03 7:59 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210423130530.GA6564@kitsune.suse.cz>
2021-04-23 14:41 ` linux-next failing build due to missing cubictcp_state symbol Yonghong Song
2021-04-23 17:55 ` Michal Suchánek
2021-04-25 11:15 ` Michal Suchánek
2021-04-26 11:32 ` Michal Suchánek
2021-04-26 12:12 ` Michal Suchánek
[not found] ` <20210426121401.GO15381@kitsune.suse.cz>
2021-04-26 15:41 ` Yonghong Song
2021-04-26 16:03 ` Jiri Olsa
2021-04-26 19:16 ` Jiri Olsa
2021-04-27 12:12 ` Michal Suchánek
2021-04-30 17:47 ` Michal Suchánek
2021-05-01 6:45 ` Jiri Slaby
2021-05-01 10:54 ` Michal Suchánek
2021-05-03 6:11 ` Jiri Slaby
2021-05-03 7:13 ` Michal Suchánek
2021-05-03 7:59 ` Jiri Slaby [this message]
2021-05-03 8:59 ` Jiri Slaby
2021-05-03 10:08 ` Jiri Olsa
2021-05-03 16:46 ` Michal Suchánek
2021-05-03 16:58 ` Michal Suchánek
2021-05-04 6:41 ` Jiri Slaby
2021-05-06 5:31 ` Martin KaFai Lau
2021-05-06 13:16 ` Jiri Olsa
2021-05-07 7:10 ` Florian Weimer
[not found] ` <20210505135612.GZ6564@kitsune.suse.cz>
2021-05-06 4:31 ` Jiri Slaby
2021-05-06 5:20 ` Martin KaFai Lau
2021-05-06 5:54 ` Jiri Slaby
2021-05-06 8:19 ` Michal Suchánek
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