From: Steven Rostedt <rostedt@goodmis.org>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: linux-kbuild@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Anders Roxell <anders.roxell@linaro.org>,
Sami Tolvanen <samitolvanen@google.com>,
Brendan Higgins <brendanhiggins@google.com>,
"David S. Miller" <davem@davemloft.net>,
Haren Myneni <haren@us.ibm.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Jiri Kosina <jikos@kernel.org>,
Joe Lawrence <joe.lawrence@redhat.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Miroslav Benes <mbenes@suse.cz>, Petr Mladek <pmladek@suse.com>,
Tal Gilboa <talgi@mellanox.com>,
kunit-dev@googlegroups.com, linux-crypto@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
live-patching@vger.kernel.org
Subject: Re: [PATCH v2 2/2] kbuild: trace functions in subdirectories of lib/
Date: Tue, 7 Jul 2020 12:02:12 -0400 [thread overview]
Message-ID: <20200707120212.7010fa4f@oasis.local.home> (raw)
In-Reply-To: <20200707092117.963394-2-masahiroy@kernel.org>
On Tue, 7 Jul 2020 18:21:17 +0900
Masahiro Yamada <masahiroy@kernel.org> wrote:
> ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
>
> exists here in sub-directories of lib/ to keep the behavior of
> commit 2464a609ded0 ("ftrace: do not trace library functions").
>
> Since that commit, not only the objects in lib/ but also the ones in
> the sub-directories are excluded from ftrace (although the commit
> description did not explicitly mention this).
>
> However, most of library functions in sub-directories are not so hot.
> Re-add them to ftrace.
I'm OK with this change, but note, it wasn't just the hot path that I
disabled ftrace on lib for, but some of these calls are done very early
at boot up. It may have been PowerPC that I was stumbling over. The
issue is that they would call mcount before the kernel was mapped
properly, and the system would crash.
My PowerPC box no longer boots so I can't test this anymore. But a lot
has changed since 2008, and all this may very well be OK.
-- Steve
next prev parent reply other threads:[~2020-07-07 16:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-07 9:21 [PATCH v2 1/2] kbuild: introduce ccflags-remove-y and asflags-remove-y Masahiro Yamada
2020-07-07 9:21 ` [PATCH v2 2/2] kbuild: trace functions in subdirectories of lib/ Masahiro Yamada
2020-07-07 16:02 ` Steven Rostedt [this message]
2020-07-22 2:08 ` Masahiro Yamada
2020-07-22 20:49 ` Steven Rostedt
2020-07-08 6:52 ` Petr Mladek
2020-07-08 9:23 ` Petr Mladek
2020-07-22 2:10 ` Masahiro Yamada
2020-07-07 19:58 ` [PATCH v2 1/2] kbuild: introduce ccflags-remove-y and asflags-remove-y Brendan Higgins
2020-07-07 21:25 ` Anders Roxell
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