Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 30 Oct 2019 16:00:58 +0100 (CET)
From:   Miroslav Benes <mbenes@suse.cz>
To:     Mark Rutland <mark.rutland@arm.com>
cc:     linux-arm-kernel@lists.infradead.org,
        Steven Rostedt <rostedt@goodmis.org>,
        linux-kernel@vger.kernel.org, amit.kachhap@arm.com,
        catalin.marinas@arm.com, deller@gmx.de, duwe@suse.de,
        James.Bottomley@HansenPartnership.com, james.morse@arm.com,
        jeyu@kernel.org, jpoimboe@redhat.com, jthierry@redhat.com,
        linux-parisc@vger.kernel.org, mingo@redhat.com,
        peterz@infradead.org, svens@stackframe.org,
        takahiro.akashi@linaro.org, will@kernel.org
Subject: Re: [PATCHv2 1/8] ftrace: add ftrace_init_nop()
In-Reply-To: <20191029165832.33606-2-mark.rutland@arm.com>
Message-ID: <alpine.LSU.2.21.1910301559340.18400@pobox.suse.cz>
References: <20191029165832.33606-1-mark.rutland@arm.com> <20191029165832.33606-2-mark.rutland@arm.com>
User-Agent: Alpine 2.21 (LSU 202 2017-01-01)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, 29 Oct 2019, Mark Rutland wrote:

> Architectures may need to perform special initialization of ftrace
> callsites, and today they do so by special-casing ftrace_make_nop() when
> the expected branch address is MCOUNT_ADDR. In some cases (e.g. for
> patchable-function-entry), we don't have an mcount-like symbol and don't
> want a synthetic MCOUNT_ADDR, but we may need to perform some
> initialization of callsites.
> 
> To make it possible to separate initialization from runtime
> modification, and to handle cases without an mcount-like symbol, this
> patch adds an optional ftrace_init_nop() function that architectures can
> implement, which does not pass a branch address.
> 
> Where an architecture does not provide ftrace_init_nop(), we will fall
> back to the existing behaviour of calling ftrace_make_nop() with
> MCOUNT_ADDR.
> 
> At the same time, ftrace_code_disable() is renamed to
> ftrace_nop_initialize() to make it clearer that it is intended to
> intialize a callsite into a disabled state, and is not for disabling a
> callsite that has been runtime enabled. The kerneldoc description of rec
> arguments is updated to cover non-mcount callsites.
> 
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Torsten Duwe <duwe@suse.de>

Reviewed-by: Miroslav Benes <mbenes@suse.cz>

M