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Date:   Wed, 13 Oct 2021 12:04:00 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Sami Tolvanen <samitolvanen@google.com>
Cc:     x86@kernel.org, Josh Poimboeuf <jpoimboe@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Sedat Dilek <sedat.dilek@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev
Subject: Re: [PATCH v5 06/15] ftrace: Use an opaque type for functions not
 callable from C
Message-ID: <202110131203.2BA230B8@keescook>
References: <20211013181658.1020262-1-samitolvanen@google.com>
 <20211013181658.1020262-7-samitolvanen@google.com>
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On Wed, Oct 13, 2021 at 11:16:49AM -0700, Sami Tolvanen wrote:
> With CONFIG_CFI_CLANG, the compiler changes function references to
> point to the CFI jump table. As ftrace_call, ftrace_regs_call, and
> mcount_call are not called by C code, but are trampolines injected
> as calls replacing the nops at the start of functions added by the
> compiler, use DECLARE_NOT_CALLED_FROM_C to declare them.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Looks right to me...

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook