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Date:   Wed, 28 Nov 2018 09:05:07 -0500
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Anders Roxell <anders.roxell@linaro.org>
Cc:     akpm@linux-foundation.org, dvyukov@google.com, mingo@redhat.com,
        linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH 1/2] kernel/kcov.c: mark funcs in
 __sanitizer_cov_trace_pc as notrace
Message-ID: <20181128090507.41791fe7@gandalf.local.home>
In-Reply-To: <20181128081239.18317-1-anders.roxell@linaro.org>
References: <20181128081239.18317-1-anders.roxell@linaro.org>
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On Wed, 28 Nov 2018 09:12:39 +0100
Anders Roxell <anders.roxell@linaro.org> wrote:

> Since __sanitizer_cov_trace_pc is marked as notrace, function calls in
> __sanitizer_cov_trace_pc shouldn't be traced either. The function
> ftrace_graph_caller() gets called for each function that isn't marked
> 'notrace', like canonicalize_ip(). This is the call trace from a run:
> 
> [  139.644550]  ftrace_graph_caller+0x1c/0x24
> [  139.648352]  canonicalize_ip+0x18/0x28
> [  139.652313]  __sanitizer_cov_trace_pc+0x14/0x58
> [  139.656184]  sched_clock+0x34/0x1e8
> [  139.659759]  trace_clock_local+0x40/0x88
> [  139.663722]  ftrace_push_return_trace+0x8c/0x1f0
> [  139.667767]  prepare_ftrace_return+0xa8/0x100
> [  139.671709]  ftrace_graph_caller+0x1c/0x24
> 
> Rework so that the functions check_kcov_mode and canonicalize_ip that is
> callef from __sanitizer_cov_trace_pc also is marked as notrace.
> 
> Co-developed-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Signen-off-by: Anders Roxell <anders.roxell@linaro.org>
> ---

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

-- Steve