From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "llvm@lists.linux.dev" <llvm@lists.linux.dev>,
Nick Desaulniers <ndesaulniers@google.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Nathan Chancellor <nathan@kernel.org>,
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH 2/2] recordmcount: Handle sections with no non-weak symbols
Date: Wed, 4 May 2022 17:10:07 +0000 [thread overview]
Message-ID: <7c235943-4ea0-1f09-bbbb-8f23fbe8bfae@csgroup.eu> (raw)
In-Reply-To: <20220504130642.7b9a301d@rorschach.local.home>
Le 04/05/2022 à 19:06, Steven Rostedt a écrit :
> On Wed, 4 May 2022 16:50:58 +0000
> Christophe Leroy <christophe.leroy@csgroup.eu> wrote:
>
>> In vmlinux, relocations are resolved, trampolines are installed for
>> unreachable destinations and you don't anymore have a section with all
>> the relocations to mcount. It means 'recordmcount' or whatever tool we
>> use will have to read the code to find all direct calls to mcount, then
>> find all trampolines to mcount then find all calls to those trampolines.
>
> OK, so what you are saying is that in the object file, we can see the
> site that calls mcount, but when it is linked, it may not call mcount,
> but instead it will call a trampoline that will call mcount, thus the
> tool will need to find these calls to the trampolines that call mcount
> as well as the locations that call mcount directly.
>
> Did I get that right?
>
Yes it is what I'm trying to say.
Christophe
next prev parent reply other threads:[~2022-05-04 17:10 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-27 9:31 [PATCH 0/2] ftrace/recordmcount: Handle object files without section symbols Naveen N. Rao
2022-04-27 9:31 ` [PATCH 1/2] ftrace: Drop duplicate mcount locations Naveen N. Rao
2022-04-27 13:46 ` Steven Rostedt
2022-04-27 9:31 ` [PATCH 2/2] recordmcount: Handle sections with no non-weak symbols Naveen N. Rao
2022-04-27 13:54 ` Steven Rostedt
2022-04-28 7:45 ` Naveen N. Rao
2022-04-28 14:06 ` Steven Rostedt
2022-04-28 17:24 ` Naveen N. Rao
2022-04-28 17:31 ` Naveen N. Rao
2022-05-02 14:44 ` Christophe Leroy
2022-05-02 23:52 ` Steven Rostedt
2022-05-03 11:20 ` Christophe Leroy
2022-05-03 16:25 ` Steven Rostedt
2022-05-04 16:50 ` Christophe Leroy
2022-05-04 17:06 ` Steven Rostedt
2022-05-04 17:10 ` Christophe Leroy [this message]
2022-08-16 14:04 ` [PATCH 0/2] ftrace/recordmcount: Handle object files without section symbols Steven Rostedt
2022-08-16 17:05 ` Naveen N. Rao
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