From: Qian Cai <cai@lca.pw>
To: Marco Elver <elver@google.com>
Cc: paulmck@kernel.org, andreyknvl@google.com, glider@google.com,
dvyukov@google.com, kasan-dev@googlegroups.com,
linux-kernel@vger.kernel.org, rostedt@goodmis.org,
mingo@redhat.com
Subject: Re: [PATCH] kcsan, trace: Make KCSAN compatible with tracing
Date: Fri, 14 Feb 2020 14:35:56 -0500 [thread overview]
Message-ID: <1581708956.7365.75.camel@lca.pw> (raw)
In-Reply-To: <20200214190500.126066-1-elver@google.com>
On Fri, 2020-02-14 at 20:05 +0100, Marco Elver wrote:
> Previously the system would lock up if ftrace was enabled together with
> KCSAN. This is due to recursion on reporting if the tracer code is
> instrumented with KCSAN.
>
> To avoid this for all types of tracing, disable KCSAN instrumentation
> for all of kernel/trace.
I remembered that KCSAN + ftrace was working last week, but I probably had a bad
memory. Anyway, this patch works fine. Feel free to add,
Tested-by: Qian Cai <cai@lca.pw>
>
> Signed-off-by: Marco Elver <elver@google.com>
> Reported-by: Qian Cai <cai@lca.pw>
> Cc: Paul E. McKenney <paulmck@kernel.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> ---
> kernel/kcsan/Makefile | 2 ++
> kernel/trace/Makefile | 3 +++
> 2 files changed, 5 insertions(+)
>
> diff --git a/kernel/kcsan/Makefile b/kernel/kcsan/Makefile
> index df6b7799e4927..d4999b38d1be5 100644
> --- a/kernel/kcsan/Makefile
> +++ b/kernel/kcsan/Makefile
> @@ -4,6 +4,8 @@ KCOV_INSTRUMENT := n
> UBSAN_SANITIZE := n
>
> CFLAGS_REMOVE_core.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_debugfs.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_report.o = $(CC_FLAGS_FTRACE)
>
> CFLAGS_core.o := $(call cc-option,-fno-conserve-stack,) \
> $(call cc-option,-fno-stack-protector,)
> diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
> index f9dcd19165fa2..6b601d88bf71e 100644
> --- a/kernel/trace/Makefile
> +++ b/kernel/trace/Makefile
> @@ -6,6 +6,9 @@ ifdef CONFIG_FUNCTION_TRACER
> ORIG_CFLAGS := $(KBUILD_CFLAGS)
> KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS))
>
> +# Avoid recursion due to instrumentation.
> +KCSAN_SANITIZE := n
> +
> ifdef CONFIG_FTRACE_SELFTEST
> # selftest needs instrumentation
> CFLAGS_trace_selftest_dynamic.o = $(CC_FLAGS_FTRACE)
next prev parent reply other threads:[~2020-02-14 19:36 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 19:05 [PATCH] kcsan, trace: Make KCSAN compatible with tracing Marco Elver
2020-02-14 19:35 ` Qian Cai [this message]
2020-02-14 21:59 ` Marco Elver
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1581708956.7365.75.camel@lca.pw \
--to=cai@lca.pw \
--cc=andreyknvl@google.com \
--cc=dvyukov@google.com \
--cc=elver@google.com \
--cc=glider@google.com \
--cc=kasan-dev@googlegroups.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=paulmck@kernel.org \
--cc=rostedt@goodmis.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).