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Date:   Thu, 1 Oct 2020 15:17:07 +0200 (CEST)
From:   Miroslav Benes <mbenes@suse.cz>
To:     Sami Tolvanen <samitolvanen@google.com>
cc:     Masahiro Yamada <masahiroy@kernel.org>,
        Will Deacon <will@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        clang-built-linux@googlegroups.com,
        kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
        x86@kernel.org, jthierry@redhat.com, jpoimboe@redhat.com
Subject: Re: [PATCH v4 04/29] objtool: Add a pass for generating
 __mcount_loc
In-Reply-To: <20200929214631.3516445-5-samitolvanen@google.com>
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References: <20200929214631.3516445-1-samitolvanen@google.com> <20200929214631.3516445-5-samitolvanen@google.com>
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Hi Sami,

On Tue, 29 Sep 2020, Sami Tolvanen wrote:

> From: Peter Zijlstra <peterz@infradead.org>
> 
> Add the --mcount option for generating __mcount_loc sections
> needed for dynamic ftrace. Using this pass requires the kernel to
> be compiled with -mfentry and CC_USING_NOP_MCOUNT to be defined
> in Makefile.
> 
> Link: https://lore.kernel.org/lkml/20200625200235.GQ4781@hirez.programming.kicks-ass.net/
> Signed-off-by: Peter Zijlstra <peterz@infradead.org>
> [Sami: rebased to mainline, dropped config changes, fixed to actually use
>        --mcount, and wrote a commit message.]
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> Reviewed-by: Kees Cook <keescook@chromium.org>

I am sorry to reply on v4. Should have been sooner.

Julien has been sending patches to make objtool's check functionality 
arch-agnostic as much as possible. So it seems to me that the patch should 
be based on the effort

I also wonder about making 'mcount' command separate from 'check'. Similar 
to what is 'orc' now. But that could be done later.

See tip-tree/objtool/core for both.

Thanks
Miroslav